Proliferative responsiveness of B cells from autoimmune NZB mice to anti-immunoglobulin and interleukin-4.

Proliferative responses of B cells to anti-IgM antibody and recombinant interleukin-4 (rIL-4) were studied in autoimmune NZB mice. While anti-IgM antibody and rIL-4 act synergistically on resting B cells to induce proliferation in BALB/c and C57BL/6 mice, they failed to produce synergistic effect on NZB B cells, although these NZB B cells responded better to the individual stimulus with anti-IgM antibody or rIL-4. Cell-fractionation analysis of NZB splenic B cells using Percoll density centrifugation showed marked increase in low-density B cells and decrease in high-density B cells. Proliferative response patterns of each subpopulation of NZB B cells were not different from those of control BALB/c B cells, except for higher response of NZB B cells to anti-IgM antibody. Thus, the accumulation of large low density B cells, probably resulting from in vivo activation, may partly account for the altered responsiveness of NZB B cells as a whole.