We examined the antigenic and functional characteristics of human peripheral blood lymphocytes that differentially express the CD16 (Leu-11) and Leu-19 (NKH-1) antigens. Leu-19 is a ~ 220,000 daltons protein expressed on ~ 15% of freshly isolated peripheral blood lymphocytes. Within the Leu-19+ subset, three distinct populations were identified: CD3-,CD16+,Leu-19+ cells; CD3+,CD16-,Leu-19+ cells; and CD3-CD16-,Leu-19(bright+) cells. Both the CD3+,CD16-,Leu-19+ and CD3-,CD16+,Leu-19+ populations mediated non-major histocompatability complex (MHC)-restricted cytotoxicity against the NK-sensitive tumor cell K562 and were large granular lymphocytes. CD3-,CD16+,Leu-19+ NK cells were the most abundant (comprising ~ 10% of peripheral blood lymphocytes) and the most efficient cytotoxic effectors. The finding that CD3+,Leu 19+ lymphocyte mediated cytotoxicity against K562 unequivocally demonstrates that a unique subset of non-MHC-restricted cytotoxic CD3+ T lymphocytes are present in the peripheral blood of unprimed, normal individuals. However, CD3+,CD16-,Leu-19+ cells comprised <5% of peripheral blood lymphocytes, and the cytoxic activity of this subset was significantly less than CD3-,CD16+,Leu-19+ NK cells. Most CD3+,Leu-19+ T cells co-expressed the CD2, CD8, and CD5 differentiation antigens. The antigenic and functional phenotype of peripheral blood CD3+,Leu-19+ cytotoxic T lymphocytes corresponds to the interleukin 2-dependent CD3+ cell lines that mediate non-MHC-restricted cytotoxicity against NK-sensitive tumor cell targets. A small population of Leu-19(bright+) lymphocytes lacking both CD3 and CD16 was also observed. This population (comprising -,CD16-,Leu-19(bright+) lymphocytes also mediate non-MHC-restricted cytotoxicity. The relationship of these CD3-,CD16-,Leu-19(bright+) lymphocytes to CD3+ T cells or CD16+ NK cells is unknown.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - 1986|
ASJC Scopus subject areas