[Significance of CD37 expression in malignant B cells]

The aim of this study was to clarify the clinical significance of CD37 expression in B cells from B acute lymphoblastic leukemia (B-ALL) and B cell non-Hodgkin's lymphoma (B-NHL). The expression level of CD37 on B cells from bone marrow samples of normal controls (n = 19), B-ALL patients [including untreated cases (n = 5) and cases with minimal residual disease (MRD, n = 15)] and B-NHL patients (n = 25) whose bone marrow was involved by lymphoma cells, was detected by multiple parameter flow cytometry. The results indicated that the B cells from both untreated cases and cases with MRD lowly expressed CD37 (1.04 ± 0.24 and 1.50 ± 0.89), the normal precursor B cells (control cases) also lowly expressed CD37 (1.64 ± 0.52). There was no difference of CD37 expression level between 3 groups of cases(P > 0.05). Meanwhile the normal mature B cells and B-NHL cells highly expressed CD37 (14.23 ± 7.84 and 14.53 ± 10.93), but there was no difference of CD37 expression between them (P > 0.05). The comparison of CD37 expression level in normal B cells of development stages showed that the progenitor B cells lowly expressed CD37 (0.88 ± 0.17), the CD37 expression of precursor B cells was enhanced (2.44 ± 0.69), while the CD37 expression level of mature B cells was highest. It is concluded that the low expression of CD37 is not the characteristic of B- ALL cells. The expression level of CD37 increases gradually during the mature process of B cells, i.e, the expression level of CD37 does not associate with benignity or malignancy of B cells.