Abstract
Mycoplasma pulmonis inoculated parenterally into athymic nude mice congenitally deficient in T cells caused a chronic arthritis of significantly greater magnitude than in immunologically normal mice. During the chronic phase of arthritis, M. pulmonis organisms were isolated from the joints and spleens of athymic nude mice more frequently and in larger numbers than from immunologically normal mice. The results support the concept that impaired T-cell function predisposes the mice to a severe degree of chronic arthritis as a result of their failure to eliminate the causative organisms.