[Isolation of the pregnancy specific beta-glycoprotein (SP1) and antigen-related proteins by means of immunoadsorption].

Purification of human pregnancy-specific beta1-glycoprotein (SP1) and antigenically related proteins of sub-human primates (chimpanzee, rhesus monkey, cynomolgus and baboon) was achieved by means of an immunoadsorbent technique. The immunoglobulins of a rabbit antiserum to human SP1 were isolated on DEAE-cellulose and coupled to CNBr-activated Sepharose. This immunoadsorbent was used to bind human SP1, respectively monkey proteins immunochemically related to SP1 from placental extract fractions. After extensive washing the proteins were eluted by an acidic glycine buffer. Contaminating serum proteins could be removed by chromatography on hydroxyapatite columns. With this method it was possible to obtain SP1 and the antigenically related proteins of monkeys in good yield and in highly purified form. The proteins thus isolated from human and sub-human primate placentae were compared in their physicochemical and immunochemical properties. The amino acid and carbohydrate compositions of human SP1 and rhesus SP1 have been determined. In a biological test certain inhibitory effect of human SP1 on the mixed leukozyte culture (MLC) could be demonstrated.