Purification and Some Properties of Anti-Testosterone Antibodies

Abstract

Antibodies to testosterone have been produced by immunization of ewes with conjugates of testosterone-17-hemisuccinate and bovine serum albumin suspended in Freund's complete adjuvant. Antibody has been separated from the sera by salt fractionation to obtain the globulin fraction, by dissolution of specific precipitates using a hapten analogue and by chromatography on DEAE-cellulose. The apparent specific precipitability of the antisera, and of all antibody-containing solutions derived from them, was markedly dependent on concentration. Our data can be expressed by the equation A_app = A₁ e^-b(f-1) where A_app is the apparent antibody titer at the dilution tested, A₁ is the antibody titer of the undiluted test solution for which f = 1, f is the dilution factor, and b is a parameter which measures the degree of variation of precipitation of antibody with dilution. The concentration effect is probably not due to the solubility of antigen-antibody aggregates or to the changed configuration of proteins in dilute solution. It may be due to the presence of relatively weakly bound antibody molecules, or, more probably, to an increased possibility of intra-particulate interaction on dilution. The preferred method for specific purification of anti-testosterone antibodies was precipitation by heterologous antigen and dissolution of the precipitate by the hapten analogue, N,N-dimethylaminoethyl- 17β-(3-keto-4-androstenyl)-carbonate, followed by separation of the antibodies on Sephadex G-25. Two of the six ewes immunized produced antibodies which were bound by DEAE-cellulose, and which, when eluted, differed from unbound antibodies in that their specific precipitation by homologous antigen was inhibited by albumin or by some component associated with albumin.