Monoclonal antibodies against unique I-region gene products expressed only on mature functional T cells

Abstract

The immune response (I) region of the murine major histo-compatibility complex (MHC) regulates specific immune responses against antigens1 and encodes cell-surface molecules designated as Ia antigens2. Ia antigens are generally detected on B cells and macrophages, and have important roles in immunocyte interactions. On the other hand, it has been reported that some T cells and their products (antigen-specific T-cell factors) carry unique I region-encoded determinants which are different from B-cell Ia antigens3–10. As T-cell factors are known to mediate T–T and T–B cell interactions11, elucidation of such unique I-region determinants on T cells is obviously important for understanding the regulatory cell interactions of the immune response. However, this has long been hampered by the lack of reagents specific for the determinants and due to the small number of T cells expressing them. To overcome this difficulty, cell hybridization techniques have been used to develop T-cell hybrids which continuously express I-region products, and monoclonal antibodies specific for these determinants have been produced. Here we report the production of monoclonal antibodies which detect a unique set of I-region determinants expressed only on functional subsets of T cells and T-cell hybridomas.