Role of B lymphocyte and its subpopulations in pathogenesis of immunorelated pancytopenia.

Objective: To measure the quantities and apoptosis-related protein levels of B lymphocyte in the patients with immunorelated pancytopenia (IRP) and explore the action of B lymphocyte in the pathogenic mechanism of IRP.

Methods: Quantities of whole B lymphocytes and CD5+ B lymphocytes as well as the expressions of Fas and Bcl-2 in B lymphocytes in 35 patients with untreated IRP, 15 IRP patients in complete remission (CR), and 10 normal controls were assayed by flow cytometry.

Results: The percentages of B lymphocyte and CD5+ B lymphocyte were significantly higher in untreated IRP patients than in CR IRP patients and normal controls (P < 0.05), and there was no significant difference between the latter two groups (P > 0.05). There was no significant difference of Fas expression in B lymphocyte among three groups (P > 0.05). The expression of Bcl-2 in B lymphocyte was significantly higher in untreated patients than in CR patients or normal controls (P < 0.01), and significantly higher in CR patients than in normal controls (P < 0.01). The apoptosis-related index was significantly lower in untreated patients than in CR patients or normal controls (P < 0.05), and significantly lower in CR patients than in normal controls (P < 0.05). The percentage of B lymphocyte was positively correlated with post-treated response time (r = 0.53, P < 0.01).

Conclusion: The production of auto-antibodies in IRP patients probably has some relationship with the abnormal quantities of B lymphocyte and its subpopulations as well as with the inhibition of B lymphocyte apoptosis.