Different cellular requirements for inducing contact sensitivity and non-specific unresponsiveness with hapten-conjugated lymphoid cells

Primary contact sensitivity (CS) to Ox and non-specific unresponsiveness to other unrelated delayed-type hypersensitivity (DTH) containing CS were induced simultaneously by i.v. administration of oxazolone(Ox)-conjugated spleen cells. The subpopulation of spleen cells which serves as carriers for the induction of primary CS consisted of plastic-adherent, Thy 1-negative macrophage-like cells, and the carriers for the induction of non-specific unresponsiveness were non-adherent, Thy 1-positive cells. Further, allogeneic spleen cells were not capable of acting as carriers for the induction of primary CS, though H-2 restriction was not observed in the induction of non-specific unresponsiveness by Ox-conjugated cells. Thus, these two phenomena were shown to be induced by distinct pathways or distinct mechanisms. Adult thymectomy or treatment with cyclophosphamide (CY) prevents the induction of non-specific unresponsiveness. Moreover, an interval of 7 days was required for almost complete suppression of CS between treatment with Ox-conjugated spleen cells and sensitization with picryl chloride (PCl). These results suggest that relatively short-lived, CY-sensitive T cells participate in the induction of the non-specific unresponsiveness induced with Ox-conjugated cells.