Monoclonal anti-GD3 antibodies selectively inhibit the proliferation of human malignant glioma cells in vitro

The frequently occurring alteration of ganglioside expression in tumor cell s has been implicated to play a role in the uncontrolled growth of these ce lls; antibodies to such gangliosides might affect tumor cell growth. We hav e studied the effect of IgM monoclonal antibodies to two glioma-associated gangliosides, GD3 and GM2, on cell proliferation of four human glioma cell lines and one renal tumor cell line. Of the two anti-ganglioside antibodies tested, only the anti-GD3 antibody resulted in a significant (p <0.005) in hibition of cell proliferation as measured by thymidine incorporation and B rd-U labeling, after 24 h incubation. The effect was not dependent on any s erum factor and no increased cell death was observed. All cell lines contai ned higher or similar amounts of GM2 than GD3, and both antigens were shown to be expressed on the cell surface and accessible to antibodies. The sele ctive effect of anti-GD3 antibodies as contrasted to the inactivity of anti -GM2 antibodies suggests a possible role for ganglioside GD3 in tumor cell proliferation.