Non-MHC-restricted T cell antigen-binding proteins

Abstract

T cell Antigen Binding Molecules (TABM) represent a new group of antigen-binding moieties produced by the immune system and some of their structural properties are discussed in the chapter. These molecules differ from known immunoglobulins although they resemble immunoglobulins produced by “lower” vertebrates. Their antigen-binding properties, while significant, are not as strong as those of immunoglobulins. These are difficult molecules to work with because their multimeric structure is easily perturbed and they can stick to plastic or glass surfaces. Accordingly, care must be taken to prevent loss during storage and to avoid nonspecific binding in binding assays. Because these molecules are globular proteins with some properties similar to immunoglobulins they may “contaminate” immunoglobulin preparations and vice versa. Fortunately, they are readily separable from “conventional” immunoglobulins. Once isolated, TABM can be used to prepare anti-TABM antibodies to be used as a general probe for these molecules, as well as defining the protein structure and functional properties of these purified proteins.