Spontaneous human lymphocyte-mediated cytotoxicity against tumor target cells. IX. The quantitation of natural killer cell activity

TNF-alpha and IFN-gamma reverse IL-4 inhibition of lymphokine-activated killer cell function

Recombinant IL-4 inhibits IL-2-induced lymphokine-activated killer (LAK) cell development of PBMC. We evaluated the effect of various cytokines in reversing IL-4-mediated LAK inhibition. PBMC were cultured in IL-2 (10-1000 u/ml) with or without IL-4 (2-100 u/ml) and tested for cytotoxicity against the NK-sensitive K562 cells and NK-resistant UCLA-SO-M14 cells. Addition of IL-4 at the beginning of culture suppresses LAK activity in a dose-dependent fashion. Addition of IFN-gamma or TNF-alpha partially reverses IL-4-mediated inhibition (30-100%) in a dose-dependent fashion. IFN-gamma and TNF-alpha must be added within the first 24 hr of initiating culture in order to reverse IL-4 inhibition. Furthermore, IFN-gamma and TNF-alpha are most effective at reversing IL-4 inhibition at low concentrations of IL-2 (less than 100 u/ml). Addition of other IL-2-induced cytokines such as GM-CSF (50 u/ml), M-CSF (250 u/ml), and IFN-alpha (10-10,000 u/ml) fails to reverse IL-4 inhibition. In addition to suppression of LAK induction, IL-4 also inhibits IL-2-induced IFN-gamma and TNF-alpha protein production in PBMC. The reversal of IL-4-mediated LAK inhibition by TNF-alpha and IFN-gamma may therefore be due to resupply of these endogenously suppressed cytokines.

Altered T-lymphocyte response following aggressive encounters in mice

Intermale aggression is a natural form of psychosocial stress that can alter a variety of physiological functions, including immune function. In Experiment 1, daily fighting between pairs of previously isolated male mice differentially altered immunological measures of T-cell responsiveness in dominant and submissive animals. Submissive mice had lower T-cell proliferation and IL-2 production, when compared to dominant, nonfought, or witness mice. Since the fighting behavior often results in wounding of the submissive animal, Experiment 2 used a relatively nonaggressive test to determine whether the immunological differences between dominant and submissive mice were due to wounding or due to the psychosocial state of dominance. Dominant mice had elevated T-cell proliferation and IL-2 production when compared to the other treatment groups. Therefore, it appears that in dominant/submissive pairs of mice a severe physical stress, such as intense fighting, influences the immune system in a different manner than psychological or mild aggressive encounters.

Antibody-dependent cellular cytotoxicity mediated by CD16+ lymphocytes from HIV-seropositive homosexual men

We investigated the ability of peripheral blood mononuclear cells (PBMC) from human immunodeficiency virus (HIV)-seropositive asymptomatic and mildly symptomatic homosexual men with known time of seroconversion to mediate antibody-dependent cellular cytotoxicity (ADCC) specific for HIV. PBMC from HIV-seronegative and -sero-positive subjects lysed T (CEM) cells persistently infected with HIV to a significantly greater degree than uninfected CEM cells in the presence of HIV antibody-positive serum in a 4-hr 51Cr release assay. The response was mediated by CD16+ cells. ADCC responses were lower in PBMC of 13 men tested 9 to 25 months (average, 16.1 months) after seroconversion to HIV as compared with seronegative subjects, and were further decreased in 11 men tested 26 to 38 months (average, 31.6 months) after seroconversion. Decreases in numbers of circulating CD16+ cells appeared to contribute to depression in ADCC activity. The suppressive effect of HIV infection on ADCC effector cell activity may be important in the immunopathogenesis of acquired immune deficiency syndrome.

Anti-tumor x anti-CD3 heteroconjugates direct human peripheral blood lymphocytes to lyse colon tumor cells

T lymphocytes normally recognize antigens through the antigen receptor complex (TCR/CD3) but can be redirected to bind and lyse unrecognized tumor cells by anti-tumor X anti-CD3 heteroconjugates. Chemical coupling of an antibody directed against the T cell receptor complex and an antibody directed against tumor antigen produces a conjugated antibody that activates the T cell lytic mechanism and bridges the T cell and tumor cell. We tested the lytic activity of heteroconjugate-treated cultured human peripheral blood lymphocytes (PBLs) in 4-h radioactive chromium release assays with human colon tumor cell targets. PBLs were enriched for T cells by the depletion of Leu11a+ and Leu19+ cells, prior to culture in rIL-2 and anti-CD3. Cultured human PBLs depleted of Leu11a+ and Leu19+ cells produced low levels of tumor cell lysis in the absence of antibodies. Anti-tumor X anti-CD3 heteroconjugates significantly enhanced tumor cell lysis by cultured PBLs when tested against four different colon tumor cell lines (P less than 0.005), but, heteroconjugates in the absence of PBLs did not augment tumor cell lysis. Cultured PBLs treated with monoclonal anti-tumor antibody, with monoclonal anti-CD3 antibody, or with irrelevant heteroconjugate did not enhance tumor cell lysis. We conclude that heteroconjugate-directed lysis is mediated by PBLs and that both the anti-tumor antibody and the anti-CD3 antibody are essential for heteroconjugate function. In addition, heteroconjugate-enhanced tumor cell lysis is mediated through a mechanism other than antibody-dependent cellular cytotoxicity or nonspecific T cell receptor crosslinking.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chlordimeform and its metabolite 4-chloro-o-toluidine on rat splenic T, B and tumoricidal effector cells

The pesticide chlordimeform (CDF) and its metabolite 4-chloro-o-toluidine (4CT) are documented animal carcinogens. Various immunological and toxicological parameters were examined following CDF or 4CT exposure in Sprague-Dawley rats: spleen wt./body wt. ratio; spleen cells/mg; splenocyte viability; T and B cell mitogenesis; natural killer (NK) and natural cytotoxic (NC) cell activity. In this study CDF produced a dose-dependent inhibition of NK activity (E:T ratio 100:1). Significant decreases in NK activity also occurred at all CDF doses, while the spleen wt./body wt. ratio was reduced only by the highest CDF dose. The compound 4CT produced no significant effects on NK or NC activity. No changes were observed in spleen cells/mg, splenocyte viability, or in T and B cell proliferation mediated by concanavalin A (Con-A) and lipopolysaccharide (LPS), respectively, with either CDF or 4CT treatment. These results have demonstrated that CDF exposure has a selective effect on splenic functionally distinct tumoricidal effector cell populations, and that this effect is evident at 1 mg/kg, a dose not inconsistent with the maximum exposure levels in workers.

Differential sensitivity of head and neck cancers to non-major histocompatibility-restricted killer cell activity

Cell lines derived from squamous cell carcinoma of the upper aerodigestive tract (head and neck cancer) were phenotypically characterized with regard to differential sensitivity to nonmajor histocompatibility restricted (non-MHCr) killer cell activity. Requirements for detectable lysis of the cell lines in a standard chromium release assay included either isolation of fresh enriched Leu 19+ large granular lymphocytes (both Leu 19+CD3+ and Leu 19+CD3- populations) or interleukin-2 (IL-2) stimulation of peripheral blood lymphocytes (PBL). In neither circumstance could lytic activity be identified among Leu 19- populations. With PBL IL-2 stimulation significant differential sensitivity to lysis expressed by the head and neck cancer cell lines (P less than 0.001 by analysis of variance) was identified and maintained regardless of PBL source, i.e., PBL from healthy controls and three differing populations of head and neck cancer patients categorized by disease status and treatment. One factor associated with a cell line's increased sensitivity was degree of tumor differentiation, poorly differentiated tumors (as defined by intermediate filament cytochemical staining [decreased keratin and increased vimentin]) being more sensitive. Furthermore, as tumor cell lytic sensitivity increased, major histocompatibility complex (MHC)-class I antigen expression diminished concurrently. In 1 of 4 cell lines tested, however, pretreatment of tumor cells with interferon-gamma induced diminished lytic sensitivity independent of changes in MHC-class I expression, indicating factors not related to MHC-class I expression are likewise relevant. In previous studies we defined the in vivo prognostic significance of non-MHCr killer cell cytotoxicity activity against K562 targets, diminished activity being principally predictive of metastatic disease development in persons with poorly differentiated head and neck cancers. This report extends these observations by demonstrating in vitro that poorly differentiated head and neck cancer target cells are highly sensitive to changes in lytic function expressed by Leu 19+ non-MHCr effector cells.

Splenic natural cytotoxic activity is enhanced during growth of a murine fibrosarcoma

We have shown previously that the natural killer (NK) cell activity of DBA/2J mice bearing M-1 fibrosarcomas is consistently depressed at the later stages of tumor growth. The apparent mechanisms of inhibition are suppressor cell activation and prostaglandin E (PGE) production by tumor and lymphoid cells. In contrast, we show here that the natural cytotoxic (NC) activity of cells from the spleen, blood, and lymph nodes of mice bearing M-1 tumors is enhanced when compared to that of age- and sex-matched control mice. This enhanced NC activity does not appear to be due to increased cytolytic activity of macrophages but, rather, to enhanced cytolytic activity of multiple populations of non-adherent cells including B and T cells. Correlated with this is the finding that the NC activity of normal spleen cells is not inhibited in vitro by either PGE1 or PGE2 at levels which are inhibitory to NK cells. NC activity, although independent of PGE, is in fact enhanced by PGE1 in a dose-related fashion. These data indicate that NK and NC cells are regulated differently by PGE and during tumor growth. Utilizing a Winn assay, we also demonstrate that a cloned cell line with NC activity is capable of slowing tumor growth in vivo and that this action is improved if mice are treated with indomethacin concomitantly.

Natural killer cell activity, interferon-gamma and antibodies to herpes viruses in patients with Behçet's disease

Interferon-gamma (IFN-gamma) titres in 20 patients with active Behçet's disease were examined and compared with those of 20 normal donors. Sera from Behçet's disease patients revealed an IFN-gamma increase but no correlation between IFN level and natural killer (NK) activity. The analysis of lymphocyte subsets by monoclonal antibodies registered an increase of CD8+ T subpopulation and cells co-expressing CD8(+)-Leu7a+ markers. Moreover, a high number of cells expressing CD25+ and HLA-DR+ phenotype has been noted in patients with active Behçet's disease. Serological analysis showed a high level of IgG antibodies to HSV-1. The increase of IFN-gamma titre, the high number of activated T cells and the increasing level of IgG antibodies to HSV-1 are important manifestations during the active stage of Behçet's disease. These findings are discussed in relation to the immunopathogenesis of Behçet's disease.

In vivo enhancement of NK-cell activity by thymopentin

Natural killer (NK) activities of fresh and IL-2-precultured peripheral blood mononuclear cells (PBMC) were investigated in 13 elderly subjects before and after thymopentin (TP-5) treatment and in 12 age-matched controls. The NK activity of fresh PBMC was found to be significantly higher in subjects given TP-5 at 50 mg s.c. three times per week for one month. Conversely, this type of treatment with TP-5 did not significantly modify the cytotoxic capacity of IL-2-precultured PBMC.

Augmentation of antimetastatic activity of interferon and tumor necrosis factor by heparin

Interferon (IFN) and tumor necrosis factor (TNF) suppress the development of experimental metastasis and when used together, TNF and IFN show synergistic activity. However, the use of TNF is limited by its ability to initiate inappropriate hemostasis. Hemostatic effects are exaggerated by the procoagulant activity of certain tumor cell lines. Therapy with anticoagulants are indicated to block the effects of tumor cell products as well as chemotherapeutic side effects. Heparin is a glycosaminoglycan with diverse biological activity, including the ability to rapidly accelerate the inactivation of active clotting factors. The present studies have explored the therapeutic effects of combining heparin with TNF or interferon on experimental metastasis in mice using a melanoma cell line (B16BL6). Our data indicate that continued heparinization augments the antitumor activity of both interferon and TNF. Alterations of the hemostatic and immune systems play a role in the producing the observed effect.

Effects of recombinant interferon-gamma and interleukin-2 on the generation of lymphokine-activated killer cells in vitro

In order to determine if recombinant interferon-gamma (rIFN-gamma) can augment the effect of recombinant interleukin-2 (rIL-2) in generating lymphokine-activated killer (LAK) cells, we have incubated normal peripheral blood mononuclear cells (PBMC) with these lymphokines for 3 days and then tested their LAK and natural killer (NK) cell activity. We have found that LAK activity in PBMC from 13 out of 13 normal donors was increased by the combined lymphokines above that due to either lymphokine alone, provided that rIL-2 was present at suboptimal concentration: Optimal levels of rIFN-gamma (100 U/ml) were able to enhance the LAK-inducing activity of suboptimal levels (5 U/ml) but not optimal levels (100 U/ml) of rIL-2. NK activity showed a similar response to these concentrations of lymphokines. Activation of LAK/NK cells was accompanied by increases in the percentages of Leu 19+ (CD56) cells and TAC+ (IL-2-receptor) cells, and in the intensity of TAC antigen expression. These results indicate that combination rIFN-gamma and rIL-2 may be more effective in generating LAK/NK cells than rIL-2 alone, particularly with suboptimal concentrations of rIL-2 such as occur during continuous infusion therapy with this agent.

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.

Natural killer cytotoxicity in the diagnosis of immune dysfunction: criteria for a reproducible assay

Current evidence indicates that natural killer (NK) cells, which are large granular lymphocytes that mediate non-major histocompatibility complex (MHC)-restricted cytotoxicity and antibody-dependent cytotoxicity and that are involved in multiple regulatory, developmental, and immunologic processes, are important in health. Immunodeficiency states presenting with low NK activity are often associated with malignancies, chronic viral infections, or autoimmune diseases. Monitoring of NK function appears to be indicated as an aid to diagnosis, prognosis, and follow-up after therapy. Reliable performance of NK assays in a clinical laboratory requires that uniform criteria be established and followed for the acceptability of results. Statistical analysis of daily variability can be of great assistance in identifying and tracking sources of error, but routine statistical adjustments are not generally advisable. The quality control program described here provides a degree of assurance that this cytotoxicity assay can be dependable whether performed at one time point or serially. The successful implementation of this program requires laboratory resources, biostatistical support, and interpretative skills, all of which are available in a modern clinical laboratory.

Immunoregulatory role of in vitro differentiated macrophages on human natural killer (NK)-cell activity

Immunoregulatory effects of human macrophages on natural killer (NK) activity were studied. Monocytes were isolated by adherence to plastic, after leukapheresis of normal blood donors, and cultured for 1 to 14 days. In vitro-differentiated (5-7 days) human macrophages consistently and significantly (P less than 0.01) augmented NK activity of fresh autologous or allogeneic PBMNC. During culture, these macrophages also developed increased antitumor cytostatic activity. The optimal time for both the expression of cytostatic activity and up-regulation of NK activity was 5-7 days in culture. In contrast, 12- to 14-day macrophages significantly suppressed NK activity and had less cytostatic activity. Macrophages in culture demonstrated shifts in Leu-M3+HLA-DR+ phenotype from the mean of 60% +/- 11 (SD) in fresh monocytes to 90% +/- 5 between Days 5 and 7 in culture and then down to 10% +/- 5 in 14-day cultures. The activity of NK (CD56+CD3-) cells, purified by Percoll gradient centrifugation and flow cytometry, was up-regulated directly by in vitro-differentiated macrophages at low macrophage to NK cell ratios, and this up-regulation was not dependent on T lymphocytes or other accessory cells. The modulation of NK activity by differentiated macrophages was not MHC-restricted and depended on the viability and cellular integrity of macrophages. Sonicated macrophages could no longer up-regulate NK activity. This study shows that antitumor effects mediated by human in vitro differentiated LeuM3+HLA-DR+ macrophages may simultaneously involve more than one mechanism, namely direct cytostasis of tumor cells and activation of NK cells.

Granulocyte-monocyte colony-stimulating-factor augments the interleukin-2-induced cytotoxic activity of human lymphocytes in the absence and presence of mouse or chimeric monoclonal antibodies (mAb 17-1A)

Blood lymphocytes stimulated for 96 h with interleukin-2 (IL-2; 100 BRMP U/ml) (lymphokine-activated killer, LAK, cells) or granulocyte-monocyte colony-stimulating-factor (GM-CSF) (10 ng/ml) became cytotoxic for Daudi cells. IL-2 was significantly more effective than GM-CSF. Only IL-2-activated cells killed SW948 (a human colorectal carcinoma cell line) while GM-CSF-stimulated cell did not. GM-CSF and IL-2 acted synergistically in a dose-dependent fashion for induction of a highly effective cytotoxic cell population (IL-2/GM-CSF cells). Il-2/GM-CSF cells were statistically significantly more effective than LAK cells in lysing Daudi cells and SW948 (P less than 0.05). The enhancing effect was most pronounced during the first 48-96 h of activation. Incubation periods longer than 192 h did not contribute to augmented cytotoxicity. The combination of IL-2 and GM-CSF significantly increased the number of CD25+ cells compared to IL-2 and GM-CSF alone. Furthermore, IL-2/GM-CSF cells were significantly more effective in antibody-dependent cellular cytotoxicity assays (SW948 + mAb 17-1A) than LAK cells. The chimeric mAb 17-1A was significantly more effective in tumor cell lysis than the mouse mAb. Thus, combination of various biological therapeutics might be a way to enhance their antitumoral effects.

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.

The effect of antidepressants on immune function in mice

Depression or its treatment with antidepressant agents may have an impact on the normal function of the immune system. To address this issue in an animal model, we studied the effect of maprotiline and desipramine treatment of mice on several immunological activities associated with host resistance to cancer and infections. Our results indicate that chronic maprotiline treatment depressed natural killer (NK) cell function, measured in vivo as clearance of tumor cells from the lung or in vitro as cytolytic activity. Cell-mediated immunity, measured as delayed hypersensitivity in vivo and T and B lymphocyte proliferative responses in vitro, was largely unaffected. Although antidepressant toxicity at high concentrations inhibited T, B, and NK cell activity, it is unlikely that this is the basis for the in vivo effects.

Phenotypic and functional differences in NK and LAK cells in the peripheral blood of sooty mangabeys and rhesus macaques

Greater than 75% of the sooty mangabey monkeys at the Yerkes Regional Primate Research Center are naturally infected with SIV without any apparent clinical symptomology. On the other hand, experimental infection of rhesus macaques with SIV results in a clinical syndrome similar to human AIDS. These differences with regard to SIV infection prompted us to examine the natural immunosurveillance system of peripheral blood mononuclear cells (PBMC) from SIV-infected and uninfected monkeys of these two species. Phenotypic and functional studies of precursor and effector NK and LAK cells in the PBMC from these two species were carried out using monoclonal reagents, flow microfluorometry (FMF), and the standard in vitro 51Cr release assay against prototype K562 (NK sensitive) and RAJI (NK resistant, LAK susceptible) target cell lines. Data indicate that both NK and LAK cell activities in the PBMC of sooty mangabeys were significantly (P less than 0.01) greater than those in rhesus macaques. The predominant NK effector cells and LAK cell precursors were shown to be Leu 19-CD8+ in the PBMC of sooty mangabeys and Leu19+ CD8- in the PBMC of rhesus macaques as determined by panning depletion techniques and FMF analysis. On the other hand, the predominant LAK effector cells were found to be dual marked Leu 19+ CD8+ in rhesus macaques and Leu 19- CD8+ in sooty mangabeys. These qualitative and quantitative differences were not due to SIV infection of these two species since PBMC from both SIV-seropositive and virus-positive and SIV-sero-negative and virus-negative monkeys gave similar results. Moreover, of importance is the finding that the functional NK and LAK precursor cells are CD8+ and CD8- in sooty mangabeys and rhesus macaques, respectively. These data may have implications for the natural SIV/SMM virus-positive asymptomatic state of sooty mangabeys and may provide useful tools for tracing the ontogeny and lineage derivation of NK and LAK cells.

In vitro effects of an acyltripeptide, FK565, on antitumor effector activities and on metabolic activities of human monocytes and granulocytes

In vitro effects of an immunostimulatory acyltripeptide, FK565, on antitumor and metabolic activities of human leukocytes were studied. Monocyte cytotoxicity against A375 melanoma targets was significantly increased following pretreatment with FK565 at concentrations of 1 microgram/ml or more. The tripeptide also up-regulated anti-tumor cytostasis by monocytes and showed a strong stimulatory effect on superoxide generation by resting monocytes over a wide range of FK565 concentrations after 18 h preincubation. The monocyte preparations contained an average of 76% LeuM3+HLA-DR+, 12% LeuM3+HLA-DR- and 10% LeuM3-HLA-DR+ cells, and this phenotype distribution was not altered after incubation with FK565. At concentrations above 1 microgram/ml and after 2 h preincubation, FK565 also increased superoxide generation by resting but not stimulated granulocytes. Pre-exposure of cultured bovine endothelial cells to the peptide resulted in a significant inhibition of fMLP-stimulated granulocyte adherence to these cells. These data indicate that in vitro incubation of human monocytes and granulocytes with FK565 (0.1-100 micrograms/ml) had resulted in simultaneous up-regulation of several anti-tumor functions mediated by these cells.

Lymphokine activated killer (LAK) cells in antibody dependent cellular cytotoxicity (ADCC) using MAb 17-1A: a combination of potential usefulness in tumor therapy

Peripheral blood lymphocytes (PBL) stimulated by interleukin-2 (IL-2) for 48-96h, generated killer cells against the human colon cancer cell line SW948. The killing capacity increased significantly when the specific mouse monoclonal antibody (MAb) 17-1A was present during the lytic process. The chimeric antibody 17-1A determined a significantly stronger cytotoxicity compared to mouse MAb 17-1A. MAb BR55-2 which recognizes a different antigen on SW948 target cells mediated a similar cytotoxicity as MAb 17-1A. Presence of alpha-interferon (IFN) during the lytic assay significantly enhanced the killing of the tumor by lymphokine activated killer (LAK) cells as well as by LAK cells and mouse MAb 17-1A. However, when chimeric MAb 17-1A and LAK cells were used alpha-IFN failed to increase the lytic activity, probably due to already maximum lysis in the system. Combinations of various biological response modifiers such as monoclonal antibodies, IL-2/LAK cells and alpha-IFN carry great promise to improve this kind of therapy for cancer patients.

The effects of gamma interferon on the natural killer and tumor cells of children with neuroblastoma. A preliminary report

Human neuroblastoma cells lack HLA-A,-B,-C molecules which can be induced in vitro by gamma interferon (gamma IFN). To test the hypothesis that the same induction would occur in vivo leading to tumor regression, a Phase I study was initiated. Seven patients with neuroblastoma were entered on a Phase I study of recombinant gamma IFN in children. Three received 0.05 mg/m2 intravenously (IV) three times a week, three received 0.1 mg/m2 for 4 weeks, and one patient withdrew from study before receiving adequate treatment for evaluation. No significant clinical response was seen. The side effects were fever and chills, and no serious toxicity occurred. Natural killer (NK) and lymphocyte activated killer (LAK) precursor activity of peripheral blood mononuclear cells was determined before and during treatment, and expression of HLA-A,B,C molecules was looked for on the tumor cells in the bone marrow of five patients. The NK activity initially low, reached control levels in six patients, but the increase was transient. The LAK precursor activity remained normal. Expression of HLA-A,B,C, initially absent, was induced on the neuroblastoma cells in four of six patients.

An immunologic profile of young adults with head and neck cancer

Numerous reports have suggested, although never demonstrated, a suppressed immune defense mechanism as a contributing factor in the development of head and neck cancer in the young adult. Twenty-four previously untreated adults less than or equal to 40 years of age with squamous cell carcinoma were examined for lymphocyte function (natural killer cell activity and in vitro lymphocyte blastogenesis response to mitogens), total lymphocyte number and percentage of lymphocyte subsets, and humoral immune status (circulating IgA, IgG, and IgM). As compared with 33 healthy young adults, no significant immunologic deficit could be identified. On the contrary, the young adult cancer population had significantly increased lymphocyte numbers (P less than 0.05) and serum IgA, IgG, and IgM levels (P less than 0.001, respectively). These young cancer patients cannot be considered to be immunosuppressed. Alternative biologic mechanisms must be defined to account for the increasing incidence of head and neck cancer over the last decade among young adults in the United States.

Social confrontation "stress" in aggressive fish is associated with an endogenous opioid-mediated suppression of proliferative response to mitogens and nonspecific cytotoxicity

We have previously shown that social confrontation between aggressive fish (e.g., Tilapia) produces a suppression of several immunological parameters--nonspecific cytotoxicity and mitogen-stimulated proliferation in pronephric leukocytes--in the subordinate fish. By using the opioid antagonist, naltrexone, we now demonstrate indirectly that this immunosuppression is in part mediated by the endogenous opioid system. Evidence is presented that naltrexone-mediated reversal of immunosuppression may be limited to the populations of the cytotoxic and T-cell lineages. The proliferation response to lipopolysaccharide is unaffected by naltrexone. Our data also demonstrate that serum from subordinate (immunosuppressed) fish is immunosuppressive in normal fish--an effect that can be reversed by naltrexone. These results support a link between the neuroendocrine and immune systems in fish, the lowest vertebrate.

Influence of ethanol consumption on natural killer cell activity in mice

Alcohol is a known suppressant to the immune system, and alcoholics frequently have impaired humoral and cell-mediated immunity. Several studies indicate that alcohol modulates natural killer (NK) cell activity. NK cells provide important defense against certain infectious diseases, spontaneously arising tumors and, in particular, to blood-borne metastasizing tumor cells. Evaluation of the effects of alcohol on NK cells is complicated by many factors including: the level and duration of alcohol abuse, polydrug use, the subject's age, and nutritional and health status. This study examined the effects of 1 and 2 weeks of alcohol consumption on baseline and interleukin 2 (IL-2) stimulated murine NK cell activity. Well nourished female C57BL/6 mice were given continuous access to 20% w/v ethanol as the sole fluid source and consumed about 40% of their total caloric intake as ethanol. Splenic baseline and IL-2 stimulated NK cell activity were significantly lower in ethanol-consuming groups compared to control groups after the 1- and 2-week test periods. The average daily intake of ethanol, blood alcohol concentration, and the percentage of ethanol-derived calories were not associated with the decreased NK cell activity of the experimental animals; nor did any other measured parameter appear to serve as an indicator of ethanol modulation of splenic NK cell activity. Whether this immunosuppression results from the "direct" modulation of ethanol or from indirect factors is presently unknown.

Lymphokine-activated killer cell activity in patients with primary and metastatic malignant liver tumors

Lymphokine-activated killer cells were generated from peripheral blood mononuclear cells of 33 patients with liver tumors (benign, 6; primary malignant, 10; metastatic, 17) and 10 healthy individuals. Although peripheral blood mononuclear cell yield was significantly lower (p less than 0.01) in patients with hepatocellular carcinoma or with metastatic colorectal cancer, natural killer activity in the peripheral blood mononuclear cell fraction was comparable in all groups tested. Optimal lymphokine-activated killer activity was demonstrated after 9 to 12 days of culture in recombinant interleukin 2. Lymphokine-activated killer activity, interleukin 2-induced lymphocyte proliferation and total lytic activity generated per culture in all patient groups studied were similar to those of normal control cells cultured under the same conditions. These in vitro data demonstrate the feasibility of obtaining lymphokine-activated killer cells from the blood of patients with liver tumors and provide a rationale for the future use of lymphokine-activated killer cells in adoptive immunotherapy of patients with primary and metastatic hepatic neoplasms.

NK sensitivity, H-2 expression and metastatic potential: analysis of H-2Dk gene transfected fibrosarcoma cells

We have used the 3-Methylcholanthrene induced T-10 fibrosarcoma tumour cell system (H-2b xH-2k)F1 to elucidate the possible correlation between metastatic potential, expression of individual H-2 antigens and susceptibility to NK cells. Transfection of the non-metastatic and NK sensitive IC9 cells (Db+, Dk-, Kb-, Kk-) with the H-2Dk gene, altered the metastatic phenotype of the parental cells, yet had no effect on the susceptibility of these tumour cells to lysis by NK and did not elicit a specific CTL response in syngeneic hosts. Variants of the metastatic and NK resistant IE7 clone (Db+, Dk+, Kb-, Kk-), lacking H-2Dk, were selected by treatment with monoclonal anti H-2Dk antibodies and complement. These variants were sensitive to NK and poorly or non metastatic. Retransfection of 'Dk' 'loss' variants with the H-2Dk gene, resulted in the isolation of several clones expressing a wide range of metastatic phenotypes but maintained sensitivity to NK. These results indicate that the H-2D region of the MHC and or closely linked genes may be involved in the complex interrelationship between target susceptibility to NK and metastasis.

Involvement of Ca2+-dependent pathways in the inhibition of human natural killer (NK) cell activity by cortisol

The role of Ca2+ as a second messenger of the glucocorticoid inhibition of human natural killer (NK) cell activity was evaluated using Ca2+ entry blockers (verapamil and its desmethoxy derivatives LU46973 and LU47093), calmodulin antagonists (pimozide and two naphthalensulfonamide derivatives, W-7 and W-13), the Ca2+ channel agonist BAY K 8644 and the calcium ionophore A23187. Peripheral blood mononuclear (PBM) cell preparations were incubated for 20 h with 1 x 10(-6) M cortisol and these agents in various combinations (concentration range: 1 x 10(-9) -1 x 10(-5) M) and then assayed in a direct 4-h cytolytic assay using 51Cr-labeled K 562 target cells. Exposure to cortisol led to a significant reduction of NK cell activity (about 50% vs. spontaneous activity). Ca2+ entry blockers and calmodulin antagonists were per se minimally effective, but significantly enhanced cortisol-dependent inhibition of NK cell activity. Raising extracellular Ca2+ by CaCl2 or intracellular Ca2+ by the calcium channel agonist BAY K 8644 or the ionophore A23187 resulted in an appreciable reduction of these effects. Similar results were obtained when these substances were added to monocyte-depleted or NK cell-enriched suspensions exposed to cortisol. Our data are consistent with the view that extra- and intracellular Ca2+ plays a role in the control of human NK cell activity. It is also conceivable that both calcium flux into the cell and the calcium calmodulin system are involved in the cortisol-induced inhibition of natural cytotoxicity.

Murine anti-CD3 monoclonal antibody induces potent cytolytic activity in both T and NK cell populations

Antibodies specific for the CD3 complex have the capacity to both stimulate and inhibit a variety of T cell functions. We show here that a monoclonal antibody to the epsilon chain of CD3 can induce efficient non-MHC-restricted cytolytic activity in murine lymphocytes with peak activity occurring after 48 hr of incubation. In a panel of targets, the anti-CD3-activated effectors lysed tumor cells but not normal lymphoblasts. Cytolysis was not dependent on the presence of the antibody in the cytolytic assay. Moderate to high cytolytic activity was elicited from lymph nodes, spleen, and thymus by anti-CD3 treatment in vitro, whereas only low activity was apparent in bone marrow. The precursors of anti-CD3-activated cells consisted largely of mature T cells, although a smaller component of immature T cells was also involved. Thus, separation of thymocytes based on adhesion to peanut agglutinin revealed that both positive (immature) and negative (mature) fractions could be activated, while cytotoxic pretreatment of spleen cells with an antibody (J11d) to immature T cells before anti-CD3 activation significantly decreased the resulting cytotoxicity. The majority of precursors in spleen were Thy 1+ and CD8+ and/or AGM1+. Antibody depletion studies showed that the effector cells have both a T and a NK component consisting of Thy 1+, CD5+, CD8+, CD4-, and AGM1- cells and Thy 1-, CD5-, CD8-, CD4-, and AGM1+ cells, respectively. The production of significant amounts of IL-2 and TNF in culture following anti-CD3 treatment, along with the synergistic effect of exogenously added IL-2, suggests that one or both of the effector cell types could be induced by lymphokines. The intraperitoneal administration of the anti-CD3 antibody induces cytolytic activity in vivo. Therefore, the direct activation of cytolysis by anti-CD3 antibody and the additional effects, both direct and synergistic, of lymphokines produced by the activated lymphocytes could conceivably provide a potent anti-tumor therapy.

Roles of interferon and cellular adhesion molecules in bacterial activation of human natural killer cells

Interaction of lipopolysaccharide (LPS) from enteric and oral bacteria with natural killer (NK) cells enhanced cytotoxicity against NK-sensitive and NK-resistant targets. This activation occurred without expansion of the NK cell population or without changes in the leukocyte function-associated antigen family of cellular adhesion molecule (CAM) expression on NK cells. Significant interferon (IFN) titers were measured in LPS-lymphocyte supernatants, and antibody to IFN-alpha blocked LPS activation. LPS-induced NK cytotoxicity was inhibited by antibodies to individual alpha chains of CAM and, more profoundly, by antibody to the beta chain of CAM. However, LPS, when preincubated with NK cells, did not compete with subsequent anti-CAM antibody binding as detected by flow cytometry. Anti-CAM antibodies had no effect on NK activation by IFN, but antibodies to either CD11a or CD11c abrogated IFN production induced by LPS. These findings suggest that LPS binds NK cells at non-CAM sites, resulting in the release of IFN. IFN then acts in an autocrine manner independent of CAM to enhance NK cytotoxicity. Interaction of anti-CAM antibodies with CAM may provide a negative signal in regulating LPS-induced IFN production.

Augmentation of natural cytotoxicity by leucine enkephalin in cultured peripheral blood mononuclear cells from patients infected with human immunodeficiency virus

Natural Killer (NK) activity of lymphocytes from acquired immunodeficiency syndrome (AIDS) patients is frequently below normal and declines as disease progresses. We studied the potential of leucine enkephalin (leu-enkephalin) to restore this immune parameter by incubating nylon wool nonadherent mononuclear cells from 14 patients in the presence or absence of leu-enkephalin, and measuring NK cytolysis in a standard 51Cr release assay. The NK activity of human immunodeficiency virus antibody positive (HIV+) individuals with some remaining NK lytic ability was significantly augmented by leu-enkephalin concentrations of 10(-10) and 10(-8) M (n = 7). HIV+ patients with no measurable basal level of NK activity (n = 3) were not responsive to stimulation with leu-enkephalin. Human immunodeficiency virus antibody negative (HIV-) individuals (n = 4) responded in a pattern similar to normals. In addition, naloxone, an antagonist of alkaloid and peptide opiates including leu-enkephalin, displayed the properties of an antagonist/agonist, reflecting the immunoregulatory capacities of the endogenous opiate system.

The effect of chemical sympathectomy on natural killer cells in mice

The nervous system affects immune regulation. We permanently ablated the sympathetic nervous system (SNS) of CBA mice with 6-OHDA at birth. Function of splenic natural killer (NK) cells in the sympathectomized mice was equivalent to controls at 2 weeks, but rose significantly above control levels at 4 weeks. NK cell function decreased below control values thereafter. NK cell numbers paralleled these changes in NK cell function. Our data suggest that the SNS may regulate the number and function of splenic NK cells during development.

A functional and phenotypic comparison of murine natural killer (NK) cells and lymphokine-activated killer (LAK) cells

Lymphokine-activated killer (LAK) cells have been defined as interleukin 2 (IL-2)-activated cytolytic effector cells exhibiting non-MHC restricted killing against a wide range of NK-sensitive and NK-resistant tumor cells. There has been considerable debate as to whether LAK cells are derived from NK cells or from a unique precursor population. In the present study, we compare LAK cells derived from T-cell-depleted nylon-wool-non-adherent spleen cells with endogenous NK cells and NK cells activated with the interferon inducer polyl.C., in terms of their phenotype and functional characteristics. The predominant splenic LAK precursor in the mouse was found to be a nylon-wool-non-adherent, thy1-, MICG-, J11d.2-, asialo GM1+ cell. This phenotype is shared by endogenous NK cells. A significant number of activated NK cells express macromolecular insoluble cold globulin (MICG) in addition to asialo GM1. Neither endogenous nor activated NK cells express a heat-stable antigen found on bone-marrow cells, immature T cells, and most B cells and defined by monoclonal antibody (MAb)J11d.2. However, J11d.2 is expressed on some LAK precursor and effector cells. The asialo GM1 marker is common to all LAK effector cells, while many are also thy1+, and/or MICG+. LAK effector cells are therefore a heterogeneous population sharing some phenotypic characteristics in common with NK cells. In addition, there is a positive correlation between LAK and NK activity in "high NK" and "low NK" mouse strains, suggesting that NK cells and LAK cells share a common lineage. Monoclonal antibodies to the alpha and beta chains of LFA-I inhibit LAK and activated NK function, while endogenous NK and CTL killing is affected only by anti-alpha chain antibodies. LAK cells, like MHC-restricted and non-restricted CTL clones, express mRNA transcripts of the C11 serine protease gene. We conclude that LAK cells share several features in common with cells of the NK lineage and may therefore represent NK cells in a unique state of activation. LAK cells appear to employ cytolytic machinery common to other lytic cell types.

In vitro effects of an acyltripeptide, FK565, on NK-cell activity, LAK-cell generation and cytokine production by human mononuclear cells

In vitro effects of an immunostimulatory acyltripeptide, FK565, on natural killer (NK)-cell activity, lymphokine-activated killer (LAK)-cell generation and cytokine production of normal human peripheral blood mononuclear cells (MNC) were studied. FK565 used at concentrations ranging from 0.1 to 100 micrograms/ml enhanced NK-cell activity only if adherent MNC were removed. The optimal NK-cell enhancing dose was 2 micrograms/ml FK565. At the same range of concentrations, FK565 activated adherent MNC to induce suppression of NK-cell activity in autologous non-adherent MNC preparations. FK565 also potentiated both the generation of LAK-cell activity in the presence of 1000 U/ml of interleukin 2 (IL2) and the effector phase of LAK cells generated at the IL2 concentration of 50 U/ml. The synergistic interaction of IL2 and FK565 on LAK-cell activity was observed for all drug concentrations used. The effects of FK565 on cytotoxic cells could not be attributed to IL2, interferon gamma or tumor necrosis factor-alpha, because FK565 alone had no detectable influence on in vitro production of these cytokines by MNC. The ability of FK56 to modulate effector cells of natural antitumor immunity indicates that it may have promise as a biological response modifier in humans.

A fluorescence-based assay for quantitation of lymphokine-activated killer cell activity

A fluorescence assay for the quantitation of tumor cell lysis by activated and non-activated killer (LAK) cells is described. The target cells are labelled with a europium chelate (Eu-diethylenetriaminopentaacetate) and after cytolysis caused by the LAK cells the Eu3+ complex is released into the culture supernatant. The addition of beta-naphthoyltrifluoroacetone to culture supernatant aliquots leads to the formation of a highly fluorescent chelate which can be measured with a time-resolved fluorometer. The influence of various assay parameters has been evaluated including incubation time, effector-to-target cell ratio, the target cell line and different concentrations of interleukin-2 during cell culture. The optimized time-resolved fluorometric assay was found to be as simple and sensitive as the commonly used cytotoxicity assay in which the release of 51Cr from the labelled target cells is measured. In addition the assay is much faster and safer since the label is not radioactive.

Evaluation of natural killer and lymphokine-activated killer (LAK) cell activity in vivo in patients treated with high-dose interleukin-2 and adoptive transfer of autologous LAK cells

This study investigated the development of peripheral blood natural killer (NK) and lymphokine-activated killer (LAK) cell activity in vivo in cancer patients treated with high doses of recombinant interleukin-2 and autologous LAK cell infusion. It was found that interleukin-2 administration by bolus injection resulted in an early but transient rise of NK and LAK cell activity in vivo during the first 5-9 days of treatment (postpriming period), whereas continuous infusion of interleukin-2 caused an increase in both cytotoxic activities in the second phase of the treatment, concomitant with infusions of autologous LAK cells. Elevated NK but not LAK cell activity in vivo in the continuous-infusion patients persisted up to 180 days after completion of therapy. In both bolus and continuous interleukin-2 protocols, augmented NK cell activity in vivo appeared to be correlated with a beneficial response to therapy.

Studies of lymphokine-activated killer (LAK) cells. I. Evidence using novel monoclonal antibodies that most human LAK precursor cells share a common surface marker

Separation of LAK precursor (LAKp) cells (as defined by LAK effector generation after incubation with IL-2 for 7 d) from cells with NK activity/LGL morphology was achieved on Percoll gradients using a longer, slower centrifugation than that used for optimal NK enrichment. mAb were generated using the various Percoll fractions as the immunizing cells and used for separation and depletion studies. Two mAbs DM-1 (IgM,k) and DM-2 (IgM,k) recognizing 2-15% and 15-30% of PBL, respectively, abrogated a large proportion of LAK generative potential after complement depletion, but had little effect on NK or LAK effector activity. Cell sorting experiments indicated that the majority of LAKp cells are found within the DM-1+ population and that DM-1+ cells are not simply an accessory cell required for LAKp generation. Further, these two mAbs do not recognize cells that are responsible for generating cytotoxicity during MLC or co-culture with the PR-1 EBV lymphoblastoid cell line. Western blot analysis indicated that DM-1 and DM-2 recognize a 38,000 and 44,000 dalton moiety, respectively. The frequency of cells bearing these antigens and the intensity of cell surface staining decreased during the 7-d culture period, suggesting that these antibodies recognize determinants found only at the precursor level. These findings indicate that cells other than NK effectors or mature T cells are capable of generating a LAK cell response. These LAK precursor cells share a common differentiation surface antigen and are different from AK or antigen-specific CTL precursors. The possibility exists that these cells are identical to, or include, the NK precursor cell.

Generation and expansion of lymphokine-activated killer cells from lymph node lymphocytes in human lung cancer

We cultured lymph node lymphocytes (LNL) from lung cancer patients in the presence of recombinant interleukin 2 (rIL2). The ability of LNL to respond to rIL2 was not affected by the advance of cancer stage when tested for proliferation and for lymphokine-activated killer (LAK) activity. The LAK activity of LNL was comparable to that of the corresponding peripheral blood lymphocytes. The rIL2-induced proliferation of macrophage-depleted LNL was augmented by the reconstitution with autologous alveolar macrophages while the LAK activity was not affected. However, macrophage-reconstituted LNL expanded rapidly and reached higher cell densities and exhibited a significantly lower LAK activity than macrophage-depleted LNL. The diminished LAK activity in macrophage-reconstituted LNL were markedly augmented by the subculture at a low cell density. From these results, we conclude that LNL can be a good material for the postoperative LAK therapy and that macrophage is useful in culture of LAK cells.

The role of T cell receptors in non-MHC-restricted cytotoxicity

The relationship between natural killer cells (NK) and cells of the T lineage has been obscured by the existence of poorly characterized clones of presumed NK origin. We have analyzed nine of these cloned cell lines displaying varying levels of cytotoxic activity against NKS YAC-1 target cells for rearrangement and expression of the genes encoding the alpha, beta, and gamma chains of the T cell receptor for antigen. Rearrangements at both the TcR beta and gamma loci were detected in all clones often at both alleles. Rearrangement patterns at the TcR beta locus were identical in several clones, despite different degrees of cytotoxicity. T cell receptor alpha, beta, and gamma genes were expressed as full length transcripts in all clones regardless of their levels of cytotoxic activity. To explore the involvement of cell surface molecules in the cytolytic events, studies were undertaken to determine whether cytotoxic activity could be inhibited by antibodies against CD3, LFA-I, and H-2KdDd. In two selected clones, both alpha and beta chains of the LFA-I molecule were expressed but only monoclonal antibodies against the alpha chain significantly blocked cytotoxicity. Cytotoxicity was also inhibited by monoclonal antibodies against epitopes of H-2KdDd and CD3, the extent of inhibition correlating with the level of surface expression on both clones. These data suggest that conventional alpha/beta heterodimers may be necessary but not sufficient for target cell recognition by these clones. Since T cell receptor rearrangement and expression occur normally in the T cell lineage but not the NK lineage, these results also indicate that a subpopulation of cells with non-MHC-restricted killer activity lies on the T cell differentiation pathway and is selected by in vitro growth with IL-2. The limited rearrangement pattern observed can be explained if only a small subpopulation of T cells is capable of non-MHC-restricted killing, and if certain rearrangements favor self-MHC recognition which is known to block cytolysis in the NK system.

Interferon-gamma in a family with X-linked lymphoproliferative syndrome with acute Epstein-Barr virus infection

A 20-month-old male with fulminant infectious mononucleosis and the X-linked lymphoproliferative syndrome (XLP) was studied. Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA) and EBV DNA were detected in various tissues. Despite a combined treatment with acyclovir, immunoglobulin, and methylprednisolone, the patient deteriorated rapidly. Following treatment with recombinant interferon-gamma (IFN-gamma), defervescence occurred and circulating EBNA-positive cells markedly decreased. IFN-gamma prior to treatment ranged from 10.8 to 24.5 U/ml in the patient's serum and increased linearly post exogenous IFN-gamma treatment. His natural killer (NK)-cell activity remained in the normal range throughout his illness but autologous EBV-infected cells were not killed in vitro by his peripheral blood lymphocytes (PBL). These results suggest that patients with the fatal infectious mononucleosis phenotype of XLP may produce endogenous IFN-gamma. Defective cytotoxic T cells against EBV-infected cells seem to be responsible for the fulminant infectious mononucleosis in this patient.

The inhibitory effect of human interferon alpha on the generation of lymphokine-activated killer activity

The generation of lymphokine-activated killer (LAK) activity and the proliferative response to human recombinant interleukin-2 (IL-2) were significantly reduced by the presence of human recombinant leukocyte interferon (IFN alpha) in cultures of human peripheral blood mononuclear cells (PBMC). Mature natural killer (NK) cells can be depleted from PBMC with the toxic lysosomotropic agent L-leucine methyl ester. The generation of cytotoxic cells from lymphocytes depleted in leucine methyl ester was also inhibited by indicating that the IFN-alpha effect is not limited to mature cytotoxic NK cells. Depletion of adherent cells from PBMC did not affect the suppression of LAK induction by IFN-alpha. Surface marker analyses of Tac antigen and transferrin receptor (TfR) showed that the presence of IFN alpha throughout the culture period significantly suppressed the typical increase in IL-2-induced Tac- and TfR-positive cells. In contrast, IFN alpha treatment before and after IL-2 culture enhanced LAK cytotoxic activity. Therefore, combinations of these biological response modifiers for clinical use should take into account the dual effect of IFN alpha on key features of the IL-2 response.

Activation of human natural killer cells by lipopolysaccharide from Actinobacillus actinomycetemcomitans

Lipopolysaccharide (LPS) from the Y4 strain of this bacterium, which is implicated in the pathogenesis of juvenile periodontitis, was incubated with human peripheral blood lymphocytes (PBL) and its action compared to that of LPS from Escherichia coli. Both LPS augmented cytotoxicity measured against natural killer (NK) cell-resistant tumour targets within 24 h of incubation. Cytotoxicity was exclusively found in NK-enriched low-density large granular lymphocyte fractions, as separated by Percoll gradient. LPS activated NK cells without stimulating high levels of proliferation. The minimum concentration of A. actinomycetemcomitans LPS required to activate NK cells was 1 microgram/ml; higher concentrations did not significantly increase this activation. LPS had no synergistic effect on the induction of PBL cytotoxicity by interleukin-2. In contrast, LPS pre-activated monocytes inhibited the induction of lymphocyte cytotoxicity by either interleukin-2 or LPS.

Biology of natural killer cells

Studies of cytotoxicity by human lymphocytes revealed not only that both allogeneic and syngeneic tumor cells were lysed in a non-MHC-restricted fashion, but also that lymphocytes from normal donors were often cytotoxic. Lymphocytes from any healthy donor, as well as peripheral blood and spleen lymphocytes from several experimental animals, in the absence of known or deliberate sensitization, were found to be spontaneously cytotoxic in vitro for some normal fresh cells, most cultured cell lines, immature hematopoietic cells, and tumor cells. This type of nonadaptive, non-MHC-restricted cellmediated cytotoxicity was defined as “natural” cytotoxicity, and the effector cells mediating natural cytotoxicity were functionally defined as natural killer (NK) cells. The existence of NK cells has prompted a reinterpretation of both the studies of specific cytotoxicity against spontaneous human tumors and the theory of immune surveillance, at least in its most restrictive interpretation. Unlike cytotoxic T cells, NK cells cannot be demonstrated to have clonally distributed specificity, restriction for MHC products at the target cell surface, or immunological memory. NK cells cannot yet be formally assigned to a single lineage based on the definitive identification of a stem cell, a distinct anatomical location of maturation, or unique genotypic rearrangements.

Association of alpha interferon production with natural killer cell lysis of U937 cells infected with human immunodeficiency virus

Mononuclear leukocytes from human immunodeficiency virus (HIV)-seronegative and -seropositive homosexual men lysed HIV-infected U937 cells to a significantly greater degree than uninfected U937 cells. Depletion of cell subsets with monoclonal antibodies and complement indicated that the effector cells were primarily of the CD16+ phenotype. Acid-stable alpha interferon (IFN-alpha) production induced by the HIV-infected cells correlated with, although was not an absolute requisite for, preferential lysis of the infected targets. The activity of these CD16+, natural killer (NK) cells decreased in relation to the duration of HIV infection and the presence of acquired immunodeficiency syndrome. Pretreatment of peripheral blood mononuclear cells from HIV-seronegative subjects, but not HIV-seropositive men, with IFN-alpha or recombinant interleukin-2 enhanced lysis of both uninfected and HIV-infected U937 cells. These results suggest that IFN-alpha-associated, NK-like mechanisms are active in the cytotoxic response against HIV-infected cells and that HIV infection results in an early and progressive depression of such responses. Prospective investigations may be useful in determining the role of this NK cell response in the natural history and pathogenesis of HIV infection and the efficacy of therapeutic modalities.

The effects of benzo(a)pyrene, nicotine, and tobacco-specific N-nitrosamines on the generation of human lymphokine-activated killer cells

The effects of four major components of snuff (fine-cut smokeless tobacco) on the development of lymphokine-activated killer cells (LAK) were measured in vitro. Of the components tested: nicotine, N'-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo(a)pyrene (BaP), only BaP suppressed LAK cytotoxicity against tumour targets and LAK DNA synthesis during 3- and 7-day incubations. BaP concentrations of 0.1-1.0 micrograms/ml suppressed lymphocyte proliferation only; there was no effect on tumour cell proliferation at these concentrations. BaP had no effect on tumour target killing when incubated during 4 h natural killer (NK) or LAK cytotoxicity assays. There was no effect on LAK binding of tumour targets after 3 days culture with BaP concentration of 0.1-1.0 micrograms/ml. These data confirm that a water-soluble extract of snuff has anti-cytolytic and anti-proliferative effects on peripheral blood lymphocytes. As NK and LAK cells are important in preventing tumourigenesis and metastasis, suppression of these cells may favour neoplastic growth associated with snuff-dipping.

Functional and phenotypic analysis of tumor-infiltrating lymphocytes isolated from human primary and metastatic liver tumors and cultured in recombinant interleukin-2

Tumor-infiltrating lymphocytes (TIL) were isolated from 40 of 51 consecutive human liver tumor samples (primary hepatocellular carcinoma, 16 of 18; metastatic, 23 of 29; benign, one of four). Functional and phenotypic characteristics of fresh and recombinant interleukin-2 (rIL-2)-expanded TIL were evaluated. The expansion of TIL from hepatic tumors in the presence of 1000 units/ml of rIL-2 was possible in 60% of cases. In comparison to TIL from metastatic liver tumors, TIL obtained from primary liver tumors expanded faster and better in rIL-2 cultures. Expanded TIL from primary tumors had significantly higher cytotoxicity against K562 targets, but not Raji targets, than those from metastatic tumors. Cytotoxicity against fresh autologous tumor targets was detected in seven of eight cultures tested. TIL from primary tumors retained antitumor reactivity significantly longer in culture. The optimal in vitro cytotoxicity was achieved between days 20 and 60 of culture in the presence of rIL-2. Antitumor activity was associated with the increase in these TIL cultures of a cell population expressing the Leu19 antigen with or without the CD3 antigen. The frequency of the CD3+Leu19+ population showed a bimodal distribution during culture: the first peak of CD3+Leu19+ cells occurred between days 30 and 60 and was associated with the increased antitumor activity; the second peak occurred after day 60 and was not associated with activity. These findings demonstrate that TIL from most human hepatic tumors can be successfully isolated, cultured in rIL-2, and enriched in Leu19+ effectors. In addition, these TIL upon IL-2 activation in vitro are capable of lysing fresh autologous and/or allogeneic tumor targets.

Unimpaired ability to generate adherent lymphokine-activated killer (A-LAK) cells in patients with primary or metastatic liver tumors

Adherent lymphokine-activated killer cells (A-LAK cells) obtained from human peripheral blood mononuclear cells represent a population of potent antitumor effectors enriched in interleukin-2(IL-2)-activated natural killer cells. This study shows that A-LAK cells can be successfully generated from the blood of patients with liver cancer not treated with adjuvant chemotherapy or irradiation. Mononuclear cells were isolated from the blood of 33 patients with liver tumors (6 benign, 10 primary malignant, 17 metastatic) at the time of liver resection. A-LAK cells were separated by adherence to plastic following activation of peripheral blood mononuclear cells in 1000 U/ml recombinant IL-2. A-LAK cells (enriched up to 92% in CD3-CD56+ cells) showed better subsequent expansion and two to six times higher antitumor cytotoxicity per cell than unseparated LAK cells cultured under the same conditions. The ability to generate A-LAK cells with superior in vitro cytotoxicity from the blood of most patients with liver cancer indicates that adoptive cellular immunotherapy may be a feasible and new way of treatment for primary and secondary hepatic neoplasms in man.