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ABSTRACT: Stable flow cytometric markers for malignant myeloid cells are highly warranted. Based on data from stem cell research, we hypothesized that the human inhibitory C-type lectin like receptor (hMICL) might represent a novel diagnostic and prognostic vehicle in a standard flow cytometry (FCM) setting.
Standard four-color FCM was employed to uncover the expression patterns of hMICL in bone marrow in a test set of 55 retrospectively collected diagnostic acute myeloid leukemia (AML) samples and in a set of 36 prospectively collected diagnostic AML samples.
Ninety-two percent of the AML patients stained positive for hMICL and in the otherwise poorly characterized CD34 negative patient group hMICL staining revealed a very homogenous expression profile in the blast cell compartment with a mean of 88% hMICL positive cells. Moreover, hMICL displayed significantly higher expression in AML as compared with normal donors as measured by median fluorescence intensity (MFI) ratios (P = 0.01). There was no difference in hMICL MFI ratios between the CD34 positive and the CD34 negative subgroups (P = 0.89). Importantly, there was no difference in MFI ratios between paired diagnostic and relapse samples (P = 0.76) in 23 cases studied, indicating stable expression of hMICL during the course of the disease. In contrast to the other stem cell associated antigens analyzed (CD34, CD96, CD117, and CD133), hMICL was expressed on myeloid blast cells only, revealing hMICL as a diagnostic marker in AML.
These data identify hMICL as a myeloid leukemia-associated antigen and establishes its applicability for diagnosis and follow-up of AML patients in a standard FCM setting.
Cytometry Part B Clinical Cytometry 01/2012; 82(1):3-8. · 2.53 Impact Factor
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ABSTRACT: Reactivation of human cytomegalovirus (HCMV) remains a serious problem in immunosuppressed individuals. To investigate whether a change in the immune status can be used as an earlier marker for HCMV reactivation than the traditional PCR analysis, eight chronic lymphocytic leukemia (CLL) patients at risk for reactivation due to commencement of alemtuzumab (anti-CD52) treatment were longitudinally followed. Five series of consecutive weekly blood samples were immunophenotyped by flow cytometry to cover both the innate and adaptive immune responses. Concurrently, patients were monitored by PCR for HCMV reactivation. We found a minor upregulation of the early activation marker CD69 on NK cells immediately before HCMV was detected in circulation by PCR. Interestingly, for the specific immune response, CD69 was highly upregulated on CD3(+) T cells, especially for the CD8(+) subset, in the two patients experiencing an HCMV reactivation between 6 and 20 d before HCMV viremia was measured by PCR. Moreover, a CD4(+):CD8(+) ratio lower than 0.6 may indicate a trend toward an increased risk for viral reactivation. In conclusion, an increase in CD69 expression is a promising candidate as an early predictor of HCMV reactivation.
Viral immunology 04/2011; 24(2):165-9. · 1.78 Impact Factor
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ABSTRACT: We have examined natural killer (NK) cell functionality of 54 B-CLL patients upon in vitro stimulation with interleukin-21 (IL-21), together with the anti-CD20 antibody, rituximab. Upon stimulation with rituximab-coated target cells IFN-γ production was reduced in patients' NK cells compared to healthy donors', while both natural- and antibody-dependent cytotoxicity (ADCC) was normal. Following additional stimulation with IL-21, IFN-γ production, natural cytotoxicity and ADCC were significantly augmented in patients. A complete restoration of IFN-γ production, however, required the depletion of malignant cells prior to stimulation. Collectively, our data show that NK cells of B-CLL patients are reversibly inhibited, but that their functionality can be normalized by stimulation with IL-21 and when inhibitory effects of the malignant B-CLL cells are eliminated by depletion.
Leukemia research 02/2011; 35(7):914-20. · 2.36 Impact Factor
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ABSTRACT: Human cytomegalovirus (HCMV) manipulates the host immune system in various ways. Allegedly, HCMV infection is associated with increased percentages of a particular natural killer (NK) cell subset expressing the activating receptor CD94/NKG2C in both healthy individuals and in patients infected with human immunodeficiency virus (HIV). Whether the HCMV-mediated induction of this specific NK cell subset is also apparent for other diseases characterized by abnormal immune responses, such as malignant blood diseases, is unknown. By comparing the fractions of CD94/NKG2C(+) NK cells in B-cell chronic lymphocytic leukemia (B-CLL) patients having either positive or negative HCMV serostatus, a proportional increase of this cell subset was obvious in the HCMV-seropositive subjects. Therapeutic intervention in the patients with positive HCMV serostatus did not seem to reduce the percentage of CD94/NKG2C-expressing NK cells. Thus, HCMV infection seemingly shapes the NK cell system in healthy individuals, HIV patients, and B-CLL patients in a uniform manner, even though these involve different immunological challenges.
Viral immunology 10/2009; 22(5):333-7. · 1.78 Impact Factor
