GENETIC SUSCEPTIBILITY TO LEISHMANIA - IL-12 RESPONSIVENESS IN T(H)1 CELL-DEVELOPMENT

The genetic background of T lymphocytes influences development of the T helper (T-H) phenotype, resulting in either resistance or susceptibi lity of certain mouse strains to pathogens such as Leishmania major. W ith an in vitro model system, a difference in maintenance of responsiv eness of T cells to interleukin-12 (IL-12) was detected between BALB/c and B10.D2 mice, Although naive T cells from both strains initially r esponded to IL-12, BALB/c T cells lost IL-12 responsiveness after stim ulation with antigen in vitro, even when cocultured with B10.D2 T cell s, Thus, susceptibility of BALB/c mice to infection with L. major may derive from the loss of the ability to generate IL-12-induced T(H)1 re sponses rather than from an IL-4-induced T(H)2 response.