In vitro synthesis of carbohydrate-binding proteins by human leucocytes

A carbohydrate-binding protein (CBP) synthesized in vitro by normal human peripheral leucocytes was isolated by affinity chromatography on asialofetuin-Sepharose. The CBP was eluted with lactose and it had a native molecular mass of 15,500 daltons. Analysis by SDS-PAGE revealed a single polypeptide of 18,000 daltons. CBP synthesis was time dependent and cell concentration dependent. The CBP appeared to be both cell bound and secreted with the apparent amount secreted inversely proportional to cell concentration. CBP did not appear to be synthesized by T and B leukemic cell lines examined. Promyelocytic HL-60 cells, however, synthesized at least two lactose-eluted CBP's corresponding to native molecular masses of 28,000 and 19,500 daltons. SDS-PAGE analysis of radiolabelled HL-60 CBP's showed the presence of two polypeptides of MM 17,700 and 16,000 daltons suggesting that one of the CBP's was a dimer.