B lymphocytes express phospholipase C-gamma(1) (PLC-gamma(1)) and phospholipase C-gamma(2) (PLC-gamma(2)) isozymes. However, the relative importance of these two isozymes in B cell signaling is not known. We report here the identification and analysis of a B cell line deficient in PLC-gamma(1). Mature splenic B lymphocytes and a panel of cell lines representing pre-B, immature and mature B cell stages expressed phospholipase C-gamma (PLC-gamma), but not the beta or delta isoforms of phospholipase C (PLC). While all the tested B cell lines and primary splenic B cells expressed PLC-gamma(1) and PLC-gamma(2) isozymes, the L1.2 B cell line exclusively expressed PLC-gamma(2), but not PLC-gamma(1) isozyme. The PLC-gamma(1) deficient L1.2 B cells expressed levels of surface IgM comparable to that of PLC-gamma(1) positive 70Z/3 B cell line. However, stimulation through the antigen receptor induced Ca(++) response in 70Z/3, but not L1.2 B cells, suggesting a requirement for PLC-gamma(1) in antigen receptor induced Ca(++) signaling in these cells. The possible use for L1.2 cells in testing the regulation of PLC-gamma(1) and PLC-gamma(2) dependent calcium mobilization in B lymphocytes is discussed.