Objective: To examine if monoclonal antibody PD4 (McAb PD4) which identifies a surface antigen of 40 kD (P40) expressed in gastric carcinoma cells could induce tumor cell apoptosis.
Methods: The antibody was tested for its effect on cell cycle and cell injury in gastric carcinoma cell MGC-803 by flow cytometry, DNA electrophoresis and TdT assay. Fas antigen expression in MGC-803 was also examined.
Results: McAb PD4 could block tumor cell proliferation cycle and trigger cell death by inducing apoptosis, but expression of Fas antigen in MGC-803 cells was negative.
Conclusion: P40 is a tumor associated antigen which is distinct from Fas antigen. Molecular cloning of P40 will clarify the pathway and mechanism of apoptosis induced by this monoclonal antibody.