AUTOANTIBODY PROFILES IN CANINE ANA-POSITIVE SERA INVESTIGATED BY IMMUNOBLOT AND ELISA

Canine systemic lupus erythematosus (SLE) has a similar disease expres sion as human SLE, but the serological characterisation of the canine disease is as yet incomplete. In the present study, we examined the sp ecificity of antinuclear antibodies (ANA) in indirect immunofluorescen ce (IIF) positive canine sera. Sixty-four canine IIF ANA positive sera were characterised using HeLa cell nuclear extract immunoblots and re combinant U1-70K ELISA. We compared these results with a previously sh own concordance between indirect immunofluorescence and immunodiffusio n in canine SLE serological diagnosis. One canine serum reacting with Sm proteins was observed, and five canine sera presented anti-RNP auto antibodies against the antigens 70K, A, C, and/or B/B'. The autoantige n most frequently recognised was a 33 kDa nuclear protein, previously described as hnRNP G. This prominent canine autoantigen was missing in the commercially available extract designed for immunodiffusion testi ng of human sera. Other prominent canine autoantigens were found not t o be identical with the principal human ones, thus making present huma n test systems deficient for the use in canine systemic connective dis ease diagnosis. The development of antigenic extract designed for cani ne autoimmune autoantigens is necessary in order to make immunodiffusi on a useful method in canine diagnosis. The anti-RNP positive canine s era were examined in more detail and we found that the human major ant igenic region of the most prominent RNP antigen, the U1-70K protein, a lso is targeted by canine autoantibodies. Thus, the response against t he RNP antigen seems to be conserved between man and dog. (C) 1998 Els evier Science B.V.