Isolation and characterization of a rabbit adrenal autoantigen.

The antigenic components of adrenal extract were fractionated by chromatography on DEAE-cellulose. Using a stepwise elution procedure, it was found that a componenet of major interest, termed Pk3b, was eluted by a buffer of pH 6.70 and 0.09 M in phosphate-chloride. This antigenic preparation reacted with several rabbit antisera that had been prepared by isoimmunization with rabbit adrenal homogenate, in contrast to several other fractions, which reacted with only one (or two) of the antisera. Pk3b also showed a high degree of homogeneity, as shown by immunodiffusion, paper electrophoresis, and analytical ultracentrifugation. By the latter technique, an extrapolated sedimentation coefficient of 4.45S was determined. The further comparison of this antigen in immunodiffusion, along with an antiserum and the adrenal extract from the antiserum-providing animal, confirmed again that this is an autoantigen, and that it is one of five autoantigens of the adrenal gland.