Differential invasion of Trypanosoma brucei bruceiand lymphocytes into the brain of C57BL/6

Trypanosoma brucei (T. b.) subspecies invade the brain parenchyma at late stages of human and experimental rodent infections. Here, we compared the outcome of infection with T. b. in MHC-matched (H2^b) C57BL/6 (B6) and 129Sv/Ev (Sv-129). While Sv-129 showed higher parasitemia and lower specific IgM (but not IgG) antibody levels than B6 mice, the number of trypanosomes, CD4⁺ and CD8⁺ T cells in the brain parenchyma was higher in B6 mice. B6 mice lost weight and showed higher cumulative mortality compared to Sv-129 mice. Higher levels of IL-1β, IL-6, IL-10, TNF-α, IFN-γ, ICAM-1 and E-selectin, but low levels of TGF-β mRNA were present in brains of B6 compared to Sv-129-infected mice. Thus, host genetics differentially determine invasion of T. b. brucei into the brain parenchyma, which is paralleled by the severity of inflammation in the brain and course of the disease, but not by parasitemia or antibody titers.