Deoxyspergualin directly suppresses antibody formation in vivo and in vitro.

The effect of deoxyspergualin (DSG, NKT-01) on humoral immunity was investigated both in vitro and in vivo. DSG inhibited the primary and secondary responses to T cell-dependent antigens and the response to T cell-independent antigens in thymic and athymic mice. However, natural antibodies in non-sensitized mice were affected less by the administration of DSG. The agent produced a dose-dependent inhibition of B cell proliferation and antibody production to lipopolysaccharide in vitro. Suppression of secondary antibody response was also shown, whenever antigen stimulation was not given, antibody production was not affected. These results suggest that DSG affects the proliferative stage of B lymphocytes in such a way as to inhibit their growth and antibody production.