LYSOPHOSPHATIDYLSERINE ENHANCES EXOGENOUS TYPE-II PHOSPHOLIPASE A(2)-INDUCED ACTIVATION OF RAT SEROSAL MAST-CELLS

We have previously shown that exogenous type II phospholipase A(2) (PL A(2)) alone elicits degranulation of mast cells, including rat serosal mast cells (SMC) and mouse bone marrow-derived mast cells (BMMC). Her e we report that lysophosphatidylserine (lysoPS), a co-factor for acti vation of rodent SMC in response to some tyrosine kinase-coupled agoni sts, enhanced type II PLA(2)-elicited histamine release from rat SMC, In contrast, mouse BMMC was insensitive to lysoPS. Our findings demons trate a novel route for activation of SMC in that type II PLA(2) can a ct as a direct activator of SMC with enhancement by lysoPS, which is g enerated from membrane phosphatidylserine possibly by the action of th e same enzyme.