OBJECTIVETo examine the quantity and apoptosis-related protein level of B lymphocyte in the patients with immunorelated pancytopenia (IRP) and explore the role of B lymphocyte in the pathogenetic mechanism of IRP.

METHODSQuantities of all B lymphocytes and CD(5)(+) B lymphocytes and the expressions of Fas and bcl-2 on B lymphocytes in 25 patients with untreated IRP, 15 IRP patients in complete remission (CR) and 10 normal controls were assayed by FACS.

RESULTSThe percentages of B lymphocyte and CD(5)(+) B lymphocytes were significantly higher in untreated IRP patients than in CR IRP patients and normal controls (P < 0.05); there was no significant difference between the latter two groups (P > 0.05). There was no significant difference of Fas expression in B lymphocytes among the three groups (P > 0.05). The expression of bcl-2 on B lymphocytes was significantly higher in untreated patients than in CR patients or normal controls (P < 0.05), and so did 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 < 0.01), and was lower in CR patients than in normal controls (P < 0.05). The percentage of B lymphocyte was positively correlated with the duration from the beginning of treatment to response.

CONCLUSIONThe production of auto-antibodies in IRP patients probably has some relationships with the abnormal quantities of B lymphocyte and its subsets, and with the inhibition of B lymphocyte apoptosis.