Response of LFA-1-deficient B cells to interleukin 4 (BSF-1) and low molecular weight B cell growth factor (BCGFlow).

T cell-depleted B cells from a patient with LFA-1 deficiency were tested in costimulation assays for responsiveness to recombinant human IL 4 (BSF-1) and purified low molecular weight B cell growth factor (BCGFlow). In both cases the response of LFA-l-deficient B cells was comparable with normal controls. Monoclonal antibodies to LFA-1 α (CD11a) and β (CD18) chains were unable to mimic the action of IL 4 on normal B cells in costimulation assays with anti-IgM, and did not inhibit normal B cell proliferation in response to IL 4 and anti-IgM. Epstein-Barr virus-transformed lymphoblastoid B cell lines (LCL) from normal and LFA-l-deficient donors both responded in proliferation assays to BCGFlow but not IL 4. Similarly, both normal and LFA-l-deficient LCL increased IgM secretion in response to BCDF, BCGFlow and, interestingly, IL4. The normal LCL also increased IgG secretion in response to these factors, but no IgG was detected in supernatants from the LFA-l-deficient LCL. These results show that LFA-1 expression is not essential for B cell responses to B cell growth and differentiation factors.