[Heterogenicity of the immune response to antigens of muscular and interstitial connective tissue of the heart in patients with rheumatic diseases. II. Association with ABO antigens].

Antibodies (Ab) reacting with myocardial fibre sarcolemma (SL) and interstitial connective tissue (ICT) were determined by means of indirect immunofluorescence technique. The Ab level was found to be dependent on the ABO. Subjects having O and A blood groups are most potent ICT Ab producers, while those with B group, the weakest. The inflammatory process activity exerts varying effects on the level of ICT and SL antibodies depending on the ABO. The ICT Ab level reduction and SL Ab level elevation in maximal inflammation activity were revealed only in O and A blood groups, but not in B-group patients. The differences are discussed. The use of ICT Ab level determination is proposed to be an indicator of the utilization system of damaged connective tissue and aging erythrocytes according to the age and ABO. The presence of SL Ab is believed to be a risk factor of cardiac disease only in O and A blood group patients.