Abstract
Human placental trophoblast interferon (tro-IFN), induced in trophoblast cultures by a superinduction procedure, was purified to a homogeneous product with retention of biological activity. The problems associated with isolation from serum-containing medium were overcome by a combination of Blue Sepharose affinity chromatography and reversed- phase HPLC (RP-HPLC) on Separon SGX C-18. This two-step purification procedure yielded tro-IFN with a specific activity of 3.4 x 10(7) international units/mg of protein. The overall recovery of interferon activity was 66.7%. The purified tro-IFN was shown to be a glycoprotein with an Mr of 24K on native and SDS-PAGE. Its antiviral activity was stable at pH 2.0 at 37 degrees C but was sensitive to heat at 56 degrees C for 1 h and was neutralized by antibodies to human IFN-beta.