Different abilities of two distinct Fc gamma receptors on guinea pig polymorphonuclear leukocytes to trigger the arachidonic acid metabolic cascade.

The nature of signals transmitted by two Fc gamma receptors (Fc gamma 2R for IgG2 and Fc gamma 1/gamma 2R for both IgG2 and IgG1) on guinea pig polymorphonuclear leukocytes was investigated. The specific binding of hen ovalbumin (OA)-complexed IgG1 antibody to Fc gamma 1/gamma 2R did not seem to trigger the release of [3H]arachidonic acid from the cells prelabeled with [3H]arachidonic acid. In contrast, marked release occurred on the binding of OA-complexed IgG2 antibody to the cells. This reaction was not inhibited, but rather enhanced, by the Fab' of a monoclonal antibody to Fc gamma 1/gamma 2R. Therefore, a signal for the activation of the arachidonic acid metabolic cascade was found to be transmitted by Fc gamma 2R, but scarcely by Fc gamma 1/gamma 2R.