COILING PHAGOCYTOSIS OF TRYPANOSOMATIDS AND FUNGAL CELLS

Coiling phagocytosis has previously been studied only with the bacteri a Legionella pneumophila and Borrelia burgdorferi, and the results wer e inconsistent. To learn more about this unconventional phagocytic mec hanism, the uptake of various eukaryotic microorganisms by human monoc ytes, murine macrophages, and murine dendritic cells was investigated in vitro by video and electron microscopy, Unconventional phagocytosis of Leishmania spp, promastigotes, Trypanosoma cruzi trypomastigotes, Candida albicans hyphae, and zymosan particles from Saccharomyces cere visiae differed in (i) morphology (rotating unilateral pseudopods,vith the trypanosomatids, overlapping bilateral pseudopods with the fungi) , (ii) frequency thigh with Leishmania; occasional with the fungi; rar e with T. cruzi), (iii) duration (rapid with zymosan; moderate with th e trypanosomatids; slow with C. albicans), (iv) localization along the promastigotes (flagellum of Leishmania major and L. aethiopica; flage llum or posterior pole of L, donovani), and (v) dependence on compleme nt (strong with L, major and L, donovani; moderate with the fungi; non e with L, aethiopica), All of these various types of unconventional ph agocytosis gave rise to similar pseudopod stacks which eventually tran sformed to a regular phagosome, Further video microscopic studies with L, major provided evidence for a cytosolic localization, synchronized replication, and exocytic release of the parasites, extending traditi onal concepts about leishmanial infection of host cells. It is conclud ed that coiling phagocytosis comprises phenotypically similar conseque nces of various disturbances in conventional phagocytosis rather than representing a single separate mechanism.