Extending the breadth of our previous investigations about the role of the kallikrein-kinin system in the immunopathogenesis of experimental Chagas disease and visceral leishmaniasis, the studies reported in this paper suggest that ecotin-like inhibitors expressed by L. major promastigotes fine-tune phagocytosis and may limit amastigote survival by inhibiting the pericellular activity of kinin-releasing serine proteases (S1a family) of macrophages. The gene discussed is KLK4; the disease is Chagas disease.