Immunoglobulin Receptor-Associated Molecules

Abstract

Publisher Summary This chapter discusses the current knowledge concerning the molecules associated with immunoglobulin receptor (IgR) and advances in the study of the B cell activation mechanism. One of the most important functional molecules in the immune system, have clarified the structure and expression of immunoglobulin molecules composed of tetramer polypeptide components, heavy and light chains. Studies of the organization and rearrangement of immunoglobulin genes in the development and maturation of B lymphocytes demonstrated the molecular mechanism of immunoglobulin variable (V) region diversity, which is the source of antibody specificity. B cells are considered to originate from the multipotent hematopoietic precursor cells in the fetal liver or in the bone marrow of adult mice. The developmental stages of B lineage cells are characterized with respect to expression of IgR and the immunoglobulin gene configurations and to expression of B cell-specific surface antigens. The chapter presents a model of B cell development. During maturation of B lineage cells, the expression, structure, and function of IgR differ with the differentiation stage. The isotypes and functions of IgR are discussed. Most peripheral B cells express two distinct immunoglobulin isotypes (IgM and IgD) simultaneously, and both IgR isotypes are capable of binding the same antigen or anti-idiotypic ligands. Antigenic stimulation or IgR crosslinking induces B cells to proliferate and differentiate into antibody-secreting cells with the help of T cells or soluble mediators.