Dendritic cells (DC), the most specialized antigen-presenting cells, can be detected in the peripheral blood (PB) and divided into two subsets of populations, DC1 and DC2, endowed with different functions. The aim of this study was to evaluate the effect on DC release and on their subsets of three regimens utilized to mobilize CD34+ cells into the PB in cancer patients and in normal CD34+ cell donors.
The mobilizing sequences were: standard-dose epirubicin+taxol+granulocyte-colony-stimulating factor (G-CSF; 15 patients with advanced breast cancer), high-dose cyclophosphamide (CTX)+G-CSF (10 patients with breast cancer patients and 7 with non-Hodgkin's lymphoma, NHL), and G-CSF alone (5 normal donors of CD34+ cells for allogeneic transplantation). Comparative data were obtained from the steady-state PB of 20 healthy volunteers. For flow cytometric analysis, DC were gated as negative for specific lineage markers (CD3, CD11b, CD14, CD16, CD56, CD19, CD20, CD34) and positive for HLA-DR. The DC1 and DC2 subsets were defined as CD11c and CDw123 positive, respectively.
The percentages of DC at baseline and the time of CD34+ cell peak were: 0.48 and 0.51 for standard-dose chemotherapy (CT); 0.55 and 0.63 for breast cancer after high-dose CTX+G-CSF; 0.53 and 0.71 for NHL after high-dose CTX+G-CSF; and 0.51 and 0.54 for normal donors of CD34+ cells after G-CSF alone (all p=n.s.). Mean DC1/DC2 ratios in each study group at the time of CD34+ cell peak were 0.10, 0.12, and 0.18, respectively. Finally, in the group of healthy volunteers, the percentage of circulating DC was 0.95 and the mean DC1/DC2 ratio was 1.28.
To our knowledge, this is the first report that demonstrates that both standard-dose or high-dose CT, when utilized together with G-CSF, do not induce DC mobilization into the PB, whereas a reversed DC1/DC2 ratio is observed. Furthermore, a lack of significant DC mobilization after G-CSF alone was also seen, in contrast to what was previously observed by others. These data should be taken in account when evaluating clinical correlations between DC number and CPC engraftment in both the transplantation setting, when monitoring the effects on the immune system of combinations of new drugs and/or cytokines, and when high numbers of DC are required for both experimental and clinical applications.
"Paclitaxel has been shown to be highly immunosuppressive at cytotoxic doses. There is clinical evidence to show that systemic administration of cytotoxic compounds such as paclitaxel can have a detrimental effect on the number of systemic DC . "
[Show abstract][Hide abstract] ABSTRACT: The potential utility of dendritic cells (DC) as cancer vaccines has been established in early trials in human cancers. The concomitant administration of cytotoxic agents and DC vaccines has been previously avoided due to potential immune suppression by chemotherapeutics. Recent studies show that common chemotherapy agents positively influence adaptive and innate anti-tumour immune responses.
We investigated the effects of paclitaxel on human DC biology in vitro. DCs appear to sustain a significant level of resistance to paclitaxel and maintain normal viability at concentrations of up to 100 micromol. In some cases this resistance against paclitaxel is significantly better than the level seen in tumour cell lines. Paclitaxel exposure led to a dose dependent increase in HLA class II expression equivalent to exposure to lipopolysaccharide (LPS), and a corresponding increase in proliferation of allogeneic T cells at the clinically relevant doses of paclitaxel. Increase in HLA-Class II expression induced by paclitaxel was not blocked by anti TLR-4 antibody. However, paclitaxel exposure reduced the endocytic capacity of DC but reduced the expression of key pro-inflammatory cytokines such as IL-12 and TNFalpha. Key morphological changes occurred when immature DC were cultured with 100 micromol paclitaxel. They became small rounded cells with stable microtubules, whereas there were little effects on LPS-matured DC.
The effect of paclitaxel on human monocyte derived DC is complex, but in the clinical context of patients receiving preloaded and matured DC vaccines, its immunostimulatory potential and resistance to direct cytotoxicity by paclitaxel would indicate potential advantages to co-administration with vaccines.
"Recently, we have demonstrated that high-dose cyclophosphamide followed by G-CSF (utilized as a mobilization regimen for CD34 + cells into the PB for autologous transplantation procedures) induces a reversed DC1/DC2 ratio without a significant increase of blood DCs (Ferrari, 2003). We also did not observe any significant changes in the circulating DC pool in advanced breast cancer patients after different schedules of standard-dose chemotherapy as well as during immunotherapy with trastuzumab in HER2 + -patient subset. "
[Show abstract][Hide abstract] ABSTRACT: Dendritic cells (DCs) are the key antigen-presenting cells controlling the initiation of the T cell- dependent immune response. Currently, two peripheral blood DC subsets have been identified on the basis of their CD11c expression. The CD11c-negative (CD11c-) DCs (expressing high levels of CD123) are designated as lymphoid-derived DCs (DC2), whereas the CD11c+/CD123- cells, do identify the myeloid-derived DCs (DC1). A growing number of studies have been conducted in recent years on both the quantitative and functional alterations of DCs and their subsets in different pathological conditions. In the present study we assessed, using two different flow cytometric (FCM) techniques, the normal profile of blood DCs in 50 italian adult healthy subjects (M/F: 25/25, median age 42.5 years, range 20-65). The percentage and the absolute number of DCs and their subsets, were obtained starting from whole blood samples in two ways: 1) by calculating the number of DCs when gated as lineage-negative/ HLA-DR+ and identifing the two subsets as CD11c+ (DC1) and CD123+ (DC2) and 2) by using three specific markers: BDCA.1 (CD11c+ high/CD123+ low, myeloid DCs); BDCA.2 (CD11c-/ CD123+high, lymphoid DCs); BDCA.3 (CD11c+low /CD123-, myeloid DCs). Six parameters, 4-color FCM analysis were perfomed with a BD FACSCanto equipment. The mean values of the percentage and of the absolute number were: 0.5+/-0.2% and 30+/-11 cells/microL for DCs; 0.2+/-0.1% and 15+/-6 cells/microL for DC1; 0.2+/-0.1% and 15+/-7 cells/microL for DC2. The same values were: 0.2+/-0.1% and 16+/-7 cells/microL for BDCA.1; 0.2+/-0.1% and 12+/-7 cells/microL for BDCA.2; 0.02+/-0.01% and 2+/-1 cells/microL for BDCA.3, respectively. Our study confirmes that the two types of FCM analysis are able to identify the DC population. We also provides the first reference values on normal rates and counts of blood DCs in italian adult healthy subjects.
European journal of histochemistry: EJH 03/2009; 52(1):45-52. DOI:10.4081/1185 · 2.04 Impact Factor
"research paper doi:10.1111/j.1365-2141.2004.04818.x protocols (Avigan et al, 1999; Gazitt, 2000; Gasparetto et al, 2002; Hock et al, 2002; Ferrari et al, 2003). Myeloablative therapy followed by autologous haematopoietic stem cell transplantation (HSC) is widely used as a therapeutic option in non-elderly patients diagnosed with intermediate or high risk acute myeloid leukaemia (AML) who lack a suitable donor for allogeneic procedures (Löwenberg et al, 1999). "
[Show abstract][Hide abstract] ABSTRACT: Dendritic cells (DC) are potent antigen-presenting cells that can induce effective tumour-specific T-cell responses. This study investigated leucapheresis products as source of DC precursors in 48 patients undergoing autologous peripheral blood stem cell (PBSC) transplantation for haematological malignancies. Strikingly, high-dose cytarabine and etoposide plus granulocyte colony stimulating factor (G-CSF) mobilized PBSC harvests from acute myeloid leukaemia (AML) patients containing the highest number of myeloid lin(neg)CD11c(pos) DC (mean: 7.04 x 106/kg, range: 1.46-19.67) which was 18.1-fold higher than in non-AML patients mobilized using chemotherapy (CT) regimens plus G-CSF. Clonality of purified lin(neg)CD11c(pos) DC from CT plus G-CSF mobilized AML patients (n = 8 ) was assessed using the human androgen-receptor locus methylation, disclosing a polyclonal pattern in five female patients. These cells displayed morphological and phenotypic features of myeloid DC precursors with expression of HLA-DR, HLA-ABC, CD86, CCR5 and CD54 molecules but lacking CD80, CD83, CD1a and CD40 antigens. Short-term culture with autologous leukaemic cell lysates plus tumour necrosis factor-alpha yielded maturated myeloid DC capable of triggering interleukin-2 and interferon-gamma production by autologous T-lymphocytes. These findings suggest that the use of post-remission CT and G-CSF as mobilizing regimen in AML patients generates PBSC containing high doses of polyclonal myeloid lin(neg)CD11c(pos) DC precursors, which could be used to design feasible immunotherapy protocols.
British Journal of Haematology 04/2004; 124(5):636-44. DOI:10.1111/j.1365-2141.2004.04818.x · 4.71 Impact Factor
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