Human Lymphokine Research Articles

Factors Influencing Proliferation and Histamine Content of Cultured Human Bone Marrow Cells

Various human lymphokines such as semipurified human interleukin 3 (IL 3), recombinanthuman IL 3, granulocyte colony stimulating factor (G-CSF), and recombinant human interleukin 4 (IL 4) stimulated growth of human bone marrow cells, but from all these factors tested, only IL 3 by itself was able to cause an increase in histamine content. Fibroblast monolayers as well as factors in their supernatants also increased proliferation and histamine content of bone marrow cells. Concentrated supernatants (Mr > 10,000) also inhibited cell proliferation and induced histamine content. The same fraction concentrated on a Mr cut-off > 50,000 enhanced cell growth and the total histamine content per culture. Thus, fibroblast supernatants contained both growth promoting and inhibitory factors. However, using the rat basophilic leukemia (RBL) cell line as a test system for such fibroblast-derived differentiation factors, we showed that if cell proliferation was inhibited, histamine content was also enhanced. Furthermore, certain drugs known to inhibit cell division, such as sodium butyrate or hydroxyurea, were also found to cause an increase in histamine content of RBL cells. Thus, our data demonstrate that basophil/mast cell differentiation, in terms of augmentation of cellular histamine levels, may be achieved by exposure to certain growth-inducing cytokines, factors inhibiting proliferation or pharmacological agents which inhibit cell proliferation.

Potential antiinflammatory effects of interleukin 4: suppression of human monocyte tumor necrosis factor alpha, interleukin 1, and prostaglandin E2.

Stimulated human monocytes/macrophages are a source of mediators such as tumor necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1), and prostaglandin E2 (PGE2), which can modulate inflammatory and immune reactions. Therefore, the ability to control the production of such mediators by monocytes/macrophages may have therapeutic benefits, and it has been proposed that glucocorticoids may act in this way. Purified human monocytes, when stimulated in vitro with lipopolysaccharide (LPS) or with LPS and gamma interferon (IFN-gamma), produce TNF-alpha, IL-1, and PGE2. Cotreatment of stimulated cells with the purified human lymphokine, interleukin 4 (IL-4 greater than or equal to 0.1-0.5 unit/ml; 12-60 pM) dramatically blocked the increased levels of these three mediators; for TNF-alpha and IL-1, the inhibition was manifest at the level of mRNA. Thus, IL-4 can suppress some parameters of monocyte activation and, as for B cells, have opposite effects to IFN-gamma. The effects of IL-4 on human monocytes are similar to those obtained with the glucocorticoid dexamethasone (0.1 microM).

Today's immunology

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T lymphocytes in allergen-induced late-phase reactions and asthma.

We have studied a number of aspects of the interrelationship between T lymphocytes and allergic inflammation. Using monoclonal antibodies and immunocytochemistry we have observed significant infiltration by CD3+/CD4+ T lymphocytes together with evidence of T cell activation in the allergen-induced late-phase skin reaction in human atopic subjects. These changes were accompanied by eosinophil infiltration and activation. Activated T cells were also detected in the blood of patients with acute severe asthma. The role of T lymphocytes in granulocyte chemotaxis and activation was also explored, using recombinant human lymphokines, and we have identified and characterized two lymphokines which have specific effects upon neutrophils.

Decreased Natural Killer (NK) Susceptibility of Human NK Target Cells after Phosphatidylinositol‐Specific Phospholipase C Treatment

Phosphatidylinositol-specific phospholipase C (PI-PLC) treatment of the human natural killer (NK) target cells Molt-4, Jurkat, and U937 reduced their susceptibility to killing by human NK cells in a dose-dependent fashion. This indicates that a cell surface structure, anchored by a glycosyl-phosphatidylinositol (G-PI) moiety, is important in NK cytotoxicity. In contrast, another common NK target cell line, K562, remained susceptible to NK killing after enzyme treatment, suggesting that distinct target structures are expressed by this cell line. PI-PLC treatment of Molt-4 cells also reduced their sensitivity to human lymphokine activated killer (LAK) cells, suggesting that NK and LAK cells share common specificity in the killing of Molt-4. In contrast, PI-PLC had no effect on the killing of the LAK target cell line, Daudi, which is only weakly sensitive to unactivated NK cells. Killing of a variety of murine target cells by murine NK cells was not affected by PI-PLC treatment, but cross-species killing of Molt-4 by murine NK cells was inhibited by PI-PLC, suggesting a common mechanism in the killing of this human target cell line. The PI-PLC treatment of effector cells from either species did not reduce their NK activity. The reduction in sensitivity of the Molt-4, Jurkat, and U937 target cells probably results from a loss of a target specific G-PI linked membrane molecule, but other possible explanations for these results are also discussed.

Leukocyte inhibitory factor stimulates neutrophil-endothelial cell adhesion.

We investigated the ability of the human lymphokine leukocyte inhibitory factor (LIF) to modulate neutrophil-endothelial cell (EC) adherence. EC were cultured from collagenase-treated human umbilical cord veins and grown in complete medium supplemented with EC growth factor. Adherence was measured as the percent of 51Cr-labeled neutrophils remaining adherent to the EC after gentle lavage. Polymorphonuclear neutrophils (PMN) were pretreated with LIF (0.5 to 8 U/ml), extensively washed, and allowed to interact with the EC monolayers. LIF was demonstrated to induce an increase in the capacity of PMN to bind EC in a dose-dependent fashion (from 30.9 +/- 2.1% adherence with control-treated PMN to 68.6 +/- 3.0% at 4 U LIF; p less than 0.001). In subsequent experiments we demonstrated that 10 min was a sufficient preincubation time for LIF to modulate the capacity of the PMN to adhere to EC. LIF has previously been observed to up-regulate expression of C receptor type 3 on PMN, a receptor which has been shown to be involved in PMN-EC binding. Exposure of PMN to anti-C receptor type 3 antibody before their incubation with LIF abrogated its effect as did inactivation of LIF by an esterase inhibitor. We also investigated the ability of LIF to stimulate EC to bind untreated PMN. EC were pretreated with LIF (0.25 to 4 U/ml), extensively washed, and adherence measured as before. LIF was shown to induce a dose-dependent increase in the capacity of the EC to bind PMN (from 28.8 +/- 3.1% for untreated EC to 91.1 +/- 4.0% at 4 U LIF; p less than 0.001). Modulation of EC function required a minimum of 30 min and was inhibited in the presence of cycloheximide or actinomycin D. Neither anti-TNF-alpha or -beta antibodies nor polymixin B abrogated the augmentation by LIF. However, anti-IL-1 antibody partially inhibited the stimulation of EC adhesiveness by LIF, suggesting the possible involvement of this cytokine. These studies provide further evidence that LIF may mediate an important pro-inflammatory role in vivo.

Procoagulant induction by human lymphokine and interferon gamma/PMA on a myelomonocytic cell line, RC2a.

The human myelomonocytic cell line RC2a expressed procoagulant activity following stimulation with human lymphokine (LK) prepared by stimulating peripheral blood mononuclear cells with either mitogens (Concanavalin A, phytohaemagglutinin or antigen (tuberculin). Induction was rapid, with optimal activity observed between 6 and 8 h, was decreased in cultures containing serum and was not inhibited by actinomycin D or cycloheximide. The LK activity was not inhibited by an anti-interferon gamma (IFN gamma) antibody. IFN gamma and phorbol myristate acetate (PMA) had no activity but acted in synergy to induce procoagulant expression; interferon alpha plus PMA were without effect. In contrast to the LK-induced response, procoagulant induced by IFN gamma/PMA was not detected for up to 8 h and steadily rose over 24-48 h culture and was dependent on new protein and RNA synthesis. Bacterial lipopolysaccharide, a potent inducer of thromboplastin on normal human monocytes, failed, either alone or in combination with LK, IFN gamma, PMA or IFN gamma plus PMA, to activate procoagulant expression on RC2a cells. Both LK and IFN gamma/PMA-induced procoagulant had properties of thromboplastin expressed both intracellularly and on intact, viable cells. This study shows that RC2a cells are responsive to factors produced as the result of an activated cell-mediated immune response which may therefore contribute to the coagulopathies common to this form of malignancy.

Heterogeneity of human lymphokine (IL-2)-activated killer (LAK) precursors and regulation of their LAK induction by blood monocytes.

Highly purified lymphocytes (greater than 99%) and monocytes (greater than 90%) were isolated by CCE from peripheral blood of healthy donors. Blood lymphocytes were separated by this CCE into 9 subpopulations. The NK activities of these lymphocyte fractions against NK-sensitive K-562 cells and their LAK activities against NK cell-resistant target (Daudi) cells were assayed promptly or after incubation of the fractions for 4 days with or without an optimal concentration of IL-2. NK and LAK activities were measured by 4-hr 51Cr-release assay. On the basis of their NK and LAK activities, these lymphocyte fractions were classified into 3 subpopulations of LAK precursors: one lacking both NK and LAK activities (Fr.2), one with moderate NK activity but low LAK activity (Fr.5), and one possessing both NK and LAK activities (Fr.8). Addition of autologous fresh monocytes to the lymphocyte cultures resulted in a significant increase in induction of LAK activity in Fr.2 and Fr.5. This up-regulation of lymphocytes in Fr. 2 and Fr.5 by monocytes was confirmed in parallel experiments by measuring the blastogenic response of the lymphocytes to IL-2. Deletion of lymphocytes in Fr. 8 of CD16+ (Leu-11+) NK cells resulted in 74% reduction in LAK induction, whereas depletion of mixtures of monocytes and lymphocytes in Fr. 2 of cells reacting with CD3+ (OKT3+) antibody resulted in a 66% reduction in LAK induction. This up-regulation of LAK cell induction from LAK precursors by monocytes was confirmed using 4 lines of human lung cancer cells as targets for LAK activity. These results clearly indicate that human monocytes may cause up-regulation of the expression of IL-2-induced LAK activity in T cells and in a subpopulation of NK cells.

Biochemical Characterization and Purification of HILDA, a Human Lymphokine Active on Eosinophils and Bone Marrow Cells

We previously described a lymphokine termed HILDA (for human interleukin DA) produced by T-lymphocyte alloreactive clones after antigenic stimulation. This factor sustains the growth of a murine IL3-sensitive cell line (DA2). In addition, HILDA is a potent activator of eosinophils and displays a burst-promoting activity on human bone marrow. In the present study, HILDA was purified to homogeneity from T-cell clone supernatant using successively sequential concentration, concanavalin A (ConA) affinity chromatography with differential elution (alpha-D glucopyranoside and alpha-D mannopyranoside), high-performance liquid chromatography (HPLC) gel filtration and reverse-phase HPLC. The pure material appeared as a 38-kd glycoprotein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing or nonreducing conditions. Biologic activity could be recovered from SDS-PAGE gel slices corresponding to the 38-kd band. We conclude from the specificity of the DA-2 cell line and biochemical characteristics described that this lymphokine is different from other known factors produced by human T lymphocytes.

Biochemical characterization and purification of HILDA, a human lymphokine active on eosinophils and bone marrow cells

We previously described a lymphokine termed HILDA (for human interleukin DA) produced by T-lymphocyte alloreactive clones after antigenic stimulation. This factor sustains the growth of a murine IL3- sensitive cell line (DA2). In addition, HILDA is a potent activator of eosinophils and displays a burst-promoting activity on human bone marrow. In the present study, HILDA was purified to homogeneity from T- cell clone supernatant using successively sequential concentration, concanavalin A (ConA) affinity chromatography with differential elution (alpha-D glucopyranoside and alpha-D mannopyranoside), high-performance liquid chromatography (HPLC) gel filtration and reverse-phase HPLC. The pure material appeared as a 38-kd glycoprotein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing or nonreducing conditions. Biologic activity could be recovered from SDS- PAGE gel slices corresponding to the 38-kd band. We conclude from the specificity of the DA-2 cell line and biochemical characteristics described that this lymphokine is different from other known factors produced by human T lymphocytes.

Differential effects of recombinant interferons alpha, beta, and gamma on induction of human lymphokine (IL-2)-activated killer activity.

The effects of three classes of recombinant interferons (IFN-alpha A, IFN-beta, and IFN-gamma) on maximal induction of lymphokine (IL-2)-activated killer (LAK) activity were studied. Highly purified lymphocytes (greater than 99%) were obtained by counter-flow centrifugal elutriation from peripheral blood of healthy donors. After incubation for 4 days with IL-2 (1 U/ml), purified lymphocytes showed maximal LAK activity against NK cell-resistant target (Daudi) cells, as assessed by 4-hour 51Cr release assay. Addition of exogenous IFN-alpha A or IFN-beta to cultures of lymphocytes plus IL-2 resulted in significant inhibition of LAK activity, but addition of IFN-gamma had no effect on LAK induction by IL-2. IFN-alpha A caused greatest inhibition of LAK activity when added at the start of culture of lymphocytes with IL-2, and was less inhibitory when added 1 day later. Similar inhibition by IFN-alpha A or IFN-beta was observed with nine lines of human tumorigenic cells as targets of LAK activity. IFN-alpha A and IFN-beta also inhibited the proliferative responses of lymphocytes to IL-2 stimulation, and the expression of IL-2 receptors on their surface, whereas IFN-gamma did not. These results suggest that IFN-alpha A and IFN-beta may be important in in situ regulation of LAK cell induction against neoplasms.

Roles of vaccinia virus in the development of new vaccines

Vaccinia virus is an efficient expression vector with broad host range infectivity and large DNA capacity. This vector has been particularly useful for identifying target antigens for humoral and cell-mediated immunity. With increased levels of gene expression, obtained either with stronger vaccinia promoters or through incorporation of the bacteriophage T7 RNA polymerase gene into the vaccinia genome, proteins may be synthesized in mammalian cells for use as subunit vaccines. For use as a live recombinant vaccine, efforts are being made to attenuate vaccinia virus further, either by inactivating genes contributing to virulence or by introducing human lymphokine genes into the vaccinia genome.

Expression of Mo3e antigen by cultured human umbilical vein endothelial cells (HUVEC) stimulated by phorbol myristate acetate (PMA) and related pharmacological inducers of protein kinase C

Mo3e is a protease-sensitive membrane antigen (p75,50) selectively expressed by human monocytic cells (monocytes and U-937 cells) stimulated in vitro by exposure to a variety of activating factors, including phorbol diester compounds, bacterial lipopolysaccharide (LPS), and muramyl dipeptide (MDP) (R. F. Todd et al., J. Immunol. 135, 3869, 1985). Here we report that primary and multiply-passaged cultures of HUVEC also express the Mo3e determinant after stimulation by phorbol myristate acetate (PMA) and related inducers of protein kinase C. As measured in a radioimmunoassay of anti-Mo3e antibody binding to monolayer cultures of HUVEC, unstimulated cells bore little if any Mo3e. After culture for 4–120 hr in medium containing PMA, 4β-phorbol dibutyrate, 4β-phorbol didecanoate, or mezerein (each at a conentration of 81 n M), or 1-oleoyl-2-acetoyl- sn-3-glycerol (1 m M), HUVEC were found to selectively express the Mo3e determinant. The magnitude of expression was dependent upon the concentration of the stimulus, maximal by 24 hr, and inhibited by cycloheximide. The combination of PMA and the calcium ionophore, ionomycin, had an additive or synergistic effect on HUVEC Mo3e expression. The biologically inactive phorbol compounds 4β-phorbol and 4α-phorbol didecanoate failed to stimulate Mo3e expression. Also inactive as inducers of HUVEC Mo3e expression were crude lymphokine and monokine supernatants, recombinant human lymphokines (interferon-γ and interleukin-2), recombinant human monokines (interleukin-1 and tumor necrosis factor), bacterial cell wall products including LPS and MDP, pharmacologic agents that increase intracellular cyclic adenosine monophosphate (prostaglandin E 2, cholera toxin, theophylline, isoproterenol and isobutylmethylxanthine), lectins (Con A and PHA), and heparin. These results indicate that Mo3e is an inducible plasma membrane antigen of not only mononuclear phagocytes but also cultured HUVEC.

Up- and down-regulation of human lymphokine (IL-2)-activated killer cell induction by monocytes, depending on their functional state.

Studies were made to determine whether freshly isolated monocytes from healthy donors could influence the induction of lymphokine (IL-2)-activated killer (LAK) activity. Highly purified lymphocytes (greater than 99%) and monocytes (greater than 90%) were isolated by counter-flow centrifugal elutriation from peripheral blood. Lymphocytes incubated for 4 days with IL-2 showed significant LAK activity against natural killer (NK) cell-resistant target (Daudi) cells, whereas monocytes treated for 4 days with IL-2 and/or IFN-gamma were not cytotoxic. Under the experimental conditions used, addition of monocytes to the lymphocyte cultures resulted in significant augmentation of the LAK activity, depending on the density of monocytes added. In contrast, monocytes stimulated by lipopolysaccharide (LPS) markedly suppressed LAK activity induced by IL-2, depending on the dose of LPS added. Similar up- and down-regulations of LAK cell induction by monocytes were observed with 4 lines of human lung cancer cells as targets for LAK activity. Although supernatants from untreated monocytes did not increase LAK induction, supernatants from LPS-stimulated monocytes suppressed LAK induction. The regulatory role of monocytes could not be replaced by the addition of exogenous interleukin I (IL-I) or tumor necrosis factor (TNF). Prostaglandin E did not seem to play a regulatory role, since addition of indomethacin did not affect the regulation of LAK cell induction by monocytes. These results clearly indicate that human monocytes may cause up- or down-regulation of the expression of IL-2-induced LAK activity, depending on their functional state.

Anti-Tumor Reactivity of Human Lymphokine Activated Killer (LAK) Cells Against Fresh and Cultured Preparations of Renal Cell Cancer

Immunotherapy utilizing the adoptive transfer of lymphokine activated killer (LAK) cells in conjunction with recombinant interleukin-2 (IL-2) is capable of mediating the regression of established cancer in a variety of animal tumor models as well as advanced metastatic cancers in humans. We have thus examined the variability of the anti-tumor lytic reactivity of LAK cells obtained from patients with metastatic renal cell cancer (RCC). Tumor cell suspensions were prepared by enzymatic digestion from 37 consecutive renal cell tumors. The mean (±SEM) total number of cells recovered was 1.5 ± 2.2 × 109 cells per tumor. The percentage of tumor cells in the suspension was 39.1 ± 3.3% (range: 6 to 75%). Thirteen of 13 different fresh renal tumor cell preparations tested in 57 experiments and two of two renal tumor lines tested in 10 experiments were all lysed by LAK cells. RCC patients, like normal donors, generated good LAK effectors with broad antitumor activity against autologous as well as allogenic tumors. Both renal and nonrenal tumors were equally lysed by LAK cells. LAK killing of the erythroleukemic tumor lines K562 and Daudi was significantly better than the lysis of fresh autologous and allogeneic tumor targets or cultured RCC tumor lines. Short term tumor cultures derived from renal cancer preparations proved to be sensitive and reliable tumor targets for studying the in vitro killing by LAK cells. Clinical trials testing the therapeutic role of LAK cells and IL-2 in patients with advanced renal cell cancer are currently in progress.

B-cell-stimulatory factor 2 (beta 2 interferon) functions as a second signal for interleukin 2 production by mature murine T cells.

Purified peripheral murine T cells, in the presence of concanavalin A, can be activated to produce interleukin 2 (IL-2) through stimulation either with a previously described murine lymphokine designated T cell-activating factor (TAF) or with a cloned human lymphokine that has been called beta 2 interferon, B-cell-stimulatory factor 2, hybridoma growth factor, inducible 26-kDa protein, or hematopoietic colony-stimulating factor 309 by different investigators. We and others propose the designation interleukin 6 (IL-6) for the latter molecule. Our experiments demonstrate that either murine TAF or human IL-6 can restore the ability of purified T cells to proliferate in response to Con A or antibodies against the T-cell antigen receptor. Most if not all of the proliferation can be blocked by antibodies against the alpha chain of the IL-2 receptor. Furthermore, highly purified CD8- T cells can be activated by IL-6 in the presence of Con A to secrete IL-2. We propose that IL-6 and murine TAF are important "second signals" in primary antigen-receptor-dependent T-cell activation. Whether or not murine TAF is a homologue of human IL-6 remains to be determined.

Products of activated lymphocytes and macrophages inhibit mouse embryo development in vitro.

The effects of activated leukocyte products on embryonic development were assessed by adding mouse and human leukocyte culture supernatants and purified murine and human lymphokines and monokines to mouse embryos in tissue culture. Supernatants from mitogen-stimulated and mixed lymphocyte cultures arrested embryonic development at the two-cell to morula stage. Of a panel of six individual lymphokines and monokines tested for effects in this system, both murine and human forms of the lymphokines colony-stimulating factor, interferon-gamma, and human B cell growth factor significantly arrested embryonic development over a wide concentration range. The monokines, interleukin 1 and tumor necrosis factor, also had significant effects but only at high doses. These results indicate that products of activated lymphocytes and macrophages can have detrimental effects on preimplantation embryos. Early abortion could result from local (intrauterine) production of such embryotoxic factors by activated lymphocytes and macrophages in response to stimulation by microorganisms or reproductive tissue antigens.

Enhancement of the interleukin 2 receptor expression on T cells by multiple B-lymphotropic lymphokines

Three new human lymphokines, interleukin-5, BSF-2 and BSF-MP6, were shown to be active in the enhancement of the IL-2 receptor expression on T cells, although they do not stimulate growth of the T cells.

An improved method for the generation of human lymphokine activated killer cells

In an effort to make interleukin-2/lymphokine-activated killer cell (IL-2/LAK) therapy safer for cancer patients, we examined the efficacy of using Fenwal PL732 bags as tissue culture flasks. These bags can be sterilly connected using tubing kits thus reducing the risk of contamination to the cells. Peripheral blood mononuclear cells were obtained from normal donors or cancer patients undergoing IL-2/LAK cell therapy. Following Ficoll-Hypaque purification, these cells were incubated in the presence of IL-2 in either PL732 plastic bags or standard tissue culture flasks. Our results showed that LAK cells could be generated from either normal donors or cancer patients in the bags as well as in the flasks. Comparisons were made of the LAK cell populations obtained from the two sources and showed that each was similar in terms of morphology as determined by Wright stain differentials. The populations of cells were also similar in regard to cell surface phenotype as determined by flow cytometric analysis. In addition, recoveries from either tissue culture vessel as well as cell viability of the LAK cells were comparable. Finally, the LAK cells obtained from both sources were assessed for cytolytic activity against the tumor cell lines K562 and Daudi. These results showed that the cytolytic activity of the LAK cells against these target cells was the same whether the cells were obtained from the flasks or the bags.

Lymphokine activation of T4+ T lymphocytes and monocytes.

The function of the T4 antigen, a marker for a differentiated T cell subset, is not well understood. Our previous observation that a chemoattractant human lymphokine, lymphocyte chemoattractant factor (LCF), which selectively induces motile responses in unactivated T4+ lymphocytes, led us to investigate whether LCF could also induce T4+ cell activation. Because LCF acts selectively on T4+ cells, we next determined whether the T4 antigen has a function in this LCF-induced cellular activation. A T4+ lymphocyte migratory response is induced by divalent anti-T4 antibody, but not by corresponding Fab fragments of the same antibody. Fab fragments of anti-T4 antibody, but not Fab fragments of anti-T3 antibody, block the migratory effect of both LCF and divalent anti-T4. Furthermore, LCF but not divalent anti-T4, evokes the expression of interleukin 2 (IL 2) receptors and HLA-DR antigen on T4+ lymphocytes in 24 hr. These effects are quantitatively similar to those observed by anti-T3 antibody activation. LCF-induced IL 2 receptor expression is blocked by co-incubation with anti-T4 antibody and anti-T4 Fab fragments, whereas anti-T3 activation is not inhibitable by anti-T4 Fab fragments. Because cultured monocytes express the T4 antigen, we investigated the action of LCF on cultured monocyte migration and HLA-DR expression. Induction of monocyte migration by LCF and anti-T4 antibody increases proportionally as T4 antigen expression increases in vitro. This enhanced migration is inhibitable by anti-T4 Fab fragments. Monocyte activation, as measured by augmented HLA-DR expression 24 hr after incubation with LCF, but not anti-T4 antibody, is quantitatively similar to the effects of interferon-gamma. Augmented HLA-DR expression is blocked by anti-T4 Fab fragments but not by antibody to interferon-gamma. These studies indicate that LCF interacts with T4+ lymphocytes and monocytes to induce migration and cellular activation.