[Modulation of IgE antibody synthesis by immunoglobulin-binding factors]

The presence of immunoglobulin-binding factors with immunomodulatory activity was described. These factors were shown in vivo and in vitro in experimental animals as well as in man. The IgG, IgA and IgE antibody response is affected in an isotype-specific manner. Binding factors are derived from Fc receptor-expressing T- and B-cells stimulated either by incubation with the respective immunoglobulin and/or antigen which leads to enhanced Fc receptor expression as well as secretion of the corresponding binding factor. In addition to the inducing antibody the biological activity appears to be defined by the environmental conditions. Binding factors not only exert a direct modulation of plasma cells but affect isotype-specific lymphocytes with helper or suppressor functions.