The transition from specific to nonspecific desensitization in human basophils

Human basophils can be desensitized to IgE-mediated stimuli either specifically (to the desensitizing antigen only) or nonspecifically (to all antigens). It has been suggested that the specificity of desensitization depends on the number of membrane-bound, antigen-specific IgE antibody molecules per basophil. We have varied the number of IgE antibody molecules/basophil by passive sensitization of mixed leukocyte preparations with increasing concentrations of purified IgE anti-penicillin (BPO) antibody. The cells were then desensitized with penicillin-human serum albumin (BPO-HSA). Desensitization was specific (lack of response to BPO-HSA only) with 1000 specific antibody molecules/basophil, and increasingly nonspecific (greater than 70% desensitization to rechallenge with anti-IgE and ragweed antigen E as well as lack of response to BPO-HSA) as the number of antibody molecules was increased to 14,000. This formally established that the number of specific IgE antibody molecules/basophil determines the mode of desensitization.