DICHOTOMY OF THE HUMAN T-CELL RESPONSE TO LEISHMANIA ANTIGENS .2. ABSENT OR TH2-LIKE RESPONSE TO GP63 AND TH1-LIKE RESPONSE TO LIPOPHOSPHOGLYCAN-ASSOCIATED PROTEIN IN CELLS FROM CURED VISCERAL LEISHMANIASIS PATIENTS

The T cell response to different Leishmania donovani antigens was inve stigated using peripheral blood mononuclear cells (PBMC) from Kenyans cured of visceral leishmaniasis and non-exposed Danes. Crude promastig ote and amastigote antigens both induced proliferation and interferon- gamma (IFN-gamma) production in PBMC from cured patients, while cells from non-exposed donors gave weak responses. A similar pattern was ind uced by lipophosphoglycan-associated protein (LPGAP). By contrast, the major surface protease of Leishmania, gp63, induced only a weak proli ferative response without IFN-gamma production in five of 17 samples f rom cured patients. Four of the five responding cultures produced IL-4 , i.e. the response to this antigen was of the Th2 type. Furthermore, sera from acutely ill visceral leishmaniasis patients contained high l evels of IgG antibodies to gp63. The Th2-like response to gp63 in pati ents cured of visceral leishmaniasis differs from the Th1-like respons e to the same antigen observed in patients cured of cutaneous leishman iasis.