Cross-linking the Leu-8 lymph node homing receptor on B cells inhibits immunoglobulin synthesis.

About one half of circulating human B cells express the Leu-8 peripheral lymph node homing receptor that has been implicated in adhesion of lymphocytes and neutrophils to vascular endothelium. A novel and unique function of the Leu-8 antigen has been found in the present study: anti-Leu-8 monoclonal antibody directly inhibits B cell antibody production induced by SAC + IL-2, without affecting B cell proliferation or other early steps of B cell activation. This effect of anti-Leu-8 is unique in that other antibodies that inhibit B cell differentiation are not selective and also inhibit B cell proliferation. The inhibitory effect is not reversed by addition of T cells, monocytes, or recombinant IL-1 or IL-6 and is not blocked by anti-TGF-beta. Thus, the natural ligand(s) for Leu-8 may be capable of transducing regulatory signals that have a selective effect on B cell differentiation.