A monoclonal anti-mouse LFA-1α antibody mimics the biological effects of B cell stimulatory factor-1 (BSF-1)

This study describes the generation of a monoclonal mouse x rat antibody (G-48) that recognizes a determinant on the serologically defined LFA-1 α-chain. It immunoprecipitates two noncovalently associated polypeptides of 176,000 and 95,000 M(r) respectively from lysates of radioiodinated BCL₁ cells, T cells, and B cells. G-48 mimics the biological actions of BSF-1 by inducing increased levels of Ia antigen expression on resting B cells, augmenting the proliferation of anti-δ-stimulated B cells, and in insolubilized form, inducing IgG1 secretion by LPS-activated B cells. G-48 does not have BCDFμ, BCGF II, nor IL 2 activity. These results demonstrate that LFA-1 plays an important role in B cell activation, proliferation, and differentiation.