Human monoclonal anti-T cell antibody from a patient with juvenile rheumatoid arthritis.

Antibody JRAI is a human monoclonal IgM antibody derived from a patient with juvenile rheumatoid arthritis that is cytotoxic to a subpopulation of normal T lymphocytes. JRAI recognizes approximately 80% of normal peripheral blood T cells, 90% of CD4+ cells, and 75% of CD8+ cells, as determined by complement-mediated cytotoxicity. Within the CD8+ population, JRAI preferentially spares OKM1+ and Leu-11+ cells. These CD8+ cells retain suppressor-effector potential and show enriched natural killer cell activity. Within the CD4+ population, JRAI preferentially kills cells within the Leu-8+ subset, which contains suppressor-inducer cells, and spares the Leu-8- subset, which contains the helpers for immunoglobulin synthesis. JRAI appears to recognize a previously undefined human lymphocyte surface molecule expressed differentially on phenotypically and functionally distinct subsets of human T cells.