Gangliosides inhibit the proliferation of human T cells stimulated with interleukin-4 or interleukin-2

T cell growth factors such as interleukin-2 (IL-2) and interleukin-4 (IL-4) act as potent comitogenic factors for purified human T cells in the presence of phorbol myristate acetate (PMA). We investigated the effects of gangliosides on the IL-4-driven or IL-2-driven proliferation of human T cells, using these comitogenic assays. Bovine brain gangliosides inhibited the proliferation of human T cells activated by PMA + IL-4 or PMA + IL-2. These inhibitory effects were dose and time-dependent and were significant at concentrations higher than 50 μM. PMA + IL-2 stimulation was more sensitive to the inhibitory effects of gangliosides (I₅₀ = 77.2 μM) than PMA + IL-4 stimulation (I₅₀ = 105.9 μM). Differential inhibitory effects were also examined among the panel of various gangliosides. GD1b and GT1b showed the most potent inhibitory actions in each assay; the inhibitory effect of GD1a was somewhat less potent than GD1b or GT1b. GM2 and GD3 were only weakly inhibitory, and the inhibitory effect of GM3 was almost negligible. These findings suggest that gangliosides may play an immunomodulatory role by interfering with IL-4 or IL-2-driven proliferation of human T cells.