Inducing specific reactivity against B cells in mice by immunizing with an Fc fusion protein containing self-Ig?

A recombinant chimeric fusion protein, muIg?-hu-y4.Fc, composed of the extracellular domain of mouse Ig? (CD79b) and the CH2-CH3 domains of human IgG-y4.Fc (hu-y4.Fc), linked via an immunologically inert flexible peptide, was prepared. The fusion protein was evaluated for its ability to induce specific auto-reactive immune response against Ig? and to modulate B cell activity in Balb/c mice. Upon immunization with muIg?-hu-y4.Fc, mice developed immunoglobulin (IgG) against self-Ig?, which could bind to the cells of a mouse B cell line expressing Ig? on the cell surface. The proportion of B cells in mononuclear cells in the peripheral blood (PBMC) of treated mice decreased as compared to that of mice immunized with hu-y4.Fc without the Ig? component. Furthermore, mice immunized against muIg?-hu-y4.Fc displayed a reduced antibody response against an irrelevant antigen. The implications of employing the present approach in developing a therapeutic strategy for regulating B cell activity has been discussed.