DETECTION OF SECRETORY PHOSPHOLIPASE A(2)S RELATED BUT NOT IDENTICAL TO TYPE IIA ISOZYME IN CULTURED MAST-CELLS

We previously reported that BALB/cJ mouse-derived bone marrow-derived mast cells (BMMC) exhibited two sequential phases of prostaglandin D-2 (PGD(2)) generation in response to Fc(epsilon) receptor I (Fc(epsilon )RI) crosslinking and cytokine stimulation, the late phase of which wa s suppressed by an antibody raised against type IIA secretory phosphol ipase Az (sPLA(2)), Here we report that BMMC derived from C57BL/6J mic e, which are genetically deficient in type IIA sPLA(2), display both i mmediate and delayed PGD(2) generation normally, Lysates of C57BL/6J-d erived BMMC contained a Ca2+-dependent PLA(2) that was absorbed to a c olumn conjugated with anti-type IIA sPLA(2) antibody and had a similar molecular mass of 14 kDa, as assessed by immunoblotting, Therefore we speculate that a sPLA(2) similar to, but distinct from, type IIA sPLA (2) would compensate for type IIA sPLA(2) deficiency in C57BL/6J-deriv ed BMMC. We found that the two type IIA-related sPLA(2) family members , type V and type IIC sPLA(2)s, were expressed in BMMC as men as in ra t mastocytoma RBL-2H3 cells. (C) 1997 Federation of European Biochemic al Societies.