Immunosuppression during Trypanosoma musculi infection in inbred strains of mice.

Inbred strains of mice inoculated with T. musculi behaved as either sensitive (A/J, CBA/J and C3H/He/J) or relatively resistant (BALB/c, DBA/2, and C57B1/6) with respect to the magnitude of parasitaemia but not to the length of infection. Spleen cells from T. musculi infected C57B1/6 (resistant) and C3H/HeJ (sensitive) mice inhibited the response of normal spleen cells to PHA and ConA; this suppressive activity was concentrated in T-cells and was higher in the resistant mice. However, infection in T-cell-deprived C57B1/6 and C3H/HeJ mice, although more severe and of much longer duration than in the respective control mice, revealed that T-cells were not responsible for the natural resistance to T. musculi.