Immunoglobulins and disease

All antibodies belong to the group of proteins called immunoglobulins. Every immunoglobulin molecule has a fundamentally similar structure made up of two identical heavy polypeptide chains attached to a pair of identical light chains. There are two major types of light chain, designated kappa and lambda, associated with the heavy chains of all immunoglobulins. The class of an immunoglobulin molecule depends on the constituent heavy chain and is independent of the light chain type. A single immunoglobulin molecule has identical light and identical heavy chains. The B lymphocyte response to a single antigen includes specific antibody molecules of all five immunoglobulin classes. Antibodies of different classes show identical antigen-binding specificities and, thus, possess identical variable regions; however, the constant regions mediate different secondary effector functions. This chapter presents some typical patterns of polyclonal increase in immunoglobulins found in diseases.