LEISHMANIA-DONOVANI INFECTS LYMPHOCYTE CELL-LINES IN-VITRO

Cellular interactions between Leishmania donovani parasites and human B (Daudi) and T (HUT78) cell lines were studied in vitro. Both promast igotes and amastigotes of L. donovani gained entry in approximately 60 % of these cells. Transmission electron microscopy revealed the existe nce of intracellular amastigotes in these cell lines after infection w ith L. donovani. Immunophenotyping by flow cytometry confirmed the lym phocytic lineages of these cell lines. There was no evidence for intra cellular replication of L. donovani in T and B cell lines. The number of intracellular amastigotes peaked on second day post-infection then gradually declined in a time-dependent manner in both the cell lines. Intracellular parasites remained more viable and transformation-compet ent when infection was performed with amastigotes. Attachment to the c ell surface but no internalization of parasites was observed when infe ction was attempted on human amnion cell line WISH. Amastigotes, not t he promastigotes of L. donovani induced IL-12 production by both monoc yte and B cell lines.