Suppressor cells in antigenic competition in contact allergy in mice.

The effects of cyclophosphamide (CY) thymectomy and splenectomy on the antigenic competition in contact hypersensitivity between dinitrofluorobenzene (DNFB) and picryl chloride (PCI) was investigated. Contact sensitivity of PCI was suppressed by a prior painting of DNFB. When these two sensitizers were painted 7 days apart and CY was injected 3 days after the painting of DNFB, the antigenic competition did not occur. On the other hand, when CY was injected 3 days before painting of DNFB, the antigenic competition was partially abolished. The antigenic competition was seen in mice 2 weeks after adult thymectomy and in splenectomized mice. However, antigenic competition did not occur in mice 6 weeks after thymectomy. These results suggest that some thymus-derived cells may be involved in the antigenic competition in contact sensitivity.