Delayed Hypersensitivity to Fungal Antigens in Mice. I. Use of the Intradermal Skin and Footpad Swelling Tests as Assays of Active and Passive Sensitization

Mice were sensitized to Coccidioides immitis and Candida albicans antigens and tested for sensitivity by the intradermal and footpad swelling methods. In mice actively sensitized with killed antigen, antigen-specific intradermal and footpad induration responses occurred 24 and 48 hr after sensitization. Antigen-specific intradermal and footpad responses were transferred to normal mice with spleen cells from immune animals. Such responses were also transferred with normal spleen cells that had been incubated in vitro with immune RNA preparations. Histologic studies of intradermal reactions showed a mixed response of neutrophilic and mononuclear leukocytes, with slight vascular involvement compatible with delayed hypersensitivity. No intradermal or footpad responses were observed 4, 24, or 48 hr after injection in recipients of serum from actively sensitized mice. Histologic examination of skin sites in these mice revealed only a polymorphonuclear response. It is concluded that these intradermal and footpad responses are the result of delayed hypersensitivity and can be used as assays for this type of immunity in mice.