The cellular immune response to a purified antigen from Leishmania mexicana subsp. amazonensis enhances the size of the leishmanial lesion on susceptible mice.

Immunization of BALB/c mice with gp10/20, a glycoconjugate purified from Leishmania mexicana subsp. amazonensis, induced a delayed-type hypersensitivity response to the antigen, and a significant increase was elicited in the size of the lesion induced by a subcutaneous infection with this parasite. The increase in the lesion size was observed when mice were immunized by the subcutaneous and the intraperitoneal routes. The subcutaneous immunization with gp10/20 was unable to reverse the prophylactic effect of an intravenous injection of irradiated promastigotes. An L3T4+ T-cell line specific for gp10/20 was able to transfer this lesion-enhancing effect and specific delayed-type hypersensitivity reactivity to normal syngeneic recipients. The same T-cell line was a good producer of a hematopoietic growth factor, granulocyte-macrophage colony-stimulating factor.