Heart‐specific autoantibodies can be eluted from the hearts of Coxsackievirus B3‐infected mice

This study was undertaken to determine if immunoglobulin G (IgG) antibodies could be eluted from the hearts of mice with Coxsackievirus B3‐induced autoimmune myocarditis and to characterize the immunorcactivity of any elutable autoantibodies. Susceptible (A/J) and resistant (B10.A) mice were administered the virus or the control treatment and killed at various times after treatment. Acid eluates from pooled heart tissue from each treatment group and each time were tested for IgG reactivity with normal heart tissue by immunohistochemistry and with normal heart extracts by Western immunostaining. Eluates from infected A/J mice reacted strongly with syngeneic heart and modestly with syngeneic skeletal muscle tissue. Eluates from infected B10.A or control mice of either strain exhibited little reactivity with either tissue. Tissue reactivity was similar when allogeneic tissue was used as the substrate. Eluates from infected A/J mice recognized the heavy chain of cardiac myosin and several other cardiac antigens by Western immunostaining while eluates from the other treatment groups exhibited little or no reactivity with any normal heart constituents. These results indicate that in vivo IgG deposition occurs in the hearts of mice with post‐infectious autoimmune myocarditis and that the specificity of these antibodies is similar to that reported for serum from animals with this disease. The mechanism(s) leading to myocardial IgG deposition and its possible role in pathogenesis remain to be elucidated.