Recombinant glycophorins C and D as tools for studying Gerbich blood group antigens

BACKGROUND: The Gerbich blood group system antigens are carried on glycophorin C (GPC) and glycophorin D (GPD) and variants thereof. These glycoproteins have been expressed in a heterologous system to study the individual antigens and to determine whether An(a) is antithetical to Ge2. STUDY DESIGN AND METHODS: cDNAs encoding GPC, GPD, GPC.Yus, GPC.Ge, GPC.Ls(a), and GPD.Ls(a) were transfected and stably expressed in a human embryonic kidney cell line (293T). Individual Gerbich antigens were analyzed with MoAbs and human polyclonal antibodies by flow cytometry and immunoblotting. Recombinant GPD and GPD.An(a) were expressed transiently and analyzed for expression of Ge2 and Ana antigens. RESULTS: All recombinant variants were detected with sialidase-resistant and -sensitive anti-Ge2, anti-Ge3, and anti-Ge4. Ge4 antigen expression was depressed in GPC.Ls(a) transfectants as well as on Ls(a+) RBCs. GPD.An(a) recombinant protein expressed An a and Ge2 antigens. CONCLUSION: Cell lines stably expressing glycosylated Gerbich proteins were developed in a heterologous system by transfecting individual variant forms of GPC and GPD. Unexpectedly, it was found that Ge4 antigen is reduced in both the GPC.Ls(a) recombinant and the Ls(a+) RBCs. It was also shown that An(a) and Ge2 antigens were expressed on a single GPD.An(a) protein and, therefore, they cannot be antithetical.