The Attenuation of Effectors and Induction of Suppressors of Delayed Type Hypersensitivity Reaction under the Treatment with Psoralen Photooxidation Products.

Psoralens, together with ultraviolet light A (PUVA), are used for the treatment of the series of T cell mediated diseases. The role of photooxidative reactions in psoralen phototherapy is not entirely clear. Using model of delayed type hypersensitivity (DTH) reaction to sheep red blood cells and evaluating the antibody production in mice, we investigated the influence of produced in vitro psoralen photooxidation products (POP) on the functions of T and B effectors. The research showed POP to induce inhibition of the DTH reaction independently on the phase of immune response it was injected. It was revealed that in vitro POP treatment of splenocytes, containing mature effectors, partially impaired their capacity to transfer the DTH reaction. The POP effect was not related to the direct cytolysis. In vivo POP injection to sensitized mice-donors resulted in much stronger alteration of DTH effectors than in the case of in vitro POP treatment. We elaborated the model for evaluation of functional activity of DTH suppressors. Using the model, we found that, being intravenously injected, POP induced DTH suppressors other then T cells. Furthermore, it was shown that intravenously injected POP did not affect antibody production. Thus, the POP selectively influenced T cells and had no effect on B cells. Probably, psoralen photooxidation products may be used for the therapy of some hyperproliferative T cell mediated diseases.