Dilated cardiomyopathy with special reference to humoral immunity

The question of whether the etiology of DCM is immune or autoimmune has been increasingly discussed. Abnormal findings on humoral immunity in DCM were investigated, especially those regarding anti-heart antibodies (AHA), IgG subclasses and soluble interleukin-2 receptor (sIL-2R). The heterophile type AHA was detected in 64.7% of cases by the indirect immunofluorescence technique (IF) with rat heart, by indirect IF with human heart AHA in 57.8% of cases, and by thin-layer chromatogram with human glycolipids AHA in 44% of cases. Also, 57.1% of the specimens were found to bind IgG on perimyocytes by direct IF with biopsy specimens taken from patients with DCM. The epitope of an antigen which reacted with the heterophile type AHA is a Gal alpha 1-3Gal structure. 200 Kd, 70 Kd and 40 Kd antigens were reacted with AHA detected by indirect IF with human heart. The possible mechanisms of AHA in the pathogenesis could be either complement dependent cytotoxicity or interference to cardiac metabolism. The concentration of sIL-2R and IgG3 in sera from patients with DCM were elevated. These results suggest that immunological abnormalities occur continuously in DCM.