NANOMOLAR CONCENTRATIONS OF GANGLIOSIDES STIMULATE PRIMARY HUMORAL RESPONSE

Exogenous gangliosides act as immunosuppressors when applied at microm olar concentrations corresponding to their average level in human plas ma. Here we show that at nanomolar concentrations the gangliosides GD3 , GD1a and GM1 can act as immunostimulators markedly enhancing the num ber of plaque-forming cells in mouse splenocyte culture responding to sheep erythrocytes. At such low concentration these gangliosides as we ll as GM3 were not able to influence significantly proliferative respo nses of splenic B and T lymphocytes or of cytotoxic T-cells. Neither d id they change significantly the production of IL-1 by antigen-represe nting cells, or of IL-2 by Con A-induced blasts In the splenocyte cult ure. It is suggested that the stimulatory effect of low ganglioside co ncentrations on humoral response is due to their influence on cooperat ive cell-cell interactions required for the differentiation of B-cells into Ig-secreting cells.