Differences in Sensitivity to a Cytotoxic Anti-Thymus-Derived Lymphocyte Serum of Cells Mediating Delayed-Onset Reactions in Guinea Pigs to Hapten-Protein Conjugates and Contactants

Lymph node cells from guinea pigs immunized with a reactive dinitrophenyl (DNP) compound in complete Freund\u27s adjuvant were treated with a cytotoxic anti-guinea pig thymus-derived lymphocyte (T cell) antiserum prior to transfer to unimmunized recipients to study the functional cell types active in mediating delayed-onset hypersensitivities. Attempts were also made to block the passive transfer of delayed-onset sensitivities with an anti-guinea pig κ chain serum. The data indicate that delaye-donset sensitivities to contactant and to PPD are mediated by T cells easily killed by a high dilution of anti-T cell serum but not affected by a low dilution of anti-κ chain serum. Surprisingly, the delayed-onset response to DNP conjugates was undiminished after treatment with anti-T cell serum which suggests that this sensitivity is not mediated by cells mediating the other delayed-onset sensitivities. In both actively and passively sensitized animals, contact sensitivity was highly specific for DNP; in contrast, delayed-onset sensitivity to conjugates was elicited nearly as well by DNP as by TNP conjugates, a characteristic cross-reactivity often seen in serum antibodies to DNP. Despite the differences among them, all three types of delaye-donset sensitivity were cell-mediated and could not be passively transferred by heat-killed cells or serum