An analysis of allergy, immunoglobulin E, and diagnostic skin tests in schistosomiasis.

Factors governing the sensitization or desensitization of basophils and mast cells are discussed. Mathematical models are proposed which illustrate the effects of rising or falling specific or non-specific IgE titres on the tendency of these cells to degranulate. The models presented are consistent with the hypothesis that fine-tuning of the degranulatory event is achieved by one or more of the following mechanisms: alteration of the number of IgE receptors on the mast cell membrane; displacement of specific anti-schistosomal IgE by anti-other-IgE molecules; clipping or otherwise inactivating mast cell-fixed specific IgE receptor sites so as to render these incapable of binding antigen. Mechanisms proposed may explain how a mast cell population may evolve from highly sensitive to non-reactive allergic states during early and/or chronic periods of schistosomiasis, only to revert to highly sensitive states once again, after the disease has been overcome.