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Title: Identification and functional characterization of guinea-pig CD4: antibody binding transduces a negative signal on T-cell activation. Author: Schäfer H, Burger R. Journal: Immunology; 1991 Feb; 72(2):261-8. PubMed ID: 1826670. Abstract: The guinea-pig (gp) CD4 protein was identified using the rat monoclonal antibody (mAb) H155 derived from an interspecies hybrid. The hybrid was obtained after immunization of rats with purified guinea-pig T lymphocytes and fusion to a mouse myeloma line. The mAb H155 reacted with a subpopulation (60-70%) of nylon-wool-purified guinea-pig T cells. The majority of thymocytes also expressed the H155 antigen. Immunohistological staining showed that predominantly the cortical thymocytes were H155-positive, whereas a part of the medullary cells did not express the antigen. After cell-surface radioiodination of T cell lines, the mAb H155 immunoprecipitated a molecule of about 55,000 MW both under reducing and non-reducing conditions. The antigen recognized by mAb H155 on guinea-pig T cells resembles the human or mouse CD4 antigen. Depletion experiments in combination with functional studies further supported this assumption. In proliferation assays mAb H155 inhibited T-cell responses in vitro. Both the antigen- and alloantigen-induced T-cell activation were impaired in the continuous presence of mAb H155. In addition, mAb H155 inhibited both the mitogen-induced T-cell activation and T-cell proliferation induced by mitogenic mAb and phorbol myristate acetate (PMA). Binding of the mAb H155 to the CD4 molecule might therefore transduce a negative signal on T-cell activation.[Abstract] [Full Text] [Related] [New Search]