Desensitization of contract allergy to 2,4-dinitro-1-fluorobenzene in mice. II. Characteristics of "immediate" desensitization.

The immediate effects and mechanisms of desensitization of contact sensitivity to 2,4-dinitro-1-fluorobenzene (DNFB) were investigated. Mice were sensitized with DNFB, desensitized with antigen 2 weeks later, and challenged 1 day after desensitization. Significant inhibition (approximately 50%) of contact sensitivity was observed after iv injections of large doses of dinitrobenzene sulfonic acid (DNBS) or dinitropenol (DNP)-labeled spleen cells. Haptenated red blood cells (RBC) did not induce any significant immediate desensitization but produced significant inhibition of an anamnestic response 2 weeks later. The immediate desensitization induced by DNBS was antigen nonspecific. Although the contact sensitivity response itself could be inhibited by afferent- or efferent-acting suppressor cells, such cells were not demonstrated in desensitized animals. DNBS appears to desensitize by inactivating effector cells for contact sensitivity, although it appears that suppressor mechanisms could be activated by other physiochemical forms of the desensitizing antigen.