Requirement of B cells for delayed type hypersensitivity-like pathology after secondary infection with Leishmania major in resistant C57BL/6 mice

B cell-deficient C57Bl/6 ( mu MT) mice were resistant to Leishmania major after both primary and secondary parasite challenge. However, unlike in wild-type mice, secondary infection in mu MT mice was not accompanied by a marked delayed type hypersensitivity-like response, and interferon- gamma (IFN- gamma ) levels were approximately half of those in wild-type mice. These results suggest that B cells are involved in IFN- gamma production and the pathology of secondary infection.