Marked acceleration of the autoimmune disease in MRL-lpr/lpr mice by the influence of the Yaa gene from BXSB mice.

MRL-lpr, Yaa males were developed by the transfer of the Yaa gene from BXSB males to the MRL-lpr strain. The early-onset autoimmune disease of MRL-lpr males was accelerated further by the action of Yaa. All the serological parameters of autoimmune disease examined, i.e., anti-DNA antibodies, rheumatoid factors and circulating immune complexes were elevated earlier in MRL-lpr, Yaa males than in MRL-lpr males. Consequently, the MRL-lpr, Yaa males showed the clinical signs of an earlier and more rapidly progressive glomerulonephritis as compared with MRL-lpr males. The lifespan of MRL-lpr, Yaa males was shortened by about 50% in comparison to MRL-lpr males, with 90% of MRL-lpr, Yaa males dead by about 4 months of age. The clinical features and overall intensity of the autoimmune responses in the terminal stages appeared to be similar in both MRL-lpr, Yaa and MRL-lpr males. Thus, Yaa appeared merely to accelerate the disease course of MRL-lpr males, without altering the essential nature of the disease.