Response of CBA/N x DBA2/F1 mice to Nocardia asteroides.

Immunized and nonimmunized B-lymphocyte-deficient CBD2/F1 (CBA/N x DBA/2) mice were infected with Nocardia asteroides GUH-2 by different routes of inoculation. The 50% lethal dose, organ clearance, footpad response, and antibody titers were measured. It was observed that B-cell-deficient male mice were not significantly more susceptible to infection than normal female controls even though the female CBD2/F1 mice produced antinocardial antibodies while the deficient male animals did not. Preimmunized male and female mice were identical in their ability to clear N. asteroides from the adrenals, brain, kidneys, liver, lungs, and spleen. Both DBA/2 and CBD2/F1 female mice were more susceptible than their male littermates to intravenous challenge with N. asteroides GUH-2. This enhanced susceptibility of the female mice as compared to the male littermates appeared to be due to a decreased resistance to nocardial infections in the brains of the female animals. These data indicate that antibody and certain B-lymphocyte subpopulations are not essential components in host resistance to N. asteroides GUH-2 in these mice.