Interrelationships of surface immunoglobulin and Fc receptors on mouse B lymphocytes

Receptors for the Fc portion of immunoglobulin (Ig) molecules have been detected on mouse B lymphocytes by an immunofluorescence technique, employing immune complexes of fluorescein conjugated KLH and rabbit anti KLH antibody. At 37⁰C, membrane bound complexes rapidly undergo capping and clearing from the surface. Modulation of Fc receptors does not alter the amount of distribution of surface Ig, indicating that these two molecules are independent moieties. However, capping of surface Ig by intact or pepsin digested anti Ig antibody leads to co capping of Fc receptors. These results suggest that ligand binding to surface Ig induces some alteration which allows the Ig to enter into an association with Fc receptors.