Heterogenous response of B cell chronic lymphocytic leukaemia (B-CLL) cells to anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1).

B cell chronic lymphocytic leukaemia (B-CLL) cells from seven patients were examined for 3H-TdR uptake with anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1)/IL-4. B-CLL cells from one patient could proliferate with anti-mu plus BSF-1, but not with BSF-1 alone. B-CLL cells from two patients responded to BSF-1 alone; one could proliferate more by adding anti-mu, but the proliferation of the other cells was inhibited by adding anti-mu. On the other hand, B-CLL cells from the other four patients responded neither to anti-mu nor to anti-mu plus BSF-1. Surface densities of membrane IgM of B-CLL cells were also analysed by fluorescence activated cell sorter (FACS), but there was no correlation between proliferative response (DNA synthesis) of B-CLL cells to anti-mu and densities of surface membrane IgM. These results show that there is a functional heterogeneity of B-CLL cells with regard to proliferative response to anti-mu and BSF-1.