Natural Killer Cell Surface Research Articles

Natural killer cell activity in monoclonal gammopathies: Relation to disease activity

Natural killer (NK) activity and NK-related cell surface markers (CD16, CD56, CD57) of peripheral blood lymphocytes were studied in patients with multiple myeloma and MGUS (monoclonal gammopathy of undetermined significance). A strong correlation (p less than 0.0001) was found between the numbers of cells positive for the different NK cell surface markers. The proportion of CD16+ cells correlated highly to the lytic capability (lytic units/10(6) cells) of K562 cells (p less than 0.0001). High NK activity and high numbers of cells with NK-related cell surface markers were found in patients with a low tumor burden compared to controls, whereas low values were seen in patients with an advanced disease. The results indicate that NK cells might be involved in the disease process in monoclonal gammopathies, perhaps by exerting a regulatory function on the proliferating B-cell clone.

Natural killer cell surface markers on lymphocytes containing parallel tubular structures

Natural killer cell surface markers on lymphocytes containing parallel tubular structures

T-lymphocyte subsets in gut and blood of liver transplant recipients with and without cytomegalovirus gastroenteritis

The effects of orthotopic liver transplantation (OLTx) and cytomegalovirus (CMV) gastroenteritis on the type of mononuclear cells within the upper gastrointestinal tract were determined. Nineteen liver transplant recipients were studied both before and after transplantation. Each underwent a pan-upper gastrointestinal endoscopy with biopsy of the antrum and duodenum before and four weeks following liver transplantation. A panel of monoclonal antibodies prepared against HLA-DR, NK, IL-2R, T11, T4, T8, and B1 cell surface antigens was used to examine the tissues. Before OLTx, none of the 19 subjects studied had clinical or histologic evidence for CMV gastroenteritis. Following OLTx, five of the 19 subjects had CMV gastroenteritis. The number of HLA-DR positive staining lymphocytes present in biopsies obtained post-OLTx was significantly greater (P less than 0.005) than those present in biopsies obtained pre-OLTx regardless of the presence or absence of CMV gastroenteritis. No difference in the intensity of HLA-DR antigen expression between pre- and post-OLTx biopsies and those with and without CMV gastroenteritis was evident. No difference in the number of natural killer (NK) cells and the number of cells expressing the interleukin-2 receptor (IL-2R) was evident between biopsies obtained pre- and post-OLTx. In contrast, the number of T lymphocytes bearing the T11, T4, and T8 markers and the calculated T4/T8 ratio differed between biopsies obtained pre- and post-OLTx and between those positive for CMV gastroenteritis post-OLTx and those without evidence for CMV gastroenteritis either before or after OLTx, although these changes were not consistent throughout the gastrointestinal tract.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of thymocytes in organ culture: migrant cells with natural killer cell characteristics.

During organ culture of foetal thymic lobes, up to 5% of the thymic cells migrate out of the lobes and a majority of these have phenotypic characteristics of thymocytes or macrophages. Interleukin-2 (IL-2) increases the number of these migrant cells, and cytotoxic cells can be detected which display natural killer cell surface markers. In contrast, although cytotoxic activity can be detected in cells from adult thymic fragments cultured with IL-2, the cytotoxic activity is not detected with natural killer sensitive target cells. The appearance of natural killer-like cells during the culture of foetal thymic lobes suggests that they are involved in differentiation events which occur at this time in the thymus.

Novel interleukin 2 (IL-2) receptor appears to mediate IL-2-induced activation of natural killer cells.

A novel IL-2 receptor, distinct from the Tac protein, has been identified on the surface of purified human natural killer (NK) cells by chemical cross-linking of 125I-IL-2. This protein is approximately 70,000 D in size (p70) and appears to be identical to the recently recognized second subunit of the human high affinity IL-2 receptor complex. Scatchard analysis of 125I-IL-2 binding to purified NK cells revealed approximately 2,300 p70 binding sites per cell with an apparent dissociation constant of 200 pM, a value intermediate between the previously recognized high and low affinity forms of the human IL-2 receptor. The monoclonal anti-Tac antibody did not inhibit the cross-linking of 125I-IL-2 to the p70 binding sites present on NK cells. Functionally, the addition of high concentrations of recombinant IL-2 to the enriched NK cells promoted a rapid augmentation of cytolytic activity and a more delayed increase in cellular proliferation. Anti-Tac effectively blocked the IL-2-induced proliferative response in these cells, but failed to alter the enhancement of cytotoxicity. Analysis of NK cytoplasmic RNA isolated at various time points after IL-2 stimulation revealed the rapid induction of c-myb and Tac gene expression that was also not inhibited by the anti-Tac antibody. These findings suggest that IL-2 binding to the p70 receptor constitutively expressed on the surface of NK cells may mediate both the development of increased cytolytic activity and rapid changes in gene expression. The activation of the Tac gene may in turn permit the formation of the high affinity IL-2 receptor complex (comprised of at least the Tac and p70 proteins) that appears to transduce the requisite signals involved in NK cell proliferation.

Aggressive Natural Killer Cell Leukemia/Lymphoma with N901-Positive:Surface Phenotype: Evidence for the Existence of a Third Lineage in Lymphoid Cells

The morphology, immunologic and functional properties of peripheral blood and bone marrow cells or cultured cells from 2 patients with clinically aggressive non-T, non-B lymphoma/leukemia are described. The leukemic cells possessed medium to large granules in the cytoplasm, antigens against CD38, CD2, CD25, OKIa1, CD16, TA-1, CD9, CD24 and NKH-1 (N901) monoclonal antibodies on their cell surface, and also showed a high natural killer (NK) activity. Phenotypically, the cells in these disorders were quite different from T gamma leukemia cells bearing Fc receptor or the traditionally reported NK leukemia cells possessing HNK-1 (Leu 7) antigens on their surface. In addition, these leukemias/lymphomas belonged to neither T- nor B-cell lineage, proved by studying clonal gene rearrangement for the T beta and T gamma receptor, and immunoglobulin. Hence, a quite interesting and important point, as suggested by our data, is that all our cases expressed an antigen for NKH-1 (N901), which is detectable on all NK cell surfaces and they lacked the antigen for Leu 7 (HNK-1), which is usually detected on the surface of leukemic NK cells. These facts indicate that we are dealing with a leukemic NK cell subset which is quite different from cells of all other reported cases of NK cell leukemias. We therefore concluded that such disorders with an aggressive clinical nature and a poor prognosis as in our cases belong to a new clinical entity originating from a portion of the NK cell subset.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural killer cell inhibition of young spherules and endospores of Coccidioides immitis.

The recent development of a method for culturing the parasitic form of Coccidioides immitis by using conditions compatible with the growth of lymphoid cells has enabled us to investigate the role of natural killer (NK) cells in defense against this pathogenic fungus. Pure cultures of spherules and endospores were grown in RPMI 1640 which contained 10% calf serum. Single cell suspensions of young spherules and endospores were incubated in the presence of freshly isolated human peripheral blood lymphocytes (PBL). After a 4-hr incubation, the colony-forming ability of the fungus was significantly reduced. Leu-11 is a monoclonal antibody that binds to the Fc receptor of NK cells. When PBL were incubated in the presence of this monoclonal antibody and complement, the colony-forming ability of C. immitis was not reduced, indicating that the effector cell involved in reduction of colony-forming units is also recognized by the Leu-11 monoclonal antibody. Classical NK activity can be enhanced by preincubation with interferon; the inhibitory activity of the PBL which are responsible for the reduction in colony-forming units of C. immitis is similarly enhanced by pretreatment with interferon. When PBL are incubated in the presence of young spherules and endospores for 24 hr, the cellfree supernatants will kill U937 target cells. In addition to stimulating the release of NK cytotoxic factor, C. immitis is susceptible to inactivation when incubated in the presence of factors released by PBL which have been incubated in the presence of either K562 or C. immitis. Other evidence reported by this laboratory demonstrates that C-reactive protein is present on the surface of NK cells and that antibody to this molecule blocks NK-mediated killing of standard tumor cell targets. Pretreatment with anti-C-reactive protein also blocks the ability of PBL to inhibit the colony-forming capacity of this fungus. These data suggest that the cell that inhibits the in vitro growth of the pathogenic fungus, C. immitis, is an NK cell.

Expression of a laminin-like substance on the surface of murine natural killer (NK) lymphocytes and its role in NK recognition of tumor target cells.

We have identified a structure on the surface of murine NK cells that is immunochemically cross-reactive with laminin. Treatment of normal CBA/J spleen cells with monospecific anti-laminin serum plus complement completely eliminated NK cytolytic activity against YAC-1 or RL male 1 target cells. In the absence of added complement, spleen cells preincubated with anti-laminin serum were also reduced in their cytolytic activity due to a reduced capacity to bind to the target cells. Treatment with anti-asialo GM1 serum plus complement also eliminated NK activity, but pretreatment of NK cells with anti-asialo GM1 in the absence of complement did not reduce cytolytic activity. Thus, anti-laminin and anti-asialo GM1 bind to structures on the surface of NK cells that distinguish functional (laminin) from nonfunctional (asialo GM1) sites. Flow cytometric analysis revealed that approximately 15% of normal nonadherent splenic lymphocytes expressed laminin-like structures, whereas 16% expressed asialo GM1 and 19% expressed the NK alloantigen NK 2.1. Treatment of alloimmune cytotoxic T lymphocytes (CTL) with anti-laminin plus complement did not affect CTL activity. Thus, anti-laminin serum appears to detect a cell surface structure present on the NK subset of lymphocytes.

Natural killer cell depletion enhances virus synthesis and virus-induced hepatitis in vivo.

The role of natural killer (NK) cells in the natural resistance of mice to infections by several viruses was examined. Mice were specifically depleted of NK cells by i.v. injection of rabbit antiserum to asialo GM1, a neutral glycosphingolipid present at high concentrations on the surface of NK cells. Control mice were left untreated or were injected with normal rabbit serum. Four to 6 hr later, these mice were infected with lymphocytic choriomeningitis virus (LCMV), mouse hepatitis virus (MHV), murine cytomegalovirus (MCMV), or vaccinia virus. The mice were sacrificed 3 days post-infection and assayed for virus in liver and spleen, spleen NK cell activity, and plasma interferon (IFN). All mice treated with anti-asialo GM1 antibody had drastically reduced NK cell-mediated lysis. Correlating with NK cell depletion, these mice had significantly higher (up to 500-fold) titers of MCMV, MHV, or vaccinia virus in their livers and spleens as compared to control mice. NK cell-depleted MCMV and MHV-infected mice had higher levels of plasma IFN than controls, correlating with the higher virus titers. These NK cell-depleted, virus-infected mice had more extensive hepatitis, assayed by the number of inflammatory foci in their livers, as compared to control virus-infected mice; these foci were also larger and contained more degenerating liver cells than those in control mice. In contrast to the results obtained with MHV, MCMV, and vaccinia virus, NK cell depletion had no effect on virus titers in the early stages of acute LCMV infection or during persistent LCMV infection. Mice depleted of NK cells had similar amounts of LCMV in their spleens and similar plasma IFN levels. Because this antibody to asialo GM1 does not impair other detectable immunologic mechanisms, these data support the hypothesis that NK cells act as a natural resistance mechanism to a number of virus infections, but suggest that their relative importance may vary from virus to virus.

NKP-15: A monoclonal antibody reactive against purified human natural killer cells and granulocytes

A monoclonal antibody of the isotype IgG 1,k, NKP-15, was produced by immunizing Balb/c mice with highly purified suspensions of human natural killer (NK) cells. By indirect immunofluorescence, NKP-15 reacted with 15 ± 5.0% of the peripheral blood lymphocytes, 90 ± 3.0% of the granulocytes and was non-reactive with T-cells, B-cells, monocytes, platelets and erythrocytes. NKP-15 reacted with 90 ± 6.0% of purified large granular lymphocytes (LGL), which displayed highly enriched NK cell activity. NKP-15, however, showed no reactivity with a panel of human tumor cell lines. Analysis of NK cell-K562 tumor cell conjugates and depletion by panning of NKP-15 + cells indicated that all functionally tumorlytic NK cells expressed the NKP-15 antigen. It was also determined by competitive blocking experiments that NKP-15 recognizes a new NK cell surface antigen not delineated by the NK-specific monoclonal antibody, Leu-7, and that the epitope for NKP-15 appears to be associated with the Fc-receptor of NK cells and granulocytes.

Gross‐virus‐induced lymphoma in the rat. V. Natural cytotoxic cells are non‐t cells

The cytotoxic cells from the spleens of normal rats, which lyse Gross-virus-induced lymphoma target cells in a short-term 51Cr release test, are predominantly small to medium-sized cells sedimenting at 4-5 mm/h as shown by velocity sedimentation analysis. Their cytotoxic activity is relatively resistant to gamma-radiation, 50% surviving 1,000 rads and 30% remaining after 5,000 rads, and to heat, since 20 min incubation at 48-51 degrees C is required for its abolition. In these properties the natural killer (NK) cells are very similar to the cytotoxic T cells from tumour-immune rats, and they share in addition a requirement for Ca++ ions for cytolysis. They differ in that they are non-T cells as defined by their resistance to anti-T-cell antiserum and complement, and by their presence in T-cell-deprived rats. They lack detectable surface Ig, Fc receptors and phagocytic or adherence properties and belong therefore to that small proportion of lymphoid cells lacking the surface markers of T or B lymphocytes, as do the comparable NK cells of mice. Cytotoxicity appears to involve an autonomous, papain-sensitive recognition structure on the surface of NK cells, rather than acquired cytophilic antibody operating through an antibody-dependent mechanism.