[Characterization of peripheral dendritic cell subsets and its implication in patients infected with severe acute respiratory syndrome].

OBJECTIVE: To investigate the dynamic changes of dendritic cell subsets in peripheral blood of patients infected with severe acute respiratory syndrome (SARS) and evaluate their roles in the immunopathogenesis of SARS. METHODS: Flow cytometry was applied to study the dynamic alteration of the number and frequencies in circulating DC cell subsets in 30 SARS patients including critical SARS (n = 11) and general SARS (n = 19). The reasons and clinic significances of the peripheral blood DC subsets changes in SARS patients were also analyzed in our study. RESULTS: The patients in critical status had a 9-week course of disease, longer than the 6-week course observed in subjects in general status. The frequency of peripheral DC cell subsets significantly dropped beginning from the onset of symptom in SARS patients and was maintained at significant low levels during the following 4 - 5 weeks, 1.7 +/- 1.8, 5.3 +/- 5.0/ micro l for DC1, 0.57 +/- 1.02, 0.98 +/- 1.11/ micro l for DC2 for cases in critical and general statuses, respectively, compared with healthy subjects; more importantly, the pDC2 even disappeared in the patients who died from SARS diseases. The possible reasons responsible for the alteration of DC subsets in peripheral blood is likely to be the direct attack of SARS-CoVin circulation and be partially involved the application of large dose of steroid. The frequency in DC cell subsets returned to normal level in convalescent stage. CONCLUSION: Our results showed SARS patients had a significant decrease of circulating DC cell subset frequency, which maybe lead to the host immunodeficiency response to SARS-associated coronavirus (SARS-CoV).

[Detection of HBcAg-specific cytotoxic lymphocytes and their association with clinical status in patients with hepatitis B].

OBJECTIVE: To investigate the difference of host immune response specific to hepatitis B virus (HBV) infections between acute self-limited and chronic persistent hepatitis by quantitative analysis of HLA-A * 2402-restricted HBcAg-specific cytotoxic T lymphocyte cells (CTL) cells. METHODS: The frequency of HBV-specific CTL cells in the peripheral blood mononuclear cells (PBMCs) from 20 patients infected with HBV were quantified by ELISPOT assays and flow cytometry using one HLA-A * 2402-HBV, 7 with acute HB and 13 with chronic HB, peptide tetrameric complex. RESULTS: High frequencies of circulating HBcAg-specific CTL cells were detected in most individuals with acute HBV infection while the number of these cells was significantly reduced at the convalescent stage. HBcAg-specific CTL cells were not detected in the PBMC from individuals with chronic HBV infection except for one patient with an acute infection exacerbation. CONCLUSION: HBcAg-specific CTL cells may play a crucial role in complete clearance of HBV from patients with acute HBV hepatitis.