Characterization of an I-E-restricted, gp63-specific, CD4-T-cell clone from Leishmania major-resistant C3H mice that secretes type 2 cytokines and exacerbates infection with L. major.

A T-cell clone (designated KLmB-3) was derived from resistant C3H mice 2 weeks after infection with Leishmania major. KLmB-3 was a CD4-T-cell clone that utilized the V beta 8.1 T-cell receptor. When adoptively transferred to naive C3H mice, KLmB-3 unexpectedly exacerbated infection with L. major (it increased the cutaneous lesion size and the parasite burden within the lesion). The ability of KLmB-3 to exacerbate disease correlated with its ability to produce the type 2-associated cytokines interleukin-4 (IL-4), IL-5, IL-10, and transforming growth factor beta. Interestingly, KLmB-3 was specific for an epitope in the amino-terminal end of the L. major surface gp63 zinc metalloproteinase (leishmanolysin) that has been shown to be capable of inducing a protective immune response. Moreover, KLmB-3 was activated when this epitope was presented in the context of H-2 I-E rather than H-2 I-A.