B-LYMPHOCYTE IMMUNOGLOBULIN RECEPTOR DESENSITIZATION IS DOWNSTREAM OFTYROSINE KINASE ACTIVATION

Resting mature B cells have two classes of immunoglobulin receptors on their surface, IgD and IgM. Activation of a cell by crosslinking one of these receptors leads to homologous and heterologous receptor anerg y as judged by the inability to induce a second calcium signal 2 hr af ter the initial activation step. The mechanism for this anergy is not known. In this report we show that this receptor anergy is downstream of tyrosine kinase activation in that cells pretreated with anti-IgM, when stimulated with anti-IgD, showed tyrosine phosphorylation compara ble to that of naive cells, but had no calcium response. (C) 1994 Acad emic Press, Inc.