Morphological Analysis of Autoimmune Disease in Mrl-lpr, Yaa Male Mice with Rapidly Progressive Systemic Lupus Erythematosus

We analyzed morphologically autoimmune disease in MRL/MpJ mice bearing both the Yaa and the lpr genes (MRL-lpr, Yaa mice), and compared it with that in MRL/MpJ-lpr/lpr (MRL-lpr) mice, in order to examine the effect of the Yaa gene on lpr-induced tissue-specific immunopathologies. MRL-lpr, Yaa male mice developed glomerulonephritis more rapidly than did MRL-lpr males. The glomerular damage in MRL-lpr, Yaa males, as evaluated by histologic and immunofluorescent methods, was significantly greater than that in age-matched MRL-lpr males. In contrast, no differences in the development of vasculitis and arthritis were noted between the two groups. Pathological examination of the dead mice revealed a similar incidence of lethal glomerulonephritis in the two groups. Lymphoid hyperplasia in the spleen consisted predominantly of unusual T cells (B220+, Thy-1+, CD4−, CD8−) in the two groups, and an increased number of B cells was not found in MRL-lpr, Yaa mice. The histological nature of the autoimmune diseases was s...