Microsomal phospholipase A₂ is activated by surfactant toxins in 3T3 mouse fibroblasts

In 3T3 mouse fibroblasts that were treated by surfactant toxins such as staphylococcal delta toxin, melittin from bee venom and lysolecithin, microsomal phospholipase A₂ (PLA₂) was activated. However, these toxins did not activate PLA₂ when added to cell-free homogenates or microsomal preparations. The maximal activation was achieved at 1 mM Ca²⁺ pH 8.5. The microsomal PLA₂ stimulated by these toxins had a high fatty acid specificity (C-2 position) toward arachidonic acid.