Enzyme immunoassay in cell monolayers for evaluation of in vitro activity of chemotherapeutic agents against Trypanosoma cruzi.

A standardized enzyme-linked immunosorbent assay (ELISA), performed directly on monolayers of mouse peritoneal macrophages or L 929 fibroblasts, was used to evaluate the activity of chemotherapeutic agents against four different stocks of Trypanosoma cruzi. Absorbance readings, performed in an automatic ELISA reader, were directly related to the number of intracellular parasites as determined by microscopic examination of tissue culture slides run in parallel. Results were highly reproducible in replicate wells and in repeated experiments. Results with nifurtimox, ketoconazole, and formycin B, compounds known to have in vivo activity against T. cruzi, revealed that the ELISA technique was capable of detecting small dose-response variations in the rate of phagocytosis of different life cycle stages of T. cruzi by normal and activated mouse macrophages.