Pathogenesis of Thymic Changes in Nzb Mice with Hemolytic Anemia

Lymphoid follicles evolve in the perivascular connective tissue of many organs, including the thymuses, in NZB/Bl mice with hemolytic anemia. In previously published studies, these thymic follicles have been held to be causal in the autoimmune genesis of the hemolytic anemia. The present study contradicts this interpretation by demonstrating: (a) lymphoid follicles develop in the perivascular connective tissue of many organs in NZB mice, and are not restricted to the thymuses; and (b) thymic lymphoid follicles develop in aged Swiss mice without hemolytic anemia. Contrary to previous reports, the thymuses of NZB mice contain normal numbers of Hassall's corpuscles, which develop from preexisting thymic epithelial cells, and not from blood vessels.