Vitamin A acetate as a regulator of accessory cell function in delayed-type hypersensitivity responses.

Mice fed on a vitamin A acetate (VAA)-supplemented diet respond to concentrations of oxazolone which are too low to elicit contact sensitivity on a standard diet. This study has investigated whether enhanced responsiveness could be due to VAA-induced changes in antigen-presenting cell function. The draining lymph nodes were used as the source for accessory cell populations, and cells from control and sensitized mice on either standard or VAA diet were compared in syngeneic and allogeneic responses. Their ability to induce delayed-type hypersensitivity reactions was also compared. There was no qualitative difference between accessory cells from the standard and VAA-fed groups respectively, but there was already a striking quantitative increase in the number of accessory cells which correlated with augmented sensitization. These findings are consistent with the postulate that the effect of VAA may be associated with regulation of accessory cell function, and that susceptibility to contact sensitization can be modified by quantitative changes in antigen presentation.