EVIDENCE FOR A PLATELET-ACTIVATING FACTOR RECEPTOR ON HUMAN LYMPHOBLASTOID B-CELLS - ACTIVATION OF THE PHOSPHATIDYLINOSITOL CYCLE AND INDUCTION OF CALCIUM MOBILIZATION

In this report we demonstrate evidence which strongly suggests that a receptor for platelet-activating factor (PAF) exists on a lymphoblastoid B cell line, LA350. PAF ranging in concentration from 10-6-10-9M initiated the incorporation of 32P into phosphatidic acid (PA) and phosphatidylinositol (PI) with no change in phosphatidylethanolamine (PE) and phosphatidylcholine (PC) over baseline. Lyso-PAF, the inactive precursor, at 10-7M had no effect on membrane phospholipid metabolism. In addition, PAF from 10-6-10-8M when added to Fura-2 containing B cells induced a rapid and significant rise of calcium within the cell, with lyso-PAF having no effect. These data suggest that PAF binds to a receptor on B cells and induces the hydrolysis of PI and a subsequent increase of intracellular calcium. © 1990.