[B cell subsets and the expression of CD40 in peripheral blood of patients with severe acute respiratory syndrome].

Wang, Chen; Xia, Cheng-qing

OBJECTIVE To explore the changing patterns of B cell subsets and the expression of CD40 on B cells in the course of severe acute respiratory syndrome (SARS) and their relationship to the severity of the disease. METHODS Peripheral blood from 162 cases of SARS, 30 cases of mycoplasma pneumonia and 30 healthy adult volunteers were measured for the number of total B cells (CD19+ B cell), CD5 positive B cells (B1 cell) and mean fluorescent intensity of CD40 on B cell (CD40MF) using tri-color flow cytometry to analyze the distribution of the above parameters in SARS, mycoplasma pneumonia and healthy adult volunteers and their relation to the severity of SARS. RESULTS The number of total B cells of clinically diagnosed SARS was (292 +/- 181) x 10(6)/L, significantly greater than that of healthy adults which was (200 +/- 65) x 10(6)/L (F = 6.17, P < 0.05) but smaller than that of patients infected with mycoplasma pneumonia which was (359 +/- 168) x 10(6)/L (F = 6.28, P < 0.05). During day 11 - 20 of the disease, the number of B1 cells of SARS patients was (24 +/- 14) x 10(6)/L smaller than that of healthy adults which was (39 +/- 20) x 10(6)/L (F = 4.23, P < 0.05). In the early stage of SARS (within 10 days), the expression of CD40 decreased significantly as compared with healthy adults (F = 5.13, P < 0.05). The number of B cells in severe SARS and mild cases were (347 +/- 156) x 10(6)/L and (268 +/- 211) x 10(6)/L respectively. The difference was statistically significant (F = 7.11, P < 0.01). CONCLUSIONS B cells, B1 cells and the expression of CD40 on B cells were involved in the pathogenesis of SARS. The B cell count correlated with the severity of SARS. The monitoring of B cells, B1 cells and the expression of CD40 on B cells is useful in the differential diagnosis of SARS.