Phorbol 12-myristate 13-acetate activates rabbit neutrophils without an apparent rise in the level of intracellular free calcium

Abstract

The addition of low concentrations of [cocarcinogen] phorbol 12-myristate 13-acetate to rabbit neutrophils induces cell aggregation, degranulation, increased O2 consumption and an increase in the amount of actin associated with the cytoskeleton without a rise in the level of intracellular free Ca as measured using the fluorescent probe quin-2. The ability of phorbol 12-myristate 13-acetate to initiate neutrophil responses similar to those produced by the chemotactic factor without causing a rise in the level of intracellular free Ca suggests 2 possibilities; that there is a 2nd messenger in addition to Ca or that it activates the cells at a point distal to Ca mobilization. The possible role of diacylglycerol in neutrophil activation is discussed.