Purification of naturally occurring antibody to human placental lactogen by affinity chromatography

Antibodies against human placental lactogen (HPL) were isolated from maternal postpartum sera and nonpregnant female sera by the technique of immunoadsorption (or affinity chromatography). HPL was linked to Sepharose gel by cyanogen bromide activation and the resultant chromatographic resin was used in a repetitive column procedure to absorb and fractionate naturally occurring antibodies to HPL. The antibody to HPL was concentrated after elution from the column with a chaotropic ion, and tested for immunologic acitivity. It was determined to be an IgG molecule, and only radioimmunoelectrophoresis was sensitive enough, among the several tests performed, to show specific anti-HPL activity after treatment.