Enhancement of contact sensitization in mice fed a diet enriched in vitamin A acetate

Various methods have been used to enhance the ability of laboratory animals to develop contact sensitivity to so-called weak sensitizers. The present studies have examined whether diets supplemented with vitamin A acetate (VAA) could enhance induction and elicitation of contact sensitivity to oxazolone in the mouse. Application of 0.3% oxazolone to VAA-fed mice resulted in increased DNA synthesis in the draining lymph nodes and increased ear thickness after challenge, in comparison with mice on a stock (standard) diet. Moreover, VAA-fed (but not control) mice were sensitized to 0.03% oxazolone as shown by DNA synthesis, increased arrival of syngeneic 51Cr-labelled lymphocytes in the draining lymph nodes, and ear swelling after challenge. These findings demonstrate that vitamin A enhances delayed hypersensitivity responses, and point to a role for vitamin A in developing an animal model capable of detecting weak contact sensitizers after topical application.