Carbohydrate composition of peripheral, cultured and leukaemic human lymphocyte plasma membranes

Abstract

Plasma membranes isolated from peripheral blood lymphocytes of normal donors, lymphocytes from patients with chronic lymphatic leukaemia (CLL), a T cell and B cell line (MOLT-3 and RPMI-1788) were analysed and compared for total carbohydrate contents. T cells and peripheral blood lymphocytes contained the highest relative amounts of sialic acid and fucose, whereas chronic lymphatic leukaemic cells possessed the highest amounts of N-acetylgalactosamine and also more total cell surface carbohydrate. The Thomsen-Friedenreich antigen (TF) was detected serologically on membrane fractions by the use of anti-TF containing sera and specific lectins from Arachis hypogaea, Agaricus bisporus and Vicia graminea. The disaccharide beta-D-galactosyl(1-3)-N-acetyl-D-galactosamine is the immunogdominant carbohydrate group of the FT antigen and was detected as its reduced form, by gas chromatography, in all cells, thus correlating serological and analytical evidence. The haemagglutinating activity of the lectins and sera used was only inhibited by plasma membranes after the removal of sialic acid showong that the native form of this antigen is normally masked by sialic acid in CLL cells as well as normal lymphocytes.