title: Relationship of large and small CD3- CD56+ lymphocytes mediating NK-associated activities.
abstract: We have defined a population of CD3-, CD56+ small lymphocytes (SLs) that exhibit the same phenotype and lytic capacity as natural killer (NK) cells. NK cells characteristically express the surface markers CD16 and CD56, mediate non-major histocompatibility complex (MHC)-restricted lysis, and have been equated with CD3- large granular lymphocytes (LGLs). In the present study we extended the observation that CD3-, CD56+ SLs can mediate NK- and antibody-dependent cellular cytotoxicity activity by studying the activation signals and lytic mechanisms that might be utilized by CD3-, CD56+ SLs in comparison to CD3- CD56+ LGLs. Our results show that CD3- SLs, similar to CD3- LGLs, exhibited activated killing in response to interleukin-2 (IL-2). In addition, after IL-2 activation, the CD3- SLs exhibited morphologic changes, including increases in size and granularity, and both morphologically and phenotypically became virtually indistinguishable from CD3- LGLs. Similar to CD3- LGLs, CD3- SLs could be directly activated by IL-2 alone to secrete significant quantities of interferon-gamma (IFN-gamma) and to express IL-2 receptor (IL-2R) p55. Examination of serine esterases and pore-forming protein (PFP) demonstrated that these cells exhibited a cytoplasmic distribution of perforin, which, unlike that of CD3- LGLs, was not associated with dense cytoplasmic azurophilic granules. Serine esterase levels were similar. However, after IL-2 activation PFP was concentrated in dense cytoplasmic granules, similar or identical to the situation in CD3-, CD56+ LGLs. These CD3-, CD56+ subsets appear to represent a continuum of activated cells that might represent various states of maturation of NK cells.
authors.affiliation: Laboratory of Experimental Immunology, BRMP, DCT, NCI-FCRDC, Frederick, Maryland 21702-1201.
authors.forename: J R
authors.initials: JR
authors.lastname: Ortaldo
authors.forename: R
authors.initials: R
authors.lastname: Winkler-Pickett
authors.forename: W
authors.initials: W
authors.lastname: Kopp
authors.forename: A
authors.initials: A
authors.lastname: Kawasaki
authors.forename: K
authors.initials: K
authors.lastname: Nagashima
authors.forename: K
authors.initials: K
authors.lastname: Okumura
authors.forename: H
authors.initials: H
authors.lastname: Yagita
authors.forename: F H
authors.initials: FH
authors.lastname: Bach
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex; D019002:CD56 Antigen; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D008213:Lymphocyte Activation; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D019002:CD56 Antigen; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D007371:Interferon-gamma