title: Functional expression of CD28 on T cell antigen receptor gamma/delta-bearing T lymphocytes.
abstract: T lymphocytes express a T cell antigen receptor (TcR) complex composed of either an TcR alpha/beta or TcR gamma/delta heterodimer in noncovalent association with the CD3 glycoproteins. CD28, a 44-kDa disulfide-linked homodimer, is present on the surface of the majority of TcR alpha/beta-bearing T lymphocytes. Monoclonal antibodies (mAb) directed against CD28 potentiate activation signals delivered through the CD3/TcR alpha/beta complex. Herein, we demonstrate that CD28 is expressed on approximately 40%-60% of TcR gamma/delta-bearing T lymphocytes in most donors. Anti-CD28 mAb substantially augmented proliferative signals delivered through the TcR gamma/delta, demonstrating the presence of functional CD28 molecules on TcR gamma/delta-bearing T lymphocytes. The majority of TcR gamma/delta+ thymocytes also expressed CD28.
authors.affiliation: Becton Dickinson Monoclonal Center Inc., Mountain View, CA 94043.
authors.forename: R
authors.initials: R
authors.lastname: Testi
authors.forename: L L
authors.initials: LL
authors.lastname: Lanier
mesh_terms: D000911:Antibodies, Monoclonal / Q000502:physiology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000276:immunology; D018106:CD28 Antigens; D002478:Cells, Cultured; D006801:Humans; D008213:Lymphocyte Activation; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D011948:Receptors, Antigen, T-Cell