Endogenous serum thrombopoietin (TPO) levels were measured in 31 patients with aplastic anaemia (AA) using an enzyme immunoassay with a sensitivity of 20 pg/ ml. The median platelet count for all AA patients was 30 +/- 29 x 10(9)/l (range 5-102) compared with a median of 284 +/- 59 x 10(9)/l (range 148-538) for normal controls. Serum TPO levels were significantly elevated in all patients compared with normals (1706 +/- 1114.2, range 375-5000 v 78 +/- 54, range 16.5-312.9, P < 0.0001). There was no correlation between serum TPO levels and the degree of thrombocytopenia in AA patients, but TPO levels were significantly higher in patients who were platelet transfusion dependent than in patients who were transfusion independent (P < 0.01). There was a trend for higher TPO levels in patients with severe AA compared with non-severe AA patients. Clinical trials of TPO and a related truncated, pegylated molecule, megakaryocyte growth and development factor (PEG-rHuMGDF), are awaited to determine whether treatment with these drugs will result in increased platelet counts in patients with AA.

Preclinical studies have suggested that purified populations of CD1c (BDCA-1) blood-derived dendritic cells (BDC) loaded with tumor-specific peptides may be a feasible option for prostate cancer immunotherapy. We performed an open-label dose-finding Phase I study to evaluate the safe use of CD1c BDC in patients with advanced metastatic hormone refractory prostate cancer. HLA-A*0201-positive patients with advanced metastatic prostate cancer were recruited and consented. The vaccine was manufactured by pulsing autologous CD1c BDC, prepared by magnetic bead immunoselection from apheresed peripheral blood mononuclear cells, with a cocktail of HLA-A*0201-restricted peptides (prostate-specific antigen, prostate acid phosphatase, prostate specific membrane antigen, and control influenza peptide) and keyhole limpet hemocyanin. The vaccine was administered intradermally or intravenously and peripheral blood was taken at predetermined intervals for clinical and immunologic monitoring. The vaccine was manufactured with a median purity of 82% CD1c BDC and administered successfully to 12 patients. Each patient received between 1 and 5 × 10 fresh CD1c BDC on day 0, followed by cryopreserved product in the same dose on days 28 and 56. The vaccine was well tolerated in all patients, with the most frequent adverse events being grade 1-2 fever, pain, or injection-site reactions. Vaccination with CD1c BDC is therefore feasible, safe, and well tolerated in patients with advanced-stage metastatic prostate cancer.

Objective. There is a breakdown of tolerance to neutrophil components during systemic vasculitis, which is marked by autoantibodies and T cells with specificity for proteinase 3 or myeloperoxidase, expressed on the surface of apoptotic neutrophils. This study was undertaken to investigate the effects of human apoptotic and necrotic neutrophils on human dendritic cell (DC) phenotype and ability to stimulate allogeneic T cell proliferation.Methods. DCs were generated from human peripheral blood mononuclear cells and allowed to interact with human apoptotic and necrotic neutrophils in the presence or absence of tumor necrosis factor ␣ (TNF␣). Effects on DC phenotype and ability to stimulate T cell proliferation were observed.Results. Immature DCs engulfed apoptotic and necrotic neutrophils, resulting in up-regulation of CD83 and class II major histocompatibility complex molecules, but down-regulation of CD40, CD80, and CD86, and a decreased ability to stimulate T cell proliferation. When TNF␣ was added in combination with apoptotic neutrophils, the inhibitory effects were overcome to some extent.Conclusion. Our results suggest that DC uptake of apoptotic or necrotic neutrophils alone does not shift the immune response from tolerance to autoimmunity in systemic vasculitis. However, cytokines found at sites of inflammation in vasculitis patients may act as maturation factors for DCs, and in combination with apoptotic neutrophils, may lead to an autoimmune phenotype.