Effect of phorbol-12-myristate-13-acetate (PMA) on the fine structure of Trypanosoma cruzi and its interaction with activated and resident macrophages.

Epimastigotes of Trypanosoma cruzi showed many filopodium-like projections from the flagellar membrane when incubated in the presence of 100 ng/ml (a concentration which does not interfere with cell motility and viability) phorbol-12-myristate-13-acetate (PMA). PMA is a substance which binds to the membrane-associated protein kinase C. Few of these projections were observed in control parasites. PMA, when added to the interaction medium, significantly increased the attachment of epimastigotes to the surface and their ingestion by resident or activated mouse peritoneal macrophages maintained in vitro. PMA, however, did not interfere with the ingestion of trypomastigotes.