Effects Of Recombinant Human Interferon-gamma Research Articles

Evolution and Clinical Significance of the T Cell Proliferative and Cytokine Response Directed Against the Fibronectin Binding Antigen 85 Complex of Bacillus Calmette-Guerin During Intravesical Treatment of Superficial Bladder Cancer

The antitumorigenic effect of intravesical bacillus Calmette-Guerin (BCG) in superficial bladder cancer was reported to be initiated by the attachment of BCG to the bladder wall via fibronectin. The antigen 85 complex secreted in BCG culture filtrate binds specifically to fibronectin and is a powerful T cell stimulus. Therefore, we investigated the evolution and clinical significance of the cellular proliferative response and cytokine production during intravesical BCG therapy against this purified antigen 85 complex. Evolution of the lymphoproliferation, interleukin-2 and interferon-gamma production of peripheral blood lymphocytes against tuberculin (purified protein derivative), purified antigen 85, BCG culture filtrate, whole BCG bacilli and pokeweed mitogen was tested before and after 6 weekly intravesical BCG instillations in 29 patients with superficial bladder cancer at intermediate or high risk for recurrence. A major increase in the lymphoproliferative response against purified protein derivative, antigen 85, BCG culture filtrate, whole BCG and pokeweed mitogen was observed in 69.0, 65.5, 79.3, 48.3 and 65.3% of the patients, respectively, analyzed after BCG therapy. Reactivity returned to baseline values at 6 months of followup. Of the patients who received a second BCG course because of tumor recurrence 66% had a novel increase in lymphoproliferation against antigen 85. An increase in the production of interleukin-2 and interferon-gamma by peripheral lymphocytes against antigen 85 was noted in 42.1 and 50% of the treated patients, respectively, after a single BCG course. During a mean followup of 23.11 months 48.5% of the patients remained tumor-free. No correlation could be found between the immunological response against any of the BCG antigens and the clinical evolution of the response. Intravesical BCG instillations induce a transient (less than 6 months) peripheral immune activation against several purified BCG antigens and among them the fibronectin binding antigen 85 complex. Reactivation is observed in most cases after additional BCG courses. The absence of long lasting immune activation after a single 6-week course of BCG could be related to the increased clinical efficacy observed with BCG maintenance instillations.

Inhibition of duck hepatitis B virus replication by interferon‐γ

Interferons have been evaluated extensively as candidate antiviral agents in hepadnaviral infection. We examined the effect of recombinant human interferon-gamma on duck hepatitis B virus replication in human hepatoma cells (Huh 7) transiently transfected with cloned duck hepatitis B virus DNA. Cells transfected in the presence of interferon-gamma display a dose-dependent reduction in the levels of encapsidated replicative intermediates in the cytoplasm, as judged by Southern blotting of purified viral core DNA. The effect is observed at interferon-gamma concentrations that do not affect growth rate or viability of Huh 7 cells or their transfection efficiency. Northern analysis of duck hepatitis B virus transcripts in transfected cells demonstrated markedly diminished levels of pre- and subgenomic RNA in interferon-gamma-treated cells. Nuclear run-on analysis was performed to determine whether these transcripts were diminished due to decreased rates of transcription initiation or increased rates of RNA degradation. Levels of transcription initiation were unaffected by interferon-gamma, implying that duck hepatitis B virus transcripts in interferon-gamma-treated cells are degraded more rapidly than in untreated cells.

Synergistic effect of recombinant interferon-gamma and interleukin-3 on the growth of immature human hematopoietic progenitors

Purified peripheral blood hematopoietic progenitors from children in early remission from cancer respond to recombinant human interleukin-3 (IL-3), but not to granulocyte colony-stimulating factor (G-CSF). With these purified cells as a target, we studied the effect of recombinant human interferon-gamma (IFN-gamma) on progenitor growth, using both liquid-suspension limiting dilution assay (LDA) and regular methylcellulose culture of progenitors. We found that in LDA with IL-3, IFN-gamma directly stimulated the growth of blood progenitors in a dose- dependent manner with single-hit kinetics, whereas IFN-gamma suppressed the growth of G-CSF-supported progenitors obtained from bone marrow. The stimulatory effect was also observed in methylcellulose culture, but the addition of antibodies for G-CSF, granulocyte-macrophage CSF, IL-1 alpha, IL-1 beta, IL-6, or tumor necrosis factor did not result in a decrease of the colony number, supporting further the possible direct effect of IFN-gamma on progenitor growth. These results suggest that the inhibitory effect of IFN-gamma on hematopoietic progenitors is limited to those in an advanced stage of maturation. IFN-gamma may be one of the essential lymphokines upregulating the growth of human hematopoietic progenitor cells.

Strain- and Donor-Related Differences in the Interaction of Mycobacterium avium with Human Monocytes and its Modulation by Interferon-

Mycobacterium avium is a cause of disseminated infection in AIDS patients. The pathogenicity of M. avium for human monocytes was examined in an in vitro model. Peripheral blood monocytes obtained from 13 healthy donors were precultured for 2 days before infection. Monocytes were infected with six AIDS-associated and three non-AIDS-associated strains and four strains of M. avium selected on the basis of colonial morphology. Uptake of M. avium detected by counting intracellular acid-fast bacilli differed according to colonial morphology: Bacteria with round and opaque colony forms were phagocytosed more readily than those with flat colonies. Virulence as defined by intracellular growth was also partly associated with colonial morphology. Some but not all bacilli with flat colony forms multiplied in human monocytes; strains of the round opaque colonial form did not. The effects of recombinant human interferon-gamma on M. avium infection also were examined. Pretreatment of monocytes suppressed phagocytosis. After infection, coculturing usually augmented mycobacterial growth inhibition by human monocytes, but these effects were variable from strain to strain. Overall, interferon-gamma produced a small but statistically significant inhibition of intracellular growth in three of four strains tested.

Essential Amino Acid Deprivation Induces Monocytic Differentiation of the Human HL-60 Myeloid Leukemia Cell Line

In this study we examine the effects of amino acid deprivation on the growth and differentiation of the human HL-60 myeloid leukemia cell line. The HL-60 cell line was chosen for study because of its ability to differentiate along either a granulocytic or monocytic pathway under appropriate culture conditions. Differentiation was determined by changes in cell morphology, nonspecific esterase (NSE) content, hydrogen peroxide (H2O2) production, and expression of the cell surface differentiation antigens LeuM3 (CD14) and OKM1 (CD11). Using a model system in which HL-60 cells were cultured in medium that selectively lacked one amino acid (AA), it was seen that deprivation of HL-60 cells for essential (but not nonessential) AAs results in decreased cell growth and viability and in differentiation of 30% to 60% of the surviving population of cells specifically along the monocytic pathway. This differentiation is irreversible as well as time- and dose-dependent. Culture of HL-60 cells in essential AA-deficient medium potentiated the differentiative effects of recombinant human interferon-gamma (IFN-gamma), recombinant human tumor necrosis factor (TNF), and dihydroxyvitamin D3 (D3), all of which have previously been shown to induce monocytic differentiation of HL-60 cells. Differentiated cells had decreased DNA and RNA synthesis, but protein synthesis was unchanged compared with control cells. The protein synthesis inhibitor cycloheximide prevented differentiation, indicating the necessity of protein synthesis in this process. Cell cycle analysis revealed that an increased proportion of cells cultured in AA-deficient medium was arrested in G0-G1 (80% and 50% for AA-deficient and control cells, respectively). These results suggest that alterations of AA metabolism and subsequent perturbations in DNA and RNA synthesis may be important in initiating differentiation or in augmenting cytokine-induced differentiation of HL-60 cells into more mature, nonreplicating, monocyte-like cells.

Differential effects of recombinant human interferon-gamma and interleukin 2 on natural killer cell activity of peripheral blood in early human development.

Ontogenic development and the lymphokine responsiveness of human NK cell activity against K562 target cells in peripheral blood lymphocytes were evaluated in fetuses, premature infants, and term neonates by using a 4-hr 51Cr-release assay. Basal NK activity and NK boosting by lymphokines were comparatively assayed after an 18-hr incubation with medium alone, recombinant human IFN-gamma (1000 U/ml), and recombinant human IL 2 (25 U/ml), respectively. Lymphocytes from 20-wk-old fetuses lacked NK cell activity even after the pretreatment with IFN-gamma. Low, but significant levels of NK activity and NK boosting by IFN-gamma were observed in premature infants after 27 wk of gestation, with a progressive intrauterine maturation of these activities. Both basal NK activity and NK boosting by IFN-gamma in term neonates were still lower than those of adult controls. The grade of NK boosting by IFN-gamma appeared to depend on the development of basal NK activity. Contrary to IFN-gamma, IL 2 could induce marked NK activity even in 20-wk-old fetuses who lacked both basal and IFN-gamma inducible NK activities. NK boosting by IL 2 was much more efficient than that by IFN-gamma at any period of human life. The facts that IL 2-induced NK boosting could occur without any appreciable production of IFN-gamma in neonatal lymphocytes, and that ample neutralizing doses of anti-IFN-gamma antibody hardly suppressed IL 2-mediated NK boosting even in adult lymphocytes, indicated that the effect of IL 2 on NK boosting might be independent of IFN-gamma production. On the basis of the ontogenic differences in the development of the lymphokine responsiveness of NK cell activity and on the different NK boosting mechanisms of these lymphokines it was suggested that so-called human "pre-NK cells" might be divided into IFN-gamma sensitive and IL 2-sensitive cells. Whether these cell populations belong to different cell lineages or different maturation stages of the same cell line, however, remains unsettled.