The specificity of the Fc receptor on murine lymphocytes for immunoglobulins of the IgG and IgM classes.

It is shown that the Fc receptor for IgG on lymph node cells recognizes IgG molecules of mouse IgG1, IgG2a and IgG2b subclasses. The presence of an intact CH3 domain is required to bind IgG to the Fc receptors. While monomeric IgG molecules are shown to bind to Fc receptors, heat aggregated IgG was found to bind more efficiently. The various forms of IgM molecules investigated show only weak or no binding in comparison. The significance of these results is discussed with relevance to the possible biological function of the Fc receptors on lymphocytes.