Independent appearance of anti-thymocyte and anti-RNA antibodies in NZB/NZW F1 mice.

NZB and NZB/NZW (B/W) mice were studied for natural thymocytoxic autoantibody(NTA) and antibody to reovirus RNA by cytotoxicity and radioimmunoassay respectively.NZB mice developed NTA by 2-3 months of age. RNA antibodies appeared later if atall. NTA and anti-RNA were present in B/W mice starting at 4-5 months and increased in frequency with age. Either activity could appear first and could be present without the other. Thus, all four possible patterns of autoantibody occurrence were found. NTA and anti-RNA in 12-month B/W sera were separable by sucrose density gradient ultracentrifugation; NTA is a 19S IgM antibody whereas anti-RNA is 7S.