Leishmania donovani parasites interact with gamma/delta+ human peripheral blood T cells and induce susceptibility to NK cell-mediated lysis.
We recently reported that Leishmania donovani infect the human T-cell line in vitro. To examine whether primary human T cells could be infected by this parasite, a direct interaction of the peripheral blood T cells with L. donovani was examined. The percentage of gamma/delta+ T cells was markedly increased when in vitro generated normal human T-cell blasts were cultured with L. donovani amastigotes. About 30% of the gamma/delta+ T cells in the parasite exposed T-cell blasts expressed parasite antigens intracellularly without detectable intracellular parasites. Parasite exposed T-cell blasts had a reduced surface expression of HLA-DR and were lysed by the sorted CD56+ cells. In contrast, neither L. donovani amastigotes nor T-cell blasts exposed to heat killed amastigotes and/or were sensitive to the NK cell-mediated lysis. Of interest is that about 10% CD3+ peripheral blood T cells in two out of three Indian Kala-azar patients tested expressed intracellular L. donovani antigens.
Saha
A
A
Indian Institute of Chemical Biology, Calcutta.
Chakrabarti
G
G
Sen
S
S
Bandyopadhyay
S
S
D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis / Q000276:immunology; D017252:CD3 Complex / Q000032:analysis; D019002:CD56 Antigen / Q000032:analysis; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007424:Intracellular Fluid / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D007893:Leishmania donovani / Q000254:growth & development / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000097:blood / Q000276:immunology; D008213:Lymphocyte Activation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D000953:Antigens, Protozoan; D017252:CD3 Complex; D019002:CD56 Antigen; D016692:Receptors, Antigen, T-Cell, gamma-delta