The control of the contact sensitivity skin reaction: T-suppressor afferent cell blocks the production of antigen-specific T-helper factor.

Lymph node cells from mice painted with the contact sensitizers picryl chloride or oxazolone produce antigen-specific T-helper factor. This is detected by its ability to increase the contact sensitivity response to the injection of small numbers of haptenized spleen cells into the footpads of naive recipients. The production of this T-helper factor is inhibited by the injection of spleen cells from mice given water-soluble, chemically reactive hapten such as picrylsulphonic (trinitrobenzenesulphonic) acid--an agent which induces unresponsiveness. The cells which inhibit the production of T-helper factor are antigen-specific T-suppressor cells. They are sensitive to cyclophosphamide given before the injection of picrylsulphonic acid, but are unaffected by adult thymectomy. In this respect, they resemble the family of Ts-aff which inhibit the development of contact sensitivity, specific antigen-induced lymph node proliferation and the specific IgG response, and differ from the T-suppressor efferent cell (Ts-eff) which acts at the expression stage of the contact sensitivity reaction. These results are fully compatible with the view that the Ts-aff inhibits the development of contact sensitivity by blocking the production of antigen-specific T-helper factor.