HOMOTYPIC AGGREGATION OF MURINE B-LYMPHOCYTES IS INDEPENDENT OF CD23

CD23 is a low-affinity receptor for IgE (Fc epsilon RII). Functions at tributed to CD23 not involving IgE suggest that it interacts with liga nds other than IgE. CD21 has recently been described as a counter liga nd for CD23. A number of lines of evidence have implicated CD23 as an adhesion molecule in human B cells. We have investigated the role of C D23 in homotypic B cell aggregation in the mouse, using lipopolysaccha ride plus interleukin-4-induced aggregation as a model system. In this system high levels of aggregation are accompanied by a massive up-reg ulation of CD23 expression. However, in contrast to what has been obse rved in human B cells, we find no evidence of a role for CD23 in homot ypic adhesion of murine B cells.