A BIOLOGICAL ROLE FOR HEMAGGLUTINATION ACTIVITY OF LEISHMANIA PROMASTIGOTES AND AMASTIGOTES

Leishmania promastigotes and axenic amastigotes possess a haemagglutin ation activity (HA). Leishmania attachment to human macrophages was st udied after a 30 min incubation in the presence of 10 mM carbohydrates at 37 degrees C. Galactosamine, sialic acid, heparin, mannose, and NA c-mannosamine impaired the attachment of promostigotes and amastigotes to monocyte-derived macrophages and the myelomonocytic cell line THP 1 whereas other carbohydrates had no effect. Preincubation experiments showed that mannose inhibits the macrophage receptor, whereas galacto samine acts on promastigotes. Moreover, the HA is considerably decreas ed after incubation with macrophages. Our results suggest that promast igotes of different Leishmania species and axenic amastigotes possess a lectin-like receptor with similar specificity, which is in some way involved in the attachment to vertebrate host cells.