In order to determine the type of the McAb which is a kind of MNSs blood group secreted by 6D7C9 cells line, the heterologous systems expressing GPA and GPB blood group antigens were constructed by molecular biological technology such as cloning,subcloning and cell transfection. These transgenic cells were used as antigens to determine the McAb secreted by 6D7C9 through ELISA and Western blot analysis. The results showed that the GPA and GPB genes could be amplified by RTPCR successfully. By inserting amplified fragments into retrovirus vector pEGZ, the constructed recombinant vectors were transfected into the package cell 293T and then infected L929 cells. The L929 cell clones stably expressing the GPA and GPB respectively were obtained in the presence of zeocin (500 μg/ml). The transcripts and proteins of GPA and GPB in L929/GPA and L929/GPB transgenic cell lines were further confirmed by RT－PCR and flow cytometry. ELISA and Western blot analysis showed that the 6D7C9 cells line was capable to secrete the McAb against GPA/GPB. The results indicated that a heterologous system stably expressing GPA and GPB at a high level was successfully constructed. The method might be used for the detection of MNSs blood group McAb and also for the study of the function of GPA and GPB proteins.