Hartwig P Huemer

Publications (27)70.13 Total impact

• Article: Investigation of bacterial and viral agents and immune status in Behcet's disease patients from Iran.

  Eveline U Irschick, Sebastian Philipp, Farhad Shahram, Michael Schirmer, Massih Sedigh, Naghmeh Ziaee, Christoph Gassner, Harald Schennach, Martina Meyer, Clara Larcher, Manfred Herold, Dieter Schoenitzer, Dietmar Fuchs, Michael Schoenbauer, Matthias Maass, Hartwig P Huemer, Fereydoun Davatchi
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  ABSTRACT: Behçet's disease (BD) is an autoimmune disorder associated with HLA-B51 positivity. Serologic/genomic findings have suggested microbes as possible causative agents and the geographical distribution suggests environmental influences. We performed comparative analyses of 40 patients with BD or related symptoms not fulfilling BD criteria. Patients originating from different regions of Iran were tested by molecular/serological methods for human herpes viruses and parvovirus B19, two Chlamydiae species, as well as Coxiella, Listeria, Yersinia, Leptospira and Mycobacterium paratuberculosis. Human leukocyte antigen-typing was performed: testing of cytokine profiles and immune mediators representative for the cellular immune system, including neopterin/kynurenine production. No apparent differences in interleukin (IL)-4, 6, 8 and 10 were observed, whereas production of soluble IL-2-receptor and tumor necrosis factor (TNF)-alpha were more pronounced in the BD group. Neopterin/kynurenine production was comparable, although both groups showed twice the levels of healthy people. No significant differences of herpes simplex virus (HSV) antibody titres were observed but higher titres against Chlamydophila pneumoniae were found in the controls. In 20 BD patients and controls neither parvovirus B19 DNA was detected nor bacterial DNA. Viral DNA of Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpes virus (HHV)8 was detected more frequently in the BD group, whereas HSV DNA was only found in the controls, indicating that stomatitis might be caused by HSV. Although no significant association of BD was detected with a single pathogen, our findings suggest that detection of HSV DNA or Chlamydiae would rather argue against classic BD. Whether there is a discriminative potential of the tested immune mediators/receptors has to be elucidated in further studies.
  International Journal of Rheumatic Diseases 08/2011; 14(3):298-310. · 0.81 Impact Factor
• Article: Persisting Paecilomyces lilacinus nail infection following pregnancy.

  Patrizia Innocenti, Elisabetta Pagani, Dunja Vigl, Reinhard Höpfl, Hartwig P Huemer, Clara Larcher
  Mycoses 05/2011; 54(6):e880-2. · 2.25 Impact Factor
• Article: Cowpox virus isolate virulent in humans shows attenuated phenotype in mice.

  Hartwig P Huemer, Caroline Lassnig, Norbert Nowotny
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  ABSTRACT: We have cultured Cowpox virus (CPXV) from skin lesion material of a human patient from Austria. Phylogenetic comparison of the HA-gene revealed a rather homogeneous cluster with other local isolates from recent years, the A36R-gene was mostly related to elephant derived strains from Germany. Despite causing disease in human, the isolate AT/Carinthia/788/07 surprisingly even at high titers showed a highly reduced virulence in BALB/c mice upon intranasal inoculation as compared to vaccinia virus. This contrasts earlier reports on other CPXV isolates. Using shotgun DNA sequencing several insertions and deletions were found in genes presumably involved in host range, immune regulation as well as established virulence factors. These preliminary data could be an indication that CPXV strains with proven pathogenicity for humans may have reduced virulence in mice and vice versa. Additionally strains with a reduced virulence may have an advantage in persisting in less dense rodent populations.
  Research in Veterinary Science 04/2011; 92(2):333-7. · 1.65 Impact Factor
• Article: Investigation of bacterial and viral agents and immune status in Behcet’s disease patients from Iran

  Eveline U. IRSCHICK, Sebastian PHILIPP, Farhad SHAHRAM, Michael SCHIRMER, Massih SEDIGH, Naghmeh ZIAEE, Christoph GASSNER, Harald SCHENNACH, Martina MEYER, Clara LARCHER, Manfred HEROLD, Dieter SCHOENITZER, Dietmar FUCHS, Michael SCHOENBAUER, Matthias MAASS, Hartwig P. HUEMER, Fereydoun DAVATCHI
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  ABSTRACT: Aim: Behçet’s disease (BD) is an autoimmune disorder associated with HLA-B51 positivity. Serologic/genomic findings have suggested microbes as possible causative agents and the geographical distribution suggests environmental influences.Methods: We performed comparative analyses of 40 patients with BD or related symptoms not fulfilling BD criteria. Patients originating from different regions of Iran were tested by molecular/serological methods for human herpes viruses and parvovirus B19, two Chlamydiae species, as well as Coxiella, Listeria, Yersinia, Leptospira and Mycobacterium paratuberculosis. Human leukocyte antigen-typing was performed: testing of cytokine profiles and immune mediators representative for the cellular immune system, including neopterin/kynurenine production.Results: No apparent differences in interleukin (IL)-4, 6, 8 and 10 were observed, whereas production of soluble IL-2-receptor and tumor necrosis factor (TNF)-alpha were more pronounced in the BD group. Neopterin/kynurenine production was comparable, although both groups showed twice the levels of healthy people. No significant differences of herpes simplex virus (HSV) antibody titres were observed but higher titres against Chlamydophila pneumoniae were found in the controls. In 20 BD patients and controls neither parvovirus B19 DNA was detected nor bacterial DNA. Viral DNA of Epstein–Barr virus (EBV), cytomegalovirus (CMV) and human herpes virus (HHV)8 was detected more frequently in the BD group, whereas HSV DNA was only found in the controls, indicating that stomatitis might be caused by HSV.Conclusion: Although no significant association of BD was detected with a single pathogen, our findings suggest that detection of HSV DNA or Chlamydiae would rather argue against classic BD. Whether there is a discriminative potential of the tested immune mediators/receptors has to be elucidated in further studies.
  International Journal of Rheumatic Diseases 03/2011; 14(3):298 - 310. · 0.81 Impact Factor
• Article: Dominance of CTX-M group 1 beta-lactamase enzymes in ESBL producing E. coli from outpatient urines in neighboring regions of Austria and Italy.

  Hartwig P Huemer, Angelika Eigentler, Richard Aschbacher, Clara Larcher
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  ABSTRACT: The importance of extended spectrum β-lactamases (ESBL) is increasing worldwide. ESBLs of the CTX-M type are on the rise in Europe, not only in the hospital environment but also in outpatients. Therefore we performed a comparative pilot study including ESBL producing Escherichia coli isolated from outpatients suffering from urinary tract infections, 28 from Innsbruck, Austria, and 34 from Bolzano, Italy. Using established PCR methods we detected in nearly 90% of ESBL producing E. coli isolates CTX-M group 1 enzymes and only a few group 2 or group 9 enzymes. bla (TEM), bla (OXA-1) and aminoacyltransferase aac(6')-lb were significantly more frequent in the Austrian region, where also bla (SHV )was found in one isolate. In 2009 the overall prevalence of ESBL in E. coli causing urinary tract infection in outpatient samples was 7.6% in a local laboratory in Innsbruck and 5% in Bolzano. Additionally, we investigated plasmid-mediated qnr genes which can contribute to quinolone resistance, qnrA was found in an AmpC producing E. coli from Innsbruck and qnrS in two ESBL producers from Bolzano. Data confirmed that ESBL-producing E. coli have emerged as important pathogens in urinary tract infections of outpatients in both regions.
  Wiener klinische Wochenschrift 01/2011; 123(1-2):41-4. · 0.81 Impact Factor
• Article: Cannabinoids lead to enhanced virulence of the smallpox vaccine (vaccinia) virus.

  Hartwig P Huemer, Caroline Lassnig, David Bernhard, Sonja Sturm, Norbert Nowotny, Maria Kitchen, Marion Pavlic
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  ABSTRACT: Indian hemp is used since thousands of years as herbal drug. We found that a single dose of cannabis resin was equally active as Δ9-tetrahydrocannabinol (THC) enhancing severity and duration of symptoms in vaccinia virus infected mice. Cowpox virus did not cause symptomatic disease, but some reduction of specific antibody production was observed in drug treated animals. In vitro cannabis was superior to THC alone at inhibiting mitogen stimulated proliferation of human and mouse spleen cells and peripheral blood mononuclear cells. Also resin sub-fractions other than THC, cannabidiol and cannabinol, recovered also from cigarette smoke, were found inhibitory, suggesting additional involvement of constituents other than psychoactive THC. The immunoregulatory effects must be differentiated from apoptotic effects on spleen cells and lymphocytic mouse cell lines, which were observed with resin and THC but not with cannabidiol or cannabinol. A significant contribution of cytotoxic effects seems unlikely as drug treated lymphocytes were still capable of producing cytokines after T-cell receptor-specific stimulation. Considering a recent case of unusually severe cowpox virus infection in a young drug taker these data confirm a risk of "soft drugs" for acquiring poxvirus infection or enhancing side effects of the smallpox vaccine and perhaps also other live vaccines.
  Immunobiology 11/2010; 216(6):670-7. · 3.20 Impact Factor
• Article: Diazepam leads to enhanced severity of orthopoxvirus infection and immune suppression.

  Hartwig P Huemer, Caroline Lassnig, Norbert Nowotny, Eveline U Irschick, Maria Kitchen, Marion Pavlic
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  ABSTRACT: Benzodiazepines are drugs widely used as tranquilizers and in various other indications. We treated Balb/c mice with diazepam and infected them with cowpox (CPXV) and vaccinia virus (VACV). Disease index, weight loss and the antibody response were determined. Additionally the influence of different benzodiazepines on the mitogen response of human peripheral blood lymphocytes and spleen cells was tested. Diazepam led to earlier disease onset, prolonged duration of symptoms, higher weight loss and overall disease index in VACV infected mice. CPXV infected mice developed poxviral skin lesions only after drug administration and a significant decrease in the specific antibody response was also observed. Diazepam and alprazolam also inhibited the proliferative response of human lymphocytes/spleen cells in vitro but did not show noteworthy apoptotic effects. It is surprising that even a single dose of diazepam has a profound influence on the immune system, sufficient to facilitate symptomatic infectious disease. These data provide first evidence that commonly used drugs like Valium may augment severity of rare poxvirus infections such as CPXV or monkeypox. As VACV is still used as life vaccine against smallpox there is also a risk of enhanced side effects or possible interference with the success of vaccination.
  Vaccine 08/2010; 28(38):6152-8. · 3.77 Impact Factor
• Article: Obstacles of Multiplex Real-Time PCR for Bacterial 16S rDNA: Primer Specifity and DNA Decontamination of Taq Polymerase.

  Sebastian Philipp, Hartwig P Huemer, Eveline U Irschick, Christoph Gassner
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  ABSTRACT: BACKGROUND: The detection of a broad range of bacteria by PCR is applied for the screening of blood and blood products with special attention to platelet concentrates. For practical use it is desirable that detection systems include Gram-positive, Gram-negative and non-Gram-stainable bacteria. It is quite challenging to achieve high sensitivity along with a clear negative control with PCR reagents, because especially Taq polymerase is contaminated with traces of bacterial DNA. METHODS: Bacterial DNA decontamination of Taq polymerase was attempted by two different methods using the restriction enzyme Sau 3A1 and microfiltration. Additionally a commercially available Taq polymerase depleted of bacterial DNA was included. A published real-time PCR specific for Gram-negative bacteria was adapted for Gram-positive bacteria, including certain Staphylococcus species and Mycobacteria, and was used to charge the three Taq polymer-ases depleted of bacterial DNA contamination RESULTS: Despite published reports about successful DNA decontamination, all three approaches performed poorly in experiments done in this study. Sensitivity ranged at approximately 50-100 colony forming units (CFU) per PCR reaction for Escherichia coli and Staphylococcus epidermidis, corresponding to 1,250-2,500 CFU/ml sample material. Conclusion: It seems unsatisfying to accept detection limits that high for diagnostic bacterial PCR even if highly multiplexed. Reliable methods for DNA decontamination of Taq polymerase are needed and would present one important step towards bacterial DNA detection with high sensitivity.
  Transfusion Medicine and Hemotherapy 02/2010; 37(1):21-28. · 1.16 Impact Factor
• Article: Active in vitro reduction of antigen presenting cells in human corneal grafts using different chemokines.

  Ulrike M Irschick, Wolfgang J Mayer, Nicole Kranebitter, Nikolaus Romani, Hartwig P Huemer, Eveline U Irschick
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  ABSTRACT: For the fate of a graft the antigen presenting cells play an important role. Chemokines can lead to enhanced migration of these cells. We therefore investigated if fresh human corneas bear the chemokine receptor 7 (CCR7) and if its ligands can force the emigration of dendritic cells in an in vitro model. We used human corneas excluded for transplantation and performed migration tests using chemokine ligands 19 (CCL19) and 21 (CCL21) or the complement factor 5a (C5a). Emigrated cells were collected up to 35 days and stained by immunofluorescent double labeling in triple layer technique with Langerin/CD207, DC-SIGN/CD209, CD14, and HLA-DR. In parallel, fresh and cultured human corneas were stained for CCR7. We found in fresh human corneas, as well as in long-term cultured ones, a low CCR7 expression that nearly diminished after 28 days. In vitro Langerhans cell emigration could be enhanced only by CCL19, whereas dendritic cells were strongly influenced by CCL19, CCL21, and C5a. HLA-DR(+) cells showed numerically the highest in vitro emigration rate. Macrophages/monocytes were not influenced by the used chemokines. Although human corneas reduce their antigen presenting cells numbers during long-term culture, this effect could be significantly enhanced by using chemokines.
  Current eye research 02/2010; 35(2):176-83. · 1.51 Impact Factor
• Article: In vitro prevention of vaccinia and herpesvirus infection spread in explanted human corneas by N-chlorotaurine.

  Hartwig P Huemer, Markus Nagl, Eveline U Irschick
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  ABSTRACT: Weak oxidants produced by activated human leukocytes are proven antimicrobial substances. We tested whether N-chlorotaurine (NCT, taurine chloramine), the chlorinated metabolite of the amino acid taurine, in addition to direct virucidal effects on viral suspensions, has the capability to prevent cell-to-cell spread of viruses in human corneal epithelium. Human corneal grafts were infected in vitro with poxvirus (vaccinia virus, VV) and herpesvirus. Different NCT dilutions were added to prevent viral spread within the corneal epithelium as detected by immune-staining and microscopy of cytopathic effects. Additionally, virus release was measured by cell culture. Addition of NCT significantly reduced the number of VV-infected epithelial cells at concentrations as low as 0.01% in culture medium, which was far beyond cytotoxic concentrations in long-term cultures. The release of virus by the infected corneal grafts was reduced by 2-3 log(10 )as well. As expected, herpesvirus infection was also positively affected. Smallpox has been known as a major cause of blindness in historical outbreaks. NCT could therefore provide an additional supportive means for treating orthopoxvirus-associated keratitis. Additionally, biocompatible local antiseptics like NCT could also serve as an experimental treatment in other keratitis of suspected viral origin.
  Ophthalmic Research 11/2009; 43(3):145-52. · 1.56 Impact Factor
• Article: Tissue damage caused by animal orthopoxviruses cowpox, ectromelia, vaccinia and parapoxvirus ovis in human cornea.

  Hartwig P Huemer, Sandra Essbauer, Eveline U Irschick
  Acta ophthalmologica 10/2009; 88(7):e275-6. · 2.44 Impact Factor
• Article: Involvement of protein kinase C in phagocytosis of human retinal pigment epithelial cells and induction of matrix metalloproteinase secretion.

  Eveline U Irschick, Gertrud Haas, Josef Troger, Florian Ueberall, Hartwig P Huemer
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  ABSTRACT: Protein kinase C (PKC) is involved in cell activation. We investigated PKC-mediated pathways and secretion of matrix metalloproteinases (MMPs) in phagocytosis by human retinal pigment epithelial cells (RPE). We used time-resolved fluorometry for europium-labeled microsphere uptake and gel zymography to assay the influence of PKC modulators. PKC inhibitors blocked phagocytosis by RPE. ARPE-19, a human RPE-cell line, showed reduced secretion of MMP-2, although MMP-9 secretion by PKC activation was conserved in both cell types, namely in the primary RPEs and in the RPE-cell line. Particle uptake by RPE cells requires activation of PKC; the use of PKC inhibitors as new anticancer drugs may possibly cause ocular side-effects.
  International Ophthalmology 10/2009; 29(5):333-41.
• Article: Generalized parapoxvirus infection associated with increased antibody titres for varicella zoster virus and measles.

  Clara Larcher, Elfriede Daniel, Elisabetta Pagani, Klaus Maier, Valentina Pasquetto, Maria Francesca Mellina-Bares, Edna Nemati, Edoardo Egarter-Vigl, Pierfrancesco Zampieri, Hartwig P Huemer
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  ABSTRACT: Human parapoxvirus infections are rare, self-limiting, zoonotic diseases. A 35-year-old veterinarian presented with a generalized rash of large umbilicated vesicles that appeared after antibiotic treatment for erysipelas on the forearm. The erysipelas arose from an erupted pustular thumb lesion that appeared after examining a sheep. An outbreak of chickenpox in the village suggested parapoxvirus or varicella zoster virus (VZV) was the most likely agent. No poxvirus was detected by electron microscopy or in cell cultures from lesion material. PCR revealed parapoxvirus DNA with a sequence similar to orf-viruses from Finland. Orf-virus immunofluorescence showed a titre increase, supporting the parapoxvirus diagnosis. VZV was not detected by PCR, but varicella antibodies increased three-fold in serum samples drawn two weeks apart. In addition, the patient had high antibody titres for measles and reported recent contact with individuals exposed to an outbreak of measles in nearby Austria. To explain the unusually generalized symptoms in this young and healthy patient, these findings could be variously interpreted as: i) a booster by community VZV infections; ii) a subclinical VZV (re)infection that was superinfected by the parapoxvirus; iii) an orf-virus mediated immune stimulation; iv) a post-infectious syndrome; or v) a temporary immunosuppression by subclinical measles.
  European journal of dermatology: EJD 06/2009; 19(4):375-9. · 2.53 Impact Factor
• Article: Epidemiology of enterovirus types causing neurological disease in Austria 1999-2007: detection of clusters of echovirus 30 and enterovirus 71 and analysis of prevalent genotypes.

  Birgit Ortner, Chiao-Wei Huang, Daniela Schmid, Ingomar Mutz, Günther Wewalka, Franz Allerberger, Jyh-Yuan Yang, Hartwig P Huemer
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  ABSTRACT: Between 1999 and 2007 1,388 stool specimens from patients with acute flaccid paralysis or aseptic meningitis were submitted to the Austrian reference laboratory for poliomyelitis. Samples (201) yielded non-poliovirus enterovirus in culture. One hundred eighty-one viruses were available for typing and 78 isolates which remained serologically untyped were further analyzed by CODEHOP-PCR and sequencing of the VP1 gene and the 5'-untranslated region (5'-UTR). Typing revealed an Echovirus 30 outbreak in northwestern Austria in 2000, which was in accordance with the situation in Europe, and no dramatic seasonal changes of Coxsackie viruses were observed. In 2002/2003 a small outbreak of enterovirus 71 (EV71), affected 12 patients in the province of Styria. This virus was identified as genotype C1 and appeared to be genetically distinct from the isolates observed in 2001/2002 in Vienna. In 2004 two unrelated cases occurred in Lower Austria, which were identified as genotype C4, which has been described associated with high mortality most recently in China. In contrast to the situation in Asia the detected EV71 cases were not associated with hand-foot-mouth disease, but with serous meningitis only. This was surprising as a recent publication suggested a reduced neurovirulence of C1 genotype in children in Norway, presumably due to alterations in 5'-UTR and polymerase gene. However, comparing the 5'-UTR of the Austrian isolates and established virulent reference strains to the Norwegian isolate and an attenuated EV71 laboratory strain we did not find an indication that the genotype C1 possesses a RNA structure in its 5'-UTR leading to reduced neurovirulence.
  Journal of Medical Virology 03/2009; 81(2):317-24. · 2.82 Impact Factor
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  Article: Comparison of human metapneumovirus genotypes from the province of Bolzano in northern Italy with strains from surrounding regions in Italy and Austria.

  Clara Larcher, Elisabetta Pagani, Patrizia Rossi, Barbara Amato, Lydia Pescollderungg, Giulia Campanini, Elena Percivalle, Hartwig P Huemer
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  ABSTRACT: The epidemiology of the genetic sublineages of human metapneumovirus (hMPV) and their clinical relevance are not fully understood. We compared hMPV genotypes isolated in the province of Bolzano in Northern Italy with strains from nearby Italian and Austrian regions by sequencing of NP- and L-gene fragments. Our results suggest that similar strains cycle through adjacent geographic areas, with the respective subtypes replacing each other on a seasonal basis.
  Japanese journal of infectious diseases 04/2008; 61(2):154-6. · 1.49 Impact Factor
• Article: Role of Epstein‐Barr virus and soluble CD21 in persistent polyclonal B‐cell lymphocytosis

  CLARA LARCHER, FALKO FEND, MANFRED MITTERER, NADJA PRANG, FRITZ SCHWARZMANN, HARTWIG P. HUEMER
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  ABSTRACT: The expression of EBV proteins and immunological properties were studied in the first stable cell line (SM) established from a patient presenting with persistent polyclonal B-cell lymphocytosis (PPBL).SM cells which represent a small population of EBV-positive atypical cells found in the peripheral blood of the patient express the KI-1 antigen (CD30) as well as the proto-oncogene bcl-2 product and cell surface markers of mature activated B lymphocytes. The cells harbour an EBV subtype A genome and contain EBNA2 protein. This argues against a transformation-incompetent virus as the main cause of the chronic active EBV infection observed in our patient. Latent membrane protein (LMP1) was weakly expressed and found predominantly in a perinuclear localization, a location which could lead to decreased immunogenicity in vivo. Similar to the EBV-transformed marmoset cell line B95-8, SM cells were in part productively infected as transcription of the immediate early gene BZLF1 could be shown and in some cells high levels of EBV-genome were detected by in situ hybridization with a BamHl W-probe. Comparable to the atypical cells in the peripheral blood of the patient, EBV small RNAs were not detected with EBER-specific probes.Of interest, we noticed a markedly increased production of soluble CD21 (sCD21) antigen by SM cells as compared to LCL-type Burkitt's lymphoma cell lines. This could explain the elevated sCD21 levels observed in the serum of our PPBL patient and confirms our previous findings in patients with acute EBV infection. It also suggests a possible role of sCD21 in EBV-mediated regulation of the immune response and provides a possible explanation for the dysregulation of the humoral immune system observed in PPB1 patients.
  British Journal of Haematology 03/2008; 90(3):532 - 540. · 4.94 Impact Factor
• Article: A simple restriction fragment PCR approach for discrimination of humanpathogenic Old World animal Orthopoxvirus species.

  Hartwig P Huemer, Bettina Hönlinger, Reinhard Höpfl
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  ABSTRACT: There are reliable polymerase chain reaction assays available for exclusion of Variola virus from other poxviruses. However, the discrimination of humanpathogenic animal Orthopoxviridae is more challenging because of the high genomic conservation. Based on the variability of the A36R gene, we describe a simple 20 min PCR assay followed by a 1 h digest with 3 different restriction enzymes. This assay enables rapid discrimination between Cowpox virus and Monkeypox virus and discrimination of the most prevalent members of the Vaccinia virus and Camelpox virus. The test was orthopoxvirus specificand did not react with parapox (Orf) virus. Moreover, the amplified fragments were also well suited for additional genotyping by direct DNA sequencing.
  Canadian Journal of Microbiology 03/2008; 54(2):159-62. · 1.36 Impact Factor
• Article: Characterization of antigen-presenting cells in fresh and cultured human corneas using novel dendritic cell markers.

  Wolfgang J Mayer, Ulrike M Irschick, Patrizia Moser, Martin Wurm, Hartwig P Huemer, Nikolaus Romani, Eveline U Irschick
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  ABSTRACT: Adult healthy human corneas bear a distinctive number of antigen-presenting cells (APCs) important for the fate of a graft. The purpose of this study was to differentiate between Langerhans cells (LCs) and other dendritic cells (DCs) and between mature and immature APCs in fresh and cultured human corneas using specific markers. Immunofluorescence double staining was performed for Langerin/CD207, CD1a, DC-SIGN/CD209, DC-LAMP/CD208, CD45, CD11c, CD11b and HLA-DR. Langerin(+)/CD1a(+)/HLA-DR(+) LCs (approximately 100 cells/mm(2) in fresh corneas) were found in the limbal and peripheral regions of corneal epithelium and the anterior stroma up to 83 days of culture. All these cells coexpressed CD45 and CD11c. DC-SIGN(+)/CD45(+) DCs (approximately 150 cells/mm(2) in fresh corneas) were detected mainly peripherally and in the anterior stroma, even in long-term cultured corneas. Most of these cells were HLA-DR(-). Few mature DCs (DC-LAMP(+)/HLA-DR(+)) were found in fresh and cultured corneas. Macrophages (CD11c(-)/CD11b(+)) were seen in the peripheral, paracentral, and even central regions of the posterior stroma. This is the first demonstration that human corneas harbor populations of Langerin(+)/CD1a(+)/HLA-DR(+) LCs and DC-SIGN(+) DCs in a distribution pattern similar to that in the skin. Few APCs are in a mature state (DC-LAMP(+)). Given the reduced but not complete depletion of APCs during organ culture, these grafts still bear a potential risk for rejection.
  Investigative Ophthalmology &amp Visual Science 11/2007; 48(10):4459-67. · 3.60 Impact Factor
• Article: Phagocytosis of human retinal pigment epithelial cells: evidence of a diurnal rhythm, involvement of the cytoskeleton and interference of antiviral drugs.

  Eveline U Irschick, Gertrud Haas, Markus Geiger, Wolfgang Singer, Monika Ritsch-Marte, Gunther Konwalinka, Manfred Frick, Wolfgang Gottinger, Hartwig P Huemer
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  ABSTRACT: Retinal pigment epithelial (RPE) cells provide crucial functions for the maintenance of the retinal environment. We investigated the phagocytotic mechanisms of RPE cells evaluating the question whether particle uptake underlies a diurnal rhythm. Additionally, a possible connection of volume regulation and the phagocytotic function of RPE cells was studied. As antiviral nucleoside analogues influence cell-volume-regulating mechanisms, we tested several antiviral drugs. Cultured primary RPE cells and a permanent cell line (ARPE-19) were tested for uptake of europium-labeled microspheres quantified by time-resolved fluorometry. Cells were also exposed to cyclic illumination or continuous light and dark culture conditions. Inhibitors of cytoskeleton (microtubuli, actin) and osmotic swelling were also tested. Ingested FITC-labeled microparticles were found in phagosomes strongly associated which the cytoskeleton as they could not be easily moved by laser tweezer microscopy. Phagocytosis was observed predominately during dark intervals and was reduced by continuous light exposure. The diurnal rhythm of unsynchronized RPE cultures was abolished by microtubule inhibitors although no inhibition of overall particle uptake by cytoskeletal blockers was observed. Hypoosmotic swelling of RPE also decreased phagocytosis. Acyclovir was found inhibitory in ARPE-19 cells, whereas azidothymidine showed a protracted inhibiting activity on primary RPE cells and ganciclovir was inactive in both cell types. The presence of a diurnal rhythm also in culture indicates genetic determination of light-regulated particle uptake. This mechanism appears to be influenced by the regulation of cell volume and microtubule function. Inhibition of RPE function by antiviral drugs is a novel finding and in accordance with interferences of the tested drugs with cellular chloride channels described earlier. It may give a hint towards possible ocular side effects in the long-term use of nucleoside-analogous substances.
  Ophthalmic Research 02/2006; 38(3):164-74. · 1.56 Impact Factor
• Article: Functional T-cell anergy in a case of persistent polyclonal B-cell lymphocytosis.

  Manfred Mitterer, Andrea J Lanthaler, Eveline U Irschick, Hartmut Engelmann, Clara Larcher, Hartwig P Huemer
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  ABSTRACT: The T-cell population of a patient with persistent polyclonal B-cell lymphocytosis (PPBL) presenting with an intermittent Epstein-Barr virus (EBV)-associated disease was studied. Unstimulated T-cells did not express CD40 ligand (CD40L), whereas activation with IL-2 led to expression of this costimulatory molecule. CD40L expression was inhibited upon incubation with the supernatant of an EBV-positive B-cell line (SM) which had been grown spontaneously from the patient's peripheral blood cells. The supernatant of SM cells effectively inhibited cytotoxic T-cells. Elevated levels of IL-10, TNF-alpha and soluble CD40 were found in the supernatant of SM cells. Additionally, enhanced levels of LMP-1 protein were detected.
  Leukemia Research 01/2006; 29(12):1479-88. · 2.92 Impact Factor