title: CD3 negative "small agranular lymphocytes" are natural killer cells.
abstract: We describe here that CD3-, CD16+ and/or CD56+ small lymphocytes, in a highly reproducible fashion, mediate a significant level of K562 killing that is, on a "per cell" basis, comparable to the cytolytic activity of CD3- LGL. The CD3- small lymphocytes appeared to have no granules based on light and electron microscopy and lack of right-angle scatter on the FACS; we thus refer to them as small "agranular" lymphocytes (SAL). The lytic activity against K562 is inhibited by treatment with either L-leucine methyl ester or EGTA, which are reported to effect granule-dependent killing. We suggest that the SAL have lytic molecules in their cytoplasm (which are sensitive to these treatments) but that these molecules are not organized into discrete granules as found in LGL. The CD3- SAL are phenotypically very similar to LGL and both SAL and LGL mediated equal and reproducible antibody-dependent cell-mediated cytotoxicity. These observations force redefinition of the concept of NK cells to include both CD3- LGL and CD3- SAL.
authors.affiliation: Department of Laboratory Medicine, University of Minnesota, Minneapolis 55455.
authors.forename: L
authors.initials: L
authors.lastname: Inverardi
authors.forename: J C
authors.initials: JC
authors.lastname: Witson
authors.forename: S A
authors.initials: SA
authors.lastname: Fuad
authors.forename: R T
authors.initials: RT
authors.lastname: Winkler-Pickett
authors.forename: J R
authors.initials: JR
authors.lastname: Ortaldo
authors.forename: F H
authors.initials: FH
authors.lastname: Bach
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity; D015703:Antigens, CD / Q000032:analysis*; D000943:Antigens, Differentiation / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D017252:CD3 Complex; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology* / Q000648:ultrastructure; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D011961:Receptors, Fc / Q000032:analysis; D017452:Receptors, IgG
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D011961:Receptors, Fc; D017452:Receptors, IgG