Lymphokine-activated killer (LAK) cells. Analysis of factors relevant to the immunotherapy of human cancer

Immunotherapy for osteosarcoma: Fundamental mechanism, rationale, and recent breakthroughs

Osteosarcoma (OS) is the most common primary malignancy of the bone and has a high propensity for local invasion and metastasis. Although combining surgery with chemotherapy has immensely improved the outcomes of osteosarcoma patients, the prognosis of metastatic or recurrent osteosarcomas is still unsatisfactory. Immunotherapy has proven to be a promising therapeutic strategy against human malignancies and improved understanding of the immune response to OS, and biomarker development has increased the number of patients who benefit from immunotherapies in recent years. Here, we review recent advances in immunotherapy in osteosarcoma and discuss the mechanisms and status of immunotherapies in both preclinical and clinical trials as well as future therapies on the horizon. These advances may pave the way for novel treatments requisite for patients with osteosarcoma in need of new therapies.

Granzyme B Attenuates Bacterial Virulence by Targeting Secreted Factors

Pathogenic bacteria secrete virulence factors that interact with the human host to establish infections. The human immune system evolved multiple mechanisms to fight bacterial invaders, including immune proteases that were demonstrated to contribute crucially to antibacterial defense. Here we show that granzyme B degrades multiple secreted virulence mediators from Listeria monocytogenes, Salmonella typhimurium, and Mycobacteria tuberculosis. Pathogenic bacteria, when infected in the presence of granzyme B or granzyme-secreting killer cells, fail to grow in human macrophages and epithelial cells owing to their crippled virulence. A granzyme B-uncleavable mutant form of the major Listeria virulence factor, listeriolysin O, rescued the virulence defect in response to granzyme treatment. Hence, we link the degradation of a single factor with the observed decrease in virulent bacteria growth. Overall, we reveal here an innate immune barrier function of granzyme B by disrupting bacterial virulence to facilitate bacteria clearance by bystander immune and non-immune cells.

Novel Biomarkers for Personalized Cancer Immunotherapy

Cancer immunotherapy has emerged as a novel and effective treatment strategy for several types of cancer. Immune checkpoint inhibitors (ICIs) have recently demonstrated impressive clinical benefit in some advanced cancers. Nonetheless, in the majority of patients, the successful use of ICIs is limited by a low response rate, high treatment cost, and treatment-related toxicity. Therefore, it is necessary to identify predictive and prognostic biomarkers to select the patients who are most likely to benefit from, and respond well to, these therapies. In this review, we summarize the evidence for candidate biomarkers of response to cancer immunotherapy.

Promising immunotherapy: Highlighting cytokine-induced killer cells

For many years, cancer therapy has appeared to be a challenging issue for researchers and physicians. By the introduction of novel methods in immunotherapy, the prospect of cancer therapy even more explained than before. Cytokine-induced killer (CIK) cell-based immunotherapy demonstrated to have potentiality in improving clinical outcomes and relieving major side effects of standard treatment options. In addition, given the distinctive features such as high safety, low toxicity effects on healthy cells, numerous clinical trials conducted on CIK cells. Due to the shortcomings that observed in CIK cell immunotherapy alone, arising a tendency to make modifications (combined modality therapy or combination therapy) including the addition of various types of cytokines, genetic engineering, combination with immune checkpoints, and so on. In this review, we have tried to bring forth the latest immunotherapy methods and their overview. We have discussed the combination therapies with CIK cells and the conducted clinical trials. This helps the future studies to use integrated therapies with CIK cells as a promising treatment of many types of cancers.

Current status of immunotherapy against gastrointestinal cancers and its biomarkers: Perspective for precision immunotherapy

Immunotherapy has shown encouraging results for some types of tumor. Although enormous efforts have been made toward the development of specific immunotherapeutic strategies against gastrointestinal cancers, such as adoptive T-cell transfer, peptide vaccines, or dendritic cell vaccines, the efficacy of immunotherapies prior to the introduction of immune checkpoint inhibitors was not substantial. This article reviews immunotherapy for gastrointestinal malignancies, including cell therapy, peptide vaccine, and immune checkpoint inhibitors, and attempts to resolve the immunosuppressive conditions surrounding the tumor microenvironment, and to construct novel combination immunotherapies beyond immune checkpoint inhibitors.

IL-2 and Beyond in Cancer Immunotherapy

The development of the T- and natural killer (NK) cell growth factor IL-2 has been a sentinel force ushering in the era of immunotherapy in cancer. With the advent of clinical grade recombinant IL-2 in the mid-1980s, oncologists could for the first time directly manipulate lymphocyte populations with systemic therapy. By itself, recombinant IL-2 can induce clinical responses in up to 15% of patients with metastatic cancer or renal cell carcinoma. When administered with adoptively transferred tumor-reactive lymphocytes, IL-2 promotes T cell engraftment and response rates of up to 50% in metastatic melanoma patients. Importantly, these IL-2-driven responses can yield complete and durable responses in a subset of patients. However, the use of IL-2 is limited by toxicity and concern of the expansion of T regulatory cells. To overcome these limitations and improve response rates, other T cell growth factors, including IL-15 and modified forms of IL-2, are in clinical development. Administering T cell growth factors in combination with other agents, such as immune checkpoint pathway inhibitors, may also improve efficacy. In this study, we review the development of T- and NK cell growth factors and highlight current combinatorial approaches based on these reagents.

Targeting Cancer Stem Cells with Natural Killer Cell Immunotherapy

INTRODUCTION

Standard cytoreductive cancer therapy, such as chemotherapy and radiotherapy, are frequently resisted by a small portion of cancer cells with 'stem-cell' like properties including quiescence and repopulation. Immunotherapy represents a breakthrough modality for improving oncologic outcomes in cancer patients. Since the success of immunotherapy is not contingent on target cell proliferation, it may also be uniquely suited to address the problem of resistance and repopulation exerted by cancer stem cells (CSCs). Areas covered: Natural killer (NK) cells have long been known for their ability to reject allogeneic hematopoietic stem cells, and there are increasing data demonstrating that NK cells can selectively identify and lyse CSCs. The authors review the current knowledge of CSCs and NK cells and highlight recent studies that support the concept that NK cells are capable of targeting CSC in solid tumors, especially in the context of combination therapy simultaneously targeting non-CSCs and CSCs. Expert opinion: Unlike cytotoxic cancer treatments, NK cells can target and eliminate quiescent/non-proliferating cells such as CSCs, and these enigmatic cells are an important source of relapse and metastasis. NK targeting of CSCs represents a novel and potentially high impact method to capitalize on the intrinsic therapeutic potential of NK cells.

Advances and Prospects in Cancer Immunotherapy

Cancer immunotherapy is a promising and effective treatment modality for patients with cancers. Cytokine, anticytokine, and antibody therapies appear to be effective in treating various forms of cancer. The human papillomavirus vaccine is protective for cervical cancer, and this discovery has paved the way to the development of cancer vaccines for other forms of virus-associated cancers such as liver cancer and Merkel cell carcinoma. Clinical trials have demonstrated that adoptive cell therapy using tumor-infiltrating lymphocytes can induce tumor regression in approximately 75% of metastatic melanoma patients, suggesting the possibility of using similar technique to effectively treat breast, lung, and renal cancers in the near future. Besides, genetically engineered T cells transduced with genes encoding specific T cell receptors and chimeric antigen receptors have been shown effective in the treatment of cancer patients. These studies suggest that combination therapies are superior choices in cancer immunotherapy for patients.

Clinical production and therapeutic applications of alloreactive natural killer cells

Recent advances have improved our understanding of natural killer (NK) cell-mediated alloreactivity after hematopoietic cell transplantation (HCT) or with adoptive transfer. NK cells contribute to a graft-versus-leukemia effect and may play a role in preventing graft-versus-host disease or controlling infectious diseases after allogeneic HCT. New discoveries in NK cell biology, including characterization of NK cell receptors and their interactions with self-HLA molecules and a better understanding of the mechanism of NK cell education have led to the development of novel strategies to exploit NK cell alloreactivity against tumors. While early studies using autologous NK cells lacked efficacy, the use of adoptively transferred NK cells to treat hematopoietic malignancies has been expanding. The production of allogeneic donor NK cells requires efficient removal of T- and B cells from clinical-scale leukapheresis collections. The goal of this chapter is to review NK cell biology, NK cell receptors, the use of NK cells as therapy and then to discuss the clinical decisions resulting in our current good manufacturing practices processing and activation of human NK cells for therapeutic use.

Beneficial effect of short-term exposure of human NK cells to IL15/IL12 and IL15/IL18 on cell apoptosis and function

Monokines IL12, IL15, and IL18 have been shown to activate NK cell function, however with high apoptosis induced by their combination within 48 h. Here, we demonstrate for the first time that CD56+ cells incubated for only 18 h with the combination of IL15/IL12 or IL15/IL18, then washed, and further cultured in plain medium, exhibit low levels of apoptosis. These shortly activated CD56+ cells show high killer activity against NK- and LAK-sensitive tumor targets that persists over a culture period of 18 days after two additional 6 h cycles of exposure to the monokines applied every 8 days and also retain their ability for high cytokine production during each exposure. Moreover, these repetitive short-term exposures of CD56+ cells to the monokine combinations result in long-lived CD56+ cells with slower rates of FcgammaRIII receptor (CD16) decline, therefore exhibiting higher antibody depended cytotoxicity, as opposed to the continuous incubation with the monokine combinations. In conclusion, short-term exposure of CD56+ cells to IL15/IL12 or IL15/IL18 at 8-day intervals may hold a promise for improved clinical results in cellular adoptive cancer immunotherapy and for the in vivo injections of the monokines.

Interleukin-2 and cancer: critical analysis of results, problems and expectations

The cancer process in a combination of two kinds of events: a multistep cellular genetic defects giving cells independent growth and great adaptation capability, a multistep interactions profiles with what is called the stromal reaction from the original in situ tumor to the invasive metastatic and angiogenic tumor. The immune system plays an important role in the control of the cancer process but always must be seen as a part integrated in the stromal reaction. In order to boost the immune system capability to treat a cancer we must never forget these cellular and tissular dimensions. Interleukins, growth factors and monoclonal antibodies are new agents are able to bring immunotherapy of cancer to reality. Interleukin 2 did not match our dreams of the ideal factor which can stimulate the defective immune system and bring the cancer evolution to an end. The little but real remissions obtained with the IL-2 high dose protocols still sustains our trust of the immune system as a critical barrier to cancer evolution but the numerous side effects reminds us that cytokines are not to be used as antibiotics and hormones. IL-2 is a regulator of the immune system at the microenvironment level, therefore flooding the blood circulation with high IL-2 doses is not appropriate. We have also to understand that IL-2 can interact directly with cancer cells and also with stromal cells (endothelial and fibroblastic cells), the outcome of IL-2 immunotherapy is not restricted to the interactions with immune cells.

Immunotherapy for pancreatic cancer: current concepts

Despite advances in chemotherapy and surgical technique, patients with pancreatic cancer often succumb to local recurrence or metastatic spread. The need for new therapeutic strategies for this disease coupled with a better understanding of basic immunology have led to the development of novel anti-tumor vaccines. This review focuses on the historical development of tumor vaccines emphasizing the identification of potential pancreatic tumor antigens. The role of both B-cell and T-cell responses in tumor rejection will be reviewed. Methods for antigen presentation, including peptides, recombinant viral and bacterial vectors, dendritic cells, and whole cell approaches will be discussed. The use of immune adjuvants and improved methods of vaccine delivery will also be explored. The full potential for the immunotherapy of pancreatic cancer awaits the results of early phase clinical trials. The development of pancreatic cancer vaccines represents a useful paradigm for the translation of basic research into the clinical arena.

Fas ligand expression in primary colon adenocarcinomas: evidence that the Fas counterattack is a prevalent mechanism of immune evasion in human colon cancer

Fas ligand (FasL) kills sensitive Fas receptor (FasR)-bearing cells by inducing apoptosis. FasL expressed by non-lymphoid cells within the eye and the testis mediates immune privilege by inducing apoptosis of Fas-sensitive infiltrating pro-inflammatory immune effector cells. It has previously been demonstrated by the present authors that the colon cancer cell SW620 expresses FasL and can kill lymphoid cells by Fas-mediated apoptosis in vitro. This 'Fas counterattack' was subsequently confirmed by others as a potential mechanism of immune privilege in various malignancies. The aim of the present study was to ascertain the prevalence of FasL expression in human colon cancer and to confirm that neoplastic colonic epithelial cells express FasL in vivo. The study of FasL expression by colon cancer cell lines was extended: it was shown that seven of eight colon adenocarcinoma cell lines expressed FasL mRNA, using reverse transcription-polymerase chain reaction (RT-PCR). Prevalent expression of FasL was confirmed in vivo: all the resected colonic tumours examined (31/31) were found to express FasL. In the tumours, FasL were co-localized to neoplastic colonic epithelial cells, using immunohistochemistry and in situ hybridization, respectively. FasL expression was independent of Dukes' stage, suggesting that it may occur throughout colon cancer progression. These results suggest that FasL is a common mediation of immune privilege in colon cancer.

Tumor lymphocytes in patients with advanced ovarian cancer: changes during in vitro culture and implications for immunotherapy

Tumor specimens and ascites of patients with advanced ovarian cancer were utilized to obtain both primary ovarian carcinoma cell cultures and lymphocytes: tumor-infiltrating lymphocytes (TILs) from solid tumor tissue and tumor-associated lymphocytes (TALs) from peritoneal fluid. Tumor lymphocytes were grown in coculture with autologous tumor cells and recombinant human IL-2 (rhIL-2) for up to 4 weeks and at weekly intervals these were examined with respect to phenotype and cytotoxicity. The phenotype was studied using flow cytometry for a variety of human immunocompetent cell surface markers (CD3, CD4 CD8, CD16, CD56, TCR alphabeta, TCRgammadelta). Cytotoxicity was investigated using 4-hr 51Cr-release assays with the primary ovarian carcinoma cell cultures and the K562 cell line as target cells. The tumor lymphocytes did not demonstrate any obvious trend in phenotype changes during culture, although for different cultures a large range was noted for the various lymphocyte populations studied. Cytotoxicity against both autologous and allogeneic targets declined with culture length for the majority (6/7) of the lymphocyte cell lines tested (greatest at 1 week and least at 3 weeks). These initial results indicate that an in vitro non-MHC-restricted cytotoxic function of peritoneal lymphocytes can be effectively activated with IL-2 and autologous tumor cells. However, if activated lymphocytes are to be employed as a form of immunotherapy, they should be given within the first week of culture for maximum cytotoxic effect.

Interleukin-7 induces differential lymphokine-activated killer cell activity against human melanoma cells, keratinocytes, and endothelial cells

To assess the potential role of interleukin (IL)-7 in immunotherapy of human malignant melanoma, we have examined the lymphokine-activated killer (LAK) cell sensitivity of four human melanoma cell lines against LAK cells generated by IL-7 or IL-2. Lysis was determined by a 24-h cytotoxicity test using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT). All melanoma cell lines were susceptible to IL-7- and IL-2-generated LAK cells. The sensitivity of melanoma cells to IL-2-induced LAK cells was higher compared to IL-7-induced LAK cells. At an effector target ratio of 20:1, the lysis by IL-7-induced LAK cells ranged between 41% and 52%, whereas IL-2-induced lysis ranged between 80% and 94% (p < 0.01). IL-7-induced LAK cells, however, showed almost no cytotoxicity towards HaCat keratinocytes and human umbilical vein endothelial cells (HUVECs). Immunophenotyping revealed a higher expression of the tac antigen (CD 25) on IL-7-generated LAK cells, particularly those cells that were CD 56 negative or CD 3 positive compared to IL-2-induced LAK cells. In contrast, IL-2-generated LAK cells killed 62% of the HaCat keratinocytes and 60% of the HUVECs. Secretion of tumor necrosis factor-alpha into culture supernatants was significantly higher in IL-2-generated LAK cells compared to IL-7-stimulated LAK cells (p < 0.01), whereas TNF-alpha levels of IL-7-induced LAK cells were in the range of unstimulated lymphocytes. Because nonspecific cytotoxicity against other normal cells such as keratinocytes and endothelial cells contributes to the dose-limiting side effects of immunotherapy with IL-2, immunotherapy using IL-7 might be a better tolerated future alternative.

A kindred with Griscelli disease: spectrum of neurological involvement

We report four members of a highly consanguineous family with silver-grey pigmentation of hair, two of whom had skin histology compatible with Griscelli disease. Unlike previously reported patients, they did not suffer from recurrent infections. In addition, there was a spectrum of neurological involvement varying from mild cognitive delay with a convulsive disorder in one patient, to a fatal degenerative course in three others. One patient developed a prolonged febrile illness with histological evidence of florid lymphoid hyperplasia.

Differentiation-related expression of adhesion molecules and receptors on human neuroblastoma tissues, cell lines and variants

The expression of cellular adhesion molecules (CAM) involved in cell adhesion and immune recognition was measured on neuroblastoma tissue samples, on a neuroblastoma (NB) cell line, SK-N-SH, and on 3 phenotypically different variants, SH-SY5Y, SH-EP, SH-IN, representing neuronal, Schwannian/glial or intermediate NB-cell types. Immunohistochemical analysis of CAM expression by NB and related tumors at different stages of differentiation revealed a co-expression of several CAM (ICAM-1/CD54, LFA-3, VLA-2 and HLA-ABC) associated with low stages and more highly differentiated NB tumors and peripheral neuroepitheliomas (PN). In contrast, N-CAM was uniformly expressed on all NB tumors. Flow cytometric analysis of CAM surface expression by SK-N-SH and variant cells revealed highly variable phenotypes. Expression of ICAM-1, LFA-3, VLA-2 and HLA-ABC molecules was associated with the epithelial cell type represented by the SH-EP variant. In contrast, low expression of these molecules and high expression of N-CAM was associated with the neuronal SH-SY5Y cells. Exposure of the NB cells to differentiation inducers (retinoic acid, 5'-bromodeoxyuridine and phorbol esters) and cytokines (tau-interferon, alpha-tumor necrosis factor) resulted in a variable up-regulation of the expression of all CAMs, except N-CAM, regardless of the type of differentiation induced. In an attempt to establish a link between the pattern of expression of CAM on NB cells and their susceptibility to natural killer (NK) or lymphokine-activated killer (LAK) cell lysis, the analysis revealed that NB cells expressing CAM and a differentiated phenotype were less susceptible to NK lysis, but no difference in the sensitivity of the NB cell types to LAK effectors was observed. Treatment of NB target cells with cytokines or PMA decreased their susceptibility to NK and LAK lysis, while induction of differentiation with RA or BUdR resulted in no changes in the sensitivity to NK and LAK lysis. In conclusion, expression of HLA-ABC and several co-regulated CAMs was shown to be associated with a differentiated phenotype in NB, with an overall decreased sensitivity to NK/LAK effector cells.

Gamma-irradiated peripheral blood mononuclear cells can express LAK activity

Peripheral blood mononuclear cells (PBMC) irradiated with high dose gamma-radiation (1000-5000 rad) are commonly used as feeder cells during the cloning of T lymphocytes, natural killer (NK) and lymphokine activated killer (LAK) cells. We report here that such gamma-irradiated PBMC can be stimulated with interleukin 2 (IL-2) to express the ability to lyse a variety of tumor cell targets. The non-major histocompatibility complex (MHC) restricted cytotoxicity demonstrated by irradiated PBMC is, however, lower than that expressed by their non-irradiated counterparts. The numbers of viable, gamma-irradiated LAK cells are significantly increased by the addition of the mitogen, phytohemagglutinin (PHA). Purification of the gamma-irradiated cells expressing cytotoxic activity by flow cytometry determined that the effector cells were predominantly CD3- cells, although some CD3+ cells also expressed moderate LAK activity. The ability of gamma-irradiated cells to proliferate in the presence of PHA alone, or with IL-2 + PHA, was maximal at day 4-5; but proliferation, as detected by 3H-thymidine uptake, was not detectable beyond 12-15 days of in vitro culture. Because many of the LAK, T cell and NK cell cloning procedures require the presence of feeder layers, growth factors (usually IL-2) and mitogens, the presence of residual feeder cells expressing cytotoxic activity may affect the specificity of such clones. Thus, efforts should be made to ensure that such gamma-radiation-resistant cells capable of expressing cytotoxic activity are completely eliminated before the cloned cells are used for further experiments.

Effect of ubenimex on the immune system of patients with hematological malignancies

The effect of in vivo administration of ubenimex (Bestatin) on the immune status of patients with hematological malignancies in remission was studied. Natural killer (NK) cell activities, lymphokine activated killer (LAK) cell activities, production of interferon-gamma (gamma-IFN) and surface antigens of peripheral lymphocytes were examined before and after administration of ubenimex. Analysis of the T, B and NK cell compartment ax conducted by assessing expression of the following antigens: CD3+CD19- (T), CD3-CD19+ (B), CD8+CD11b- (Tc), CD8+CD11b+ (Ts), CD4+Leu8-(Th), CD4+Leu8+(Ti), CD16CD57 (NK) using a 2-color flow cytometric analysis. NK and LAK activity was significantly lower in patients with hematological malignancies as compared to normal subjects. The absolute numbers of lymphocytes and NK cells were also lower than those in healthy controls. The reduced NK and LAK activity, however, was elevated after ubenimex administration. The absolute numbers of helper T cells, cytotoxic T cells and NK cells were also increased after administration of the drug. These findings were not observed in patients treated without ubenimex. Serum levels of IFN-gamma were not markedly changed after ubenimex administration. But peripheral blood mononuclear cells cultured with rIL2 showed appreciable levels of IFN-gamma production, and production increased after ubenimex administration. These results shows that ubenimex is a powerful immunomodulator that augments or restores some immune functions in patients with hematological malignancies.

The role of autologous tumor cells in preventing lymphokine-activated killer cell induction in vitro

Peripheral blood lymphocytes (PBL), when cultured in vitro in the presence of autologous irradiated tumor and interleukin-2 (IL-2), become more restricted in the spectrum of their cytotoxicity. The cells continue to exhibit cytotoxicity for autologous tumor cells and major histocompatibility complex (MHC)-concordant allogeneic tumor cells of similar histologic type but not for the natural killer target cell line, K562. Furthermore, the addition of autologous tumor at different time points after the initiation with IL-2 alone of conventional lymphokine-activated killer cell cultures modifies both the specificity and the degree of cytotoxicity of these lymphocytes for tumor targets. By varying the culture conditions it may be possible to generate killer cells that will exhibit similarly enhanced and more restricted antitumor effects in vivo.

Elevations of cytokines interleukin-1, interleukin-2 and tumor necrosis factor in the urine of patients after intravesical bacillus Calmette-Guerin immunotherapy

In an attempt to elucidate further the immunological mechanisms responsible for the effectiveness of intravesical bacillus Calmette-Guerin in the therapy of superficial urothelial bladder cancer, a prospective study was performed in which the urine of patients was examined before and after 6 intravesical instillations of bacillus Calmette-Guerin for the presence of the cytokines interleukin-1, interleukin-2 and tumor necrosis factor-alpha. Biological assays such as specific sandwich enzyme-linked immunosorbent assays were used for the analysis of each cytokine. Urinary titers of interleukin-1, interleukin-2 and tumor necrosis factor increased significantly after bacillus Calmette-Guerin instillation but showed inter-individual differences. The maximum of secretion into the urine was seen between 4 and 8 hours after the instillation, and titers returned to baseline values within 24 hours. The differences in 24-hour secretion between the bacillus Calmette-Guerin-treated (10 patients) and the control (10) groups were significant with respect to all cytokines as tested in both assays each, except for the interleukin-1 biological assay. These results reflect the strong inflammatory response in the bladder wall to bacillus Calmette-Guerin, in which the urinary secretion of the detected cytokines may be associated with the local tumor control.

Cytotoxicity of lymphokine-activated killer cells against human neuroblastoma cells: modulation by neuroblast differentiation

The cytolytic activity of lymphokine-activated killer (LAK) cells against human neuroblastoma (NB) cells was investigated using the continuous NB cell lines, IMR-32, Kelly, and two subclones of SK-N-SH, SH-SY5Y (neuroblastic phenotype), and SH-EP (non-neuronal phenotype). NB cells were found to be sensitive targets of LAK. Of the SK-N-SH subclones, the neuroblasts, SH-SY5Y, were more susceptible to LAK killing than were the non-neuronal cells, SH-EP. Pretreatment of the targets SH-SY5Y and SH-EP with the differentiating agents, retinoic acid (RA, 10 microM), herbimycin A (236 nM), or nerve growth factor (10 ng/ml), did not substantially alter LAK killing. Furthermore, these differentiating agents did not measurably affect LAK activity during the cytolysis assay or with 1-h preincubation of the LAK effectors. However, co-incubation of the LAK cultures over the 3-day activation period with RA (1 microM) or PGE2 (1 microM) inhibited cytolysis by 80%, suggesting that these agents interfere with an early activation step of LAK. These results support the potential use of LAK treatment for neuroblastoma, in combination with differentiation agents that do not affect neuroblastoma sensitivities toward LAK cells. However, some differentiation agents, (e.g., RA) and endogenous prostaglandins (e.g., PGE2) may interfere with LAK activation.

Effect of host age upon interleukin-2-mediated anti-tumor responses in a murine fibrosarcoma model

The age-associated decline in immune function may be an important factor in both the pathogenesis of neoplastic diseases and the response to immunopharmacological therapies. With the increased efforts to develop immunotherapy with such agents as interferon and interleukin-2 (IL-2), the question of the effect of host age upon response is of practical importance. Phase I and phase II clinical trials of IL-2 have included primarily young patients, and toxicity and efficacy have not been reported with specific reference to host age. In this study, we examined young and old mice with regard to in vitro natural killer and lymphokine-activated killer (LAK) cell functions. We also assessed the effects of exogenously administered recombinant human IL-2 in tumor-bearing mice of various ages. We found that natural killer cell function was demonstrably lower in old mice but that LAK cell function was comparable (young versus old). Furthermore, IL-2 treatment was successful in increasing survival time in old mice, similar to results in young mice. Our observations allow the prediction that immune senescence per se does not preclude successful anti-neoplastic treatment with IL-2.

Generation of human LAK cells in tissue culture bags using recombinant IL-2 and serum free medium. Effects of pretreatment with phenylalanine-methylester

A technique for processing and culturing of human LAK cells using an automated closed system and tissue culture bags is described. To circumvent the inhibitory effects of monocytes on LAK cells the peripheral blood mononuclear cells (PBMC) were pretreated with phenylalanine-methylester (PheOMe). PBMC were obtained from healthy donors by leukapheresis of whole blood. After pretreatment with PheOMe and culturing with IL-2 for 96 h, 60% of the cells remained. PheOMe significantly reduced the number of monocytes (Leu-M3+ cells) from 20-12%. The lytic activity (against K562 and Daudi) of non-PheOMe-treated cells reached a plateau at 72-96 h while PheOMe-treated cells reached maximum activity at 96 h. The total lytic activity/tissue culture bag at 96 h of PheOMe-pretreated cells was significantly augmented in comparison to non-PheOMe-pretreated cells. The present technique allows rapid and simple generation of LAK cells without serum in sterile receptacles suitable for therapy. Additionally, the LAK cell efficacy was improved by reducing the inhibitory effects of monocytes.

Adoptive immunotherapy with lymphokine-activated killer cells plus recombinant interleukin 2 in patients with unresectable hepatocellular carcinoma

Ten patients with hepatocellular carcinoma, three of whom had pulmonary metastasis, were treated with adoptive immunotherapy using autologous lymphokine-activated killer cells plus recombinant interleukin 2. Patients received 15 micrograms per day of recombinant interleukin 2 consecutively (for 14 to 64 days), from Day 7 prior to the first leukapheresis, and received 10(9) to 10(10) lymphokine-activated killer cells once or twice per week intravenously; the lymphokine-activated killer cells had been generated from mononuclear cells obtained through leukapheresis. Preadministration of recombinant interleukin 2 prior to the first leukapheresis resulted in a remarkable increase of lymphokine-activated killer activity in seven of nine cases in whom lymphokine-activated killer activity had been poorly inducible even at high concentrations of recombinant interleukin 2. At the end of the treatment, liver tumor regression (34 and 63%, respectively, of two-dimensional size) was observed in two of two patients with a solitary tumor; no increase of liver tumor size was observed in seven patients with massive or multiple tumors, and no changes in the size or number of pulmonary metastatic tumors in any patients were observed. More than a 35% decrease in serum alpha-fetoprotein level was noted in four of nine alpha-fetoprotein-positive patients. However, Child's grades, performance status and lymphokine-activated killer activity on entry into the study could not be used as parameters to predict therapy responsiveness. Neither serious side effects nor significant changes of serum bilirubin, ALT and creatinine were noted. Thus, this treatment seems to be well tolerated even in advanced hepatocellular carcinoma with poor liver function reserve, and tumor regression could be expected in small-burden hepatocellular carcinoma. The assessment of the therapeutic effects and application in hepatocellular carcinoma awaits the development of this trial.

A phase I study of interleukin-2 in children with cancer and evaluation of clinical and immunologic status during therapy. A Pediatric Oncology Group Study

The authors performed a Phase I study to assess the toxicity and hematologic effect of recombinant human interleukin-2 (rIL-2) in seven children with advanced malignancies. The rIL-2 was given as a bolus injection of 1 or 3 X 10(6) U/m2/dose three times a week (Monday, Wednesday, and Friday) for 3 weeks. No life-threatening toxicity occurred with the dose of 1 X 10(6) U/m2 of rIL-2. At a dose of 3 X 10(6) U/m2, therapy had to be terminated due to cardiovascular toxicity in two patients. Toxic effects at low-dose rIL-2 included fever, nausea, vomiting, and mild hypotension. High-dose rIL-2 toxicity included fluid retention, increased creatinine, oliguria, elevated liver enzymes, and significant hypotension. Immunologic studies showed that rIL-2 caused a drop in the number of circulating peripheral blood mononuclear cells, T-cells, and natural killer cells which returned to pretherapy levels or above by 24 to 48 hours. The rIL-2 exerted no growth or stimulatory activity on the leukemic cell population. To the authors' knowledge, this is the first report of a Phase I study of IL-2 therapy in children.

Treatment of malignant ascites with allogeneic and autologous lymphokine-activated killer cells

Two cases of peritonitis carcinomatosa with gynecological cancer, which did not respond to conventional treatment, were treated by intraperitoneal adoptive immunotherapy with allogeneic or autologous lymphokine-activated killer (LAK) cells plus interleukin-2. In case 1, reduction of acute ascites and disappearance of malignant cells from the peritoneal fluid and decreased levels of tumor markers (CA12-5 and CA19-9) were demonstrated during the treatment. In case 2, which also received additional treatment for pleuritis carcinomatosa, reduction of ascites and pleural effusion and disappearance of malignant cells from the pleural fluid were noted. In these cases allogeneic LAK therapy was well tolerated. This therapy did not prolong the patients' lives, but the findings indicate that it had appreciable local antitumor effects on peritonitis and pleuritis carcinomatosa in these patients with gynecological cancer.

Ganglioside GM2 expression on human melanoma cells correlates with sensitivity to lymphokine-activated killer cells

Ganglioside GM2 is expressed on cell surface membranes of a variety of human malignant cells and has been demonstrated to be immunogenic in humans. We have assessed the role of the antigen GM2 on melanoma cells as a recognition structure for lymphokine-activated killer (LAK) cells. LAK cells were generated by stimulation of non-adherent peripheral blood lymphocytes (PBL) from human donors with recombinant interleukin-2 (IL-2). The selection of target cells was based on GM2 content and included 11 human melanoma cell lines and 2 human leukemia lines. Using a single-cell binding assay, LAK cell binding to target lines expressing high levels of GM2 was significantly greater than to those expressing minimum GM2. This cell-binding was specifically inhibited by addition of purified GM2 but not by other gangliosides. LAK-melanoma cell-binding was also specifically inhibited by anti-GM2 monoclonal antibody (MAb). For further analysis LAK cell lysis of melanoma target cells expressing various amounts of GM2 was assessed. A significant correlation occurred with GM2 expression and LAK cell lysis (p less than 0.025; r = 0.623). Three other gangliosides commonly expressed on human melanoma, GM3, GD3 and GD2, had no correlation with LAK cell lysis. These studies suggest that GM2 on melanoma cells is a marker for LAK cell sensitivity, as well as indicate that GM2 is a potential target recognition structure for human LAK cells.

In vitro activation of lymphocytes from nonsmall cell cancer patients by interleukin 2 and anti-CD3 antibody

The current interest in adoptive immunotherapy of cancer has stimulated research into novel approaches of activating lymphocytes in vitro. We have studied the effect of anti-CD3 antibody on the in vitro activation of peripheral blood lymphocytes and tumor infiltrating lymphocytes (TIL) taken from patients with nonsmall cell cancer of the lung (NSCC). We demonstrate that anti-CD3 substantially enhances the proliferative response and bulk culture growth of interleukin 2 (IL-2)-activated killer cells. The addition of anti-CD3 to IL-2-treated TIL enhances their cytotoxicity against fresh autologous NSCC tumor targets, but not against the cancer cell lines K562 and M14. The effectors generated by culture in IL-2 and anti-CD3 have greatly increased IL-2 receptor expression and are predominantly CD4+ cells. These results establish anti-CD3 as a potentially powerful agent in the in vitro activation of lymphocytes from cancer patients.

Histological evidence of natural killer cell aggregation against malignant melanoma induced by adoptive immunotherapy with lymphokine-activated killer cells

Adoptive immunotherapy with lymphokine-activated killer (LAK) cells and systemic administration of recombinant Interleukin-2 (RIL-2) was carried out in a case of malignant melanoma with lung metastases. Histological specimens from the lung showed a metastatic melanoma heavily invaded by atypical lymphoid cells with convoluted nuclei of varying size. Immunohistochemistry revealed that these cells had the characteristic exclusively of natural killer cell (Leu-7+). Nodules of these cells mimicked the appearance of non-Hodgkin's lymphoma of pleomorphic type. Molecular cytogenetic analysis, however, showed the absence of rearranged bands for the T-cell receptor beta-chain gene, indicating the absence of T-cell clones. At autopsy, 1 month after the LAK therapy, the heavy invasion of convoluted cells had disappeared. These findings clearly indicate that the LAK cell plus RIL-2 therapy induced Leu-7+ lymphoid cells, phenotypically suggestive of natural killer cell aggregation in the tumours.

Cytokines and pancreatic cancer. The effect of rIFN-gamma, HuLeIFN, rTNF-alpha, and LAK-cells on pancreatic and other gastrointestinal tumors in vitro

A panel of 10 digestive tract carcinoma cell lines (6 pancreatic carcinomas) was assayed for their sensitivity to HuLeIFN, human rIFN-gamma, rTNF-alpha and allogeneic human LAK-cells in vitro. In addition, a combination of rIFN-gamma + rTNF-alpha was tested on 3 pancreatic carcinoma cell lines. Whereas 6/7 cell lines were completely resistant to HuLeIFN, rIFN-gamma and rTNF-alpha did inhibit growth of some carcinomas tested. The individual sensitivity was heterogenous as is already known from cytostatics. Response to rIFN-gamma tended to increase with increment of cell doubling time. Only high concentrations (greater than 1000 U/ml) of rIFN-gamma displayed cytotoxicity on sensitive tumors. The antitumoral effect of rIFN-gamma was stimulated by rTNF-alpha. As revealed by isobole analysis this interaction was synergistic in all pancreatic carcinomas tested. In comparison to rIFN-gamma or rTNF-alpha the response to LAK-cells was slightly superior at high effector target ratios, even though heterogenous.

Phenotypic and functional analysis of lymphokine-activated killer (LAK) cell clones. Ability of CD3+, LAK cell clones to produce interferon-gamma and tumor necrosis factor upon stimulation with tumor targets

Lymphokine-activated killer (LAK) cells are generated by the culture of peripheral blood lymphocytes with interleukin-2 (IL-2). A variety of cells, including T-lymphocytes and natural killer (NK) cells, can be activated by IL-2 to exhibit the ability to kill multiple tumor and "modified-self" targets. Recent reports indicate that culture conditions can determine the phenotype of cells expressing LAK activity. Using limiting dilution techniques, we first generated cloned LAK cells with three culture conditions: autologous human serum (AHS) + IL-2; AHS + IL-2 + 0.1 micrograms/ml phytohemagglutinin and fetal bovine serum and IL-2. We determined that all but one of the 47 LAK cell clones generated with the three culture conditions were CD3+ and T-cell like; one NK-like clone was observed. Clones that were cytotoxic for one target could generally kill multiple targets, and the absence of phytohemagglutinin did not significantly affect the ability of the LAK cell clones to kill multiple targets. The presence of phytohemagglutinin was, however, necessary for the long-term maintenance of proliferation and cytotoxic activity of the LAK cell clones. The mechanism by which LAK cells kill tumor targets is not known. We here demonstrate that LAK cells and LAK cell clones can produce interferon-gamma and tumor necrosis factor (TNF) when stimulated with an erythroleukemia cell, K562. Five of the six CD3+, LAK cell clones tested could be stimulated by K562 cells to produce both interferon-gamma and TNF. However, the ability of the cloned LAK cells to kill K562 cells, as measured in a 4-h 51Cr-release assay, did not correlate with their ability to produce these cytokines. Furthermore, specific antibodies that neutralize the cytotoxic activity of interferon-gamma and TNF did not inhibit killing of K562 cells by LAK cells as measured with a 4-h cytotoxic assay. The cytostatic and cytotoxic activities of interferon-gamma and TNF for tumor cells are well documented, but these cytolytic activities are slower acting and exhibit their maximum effect after 48-96 h. We here propose that LAK cells kill tumor targets by a combination of cell-to-cell-mediated killing and by the release of slower acting cytostatic/cytotoxic cytokines that can inhibit the growth of tumors some distance from the effector cells.

The cellular immunotherapy of cancer: current and potential uses of interleukin-2

The potential for immune-mediated destruction of neoplasms was suggested nearly one century ago. Despite this, no "magic bullet" has yet been identified. Nevertheless, the physiology of cell-mediated immune reactions has been well characterized in molecular, cellular, and clinical studies of allograft and microbial immunity. Extensive studies performed in laboratory animal models have documented the in vitro and in vivo destruction of various neoplastic tissues by immune cells. This destruction can be directed against autologous, syngeneic, or allogeneic tumors in several systems with varying degrees of "tumor specificity". Two approaches exist towards utilizing these immune reaction in vivo. The first involves providing the tumor bearer with immunostimulatory agents, either specific or nonspecific, designed to activate and amplify the destructive potential of the individual's endogenous immune cells able to recognize and destroy autologous tumor. The second approach provides immune cells with antitumor capacity to a tumor-bearing individual, these cells having been activated exogenously. A number of successful regimens involving these two approaches, and combinations of them, have been delineated in animal tumor models. These experimental studies lay a strong foundation for initiating clinical trials of these concepts for patients with cancer. This review summarizes the diverse experimental studies in animals leading to clinical trials, presents recent data from ongoing clinical trials directly testing the potential for cellular immunotherapy, and then presents some of the major challenges facing further development and application of this potential therapeutic approach.

Induction of cytotoxicity from fresh splenocytes after in vivo administration of cyclophosphamide. Importance of long-term culture with high-dose recombinant interleukin-2

Cyclophosphamide, combined with lymphokine-activated killer (LAK) cells and recombinant interleukin-2 (rIL-2), is known to mediate regression of tumors, but the effects of cyclophosphamide on the subsequent generation of LAK cells are unclear. It was the aim of the experiments in this paper to determine whether fresh splenocytes cultured with rIL-2 would maintain or regain their cytotoxicity in vitro after being exposed to the cytotoxic agent cyclophosphamide in vivo. Functional monitoring of splenocytes after in vitro incubation with rIL-2 was performed at various times through chromium-release assays, thymidine assays and cell-cycle analysis. Chromium-release assays determined that the cytotoxicity of cultured splenocytes returned to normal after 12 days of in vitro culture with rIL-2. The thymidine assays indicated a normal rate of uptake of thymidine after 7 days in culture, while the cell cycle was still abnormal by day 12 of culture. The growth and expansion of rIL-2-activated splenocytes after different times of in vitro culture indicated a return to normal compared to control animals after 7 days of continuous in vitro exposure to rIL-2. It is concluded that murine splenocytes can demonstrate cytotoxicity after exposure to cyclophosphamide, through prolonged continuous in vitro culture with rIL-2. Since cyclophosphamide did not jeopardize the production of splenocyte cytotoxic effectors generated with rIL-2, it appears to be a strong contender for use in chemoimmunotherapy protocols.

Recombinant interleukin-2 activates peripheral blood lymphocytes from children with acute leukemia to kill autologous leukemic cells

In order to determine if recombinant interleukin-2 (rIL-2) can induce lymphokine-activated killer (LAK) cells able to lyse autologous leukemic cells, we incubated peripheral blood (PB) mononuclear cells from children with acute leukemia with 50 U/ml rIL-2 for 5 days. These PB effector cells were then tested for their ability to lyse autologous leukemic cells in a 51CR release assay. The PB cells before incubation with rIL-2 showed little or no cytotoxicity for autologous blasts (range, 0 to 12%; mean, 2%). However, after incubation with rIL-2, PB cells from four of five children with acute lymphoblastic leukemia (ALL) at diagnosis or in relapse, and from six of eight children with ALL in remission were able to lyse autologous blasts. The percent lysis (range) was 0 to 69% (mean, 37%) for the former group, and 0 to 113% (mean, 43%) for the latter group. The PB cells from three patients (one in relapse and two in remission) failed to develop LAK activity after incubation with rIL-2. However, in each case cytotoxicity versus K562 was increased after incubation with rIL-2. Furthermore, in a Phase I study of rIL-2 for the treatment of refractory leukemia, a patient was treated with rIL-2 for 3 weeks (nine injections of 3 x 10(6) U/m2 each). Her fresh PB mononuclear cells developed a low level of cytotoxicity (11% lysis) against her autologous blasts during this time. The finding that rIL-2 in vitro and in vivo induces LAK cells with cytotoxicity against autologous leukemic cells provides the rationale for the clinical trial of this agent in the treatment of children with ALL.

Lymphokine-activated killer (LAK) activity against autologous malignant tumors of the skin

When peripheral blood mononuclear cells (PBMC) cultured with interleukin 2 (IL-2) develop the ability to lyse fresh tumor cells, such activity is referred to as lymphokine-activated killer (LAK) activity. In this paper, we examined LAK activity against the autologous skin tumors, malignant melanoma (MM), squamous cell carcinoma (SCC), and basal cell epithelioma (BCE), which have distinct clinical characteristics. Similar levels of LAK activity against Daudi 1A4, an NK resistant cell line were significantly obtained from all cancer patients. However, different levels of LAK activity against autologous tumor cells were found from three kinds of cancer patients using mixtures of autologous tumors and LAK. The levels of cytotoxicity were 29.8 +/- 7.0% in five MM, 15.9 +/- 4.9% in seven SCC, and 4.0 +/- 2.3% in five BCE patients at an effector/target ratio of 50/1. Allogeneic MM targets were lysed by LAK from all three types of cancer patients at similar levels, implying that LAK is not restricted to major histocompatibility complex (MHC) antigens. These results indicate that the levels of autologous LAK activity were significantly associated with the magnitude of clinical malignancy of the tumor targets, and suggested the selective lysis of tumor targets by LAK. NK activity of cancer patients bearing tumors was also examined prior to therapy. The levels of NK activity observed in MM patients were considerably lower than those in two other cancer patients.

Immunoregulation of lymphokine-activated killer cells

The in vitro effects of Concanavalin A (Con A) and prednisolone (PRD) on the cytotoxic functions of lymphocytes and the generation of lymphokine-activated killer (LAK) cells were investigated. Con A at concentrations ranging from 1 to 40 micrograms/ml did not significantly affect the cytotoxicity of LAK cells when added directly to the effector and target cell mixture in a 4-hr 51Cr release assay. The generation and lytic capacity of LAK cells were significantly affected by Con A in a dose-dependent manner when lectin was added at the initiation of culture. Suppression of LAK cell activity was demonstrable at effector: target (E:T) cell ratios. Lymphocyte cultures incubated with PRD at concentrations ranging from 10(-9) to 10(-4) M showed a decrease in both the numbers of and activity of LAK cells using a variety of target cells. Pretreatment of target cells with either PRD or Con A did not affect their sensitivity to lysis by LAK cells and incubation of lymphocytes with Con A did not induce autoreactive cytotoxic or suppressor cells directed against LAK cell activity. Thus while PRD and Con A can inhibit the generation of LAK cells, they also directly inhibit their specific cytotoxic activity on a per cell basis. These results suggest that like other cytotoxic cells, LAK cells are also under active immunologic control.

In vitro cytolysis of primitive neuroectodermal tumors of the posterior fossa (medulloblastoma) by lymphokine-activated killer cells

Short-term stimulation of nonantigen-primed peripheral blood mononuclear leukocytes with interleukin-2 generates a population of oncolytic effectors designated "lymphokine-activated killer" (LAK) cells. These LAK cells express potent lytic activity against a wide spectrum of fresh or cultured autochthonous (patient's own) and allogeneic (unrelated) tumors, yet specifically spare normal tissues. In this study, cells derived from primitive neuroectodermal tumors of the posterior fossa (PNET-PF) were examined for their sensitivity to LAK cytolysis utilizing an in vitro 4-hour chromium-51-release assay. Five early-passage cell lines, derived from primary PNET-PF, demonstrated significant sensitivity to LAK cell cytolysis. Lysis was equally effective in culture medium and cerebrospinal fluid. Three freshly excised PNET-PF exhibited similar susceptibility to lysis by autochthonous LAK cells. Greatly increased expansion of LAK cell cultures could be achieved by short-term stimulation with monoclonal anti-CD3 antibodies in addition to interleukin-2 activation. These findings constitute the preliminary in vitro foundations for potential intrathecal adoptive immunotherapy of PNET-PF with LAK cells.