Differential expression of the plasma membrane Mg2+ ATPase and Ca2+ ATPase activity during adhesion and interiorization of Leishmania amazonensis in fibroblasts in vitro.

With ultrastructural cytochemistry we localized the activity of the plasma membrane enzyme markers Mg2+ ATPase and Ca2+ ATPase during the interaction between Leishmania amazonensis and in vitro primary culture fibroblasts. The expression of the enzymes was followed during the parasite adhesion and its interiorization. After the interiorization step, a striking difference was seen between the two enzymes studied when the parasite was found within the parasitophorous vacuole in the fibroblast cytoplasm. The activity of the Ca2+ ATPase found at the Leishmania amazonensis plasma membrane during the attachment step of the infection remained also present inside the phagosome, whereas the Mg2+ ATPase activity disappeared. So far, all the reports in the literature referred the presence of Ca2+ ATPase in Leishmania parasite only in the crude ghost plasma membrane. The Ca2+ ATPase present at the parasite plasma membrane may be involved in the regulation of calcium levels inside the phagosome. Further characterization of this Ca2+ ATPase at the plasma membrane of the parasite, when still inside the phagosome, should permit a better understanding of its functional role in maintaining the parasite surface membrane structure necessary for its existence.