Autoantibodies to thyroid tissue sediment detected by the antiglobulin consumption test

The antiglobulin consumption test (AGCT) has been adapted to the demonstration of autoantibodies in the serum of patients with chronic thyroiditis. Human thyroid tissue was homogenized and washed 15 times with buffered saline so that the supernatant was free of detectable thyroglobulin and serum. The lyophilized tissue sediment was then used in the AGCT. Positive reactions were obtained with 23 of 64 human thyroiditis sera. No reaction occurred with normal human sera. The results of the consumption tests were compared with hemagglutination tests employing tanned red blood cells coated with soluble human thyroid extracts. A direct correlation between the 2 titers was seen in most but not all cases. The reactions observed in the AGCT appeared to be species and organ specific and were not due to isoantibodies. Absorption of thyroiditis serum with purified human thyroglobulin removed part of the consumption titer. This finding suggested that some of the thyroglobulin was either tightly bound to the insoluble tissue components or was present in an insoluble form. It also points to the possible presence of antibodies to other insoluble antigens of the thyroid tissue sediment. When compared with lyophilized human thyroid tissue sediment or lyophilized thyroid tissue microsomes, frozen microsomal fractions gave additional consumption in tests with thyroiditis serum absorbed with thyroglobulin. Boiling of the microsomal fraction reduced consumption with absorbed serum which indicated the thermolability of the insoluble tissue antigen(s).