Study of the immune state in patients with a history of subacute bacterial endocarditis and in their direct relatives. Pathogenic implications.

Immunologic investigations were performed in 18 patients at a mean interval of 1.8 years after cure of subacute bacterial endocarditis (SBE) and in 17 of their direct relatives. The results were compared with those obtained in a control group of 52 healthy subjects. Assay of serum immunoglobulins revealed deviations from the normal (mean +/- 2 SD) in 65% of the post-SBE patients and in 77% of their relatives. Tests for the presence of nuclear, smooth muscle, mitochondrial, cytoplasmatic, albumin and interstitial antibodies showed the presence of such autoantibodies, either single or associated, in 55% of the post-SBE patients and in 58% of their relatives. The serum complement titer was low in 54% of the former SBE patients and in 66% of their relatives. A series of antimicrobial skin tests or intradermal reaction to dinitrochlorobenzene showed hypergy or anergy in 54% o the post-SBE patients investigated. These results, alongside with the data in the literature, support the hypothesis of the preexistence of the immune deficit (probably inherited) in the cardiac patients who develop SBE.