Antigen-Specific Immunocompetency, B Cell Function, and Regulatory Helper and Suppressor T Cell Activities in Spontaneously Autoimmune Mice

Abstract

A comprehensive analysis of the immunocompetency of three murine strains displaying spontaneous autoimmune disease was conducted at various times during the lifespan of these mice. Qualitative and quantitative comparisons have been made for antibody responses to well defined hapten-carrier conjugates between young and old autoimmune as referenced against nonautoimmune inbred mice of the same ages. Responses of intact autoimmune and normal murine strains in two immunoglobulin classes, i.e., IgG and IgE, failed to reveal any general pattern of abnormal immune reactivity that could be ascribed solely to the autoimmune phenotype; grossly deficient antibody-producing capacities that were observed in old mice of the MRL/1 strain do not necessarily relate to the existence of autoreactivity in such animals. In addition to studies in intact mice, the immunocompetency of isolated B lymphocyte and regulatory T lymphocyte populations of these autoimmune mice were assayed for functional abnormalities by utilizing adoptive transfer systems. No significant differences were observed between young and old autoimmune mice and normal control strains either in the antibody-producing abilities of adoptively primed hapten-specific B lymphocytes or in regulatory functions of antigen-specific helper and suppressor T cells. Even in those circumstances in which intact mice showed marked deficiencies in antibody responses, i.e., old MRL/1, lymphocytes removed from the native environment of such mice displayed normal reactivity patterns in adoptive transfer situations. Of special note are the results presented herein that clearly demonstrate that antigen-specific regulatory T cell functions of both helper and suppressor types are, in fact, normal in both old as well as young animals of all three autoimmune murine strains. These findings raise serious questions about previous concepts concerning the existence of any single defect or combination of immunoregulatory defects as universal pathogenetic mechanisms in the development of autoimmune diseases.