Studies on precipitating and hemagglutinating antibodies in systemic lupus erythematosus

We studied the precipitating and hemagglutinating autoantibodies in the sera of patients with various connective tissue diseases in general and lupus in particular. Saline soluble extract of goat thymus had adequate antigenic materials as compared to other organs. Twenty per cent of patients with systemic lupus erythematosus were positive for precipitating autoantibodies by immunodiffusion and 44% by counterimmunoelectrophoresis. Normal human subjects, nonrheumatic disease patients and patients with rheumatoid arthritis and progressive systemic sclerosis were all negative. Forty seven per cent of positive systemic lupus erythematosus sera showed two precipitin systems. Enzyme sensitivities were used as the basis of identification of most of the antigenic specificities. Passive hemagglutination was carried out to identify antibodies to non-histone nuclear protein and nuclear ribonucleo-protein antigens. Thirty eight % of systemic lupus erythematosus patients were positive by this technique. Passive hemagglutination although a highly sensitive technique could not detect antibodies against antigenic systems other than non-histone nuclear protein and nuclear ribonucleoprotein.