Host defense against the pneumococcus in T-lymphocyte-deficient, nude mice.

Resistance to pneumococcal infection was tested in T-lymphocyte-deficient, nude (nu/nu) mice. Pneumococcal serum opsonizing activity, in vivo phagocytosis of the pneumococcus, and the mean lethal dose for the pneumococcus were all found to be the same in nude mice as in control (+/+) mice. T-lymphocytes do not appear to play a significant role in the host's defense against the pneumococcus.