EXPRESSION OF HUMAN PLATELET-ACTIVATING-FACTOR RECEPTOR GENE IN EOL-1CELLS FOLLOWING BUTYRATE-INDUCED DIFFERENTIATION

Platelet-activating factor (PAF) is a potent lipid mediator of allergi c inflammation through its interaction with eosinophils. Expression of the PAF receptor is modulated by many agents, including those respons ible for cell differentiation. We report here that differentiation of a human eosinophilic leukaemia cell line, EoL-1, by sodium n-butyrate is associated with induction of PAF receptor gene expression, as indic ated by: PAF receptor mRNA accumulation; increases in the binding of [ H-3]WEB 2086, a PAF antagonist; analysis of cell-surface expression of PAF receptor protein using a monoclonal anti-(PAF receptor) antibody; and augmentation of PAF-induced increase in the intracellular concent ration of calcium. Using cDNA cloning, the receptor expressed in EoL-1 cells was identified as 'Transcript 1', one of two transcripts which was previously reported from human genomic analysis (Mutoh, Bite, Mina mi, Nakamura, Honda, Izumi, Nakata, Kurachi, Terano and Shimizu (1993) FEES Lett. 322, 129-134). The PAF-induced calcium response and phosph oinositide turnover were decreased by pertussis toxin (PTX) treatment, suggesting that these signals are coupled largely with PTX-sensitive G-protein(s) in EoL-1 cells. These systems may provide a useful experi mental model with which to investigate the relationship between eosino philic differentiation and PAF receptor induction, and the role of eos inophils in allergic responses.