Mechanisms of regulation of cell-mediated immune responses. I. Effect of the route of immunization with TNP-coupled syngeneic cells on the induction and suppression of contact sensitivity to picryl chloride.

A new method for inducing contact sensitivity (CS) responses has been developed. The subcutaneous injection of trinitrophenyl (Tnp)-derivatized syngeneic spleen cells into BALB/c mice, without adjuvant, could lead to significant ear swelling CS responses upon challenge of the ear with the same hapten, i.e., picryl chloride (PCI). This response was transferred by lymphoid cells obtained from immunized animals. Such cells were judged to be thymus-derived (T) cells as they could be obtained by nylon wool passage and were sensitive to treatment with AKR anti-Thy 1.2 serum and C. The response displayed the characteristic time course of cell-mediated immune reactions and was maximal at 24 hr after challenge. Histologic investigation revealed a marked mononuclear cell infiltration into the lesion site. The i.v. administration of either 2,4,6-trinitrobenzene-sulfonic acid (TNBS), or the same moieties capable of eliciting CS, viz, Tnp cells or Tnp cell membranes, could suppress the generation of Tnp cell-induced CS reactions. It was also possible to suppress the CS response by the i.v. transfer of suppressor T cells or factor(s) obtained from suppressed mice. Furthermore, it was found that Tnp-derivatized syngeneic macrophage (Mø) were more capable of inducing CS responses than similarly derivatized spleen cells or thymocytes, suggesting that Mø surface was a better presentation template for the induction of CS. The notion that the route of presentation of hapten-modified syngeneic membranes dictates the response evoked, i.e., immunity when presented subcutaneously but suppression when the encounter is via the i.v. route, is discussed.