Tissue distribution of human NK cells studied with anti-Leu-7 monoclonal antibody

The distribution and numbers of human natural killer (NK) cells in different lymphoid tissues and several tumors were determined with the use of monoclonal antibody to the Leu-7 antigen and immunohistologic methods. Anti-Leu-7 reacts with large granular lymphocytes containing most of NK activity in the peripheral blood. The Leu-7+ cells were found mainly in the germinal centers of secondary follicles in lymph nodes, spleens, and tonsils. The mean number of Leu-7+ cells in 40 germinal centers was 223 +/- 103 SD. Only rare cells were found in the thymus. In the follicles studied in serial sections, the distribution of the Leu-7+ cells was distinctly different from that of T cells, B cells and Ia+ cells. The Leu-7+ cells did not react with OKT 6 antibody specific for immature (control) thymocytes and Langerhans' cells. By double staining techniques, two populations of Leu-7+ cells were identified in lymphoid tissues: those that did and did not express the Ia-like antigen. The numbers and localization of the Leu-7+ cells varied in different tumors, but often the Leu-7+ cells surrounded the neoplastic nodules or were seen in contact with individual cancer cells. Anti-Leu-7 may be a useful reagent for monitoring the presence and localization of NK cells in normal and malignant human tissues.