DISTINCT GRANZYME EXPRESSION IN HUMAN CD3(-) CD56(-) CD56(+) SMALL HIGH-DENSITY LYMPHOCYTES DISPLAYING NON-MHC-RESTRICTED CYTOLYTIC ACTIVITY() LARGE GRANULAR AND CD3()

Cultured natural killer (NK) cells derived from CD3(-) CD56(+) high-de nsity small lymphocytes (HDLs) exhibit similar morphology and high lev els of non-major histocompatibility complex-restricted (NK) cytotoxici ty equivalent to those of cultured NK cells from CD3(-) CD56(+) low-de nsity large granular lymphocytes (LGLs). To examine the similarities a nd differences between NK cells from HDLs and NK cells from LGLs, we i nvestigated the expression of three distinct members of the granule se rine protease (granzyme) family within cultured CD3(-) CD56(+) LGLs an d HDLs. CD3(-) subpopulations of nonadherent peripheral blood mononucl ear cells, LGLs (density < 1.063 g/ml), and HDLs (density > 1.063 g/ml ) were stimulated to proliferate in culture. The cultured cells from e ach population were entirely CD3(-) CD56(+) and were indistinguishable in terms of their increased granularity and size once activated. All cultured CD3(-) CD56(+) LGLs and HDLs displayed cytolytic activity aga inst K562 and immunoglobulin-coated P815. Western analysis detected pe rforin in both cultured LGL and HDL populations. Cultured HDLs and LGL s both expressed BLT-esterase activity and human granzyme A mRNA. Gran zyme B mRNA and protein and Asp-ase activity were detected in unstimul ated and cultured LGLs and cultured HDLs. By contrast, unstimulated HD Ls did not express significant levels of granzyme B. High levels of Hu -Met-1 granzyme mRNA and Met-ase activity were detected only in cultur ed LGLs. Thus, despite the development of large granular morphology du ring proliferation, interleukin-2 cultured CD3(-) CD56(+) HDLs display a different pattern of granzyme expression from CD3(-) CD56(+) LGLs. These data also further suggest an unusually restricted expression of the Hu-Met-1 granzyme in LGLs.