Long Term Subclinical Effects of Parainfluenza (SENDAI) Infection on Immune Cells of Aging Mice 1

Summary

The long-term effects of subclinical parainfluenza virus infection on the immune system of eight strains and hybrids of aging mice were studied. The results demonstrated that 55 of the 63 weight, cellular, activity, and autoimmune indices tested were abnormal as late as 8 months after disappearance of clinical symptoms. Probably the most significant changes were the increase in the fragility of T and B cells and decrease in their proliferative capacities, which were associated with an increase in susceptibility to autoimmune disease. The long term sequelae of the viral infection including autoimmune disease were most severe in immunologically immature young, immunodepressed adult, and immunologically deficient old mice; e.g., the mortality of adult mice rendered T cell deficient by either thymectomy alone or thymectomy followed by irradiation-bone marrow reconstitution was about 5% for both groups prior to infection and increased to 30 and 80%, respectively, after infection. All old mice converted to Coombs'positivity. These findings may be of importance to studies of the pathogenesis of autoimmune disease in aging animals and humans.