Enhancement of the in vitro antibody response in dietary protein restriction. Failure in the regulation of antibody synthesis

We have studied the antibody response in vitro of spleen cells from C57BL/6 mice kept on a protein deficient (D) or a normal diet (N). Short or long term protein restriction initiated after weaning led to increased plaque forming cell (PFC) responses to sheep red blood cells (SRBC), TNP-ficoll and TNP lipopolysaccharide. The influence of dietary restriction on the suppression of the antibody response to SRBC was studied in mixed cultures of antigen sensitized and fresh, non-immune cells from either D or N donors. Addition of pre-sensitized D or N cells to non-immune N spleen cells in a 1:1000 ratio resulted in marked suppression of the PFC response whereas co-cultures of pre-sensitized cells and non-immune D spleen cells did not result in significant suppression. Similarly, non-immune T cells from DF mice exerted a lower suppressor effect than non-immune T cells from N mice. Either dietary restriction or low dose cyclophosphamide treatment of the donors of non-immune spleen cells determined a similar reduction in suppression. It is suggested that nutritional deficiency selectively depletes short-lived suppressor effector lymphocytes which are activated in the presence of antigen-stimulated inducer cells.