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Antigen-specific desensitization of human basophils.

Previous studies with isolated cell systems have shown desensitization (i.e., the induction of immunologic unresponsiveness after exposure to a stimulus under suboptimal conditions) to be antigenically nonspecific. Using pollen antigens and a bivalent penicillin antigen, [BPO] 2 , we found that, under conditions of passive sensitization, antigen-specific basophil desensitization occurred. Nonspecific desensitization always occurs with anti-IgE, and basophils of most atopic donors show nonspecific desensitization to antigens. Atopic donors were found, however, whose cells could be desensitized to one antigen while responding to noncross-reacting antigens and anti-IgE. Kinetic studies of desensitization revealed no differences between cells undergoing specific vs nonspecific desensitization. In the [BPO] 2 system, removal of the antigen from the basophils by washing or by hapten ([BPO] 1 ) competition did not reverse the specific desensitization to [BPO] 2 ; passive replacement of specific IgE antibody did restore the response. Two types of desensitization, therefore, exist: 1) specific, which probably occurs due to the functional loss of some part of the IgE antibody-receptor complex and 2) nonspecific, involving the change noted above as well as an intracellular, biochemical alteration. Our data indicate that basophils with few IgE molecules undergo specific desensitization, whereas nonspecific desensitization occurs in basophils with many surface IgE molecules.