PHORBOL ESTER RESPONSIVENESS OF MURINE LY-1-LINEAGE B-CELLS FROM NORMAL AND VIABLE MOTH-EATEN MUTANT MICE

Simultaneous analysis of stimulated cells for surface phenotype and DNA content by flow cytometry was used to delineate the characteristics of murine lymphocytes that respond to phorbol esters. Peritoneal cells that expressed high-density sIgM, Ly-1, Mac-1 and high-density Pgp-1, were preferentially stimulated to enter the S + G2/M phases of the cell cycle by the protein kinase C agonist, phorbol 12-myristate 13-acetate (PMA). Since these phenotypic characteristics correspond well with those of Ly-1-lineage B cells, non-peritoneal sources of Ly-1+ B cells were examined to test the relative role of lineage and environment in determining phorbol ester responsiveness. Splenic sIgM+ lymphocytes from adult me(v)/me(v) mice, and Ly-1+ splenic B cells from neonatal normal mice, were stimulated to enter the S + G2/M phases by PMA, although not to the same extent as peritoneal Ly-1+ B cells. These results suggest that responsiveness to phorbol ester, acting alone, is characteristic of murine Ly-1-lineage B cells regardless of tissue of origin; however, a role for environmental influences has not been completely ruled out.