Differential expression of lymphokine-activated killer cells and natural killer cells in adoptive transfer experiments utilizing fractionated bone marrow

Precursors of murine natural killer (NK) cells and lymphokine-activated killer (LAK) cells can be distinguished by utilizing an adoptive transfer system in which donor bone marrow is fractionated on Percoll discontinuous gradients. Although precursors of LAK cells are present in all fractions, one fraction (greater than 65% Percoll) contains LAK precursors and is depleted of NK precursors. Both in vitro NK activity and in vivo hybrid resistance is abrogated in recipients of bone marrow from the greater than 65% Percoll fraction, whereas LAK activity can be readily demonstrated.     

A phase I trial of adoptive transfer of allogeneic natural killer cells in patients with advanced non-small cell lung cancer

HLA-mismatched natural killer (NK) cells have shown efficacy in acute myeloid leukemia, and their adoptive transfer in patients with other malignancies has been proven safe. This phase I clinical trial was designed to evaluate safety (primary endpoint) and possible clinical efficacy (secondary endpoint) of repetitive administrations of allogeneic, in vitro activated and expanded NK cells along with chemotherapy in patients with advanced non-small cell lung cancer (NSCLC). Patients with unresectable, locally advanced/metastatic NSCLC receiving 1st/2nd line chemotherapy were eligible to receive 2–4 doses of activated NK cells from two relative donors. Donor’s CD56⁺ cells were cultured for 20–23 days with interleukin-15 (IL-15) and hydrocortisone (HC) and administered intravenously between chemotherapy cycles. Premedication with corticosteroids and/or H1 inhibitors was allowed. Sixteen patients (performance status 0–1) with adenocarcinoma (n = 13) or squamous cell carcinoma (n = 3) at stage IIIb (n = 5) or IV (n = 11) receiving 1st (n = 13) or 2nd (n = 3) line treatment were enrolled. Fifteen patients received 2–4 doses of allogeneic activated NK cells (0.2–29 × 10⁶/kg/dose, median 4.15 × 10⁶/kg/dose). No side effects (local or systemic) were observed. At a median 22-month follow-up (range, 16.5–26 months) 2 patients with partial response and 6 patients with disease stabilization were recorded. Median progression free survival and overall survival were 5.5 and 15 months, respectively. A 56% 1-year survival and a 19% 2-year survival were recorded. In conclusion, repetitive infusions of allogeneic, in vitro activated and expanded with IL-15/HC NK cells, in combination with chemotherapy are safe and potentially clinically effective.     

Transiently redirected T cells for adoptive transfer

Background aimsT cells can be redirected to reject cancer by retroviral transduction with a chimeric antigen receptor (CAR) or by administration of a bispecific T cell engager (BiTE). We demonstrate that transfection of T cells with messenger (m) RNA coding for CAR is an alternative strategy.MethodsWe describe the pre-clinical evaluation of a method based on transient modification of expanded T cells with a CD19 CAR directed against B-cell malignancies. CAR mRNA was generated under cell-free conditions in a scalable process using recombinant RNA polymerase. Efficient and non-toxic square-wave electroporation was used to load the mRNA into the cytoplasm of T cells with no risk of insertional mutagenesis.ResultsAfter transfection > 80% of T cells were viable, with 94% CAR expression. Transfected T cells were cytolytic to CD19⁺ targets and produced interferon (IFN)-γ in response. Killing of CD19⁺ target cells was demonstrated even at day 8 with undetectable CAR expression. Increasing the concentration of mRNA resulted in higher surface CAR expression, better killing and more IFN-γ release but at the expense of increased activation-induced cell death. Finally, we demonstrated that a second transgene could be introduced by co-electroporation of CXCR4 or CCR7 with CAR to also modify chemotactic responses.ConclusionsWe advocate the transient redirection approach as well suited to meet safety aspects for early phase studies, prior to trials using stably transduced cells once CAR has been proven safe. The simplicity of this methodology also facilitates rapid screening of candidate targets and novel receptors in pre-clinical studies.     

Successful adoptive immunotherapy with OK432-inducible activated natural killer cells in tumor-bearing mice

We had demonstrated that the NK cell mediated cytotoxicity of murine spleen cells could be augmented byin vivo priming and subsequentin vitro challenge with a streptococcal preparation OK432, and the cell surface phenotype of induced killer cells was Thy-1⁺, asialo GM1⁺, suggesting that the activated cells were of NK lineage (OK-NK cell). We had also clarified that IL-2 played a major role in inducing the OK-NK cells via the production of IFN-. In this study, we examined the effect of adoptive transfer of OK-NK cells on syngeneic tumors in mice. Mice were implanted with SP2 myeloma cells intraperitoneally (i.p.), or C26 colon adenocarcinoma cells subcutaneously to make the models of peritonitis carcinomatosa or solid tumor, and the OK-NK cells were transferred i.p. or intratumorally, adoptively. By the adoptive transfer of OK-NK cells, 92% of mice bearing SP2-tumor had be cured. The tumor growth of C26-solid tumor was inhibited, and the survival rate of mice bearing C26-tumor was significantly increased. The intratumoral remnants of¹²⁵I-labelled OK-NK cells were 61, 27 and 8% at 4, 12 and 36h after intratumoral transfer, respectively. By multiple transfer of OK-NK cells, the antitumor effect was more effectively augmented than that of a single transfer. Results in this study suggested that OK-NK cells could be useful for the therapy of cancer patients.     

Allogeneic natural killer cells for refractory lymphoma

We reported that IL-2 activated autologous NK cells can induce, but not maintain durable remissions in lymphoma patients. We hypothesized that allogeneic NK cells may overcome class I MHC-mediated inhibition of NK cell killing. In a pilot study, we evaluated infusion of haploidentical donor NK cells for antitumor efficacy. Six patients with advanced B cell non-Hodgkin lymphoma (NHL) received rituximab, cyclophosphamide, and fludarabine as immunosupression to permit homeostatic NK cell expansion, followed by CD3-depleted NK cell-enriched cell products followed by subcutaneous IL-2 administration (10 × 10⁶ units every other day × 6 doses). At 2 months, four patients showed an objective clinical response. We observed early donor cell persistence in two patients (blood and in tumor-bearing node), but this was not detectable beyond 7 days. All patients demonstrated substantial increases in host-regulatory T cells (Treg) after NK cell and IL-2 therapy (180 ± 80 cells/μl vs. baseline: 58 ± 24 cells/μl, p = 0.04) which may have limited donor cell expansion in vivo. These findings suggest safety and feasibility of allogeneic NK cell therapy in patients with lymphoma; however host Treg and inadequate immunodepletion may contribute to a hostile milieu for NK cell survival and expansion. Cell therapy trials should incorporate novel strategies to limit Treg expansion.     

Trafficking of natural killer cells

Natural killer (NK) cells comprise a set of lymphocytes that is capable of mediating innate immune responses to viral infections, malignancies, and allogeneic bone marrow grafts. This review summarizes what is known about the mechanisms NK cells use to arrive at their sites of action. NK cells express a wide array of adhesion molecules including alphaLbeta2, alphaMbeta2, alphaXbeta2, and alpha4beta1 integrins, ICAM-1, PSGL-1, and L-selectin. Like other immune and inflammatory cells, NK cells use the blood circulation to enter tissues and organs, which requires that they interact with the vessel wall under flow conditions, arrest, and transmigrate. NK cells are able to chemotax to a variety of cytokines and chemokines, including IL-12, IFN-(alpha/beta, CCL2, 3, 4, 5, 7, 8, CXCL8, and CX3CL1. In many cases, NK cells appear to migrate towards these soluble factors without any kind of priming. These cells also appear to distribute in secondary and tertiary lymphoid sites (i.e., spleen, bone marrow, liver, lung, and lymph nodes) both with and without stimulation. In addition to their ability to move throughout the body in an unprimed state, activated NK cells may have increased specificity in homing to sites of inflammation. NK cells not only react to, but also produce IFN-gamma, TNF-alpha, GM-CSF, CCL3, CCL4, and CCL5, enabling them to recruit various immune cells to sites of immune response.     

Self-tolerance of natural killer cells

Natural killer (NK) cells, similar to other lymphocytes, acquire tolerance to self. This means that NK cells have the potential to attack normal self cells but that there are mechanisms to ensure that this does not usually occur. Self-tolerance is acquired by NK cells during their development, but the underlying molecular and cellular mechanisms remain poorly understood. Recent studies have produced important new information about NK-cell self-tolerance. Here, we review the evidence for and against possible mechanisms of NK-cell self-tolerance, with an emphasis on the role of MHC-specific receptors.     

Homeostasis of natural killer cells

Natural killer (NK) cells are important players of innate immunity, dedicated to the host defense against viruses and also involved in the immune surveillance of tumors. NK cells are widely distributed in the body and their number may increase locally during infection. They develop mainly in the bone marrow and perhaps in other lymphoid organs. They are constantly renewed, with a half-life of about 17 days at the periphery. In this article, we review the factors that regulate the homeostasis of NK cells including their development, differentiation, export to the periphery, their turnover, their homeostatic or antigen-induced proliferation and their survival before or after activation. In addition, we discuss the homeostasis of recently described so-called "memory" NK cells.     

Lymphokine-activated killer cells in rats: generation of natural killer cells and lymphokine-activated killer cells from bone marrow progenitor cells

The coculture of rat bone marrow cells with recombinant interleukin-2 induced the generation of cells mediating natural killer (NK) activity and subsequent lymphokine-activated killer (LAK) activity depending upon the dose of IL-2 and time of culture. NK activity was detected as early as 4 to 5 days after the addition of IL-2 and could be evoked with as little as 5 to 50 U/ml. The induced NK cells had large granular lymphocyte (LGL) morphology and expressed 0X8 and asialo GM1 surface markers but did not express 0X19 or W3/25 markers. LAK activity was detected only after 5 days of culture, and required above 100 U/ml IL-2. Cells mediating LAK activity also expressed 0X8 and asialo GM1 but not 0X19. The generation of detectable NK and subsequent LAK activity was due to induction of early progenitor cells and not contaminating mature LGL/NK cells within the bone marrow population since of removal of such mature NK cells with L-leucine methyl ester (L-LME) did not affect the subsequent generation of either activity. Moreover, the removal of actively dividing cells as well as mature NK cells from the bone marrow by treatment with 5-fluorouracil (5-FU) in vivo enriched the remaining bone marrow population for both NK and LAK progenitor cells. The phenotype of the L-LME- and 5-FU-resistant NK and LAK progenitor cells within populations of bone marrow was determined by antibody plus complement depletion analysis. Although treatment of normal bone marrow with anti-asialo GM1 + C reduced the induction of NK and LAK activity in 5-day cultures, treatment of 5-FU marrow with anti-asialo GM1 + C did not affect either activity. Treatment with a pan-T cell antibody + C did not affect the development of NK or LAK activity under any conditions. Thus, the 5-FU-resistant NK/LAK progenitors were asialo GM1 negative but became asialo GM1+ after induction by IL-2. Finally, evidence that bone marrow-derived LAK cells were generated directly from the IL-2-induced NK cells was obtained by treating the IL-2-induced LGL/NK cells with L-LME.(ABSTRACT TRUNCATED AT 400 WORDS)     

Human killer cells and natural killer cells: distinct subpopulations of Fc receptor-bearing lymphocytes

Unstimulated human peripheral blood lymphocytes were depleted of K cells, which mediate antibody-dependent cellular cytotoxicity (ADCC) without removing NK cells, which mediate natural killing (NK). K cell depletion was achieved by buoyant centrifugation removal of lymphocytes that bound to glutaraldehyde-treated P815-AB cells at high lymphocyte-to-target ratios. Likewise, NK cells were removed with glutaraldehyde-treated K562 cells without removing K cells. Furthermore, both cytotoxic cell populations were observed directly in one agarose single-cell cytotoxic assay (ASCA) using P815-AB and K562 cells simultaneously as target cells. Moreover, the percentage of total cytotoxic cells was equal to the sum of the percentage of K and NK cells observed in separate ASCA. Collectively, these results indicate that K cells and NK cells are distinct subsets of FcR-bearing lymphocytes. One subset, K cells, has more avid Fc receptors (fcR) than NK cells and are 'activated' via thier FcR to kill antibody-coated target cells. The second subset, NK cells, have less avid FcR and are not 'activated' through their FcR to kill antibody-coated target cells.     

Natural killer cells and natural killer T cells in Lyme arthritis

Introduction

Natural killer (NK) and natural killer T (NKT) cells provide a first line of defense against infection. However, these cells have not yet been examined in patients with Lyme arthritis, a late disease manifestation. Lyme arthritis usually resolves with antibiotic treatment. However, some patients have persistent arthritis after spirochetal killing, which may result from excessive inflammation, immune dysregulation and infection-induced autoimmunity.

Methods

We determined the frequencies and phenotypes of NK cells and invariant NKT (iNKT) cells in paired peripheral blood (PB) and synovial fluid (SF) samples from eight patients with antibiotic-responsive arthritis and fifteen patients with antibiotic-refractory arthritis using flow cytometry and cytokine analyses.

Results

In antibiotic-responsive patients, who were seen during active infection, high frequencies of CD56bright NK cells were found in SF, the inflammatory site, compared with PB (P <0.001); at both sites, a high percentage of cells expressed the activation receptor NKG2D and the chaperone CD94, a low percentage expressed inhibitory killer immunoglobulin-like receptors (KIR), and a high percentage produced IFN-γ. In antibiotic-refractory patients, who were usually evaluated near the conclusion of antibiotics when few if any live spirochetes remained, the phenotype of CD56bright cells in SF was similar to that in patients with antibiotic-responsive arthritis, but the frequency of these cells was significantly less (P = 0.05), and the frequencies of CD56dim NK cells tended to be higher. However, unlike typical NKdim cells, these cells produced large amounts of IFN-γ, suggesting that they were not serving a cytotoxic function. Lastly, iNKT cell frequencies in the SF of antibiotic-responsive patients were significantly greater compared with that of antibiotic-refractory patients where these cells were often absent (P = 0.003).

Conclusions

In patients with antibiotic-responsive arthritis, the high percentage of activated, IFN-γ-producing CD56bright NK cells in SF and the presence of iNKT cells suggest that these cells still have a role in spirochetal killing late in the illness. In patients with antibiotic-refractory arthritis, the frequencies of IFN-γ-producing CD56bright and CD56dim NK cells remained high in SF, even after spirochetal killing, suggesting that these cells contribute to excessive inflammation and immune dysregulation in joints, and iNKT cells, which may have immunomodulatory effects, were often absent.     

Generation of cloned mice by direct nuclear transfer from natural killer T cells

Cloning mammals by nuclear transfer (NT) remains inefficient. One fundamental question is whether clones have really been derived from differentiated cells rather than from rare stem cells present in donor-cell samples. To date, cells, such as mature lymphocytes, with genetic differentiation markers have been cloned to generate mice only via a two-step NT involving embryonic stem (ES) cell generation and tetraploid complementation [1, 2 and 3]. Here, we show that the genome of a unique T-cell population, natural killer T (NKT) cells, can be fully reprogrammed by a single-step NT. The pups and their placentas possessed the rearranged TCR loci specific for NKT cells. The NKT-cell-cloned embryos had a high developmental potential in vitro: Most (71%) developed to the morula/blastocyst stage, in marked contrast to embryos from peripheral blood T cells (12%; p < 1 x 10(-25)). Furthermore, ES cell lines were efficiently established from these NKT-cell blastocysts. These findings clearly indicate a high level of plasticity in the NKT-cell genome. Thus, differentiation of the genome is not always a barrier to NT cloning for either reproductive or therapeutic purposes, so we can now postulate that at least some mammals cloned to date have indeed been derived from differentiated donor cells.     

Radiosensitivity of human natural killer cells: binding and cytotoxic activities of natural killer cell subsets

The sensitivity of human natural killer (NK) cell activities (both binding and killing) after exposure of peripheral blood mononuclear cells to different doses of gamma radiation was studied. A panel of monoclonal antibodies was used to identify the NK and T-lymphocyte subsets and to evaluate their radiosensitivity. Peripheral blood mononuclear cells were irradiated with low (2-6 Gy) and high (10-30 Gy) doses and NK cell binding and cytotoxic activity against K562 target cells were studied after 3 h and 48 h in culture. The primary damage to NK cell activity was identified at the postbinding level and affected mainly the lytic machinery. After 48 h culture postirradiation, an overall depression of cytotoxic activity was observed, but ionizing radiation produced either a selection of the more cytotoxic NK cell subsets, which therefore might be considered more resistant to radiation damage than the less cytotoxic NK cells, or a long-term stimulation of cytotoxic activity in surviving cells.     

Multimer technologies for detection and adoptive transfer of antigen-specific T cells

Identification and purification of antigen-specific T cells without altering their functional status are of high scientific and clinical interest. Staining with major histocompatibility complex (MHC)-peptide multimers constitutes a very powerful method to study antigen-specific T-cell subpopulations, allowing their direct visualization and quantification. MHC-peptide multimers, such as dimers, tetramers, pentamers, streptamers, dextramers and octamers have been used to evaluate the frequency of CD8⁺ T cells, specific for tumor/leukemia-associated antigens as well as for viral antigens, e.g., CMVpp65 and EBV-EBNA. Moreover, MHC-peptide multimers have been used for rapid and efficient ex vivo isolation and expansion of T cells. A recent development in the field of MHC-peptide multimers led to the purification of CD8⁺ T cells specific for leukemia antigens. This might help to select leukemia-specific donor lymphocyte infusions (DLIs), thus allowing dissection of the noxious graft-versus-host disease (GvHD) from beneficial anti-viral and even anti-leukemic effects. This review covers different types of MHC-peptide multimers and their applications, as well as the impact that multimers might have on further development of DLIs.     

Renewal of natural killer cells in mice having elevated natural killer cell activity

The present study was designed to examined the dynamics of splenic natural killer (NK) cells under two conditions of enhanced NK cell activity: (1) CBA/J mice given polyinosinic-polycytidylic acid (poly-I:C), an NK-cell-enhancing agent, and 62) untreated athymic nude (nu/nu) mice. The 'total NK cell activity' of the spleen (percentage specific lysis corrected for changes in organ cellularity) increased 5-fold and 2.7-fold after poly-I:C treatment for 1 day and 4 days, respectively. An injection of hydroxyurea (HU), a cell-cycle-toxic drug, given together with either poly-I:C or saline to CBA/J mice resulted in both cases in a 25% reduction in total NK cell activity 1 day later. This suggests that the renewal rate of nondividing NK cells is similar in poly-I:C-treated and saline-injected mice, and that the NK-enhancing effect of poly-I:C is not due to a stimulation of proliferation among NK cell precursors. HU administered simultaneously with poly-I:C or saline for 4 days eliminated NK cell activity in both cases, indicating that spleen NK cell activity is mediated almost entirely by newly formed (less than or equal to 4 days) cells. In nude mice, NK cell activity was assayed at various intervals after an HU depletion period of 2 days. NK depletion was initially more rapid in nu/nu mice than in control (nu/+) mice, although equally profound, and the subsequent recovery of NK cell activity after cessation of HU was also more rapid than in control (nu/+) mice.(ABSTRACT TRUNCATED AT 250 WORDS)