Immunological studies on adrenal glands. V. Chemical studies on the rabbit adrenal-specific autoantigen.

Extracts of rabbit adrenal tissue, containing an adrenal-specific antigen able to elicit the formation of autoantibody, have been characterized physically and chemically. The extinction coefficient was shown to be 10.3 at 280 mμ. Ultracentrifugal analysis revealed a group of components; the predominant one was a 3.9S boundary. Additional components had sedimentation coefficients of 6.6S, 10.0S, 11.8S and 18.1S. Starch block electrophoresis was unsuccessful in providing significantly purified antigen. There was a suggestion of a possible occurrence of two antigens. Some degree of fractionation was achieved by salting-out with ammonium sulphate. The antigenic material was associated with the fraction precipitating between 0.00 and 1.50 M of this salt. These studies also provided some evidence that the antigen was associated with the 6.6S sedimenting component. Enzymic digestion with chymotrypsin readily caused destruction of the activity, indicating that the antigen is essentially a protein.