ELEVATED EXPRESSION OF PGP-1 (LY-24) BY MURINE PERITONEAL LYMPHOCYTES-B

B cell expression of the surface glycoprotein, Pgp‐1 (Ly‐24), was evaluated using flow cytometric analysis. Pgp‐1 expression on naive, conventional (splenic) B cells was low but could be increased by mitogenic stimulation. Pgp‐1 expression on naive peritoneal B cells was higher than expression by unmanipulated conventionalB cells, suggesting the possibility that peritoneal B cells have been activated in vivo. However, the elevated expression of Pgp‐1 by peritoneal B cells was not accompanied by increased expression of surface Ia but was correlated with Ly‐1 status. Further, Pgp‐1 expression by B cells from germ‐free mice did not differ from that of normal animals. The elevated expression of Pgp‐1 by peritoneal B cellsis superficially similar to that provoked by mitogenic stimulation of conventional B cells; however, several characteristics suggest that the elevated expression of Pgp‐1 by peritoneal B cells does not reflect prior activation of these cells. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim