DIFFERING ANTIBODY IGG ISOTYPES IN THE POLAR FORMS OF LEPROSY AND CUTANEOUS LEISHMANIASIS CHARACTERIZED BY ANTIGEN-SPECIFIC T-CELL ANERGY

Leprosy and American cutaneous leishmaniasis are tropical diseases whi ch present a spectrum of clinical and immunological manifestations. Le promatous leprosy and diffuse cutaneous leishmaniasis are the severe, progressive polar forms of disease characterized by persistent T cell anergy. Relative concentrations of antibodies belonging to the four Ig G isotypes have been determined in these forms of disease as well as a ctive visceral leishmaniasis, which presents transitory T cell anergy. Leishmania-specific IgG4 antibodies predominated in 19/20 sera from p atients with diffuse cutaneous leishmaniasis, and IgG1 antibodies pred ominated in 9/10 cases of untreated visceral leishmaniasis. The predom inant IgG isotype of Mycobacterium leprae-specific antibodies in untre ated lepromatous leprosy was remarkably variable (IgG1, IgG2, IgG3 and IgG4 in 8, 6, 2 and 1 sera, respectively). Differing IgG antibody iso types have been associated with distinct CD4(+) T cell helper subpopul ations and their characteristic lymphokine profiles in several patholo gies. These results suggest that T cell anergy in chronic intracellula r infections may be associated with as yet undefined mechanisms which modulate reported T helper cell-lymphokine isotype relationships.