Use of indirect immunofluorescence and western blotting to assess the role of circulating antimyocardial antibodies in dogs with dilated cardiomyopathy.

The presence of circulating anti-heart IgG and IgM autoantibodies was assessed by indirect immunofluorescence and by probing Western blot transfers of normal canine myocardial proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis with samples of sera from dogs with dilated cardiomyopathy (n = 27) and from healthy control dogs (n = 20). No difference was demonstrated between the two groups using either method. Sera taken from the affected dogs at three monthly intervals throughout the course of the disease showed no change at all in the pattern of reactivity. The results of this study suggest that indirect immunofluorescence and the probing of Western blot transfers of a crude preparation of normal canine myocardium with canine sera will demonstrate too many apparent autoantigens for the technique to identify unique, disease-associated autoantibodies.