Patients with condyloma acuminatum exhibit decreased interleukin-2 and interferon gamma production and depressed natural killer activity

Peripheral blood mononuclear cells were obtained from 20 untreated condyloma acuminatum patients and from an equal number of sex- and age-matched controls and assayed for cell surface antigen expression, natural killer activity, and lymphokine production. Patient peripheral blood mononuclear cells had significantly lower helper-to-suppressor T-cell ratios (Leu3/Leu2) (p<0.05) and significantly higher percentages of Leu 2+ Tac+ cells (activated suppressor/cytotoxic cells) (P<0.05) and Leu 2+ OKM1+ cells (suppressor cells) (P<0.01). Natural killer activity of condyloma acuminatum patients was significantly lower (P<0.05) than that of controls. Production of interleukin-2 and interferon gamma, but not interferon alpha, was significantly (P<0.01) decreased in condyloma acuminatum patients. There was an inverse correlation between thein vitro production of interleukin-2 and interferon gamma and the percentage of Leu 2+ OKM1+ cells (suppressor) (P<0.01). Thus, patients with condyloma acuminatum differ from controls by demonstrating (1) decreased natural killer-cell activity, (2) decreased production of lymphokines which enhance natural killer-cell activity (i.e., interferon gamma and interleukin-2), and (3) an increased proportion of T cells with a suppressor phenotype.     

Modulation of in vitro porcine natural killer cell activity by recombinant interleukin-1 alpha, interleukin-2 and interleukin-4.

Stimulation with lipopolysaccharide (LPS) initiated monocytes to produce interleukin-2 receptor light chain (p55 IL-2R). After stimulation with LPS for 48 hr, considerable quantities of soluble IL-2R were found in the supernatants of monocytes, exceeding even the amount of soluble IL-2R produced by activated T lymphocytes. Cell-associated p55 IL-2R was also increased during the first 24 hr of stimulation, after which time it remained constant. Fractionation of cells and analysis of cytoplasm, mitochondria, plasma membranes and nuclei for the presence of p55 IL-2R revealed that the main portion of receptor was present in the cytoplasm. This led to the conclusion that in monocytes cell-associated p55 IL-2R is not necessarily attached to membranes but is present in a soluble form in the cytoplasm, presumably freshly produced with the aim of being secreted. Stimulation of monocytes with pure recombinant interferon-gamma did not lead to augmentation of p55 IL-2R, as shown by enzyme-linked immunosorbent assay, binding of antibodies directed against the receptor (anti-Tac, CD25) and analysis of p55 IL-2R gene expression.     

Reversal of human immunodeficiency virus type 1 protein-induced inhibition of natural killer cell activity by alpha interferon and interleukin-2

A recombinant fusion peptide, Env-Gag, derived from the human immunodeficiency virus type 1 (HIV-1) genome corresponding to a defined portion of the envelope (Env) and internal core (Gag) proteins was examined for immunoregulatory effects on the cytotoxic activity of natural killer (NK) cell-enriched, large granular lymphocytes (LGL) from healthy donors. Percoll-separated, NK cell-enriched LGL precultured for 24 h with Env-Gag at 10- and 50-ng/ml concentrations, which significantly stimulated lymphocyte proliferation, caused significant suppression of NK cell activity. Denatured Env-Gag did not cause any effect on the NK cell activity of LGL. Two other control peptides, one derived from the Escherichia coli vector used to clone the HIV Env-Gag fusion peptide and the other derived from a non-HIV-1 viral antigen (rubeola virus), did not produce any observable effect on the NK cell activity of LGL, demonstrating the specificity of the effect produced by Env-Gag. Subsequent treatment of LGL with alpha interferon (IFN-alpha) or interleukin 2 (IL-2) alone partially reversed the Env-Gag-induced suppression of NK cell activity. However, LGL treated with both IFN-alpha and IL-2 completely reversed the suppression of NK cell cytotoxicity by Env-Gag. The combined effect of IFN-alpha and IL-2 in enhancing NK cell activity may provide a novel therapeutic approach to the restoration of depressed NK cell activity observed in HIV-infected patients.     

Augmentation of natural killer cytotoxicity by alpha or gamma natural and recombinant interferons and interferon inducers. Effect of monocytes

We investigated the effect of human peripheral blood monocytes on the augmentation of natural killer cytotoxicity by alpha or gamma natural and recombinant interferons (IFN) and certain interferon inducers. We observed that: (1) in the majority of the donors examined (75%) human peripheral blood monocytes do not affect natural killer cytotoxicity, determined by a 4-hour chromium-51 release assay, against target cells from hemopoietic human tumor cell lines. (2) Monocytes are not required and do not affect the augmentation of natural killer cytotoxicity by Escherichia coli-derived IFN-gamma, natural human IFN-gamma, E. Coli-derived IFN-alpha 2 or natural human IFN-alpha. E. Coli-derived IFN-gamma and natural human IFN-gamma have been reported to activate monocyte cytotoxicity determined in 72-hour assay. (3) Monocytes are not required for the augmentation of natural killer cytotoxicity against target cells from hemopoietic tumor cell lines by polyinosinic acid-polycytidylic acid or staphylococcal enterotoxin A.     

Impairment of natural killer cell activity in Indian kala-azar: restoration of activity by interleukin 2 but not by alpha or gamma interferon.

Indian kala-azar patients have normal numbers of peripheral blood NK cells but impaired functional activity due to decreased binding and lysis of target cells. This impairment of NK activity could not be corrected by exogenous recombinant human alpha or gamma interferon. However, recombinant human interleukin 2 was able to restore this activity by augmenting conjugate formation and lysis of target cells.     

Potentiation of human natural killer cell activity by recombinant interleukin-2 towards multidrug-resistant human epidermoid carcinoma

Relatively little is understood about the antigen recognition and target structures used by natural killer (NK) cells. The purpose of this study was to analyze the relationship of a multidrug-resistant cell line expressing the P-glycoprotein (GP170 surface glycoprotein) derived from the parent non-drug-resistant malignant tumor cell line for susceptibility to lysis by either NK or lymphokine-activated killer cells. Our results demonstrate no significant difference in NK activity against either the non-drug-resistant or drug-resistant malignant cell line; Interleukin-2 induces a significant increase in cytolytic activity toward the multidrug-resistant cell line. These data suggest that malignant cells refractory to treatment or occurring after successful treatment are susceptible to immunotherapeutic intervention.     

Potentiation of lymphocyte natural killing by mixtures of alpha or beta interferon with recombinant gamma interferon.

Human lymphocytes were treated with human alpha (IFN-alpha), beta (IFN-beta), or recombinant gamma (IFN-gamma) interferons separately or in combination to determine their ability to enhance natural killing against mouse L cell targets. Our results showed that recombinant IFN-gamma was approximately 50 times more active per unit of antiviral activity than either IFN-alpha or IFN-beta. Moreover, the levels of natural killing by lymphocytes treated with combinations of IFN-alpha and IFN-beta were additive, whereas combinations of recombinant IFN-gamma and IFN-alpha or recombinant IFN-gamma and IFN-beta were synergistic. The development of natural killing in lymphocytes treated with recombinant IFN-gamma did not occur more rapidly but reached higher levels (62%) than that observed with lymphocytes treated with IFN-alpha or IFN-beta (15%). The results suggest the importance of IFN-gamma and mixtures of IFN-gamma with IFN-alpha or IFN-beta in the enhancement of natural killing activity against virus infections and neoplasia.     

Interleukin 2 enhances natural killer cell activity through induction of gamma interferon

Highly purified interleukin 2 (IL 2), free of interferon activity, enhanced natural killer (NK) cell activity against tumor cells in mouse spleen cell cultures and in human peripheral lymphocyte cultures in a manner similar to that of interferon (IFN). We determined that IL 2 enhanced NK activity indirectly in a cascade manner by the induction of gamma IFN (IFN-gamma) in the cultures, which actually mediated the enhanced killing. Accordingly, lymphocyte cultures treated with IL 2 alone produced 10 to 100 U of IFN per ml in 6 to 24 h of culture. The IFN was typed as IFN-gamma by specific antibodies. Specific antibodies either to natural IFN-gamma or to a synthetic peptide corresponding to the human IFN-gamma N-terminal amino acids, when added to cultures treated with IL 2, completely blocked IL 2 enhancement of NK cell activity for both the mouse and human systems. IL 2-induced proliferation was not affected by the antibodies. Thus, the enhancement of NK cell activity by IL 2 is completely mediated by IL 2-induced IFN-gamma. The findings clearly indicate a cascade effect whereby one lymphokine (IL 2) induces the production of another. The latter lymphokine (IFN-gamma) then mediates an important biological effect (natural killing).     

Production of gamma interferon by natural killer cells from Toxoplasma gondii-infected SCID mice: regulation by interleukin-10, interleukin-12, and tumor necrosis factor alpha.

Previous studies of mice have implicated natural killer (NK) cells as mediators of protective activity against Toxoplasma gondii through their production of gamma interferon (IFN-gamma). In the present study, we have compared NK-cell activity in infected and uninfected SCID mice. Our data reveal that infection results in increased levels of IFN-gamma in serum and elevated NK-cell activity but that these NK cells were not cytotoxic for T. gondii-infected P815 cells. Treatment with anti-IFN-gamma antibody abrogated the increase in NK-cell activity and resulted in earlier mortality of infected mice. In vivo treatment with anti-asialo GM1 antiserum reduced NK cell activity and levels of IFN-gamma in serum but did not alter time to death. Spleen cells from infected mice produced higher levels of IFN-gamma than those from uninfected mice when stimulated in vitro with live T. gondii or parasite antigen preparations. Further analysis revealed that interleukin 10 (IL-10) inhibited, whereas tumor necrosis factor alpha (TNF-alpha) and IL-12 enhanced, IFN-gamma production by spleen cells from infected or uninfected mice. The combination of IL-12 and TNF-alpha induced higher levels of IFN-gamma from whole spleen cells of infected mice than from those of uninfected mice. Depletion of the adherent cell population from the spleen cells of infected mice led to a significant reduction in the levels of IFN-gamma produced after stimulation with IL-12 plus TNF-alpha. Similar results did not occur with cells from uninfected mice. These data indicate that other cytokines produced by the adherent cell population from infected mice may be involved in maximal production of IFN-gamma by NK cells stimulated with IL-12 and TNF-alpha. To assess the importance of endogenous IL-12, a polyclonal anti-IL-12 was administered to infected SCID mice. This treatment led to earlier mortality, indicating that endogenous IL-12 mediates resistance to T. gondii.     

Separate and combined effects of recombinant interleukin-1 alpha and gamma interferon on antibacterial resistance.

Our laboratory has previously reported that administration of murine recombinant interleukin 1 alpha (rIL-1 alpha) substantially enhanced the resistance of mice to Listeria monocytogenes infection. Other investigators have reported that gamma interferon (IFN-gamma) plays a pivotal role in antilisteria resistance. In the present study, we have defined doses of human rIL-1 alpha that enhanced the antilisteria resistance of mice. We then addressed the possibility that combined immunotherapy with rIL-1 alpha and recombinant IFN-gamma (rIFN-gamma) might result in an additive or synergistic enhancement of antibacterial resistance. Simultaneous administration of rIL-1 alpha and rIFN-gamma enhanced antilisteria resistance (at 3 days after infection) to a greater extent than did either cytokine alone, although the results did not imply a synergistic action between the two cytokines. Experiments which examined the effects of the timing of cytokine administration indicated that maximal protection was observed when rIL-1 alpha and rIFN-gamma were administered together concomitantly with the L. monocytogenes challenge. When we compared the separate and combined protective effects of rIL-1 alpha and rIFN-gamma throughout the course of a primary L. monocytogenes infection, we observed an additive effect of the two cytokines only at 3 days after challenge, the time at which the peak bacterial burden occurs in the spleens and livers of infected mice. Histopathological comparisons of livers and spleens from cytokine-treated and control listeria-infected mice verified that cytokine treatment reduced the severity of tissue damage in cytokine-treated listeria-infected mice. In an attempt to provide a potential mechanism for the protective effects of rIL-1 alpha and rIFN-gamma administration, we compared levels of colony-stimulating activity in sera from cytokine-treated and control listeria-infected mice. The highest levels of colony-stimulating activity were detected in sera from control listeria-infected mice; somewhat lower levels were found in sera from listeria-infected mice that received rIL-1 alpha and rIFN-gamma either alone or in combination.     

Recombinant interferon alpha 2 stimulation of target-binding by natural killer cells

Summary Even though the enhancement of the lyitc capacity and the kinetics of lysis of natural killer cells (NK) by interferon has been well documented, an increase of the target-effector cell binding percentage is still disputed. We, therefore, modified the Grimm-Bonavida single-cell assay so that 400 to 600 cells per individual determination could be reliably evaluated. Using this assay, which makes possible separate determination of effector-target cell binding and target lysis, we demonstrated that, in addition to lytic capacity, target-effector cell binding is also increased by preincubating NK with 100 to 1,000 IU interferon alpha 2 per 10⁶ cells. Our data indicate that interferon alpha 2 induces pre-NK cells to bind target cells and that it activates these pre-NK cells to kill the targets.Abbreviations NK Natural killer cells - LCMV Lymphocytic choriomeningitis virus - IFN Interferon - FCS Fetal calf serum - RPMI 1640 Culture medium Dedicated to Prof. H.D. Waller on the occasion of his 60^th birthday     

Regulation of human natural killer cell activity by an interferon inhibitor

Laboratory of Immunochemistry and Department of Interferons, N. F. Gamaleya Research Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 395–397, October, 1991.     

Regulation of human natural killer activity with autologous interferon

A study is performed of the effects of α-interferon and γ-interferon induced in 8 healthy donors and 9 patients with multiple sclerosis on thein vitro cytotoxic activity of natural killers in an autologous and allogeneic systems. The general characteristics of regulation are estimated on the basis of the results. There is found to be an inhibitor regulating the effect of interferon on natural killer activity, which is produced in parallel with interferon in response to interferon induction, the efficacy of this inhibitor being dependent on the initial natural killer activity; the inhibitor is absent in commercial interferon preparations. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 281–284, September, 1994     

Production of interleukin-2 by YAC-1 cells stimulated with interleukin-1 and its augmentation of the natural killer activity

The production of interleukin-2 (IL-2) by YAC-1 cells stimulated with interleukin-1 (IL-1) was examined in the in vitro culture system. The IL-2 activity was detectable in the culture supernatant of YAC-1 cells stimulated with either a mouse IL-1 preparation or human purified IL-1. This activity could be detected 1 h after stimulation with IL-1. The addition of monoclonal antibody reactive with mouse IL-2 receptor completely blocked the IL-2 activity in the culture supernatant of IL-1-stimulated YAC-1 cells. Further, the culture supernatant of IL-1-stimulated YAC-1 cells augmented the NK activity in mouse spleen cells. The role of the IL-2 activity in the culture supernatant of IL-1-stimulated YAC-1 cells on augmentation of the NK activity is discussed.     

Effect of hydrocortisone on human natural killer activity and its modulation by beta interferon

It is well known that glucocorticoids depress the natural killer (NK) activity of human peripheral blood lymphocytes when used both in vivo and in vitro. Since interferons enhance natural cytotoxicity, potential interaction between beta-interferon and hydrocortisone hemisuccinate has been investigated using mononuclear cells of peripheral blood obtained from 17 healthy donors. At the end of in vitro treatment mononuclear cells were tested for NK activity against K562 cells in a 4 h 51Cr-release assay. The results suggest that beta-interferon at the optimal treatment schedule (i.e. before and after exposure to hydrocortisone) is capable of abrogating the hydrocortisone-mediated impairment of NK function. These findings provide valuable suggestions for optimal treatment schedules with beta-interferon (i.e. beta-interferon treatment before and after exposure of effector cells to hydrocortisone) for overriding the suppressive effects of glucocorticoid therapy on natural immunity.     

Effects of dexamethasone on human natural killer cell cytotoxicity, interferon production, and interleukin-2 receptor expression induced by microbial antigens.

Dexamethasone inhibits the expression of the interleukin-2 receptor, the synthesis of immune interferon, and the development of natural killer cells when added to peripheral blood mononuclear cells cultured with soluble microbial antigens (purified protein derivative and a polysaccharide extract from Candida albicans [MPPS]) or human recombinant interleukin-2.     

Synergistic activation of human natural killer cell cytotoxicity by histamine and interleukin-2

Interleukin-2 (IL-2) is recognized as a major activating signal for human natural killer (NK) cells. The presence of monocytes alters NK cell responsiveness to IL-2. Thus, while IL-2 effectively augments NK cell cytotoxicity (NKCC) in monocyte-depleted NK effector cells, it is relatively ineffective or even suppressive for NK cells in monocyte-containing, NK-cell-enriched mononuclear cell fractions. Here we report that concomitant treatment with IL-2 and the biogenic amine histamine synergistically augmented NKCC against K562 and Daudi target cells of CD3-/CD16+ human NK cells in the presence but not in the absence of monocytes. Addition of peripheral-blood monocytes, recovered by countercurrent centrifugal elutriation, to purified NK cells abrogated IL-2 induced NK cell activation, reconstituted the synergistic, NK-activating effects of histamine and IL-2, and strongly reduced baseline NKCC. The effects of histamine on baseline NKCC and on NK cell responsiveness to IL-2 were related to counteraction of monocyte-mediated NK cell suppression. By contrast, histamine did not affect baseline or IL-2-induced NKCC in mixtures of NK cells and monocytes when the latter cells were recovered after adherence. The effect of histamine on NK cell responsiveness to IL-2 was mediated by H2-type histamine receptors, as judged by mimicry exerted by the specific H2 receptor agonist dimaprit, but not by an H2-receptor-inactive derivative of this compound, N-methyldimaprit, and blocking by the H2 receptor antagonist ranitidine. Experiments in which monocytes and nonadherent NK cells were separately pretreated with ranitidine prior to histamine treatment suggested that NK-regulatory effects of histamine were mediated by H2 receptors on monocytes. Our data suggest that histamine may provide an important signal in the regulation of NK cell responsiveness to IL-2.     

Co-stimulation of human decidual natural killer cells by interleukin-2 and stromal cells

At the late secretory phase of the menstrual cycle and in early pregnancy, the uterine mucosa is infiltrated by large numbers of natural killer (NK) cells with a distinctive phenotype (CD56bright CD16- CD3-) and large granular lymphocyte (LGL) morphology. Circulating CD56bright NK cells generally proliferate in the presence of interleukin-2 (IL-2), but it is clear that cofactors besides IL-2 are required for optimal response. In the bone marrow, this co-stimulating signal is provided by stromal cells. In the present study we observe that uterine CD56+ cells from early pregnancy decidua similarly proliferate vigorously when cultured with decidual stromal cells and a suboptimal dose of IL-2. This response is dependent on cell-cell contact, as no proliferation of decidual NK cells was observed when they were separated from stromal cells by a permeable cyclopore membrane. In addition, we have studied the expression of Bcl-2 by decidual CD56+ cells. Our results show that the microenvironment of the uterus is likely to have a significant influence on the proliferation and survival of uterine CD56+ cells.