Induction of macrophage tumoricidal activity by granulocyte-macrophage colony-stimulating factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) counteracts the inhibiting effect of monocytes on natural killer (NK) cells

GM-CSF is known to accelerate haematopoietic recovery following allogeneic bone marrow transplantation (BMT). In addition, it may restore and enhance both granulocyte and monocyte functions. Stimulation of monocyte functions may induce a direct or an indirect anti-leukaemic activity due to an increase of cellular cytotoxicity and production of cytokines which may result in a reduction of the relapse rate after BMT. NK cells may play a crucial role in this activity. Therefore we studied the influence of monocytes on NK activity in combination with GM-CSF. Lymphocytes and monocytes were isolated from buffy coats of healthy individuals by counterflow centrifugation elutriation (CCE). NK activity was exerted by CD3-CD56+ cell populations and could be enhanced by IL-2 incubation overnight. Incubation of CD3-CD56+ cells with GM-CSF in the presence or absence of IL-2 hardly influenced NK activity of the lymphocyte population. Low amounts of monocytes enhanced NK activity. NK activity in lymphocyte population in the presence of equivalent numbers of monocytes with or without IL-2 was strongly decreased irrespective of the effector:target ratio (ETR). This appeared not to result from sterical hindrance effects of the present number of cells. However, addition of GM-CSF abrogated the inhibition of NK activity by monocytes in the presence of IL-2. In monocyte fractions neither IL-2 nor GM-CSF yielded NK activity. Our findings indicate that GM-CSF can affect NK activity by counteracting the suppressing effects of monocytes, and hence may improve the outcome after BMT.

Cyclophosphamide in combination with sargramostim for treatment of recurrent medulloblastoma

Thirteen patients with recurrent medulloblastoma were treated with cyclophosphamide in association with Sargramostim. Cyclophosphamide was given at doses ranging between 1.0-2.5 g/m2 daily for two doses. Sargramostim was given at a fixed dose of 250 micrograms/m2 subcutaneously twice a day beginning 24 hours after the second cyclophosphamide dose and continuing through the leukocyte nadir until the ANC was more than 1,000 cells/microliters for two consecutive days. A total of 33 courses were given with toxicity consisting of grade 4 neutropenia in all courses and grade 3-4 thrombocytopenia in 10 of 13 patients. There were no deaths related to infection or bleeding. Four patients were taken off study because of prolonged myelosuppression. Three of these patients were at the 2.5 g/m2 level, and of these three, two developed lung toxicity (grades 2 and 4, respectively). One patient developed an allergic reaction following the first injection of Sargramostim and was also taken off study. Of 10 evaluable patients, there were 9 PR and 1 SD. We conclude that cyclophosphamide at a dose of 2.0 g/m2/day x 2 days q 4 weeks in association with Sargramostim demonstrates marked activity with acceptable toxicity in patients with recurrent medulloblastoma.

Leukocytes express connexin 43 after activation with lipopolysaccharide and appear to form gap junctions with endothelial cells after ischemia-reperfusion

Levels and subcellular distribution of connexin 43 (Cx43), a gap junction protein, were studied in hamster leukocytes before and after activation with endotoxin (lipopolysaccharide, LPS) both in vitro and in vivo. Untreated leukocytes did not express Cx43. However, Cx43 was clearly detectable by indirect immunofluorescence in cells treated in vitro with LPS (1 micrograms/ml, 3 hr). Cx43 was also detected in leukocytes obtained from the peritoneal cavity 5-7 days after LPS-induced inflammation. In some leukocytes that formed clusters Cx43 immunoreactivity was present at appositional membranes, suggesting formation of homotypic gap junctions. In cell homogenates of activated peritoneal macrophages, Cx43, detected by Western blot analysis, was mostly unphosphorylated. A second in vivo inflammatory condition studied was that induced by ischemia-reperfusion of the hamster cheek pouch. In this system, leukocytes that adhered to venular endothelial cells after 1 hr of ischemia, followed by 1 hr of reperfusion, expressed Cx43. Electron microscope observations revealed small close appositions, putative gap junctions, at leukocyte-endothelial cell and leukocyte-leukocyte contacts. These results indicate that the expression of Cx43 can be induced in leukocytes during an inflammatory response which might allow for heterotypic or homotypic intercellular gap junctional communication. Gap junctions may play a role in leukocyte extravasation.

Alterations in phenotype and cell-surface antigen expression levels of human monocytes: differential response to in vivo administration of rhM-CSF or rhGM-CSF

We investigated, via multicolor flow cytometry, the in vivo effects of colony-stimulating factors (CSFs) on cell size, frequencies, and expression of surface antigens on peripheral blood monocytes from melanoma patients treated concurrently with CSFs and tumor-specific monoclonal antibody (mAb) R24. Recombinant human macrophage colony-stimulating factor (rhM-CSF) increased cell size, relative percentages of monocytes, percentages of CD14+, HLA-DQ+, CD11b+, and CD16+ monocytes, and cell-surface expressions of HLA-DR and CD11b; rhM-CSF also up-regulated cell-surface expression of CD14 on CD14brightCD16- monocytes. Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) increased cell size, percentages of CD14+, HLA-DQ+, and CD11b+ monocytes, and cell-surface expressions of HLA-DR, HLA-DQ, CD11b, and CD58. Relative percentages of monocytes and CD16+ cells and cell-surface expression of CD14 on CD14brightCD16- monocytes decreased. In addition, monocytes derived from patients treated with rhM-CSF showed functional activity when assayed in vitro for antibody-dependent cellular cytotoxicity (ADCC). During treatment and coincident with increased CD16 expression, monocytes derived from rhM-CSF patients had enhanced levels of cytotoxicity towards melanoma target cells compared to healthy controls and to patients treated with rhGM-CSF.

Cutaneous side effects in breast cancer patients treated with cytostatic polychemotherapy and rh GM-CSF: immune phenomena or drug toxicity?

The application of recombinant colony stimulating factors for chemotherapy induced granulocytopenia is becoming common in clinical oncology. Here we report on localized cutaneous side effects after subcutaneous administration of recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) in 11 patients with breast cancer receiving cytostatic treatment. Seven patients suffering from inflammatory breast cancer received cytostatic chemotherapy with mitoxantrone/cyclophosphamide, whereas four patients suffering from noninflammatory breast cancer received high-dose epirubicin/cyclophosphamide, respectively. rh GM-CSF was applicated subcutaneously in a dose of 5 micrograms/kg/d for at least ten days. In all patients, sharply demarked, maculous itching and burning erythemas restricted to the injection sites occurred after three to four injections of rh GM-CSF. These eruptions cleared within 2 to 3 weeks, but reappeared after reexposure to rh GM-CSF. In contrast to previous sporadic reports, no generalized erythemas were observed. Because of this unexpected and subjectively intolerable side effect, rh GM-CSF administration had to be interrupted in all patients. Histopathological findings revealed skin infiltration with lymphocytes, monocytes/macrophages, neutrophils, and occasionally eosinophils, respectively. Since GM-CSF is known to alter immune functions, it seems likely that the eruptions were at least in part due to local immune reactions.

Dose escalation trial of cyclophosphamide with Sargramostim in the treatment of central nervous system (CNS) neoplasms

We conducted a dose escalation trial of cyclophosphamide plus Sargramostim in the therapy of patients with newly diagnosed or recurrent central nervous system tumors. Cyclophosphamide was administered at doses ranging between 1.0 and 2.5 g/m2 daily for two doses. Sargramostim was administered at a fixed dose of 250 micrograms/m2 subcutaneously twice a day beginning 24 hours after the second cyclophosphamide dose and continuing through the leukocyte nadir until the absolute neutrophil count (ANC) was > 1,000 cells/microliters for two consecutive days. The MTD for patients who had not received any prior chemotherapy and who had received either no radiotherapy or radiotherapy confined to the cranium was 2.0 g/m2 daily for two doses. The MTD for patients previously treated with chemotherapy or neuraxis radiotherapy was also 2.0 g/m2 daily for two doses. Responses were seen in patients with medulloblastoma (8/9), glioblastoma multiforme (2/13), germinoma (1/1), and pineoblastoma (1/2).

Relationship between granulocyte macrophage-colony stimulating factor, tumour necrosis factor-alpha and Trypanosoma cruzi infection of murine macrophages

Gamma interferon (IFN-gamma)-activated macrophages control Trypanosoma cruzi infection via nitric oxide (NO), recently recognized as a major effector molecule. Granulocyte macrophage-colony stimulating factor (GM-CSF) is a multipotent cytokine secreted by macrophages and many other cells. It induces the production of tumour necrosis factor alpha (TNF-alpha), another cytokine also secreted by macrophages and involved in the control of T. cruzi infection. However, no data are available on the relationship between GM-CSF, TNF-alpha and NO produced by macrophages activated by IFN-gamma and infected with T. cruzi. To highlight this relationship, mouse peritoneal macrophages (MPM) and two c-myc retrovirus-induced macrophage cell lines (9.1.1 and BMM8), respectively characterized by a constitutive and an inducible production of GM-CSF, were activated with IFN-gamma and/or GM-CSF and infected with T. cruzi. Our results indicate that T. cruzi upregulates GM-CSF release from MPM and from the two macrophage cell lines, activated (or not) by IFN-gamma. A high autocrine production of GM-CSF or an exogenous supply of GM-CSF is correlated with an enhanced release of TNF-alpha and NO, inducing an improved control of T. cruzi infection by IFN-gamma-activated MPM.

Recombinant growth factors

Recombinant human growth factors are expected to have a significant impact on the use of allogeneic blood components. For example, subsequent to the approval of recombinant human erythropoietin, blood transfusions in renal dialysis patients declined substantially. Likewise, myeloid growth factors have reduced infections and hospital stay by promoting hematologic recovery after high dose ablative chemotherapy. The high costs of these agents mandate that their use be limited to settings where they are clinically indicated. The use of growth factors may be monitored at medical centers by hospital transfusion committees. This chapter reviews the emerging clinical guidelines for the use of hematopoietic growth factors.

In vivo administration of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor increases neutrophil oxidative burst activity

The influence of CSF therapy on the superoxide (O2-) releasing capacity in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) of neutrophils from 32 patients with testicular cancer receiving high-dose chemotherapy followed by autologous bone marrow transplantation (ABMT) was assessed: 8 patients were treated as control group without CSF therapy, 12 patients received GM-CSF, and 12 patients received G-CSF. To monitor the kinetics of the respiratory burst, leukocytes were collected before initiation of chemotherapy and ABMT, during CSF administration on days 1 and 3 after leukocyte recovery, and 7 days after leukocyte recovery (controls) or 3 days after the end of CSF therapy. Neutrophils from patients who received GM-CSF showed a significantly higher superoxide anion release compared with control patients (p < 0.001). O2- production in these patients was higher than that achieved by in vitro preincubation of neutrophils from control patients. Increased burst activity was seen only during infusion of GM-CSF and returned to pretherapeutic values after the end of GM-CSF administration. A similar but less pronounced increase was seen in patients who received G-CSF. In vitro preincubation of neutrophils from the same patients with GM-CSF, G-CSF, or TNF showed that O2- production by neutrophils from patients receiving GM-CSF could not be further enhanced, whereas O2- production by neutrophils derived from patients receiving G-CSF could be further augmented by TNF but not by GM-CSF. Interestingly, neutrophils from patients treated with GM-CSF but not those with G-CSF therapy retained a higher response to in vitro stimulation with GM-CSF or TNF after the end of CSF administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Is there a place for immunotherapy with interleukin-2 to prevent relapse after autologous stem cell transplantation for acute leukemia?

Chemotherapy-resistant cells cause disease recurrence in a significant proportion of patients with acute leukemia treated with autologous stem cell transplantation due to the lack of immune-mediated effects which contribute significantly to the prevention of post-treatment disease recurrence. This conclusion is based on the observation that relapse after high dose chemotherapy supported by a stem cell transplant from a twin donor is 3-4 times higher than after transplant from an allogeneic donor. This anti-leukemic mechanism of transplanted donor cells has been termed graft-versus-leukemia (GVL) effect, and efforts are being directed toward utilizing such an immune-mechanism after autologous transplantation. Since interleukin-2 (IL-2) can induce remissions in selected patients with advanced leukemia, it has become a candidate cytokine to be used in attempts to introduce GVL after autologous stem cell transplantation. Here we review the available clinical data with IL-2 and critically evaluate whether IL-2 has a place as adjunct treatment to prevent relapse after autologous transplantation for acute leukemia.

Tumor vaccines: effects and fate of IL-2 transfected murine melanoma cells in vivo

We have previously demonstrated the general usefulness of the adenovirus-enhanced transferrinfection (AVET) in the generation of IL-2 producing tumor vaccines. By optimizing different parameters of the transfection protocol we were able to transform the poorly immunogenic M-3 mouse melanoma cell line into a potent immunogen. A long-lasting immunity was demonstrated after administration of the IL-2 releasing vaccine, since immunized animals successfully rejected native M-3 melanoma cells even after a period of more than 6 months. We also demonstrated that in vivo administration of such a vaccine is safe since transmission of the transfected IL-2 gene in host organs was not detected. IL-2 production ceased 2 days after injection because the engineered cells were destroyed. However, RT-PCR analysis of the site of vaccine injection suggests that IL-2 exerts its effects not only directly but also by inducing a set of other immunomodulator cytokines in situ that are probably indispensable in inducing a host response. We conclude that AVET of IL-2 into tumor cells is a safe and efficient method for the generation of tumor vaccines.

Effects of granulocyte-monocyte colony-stimulating factor (GM-CSF) on expression of adhesion molecules and production of cytokines in blood monocytes and ovarian cancer-associated macrophages

The present study was aimed at characterizing the effects of in vitro exposure to GM-CSF on blood monocytes and tumor-associated macrophages (TAM) in human ovarian cancer. Purified populations of TAM from ovarian cancer patients were studied in terms of expression of surface molecules, cytokine production and tumor cytotoxicity after overnight incubation with GM-CSF or IFN gamma and LPS, used as reference activators. GM-CSF augmented the surface expression of ICAM-I and CD18 in TAM and in blood monocytes. Stimulation was more prominent in monocytes than in TAM, which showed higher baseline expression of this adhesion molecule. ICAM-3 was not influenced by GM-CSF or by IFN gamma/LPS. GM-CSF-augmented ICAM-I expression was associated with higher levels of mRNA transcripts. The protein synthesis inhibitor cycloheximide super-induced basal and GM-CSF-induced ICAM-I transcripts, thus excluding a role for secondary polypeptide mediators. In the absence of stimuli, TAM produced higher levels, compared to monocytes, of IL-6 and IL-8 but not of IL-1 and TNF. GM-CSF augmented the production of IL-6 and IL-8 (but not that of IL-1 and TNF) in TAM, whereas it had little effect on blood monocyte. Tumoricidal activity was tested against two ovarian tumor cell lines (OVCAR3 and SW626). GM-CSF more prominently augmented monocyte cytotoxicity, while only 2 of 6 TAM preparations were stimulated by GM-CSF. These results suggest that GM-CSF selectively regulates the function of blood monocytes and TAM, the effect of this cytokine varying with the parameter and cell population examined. These data provide a rational and biological endpoint for further studies with GM-CSF as an activator of mononuclear phagocyte function in ovarian cancer.

Dextran sulfate sodium-induced colitis occurs in severe combined immunodeficient mice

BACKGROUND/AIMS

Oral administration of dextran sulfate sodium (DSS) has been reported to induce colitis in mice. The purpose of this study was to determine whether the possible pathogenic mechanism involved the acquired immune system.

METHODS

Normal BALB/c and related C.B17 severe combined immunodeficient mice were fed 5% DSS (40 kilodaltons) in their drinking water for 7 days; controls were fed only water. Colons were scored for histological activity at various times. Cytokine production by cultures of colon and of draining lymph node cell was measured. The effect of DSS on the proliferation of the MCA-38 colonic epithelial cell line was assessed.

RESULTS

DSS feeding resulted in a very reproducible acute distal colitis in both BALB/c and C.B17 severe combined immunodeficient mice. The lesions of BALB/c mice had an increased production of macrophage-derived cytokines, such as interleukin (IL) 1 beta, IL-6, tumor necrosis factor, and granulocyte-macrophage colony-stimulating factor, but not the T-cell cytokines IL-3 or interferon gamma. Draining lymph node cells produced these cytokines plus interferon gamma and IL-3. DSS inhibited MCA-38 cells at doses that would be easily achieved in the distal colon.

CONCLUSIONS

Acute DSS-induced colitis does not require the presence of T cells or B cells because it occurred in C.B17 severe combined immunodeficient mice that lack these cells. Its induction may result from a toxicity of DSS for colonic epithelial cells.

An immunodominant epitope in a functional domain near the N-terminus of human granulocyte-macrophage colony-stimulating factor identified by cross-reaction of synthetic peptides with neutralizing anti-protein and anti-peptide antibodies

We produced polyclonal and monoclonal antibodies (MAbs) against recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF) and performed studies of epitope mapping by ELISA, using five synthetic peptides corresponding to sequences along this molecule. Additionally, anti-peptide MAbs were generated. The antibody ability to inhibit rhGM-CSF activity was determined using as bioassay the MO7e cell line, which is dependent on hGM-CSF for growth in vitro. An immunodominant epitope able to induce the highest neutralization antibody titers was identified near the N terminus of hGM-CSF. A synthetic peptide 14-24, homologous to a sequence including part of the first alpha-helix of the molecule, was recognized by neutralizing anti-protein antibodies. Similarly, MAbs anti- 14-24 cross-reacted with rhGM-CSF and specifically blocked its function. Replacement of Val16 or Asn17 with alanine greatly reduced the antibody-binding capacity to peptide 14-24, whereas substitution of Gln20 or Glu21 was less critical. Monoclonal antibodies generated against residues 30-41 (corresponding to an intrahelical loop) and 79-91 (homologous to a sequence including part of the third alpha-helix) or its analog [Ala88](79-91)beta Ala-Cys, were conformation dependent and nonneutralizing: they failed to react or bound poorly to rhGM-CSF in ELISA, but readily recognized the homologous sequence in the denatured protein, by Western blotting.

Purification of recombinant human granulocyte-macrophage colony-stimulating factor from the inclusion bodies produced by transformed Escherichia coli cells

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), produced as inclusion bodies in genetically transformed Escherichia coli cells was purified to homogeneity by a three-step chromatographic procedure involving hydrophobic interaction, ion exchange and gel filtration. Each purification step is reproducible and well suited for process-scale operations. The purification process also leads to a significant decrease in DNA and endotoxin levels in the final product. Of the three gel media used, Phenyl Sepharose 6 FF (high sub) was most effective in reducing the DNA content (by a factor of ca. 2000) while Superdex 75 prep grade was more effective for removing endotoxins (reduction factor ca. 15). The recovery of purified rhGM-CSF was 35% by enzyme-linked immunosorbent assay and 70% by a biological assay method. The overall purification factor obtained was about 4.6, which is in the range of those reported for recombinant proteins produced in E. coli as inclusion bodies. The purified rhGM-CSF is an acidic protein (pI = 5.4) and has a specific activity of ca. 3.3 x 10(7) units/mg, which is in excellent agreement with that reported for its natural counterpart. Its monomer molecular mass of 14,605, as determined by electrospray mass spectrometry, corresponds exactly to the mass calculated from its cDNA sequence. Its amino acid composition and partial NH2-terminal sequence (up to seventeen residues) are also identical with those reported for this protein. These and other results confirm the identity of the purified rhGM-CSF with its natural counterpart. However, the results also showed that it is apparently heterogeneous from its NH2-terminal side as it is composed of three polypeptides having Met, Ala and Pro as the NH2-terminal residues in which the intact Met analogue accounts for 60% for the mixture. This heterogeneity does not seem to have any biological significance since the specific activity of the purified rhGM-CSF is identical with that of its natural counterpart.

Macrophage-colony stimulating factor (M-CSF) stimulation induces cell death in HIV-infected human monocytes

We show here that HIV-infected monocyte-macrophages stimulated by macrophage-colony stimulating factor (M-CSF) undergo massive syncytia formation and die. The M-CSF-stimulated HIV-infected monocyte-macrophages (M/M) destroy themselves by blebbing out particles (resembling apoptotic bodies) which may contain condensed and marginated chromatin. The death of monocyte-macrophages is also characterized by the expression of "Tissue" Transglutaminase (tTG) which is one of the genes specifically expressed and activated in apoptising cells. Noteworthy, when the syncytia formation and consequently death is prevented, infected monocyte-macrophages remain viable and produce large amounts of virus for an extended period. The concentrations of M-CSF (1000 U/ml) used in this work are similar to those that stimulate macrophages in vivo. This suggests that HIV killing of M/M in the presence of M-CSF could lead, in vivo, to a greater than expected loss of immune cells and may contribute to explain the complex derangement of the immune function observed in HIV-infected patients.

Enhanced killing capacity of human Kupffer cells after activation with human granulocyte/macrophage-colony-stimulating factor and interferon gamma

In this study we investigated the effect of the cytokines human granulocyte/macrophage-colony-stimulating Factor (hGM-CSF) and interferon gamma (IFN gamma) on human Kupffer-cell-mediated cytotoxicity against the SW948 colon carcinoma cell line. Kupffer cells were isolated from small liver wedge biopsies, taken from 14 patients who had had abdominal surgery for colon carcinoma or partial hepatectomy. The cells were incubated with hGM-CSF (100 ng/ml), or with IFN gamma (100 U/ml) or with their combination and the percentage cytotoxicity was determined using a recently described modified assay. Additional experiments were performed with tumour-necrosis-factor-alpha (TNF alpha)-sensitive U937 cells as target. The TNF alpha secretion of Kupffer cells was measured and we evaluated the effect of TNF alpha on colon tumour targets. We performed human-Kupffer-cell-mediated cytotoxicity blocking experiments with anti-TNF alpha and used paraformaldehyde-fixed Kupffer cells to demonstrate lysis of TNF alpha-sensitive WEHI-164 cells and of SW948 cells. The overall cytotoxicity against SW948 caused by unactivated Kupffer cells (n = 14), and by Kupffer cells activated with hGM-CSF (n = 14), IFN gamma (n = 6) or their combination (n = 6) was respectively: 19.5 +/- 2.6%, 25.3 +/- 2.9%, 41 +/- 9.4% and 45.6 +/- 8% at E/T = 1 and 28.2 +/- 2.9%, 35.6 +/- 3.2%, 55.6 +/- 9.7% and 62.8% at E/T = 5. All differences were statistically significant (P < 0.05). No growth-promoting activity by hGM-CSF on the SW948 tumour cells was observed. U937 cells were highly susceptible to Kupffer-cell-mediated cytotoxicity. The TNF alpha secretion by human Kupffer cells increased in parallel to their cytotoxicity after incubation with these cytokines. Soluble TNF alpha had only a slight anti-proliferative effect on SW948 cells, while specific anti-TNF alpha blocked Kupffer cell cytotoxicity by up to 80%. Finally, paraformaldehyde-fixed Kupffer cells were able to lyse WEHI-164 and SW948 cells. This indicates that expression of cell-associated TNF alpha is the main cytolytic mechanism of human-Kupffer-cell-mediated cytotoxicity. The implications for the use of hGM-CSF and IFN gamma in vivo are discussed.

Serum levels of cytokines in patients with colorectal cancer: possible involvement of interleukin-6 and interleukin-8 in hematogenous metastasis

Serum levels of interleukin-1 (IL-1 beta), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured preoperatively in 24 patients with colorectal cancer. IL-1 beta was not elevated, IL-6 and IL-8 were markedly elevated, and GM-CSF was slightly elevated. TNF-alpha was not detected in most patients. Serum IL-6 levels correlated closely with serum IL-8 levels and with serum carbohydrate antigen (CA) 19-9 levels. Serum IL-6 levels were significantly higher in patients whose tumors exceeding 5.0 cm in diameter or spreading circumferentially. Serum IL-8 levels showed significant differences according to histological type, being lower in well differentiated adenocarcinoma compared to other types. Serum levels of IL-6 and IL-8 were significantly higher in patients with liver metastasis than in those without liver metastasis and serum levels of both these cytokines were also significantly higher in patients with lung metastasis than in those without lung metastasis. These results suggest that IL-6 and IL-8 may play an important role in the hematogenous metastasis of colorectal cancer.

Synergistic effects of IL-4 and either GM-CSF or IL-3 on the induction of CD23 expression by human monocytes: regulatory effects of IFN-alpha and IFN-gamma

CD23 expression by B cells and monocytes can be regulated by cytokines including IL-4, IFN-gamma and IFN-alpha. We recently reported that GM-CSF and IL-3 are also capable of regulating CD23 expression, with GM-CSF enhancing CD23 expression by monocytes and IL-3 enhancing CD23 expression by both monocytes and B cells. In this study, we have assessed the effect of combinations of cytokines on monocyte CD23 expression. IL-4 acted in a synergistic manner with either GM-CSF or IL-3 to induce monocyte CD23 expression. Interestingly, culture of monocytes with GM-CSF, IL-3 or IL-4 resulted in two subpopulations of cells, one negative or dull for surface CD23 and the other expressing relatively high levels of CD23. In contrast, culturing monocytes in the combination of IL-4 with either GM-CSF or IL-3 resulted in a single population of cells expressing very high levels of CD23. The synergy between IL-4 and either GM-CSF or IL-3 was also reflected at the level of release of soluble CD23 and CD23 mRNA expression and was seen at both sub-optimal and optimal cytokine concentrations. GM-CSF, IL-3 and IL-4 all enhanced monocyte expression of class II MHC, though no additive or synergistic effects were seen with cytokine combinations. IFN-gamma failed to induce monocyte CD23 expression when acting alone, though it enhanced both surface and soluble CD23 when acting in the presence of GM-CSF, IL-3 or IL-4. In contrast, IFN-alpha was a potent inhibitor of monocyte CD23 expression induced by these three cytokines.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective expression of interleukin-10 gene within glioblastoma multiforme

Little information exists regarding which glioma cells are able to escape immune system detection and progress within the host. In order to elucidate some of the mediators which facilitate the growth and spread of glioma cells, the expression of cytokines, TNF-alpha, IL-6, gamma-IFN, IL-10, and GM-CSF, within 12 human glioma specimens was investigated by the polymerase chain reaction. The twelve patients with malignant glioma were categorized into a localized (n = 4) and an invasive glioma (n = 8) groups, mostly glioblastoma multiforme, based upon the CT and MRI scans. We examined the correlation between specific cytokine gene expression and the clinical category of each patient. The results showed that while IL-10 mRNA transcripts were expressed in most of the tumors from the invasive glioma group (7/8), they were not expressed in tumors from the localized group. On the other hand, gamma-IFN gene expression was more frequent in tumors from the localized group (3/4 vs 1/8 from the invasive group). The mRNA transcripts of IL-6 and GM-CSF were more frequently expressed in tumors from the localized group. No consistent pattern was seen in TNF-alpha gene expression between the two groups. Among the five cytokines studied, IL-10 mRNA was selectively expressed within invasive gliomas compared to less malignant, localized glioma group. Our results demonstrate specific cytokine mRNA profiles in glioma patients, which might have prognostic significance for immunotherapy.

Dysfunctional monocytes from a patient with disseminated Mycobacterium kansasii infection are activated in vitro and in vivo by GM-CSF

A 27 year-old woman presented with disseminated infection due to Mycobacterium kansasii. Signs and symptoms of disseminated infection persisted despite the administration of multiple antimycobacterial agents to which her organism was sensitive for 15 months. She was seronegative for HIV-1 and functional studies of T and B lymphocytes and granulocytes failed to demonstrate any abnormality. Peripheral blood monocytes proved abnormally permissive to the intracellular growth of Mycobacterium avium and M. kansasii, and expressed normal number of receptors to interferon-gamma, but reduced numbers of receptors to granulocyte monocyte colony stimulating factor and tumor necrosis factor. These defects were partially reversed with in vitro exposure of her cells to recombinant GM-CSF. In addition, administration of recombinant human GM-CSF in vivo (250 mg/M2 per day) for 10 days armed her circulating monocytes as evidenced by increased production of O2- in response to phorbol esther and, when infected ex vivo with M. kansasii, enhanced inhibition of intracellular growth compared with pre-therapy monocytes. These defects reappeared with discontinuation of GM-CSF and resolved with its re-administration. While a salutary clinical and microbiologic effect was difficult to assess, administration of GM-CSF in vivo was associated with in vitro activation of monocytes and enhanced mycobactericidal activity in this patient with a defect in monocyte function.

IL-1 alpha and TNF alpha act synergistically to stimulate production of myeloid colony-stimulating factors by cultured human bone marrow stromal cells and cloned stromal cell strains

Human bone marrow stromal cells respond to stimulation by the monokines IL-1 and TNF by producing colony-stimulating factors such as GM-CSF and G-CSF. In this study we show that IL-1 alpha and TNF alpha act synergistically to stimulate GM-CSF and G-CSF production by cultured marrow stromal cells. We further show that IL-1 alpha and TNF alpha synergistically stimulate production of GM-CSF and G-CSF by a clonal stroma-derived cell strain. Although IL-1 and TNF share many of the same biological activities, we show that IL-1 alpha and TNF alpha have an unequal ability to induce myeloid-CSF production by both cultures, with IL-1 alpha being the more potent inducer. We found that induction by IL-1 alpha and TNF alpha was independent of cell proliferation. The effect of IL-1 alpha and TNF alpha on production of the two myeloid-CSFs by the clonal cells was significantly greater than the unfractionated passaged stromal cultures, having the greater effect on G-CSF production. The clonally derived stromal cells constitutively produced colony-stimulating activity, in particular GM-CSF, at levels easily detected by ELISA. These findings show that, in addition to the overlapping and additive activities of IL-1 alpha and TNF alpha, they can interact synergistically. Our findings further suggest that a small subpopulation of stroma cells may be the major producer of G-CSF in the marrow microenvironment during immune response.

Future uses of granulocyte-macrophage colony-stimulating factor (GM-CSF)

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been used extensively to restore hematopoietic system function after damage by diseases such as myelodysplastic syndrome or by cytotoxic anti-cancer agents used during cancer chemotherapy or prior to bone marrow transplantation. The clinical benefits of this approach have included fewer infections, fewer hospital days and less antibiotic use. In the future, the use of GM-CSF will be focused on special situations within these general areas, plus new directions that were not previously given sufficient attention. Examples of focused approaches include the use of GM-CSF in the control of fungal or protozoal disease and to take advantage of anti-tumor effects of myeloid cell activation. The anti-microbial effects will also be explored in patients who are not neutropenic but have serious infections which may be benefited by increased stimulation to myeloid cell function. The use will also be focused on mobilization of peripheral blood progenitor cells and in cycling of normal hematopoietic and malignant cells. The new directions will include use of GM-CSF by local application in healing of cutaneous ulcers, rapid wound closure and skin grafting. Because of its potent effects on immunologic mechanisms of antigen presentation, it will be used in several ways as a vaccine adjuvant. This adjuvant action will be directed at enhancing immunologic responses to antimicrobial antigens and anti-tumor antigens. The future of GM-CSF as a tool for hematopoietic and immunologic stimulation with resulting important clinical benefits is clear.

An enzyme-linked immunosorbent assay (ELISA) for quantitation of adducts of granulocyte-macrophage colony stimulating factor (GM-CSF) and human serum albumin (HSA) in stressed solution mixtures

HPLC analyses of GM-CSF in solution mixtures containing both GM-CSF and HSA showed losses of GM-CSF which could not be accounted for using conventional electrophoretic and/or RP-HPLC techniques. Further investigation of these mixtures by immunoblotting and by immunoaffinity chromatography demonstrated the presence of high molecular weight (> 67,000 GM-CSF related species. No such species was detectable in solutions of GM-CSF alone. This experiment pointed to the formation of an adduct between GM-CSF and HSA in the solution mixtures. To probe further the hypothesis of a GM-CSF/HSA adduct, an immunologically based test was conceived which could react only with this type of hybrid molecule. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed using two antibodies, anti-GM-CSF (capture antibody) and anti-HSA (detection antibody), as part of the quantitation of GM-CSF/HSA adducts. After confirming its existence by ELISA, a GM-CSF/HSA adduct was isolated from the solution mixture containing both GM-CSF and HSA. This isolate served as a primary reference standard in the ELISA assay. The immunoassay has a subnanogram sensitivity and is highly specific for GM-CSF/HSA adducts in the presence of either free GM-CSF or free HSA. As a verification, conjugates of GM-CSF/HSA were synthesized using a cross-linking reagent. These covalent conjugates reacted positively in the ELISA and are employed as a convenient alternative reference standard.

Activation of the granulocyte-macrophage colony-stimulating factor promoter in T cells requires cooperative binding of Elf-1 and AP-1 transcription factors

The granulocyte-macrophage colony-stimulating factor (GM-CSF) gene has been studied extensively as a model system of transcriptional induction during T-lymphocyte activation. The GM-CSF gene is not expressed in resting peripheral blood T cells but is rapidly induced at the transcriptional level following activation through the cell surface T-cell receptor. A highly conserved 19-bp element located immediately 5' of the human GM-CSF TATA box (bp -34 to -52), herein called purine box 1 (PB1), has been shown to bind a T-cell nuclear protein complex and to be required for transcriptional induction of the GM-CSF gene following T-cell activation. The PB1 sequence motif is highly conserved in both human and murine GM-CSF genes. In this report, we demonstrate that the PB1 element alone confers inducibility on a heterologous promoter following transfection into human Jurkat T cells. In addition, we identify a major PB1 nuclear protein-binding complex that is not present in resting peripheral blood T cells but is rapidly induced following T-cell activation. Sequence analysis revealed that PB1 is composed of adjacent binding sites for Ets and AP-1 transcription factors. In vitro mutagenesis experiments demonstrated that both the Ets and AP-1 sites are required for binding of the inducible PB1 nuclear protein complex and for the transcriptional activity of this element and the GM-CSF promoter in activated T cells. Using antibodies specific for different Ets and AP-1 family members, we demonstrate that the major inducible PB1-binding activity present in activated T-cell nuclear extracts is composed of the Elf-1, c-Fos, and JunB transcription factors. Taken together, these results suggest that cooperative interactions between specific Ets and AP-1 family members are important in regulating inducible gene expression following T-cell activation.

Activation of the granulocyte-macrophage colony-stimulating factor promoter in T cells requires cooperative binding of Elf-1 and AP-1 transcription factors

The granulocyte-macrophage colony-stimulating factor (GM-CSF) gene has been studied extensively as a model system of transcriptional induction during T-lymphocyte activation. The GM-CSF gene is not expressed in resting peripheral blood T cells but is rapidly induced at the transcriptional level following activation through the cell surface T-cell receptor. A highly conserved 19-bp element located immediately 5' of the human GM-CSF TATA box (bp -34 to -52), herein called purine box 1 (PB1), has been shown to bind a T-cell nuclear protein complex and to be required for transcriptional induction of the GM-CSF gene following T-cell activation. The PB1 sequence motif is highly conserved in both human and murine GM-CSF genes. In this report, we demonstrate that the PB1 element alone confers inducibility on a heterologous promoter following transfection into human Jurkat T cells. In addition, we identify a major PB1 nuclear protein-binding complex that is not present in resting peripheral blood T cells but is rapidly induced following T-cell activation. Sequence analysis revealed that PB1 is composed of adjacent binding sites for Ets and AP-1 transcription factors. In vitro mutagenesis experiments demonstrated that both the Ets and AP-1 sites are required for binding of the inducible PB1 nuclear protein complex and for the transcriptional activity of this element and the GM-CSF promoter in activated T cells. Using antibodies specific for different Ets and AP-1 family members, we demonstrate that the major inducible PB1-binding activity present in activated T-cell nuclear extracts is composed of the Elf-1, c-Fos, and JunB transcription factors. Taken together, these results suggest that cooperative interactions between specific Ets and AP-1 family members are important in regulating inducible gene expression following T-cell activation.

Salmonella enteritidis immune leukocyte-stimulated soluble factors: effects on increased resistance to Salmonella organ invasion in day-old Leghorn chicks

Cytokines, derived from either concanavalin A-stimulated Salmonella enteritidis-immune chicken T lymphocytes [SE-immune Lymphocyte Stimulated Soluble Factor (LSSF)] or lipopolysaccharide-stimulated SE-immune chicken macrophages [SE-immune Macrophage Stimulated Soluble Factor (MSSF)], were evaluated for their ability to increase resistance to SE organ invasion in day-old Leghorn chicks. In Trial 1, day of hatch chicks were injected i.p. with either SE-immune LSSF or SE-nonimmune LSSF (control). In Trial 2, chicks were similarly injected with either SE-immune MSSF, SE-nonimmune MSSF, or SE-immune LSSF (positive control). Thirty minutes postinjection, all chicks were gavaged with an invasive dose of SE. Twenty-four hours later, livers and spleens from all chicks were cultured for SE. In Trial 1, SE-immune LSSF caused a rapid and marked protection (P < .01) against SE infection as determined by the number of chicks that were culture positive regardless of challenge dose. In Trial 2, SE-immune MSSF was not associated with protection against SE organ infection. These experiments demonstrate that SE-immune LSSF, but not MSSF, are able to confer protection against SE organ invasion in day-old Leghorn chicks. Thus, it appears that the stimulated immune T cell, and not the macrophage, is responsible for producing the soluble products that protected the chicks.

Granulocyte-macrophage colony-stimulating factor inhibits tumour growth

The effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on murine antitumour responses was examined. Sixty mice received Lewis lung carcinoma implants and were then randomized to receive GM-CSF 1 microgram/day, GM-CSF 0.5 microgram/day or saline for 10 days and studied with regard to tumour volume, carcass weight and food intake. Macrophage antitumour mechanisms including oxygen free radical production and nitric oxide release were studied in peritoneal macrophages after co-culture with GM-CSF in vitro and in vivo. GM-CSF 1 microgram/day decreased tumour growth after 5 days (mean(s.e.m.) 0.62(0.14) versus 1.24(0.19) cm3, P = 0.017). GM-CSF upregulated macrophage antitumour mechanisms by enhancing the in vivo production of superoxide radicals (mean(s.e.m.) 0.69(0.06) versus 0.45(0.10) nmol, P < 0.05) and nitric oxide (mean(s.e.m.) 48(3) versus 24(4) mumol, P < 0.01). GM-CSF functions through the enhancement of macrophage tumoricidal activity, suggesting a therapeutic potential for this cytokine in the tumour-bearing host.

Leukemic cell lysis by activated human macrophages: significance of membrane-associated tumor necrosis factor

In this study, we analyzed the mechanism(s) of leukemic cell lysis by human macrophages. Peripheral blood monocyte-derived macrophages were activated with recombinant interferon-gamma and lipopolysaccharide and their lytic activity against two leukemic cell lines (K562 and HL-60 cells) was assessed by an 111In releasing assay. Activated macrophages lysed these leukemic cells, and the lytic activity against leukemic cells was almost completely inhibited by anti-tumor necrosis factor (TNF) antibody. The macrophage-lysate prepared from activated macrophages also exhibited significant lytic activity against leukemic cells; this lytic activity was inhibited by anti-TNF antibody. The leukemic cells that we used for the cytotoxicity assays were resistant to recombinant TNF. The culture supernatant of activated macrophages did not show any lytic activity. These findings suggest that cell-associated TNF plays a role in macrophage-mediated cytotoxicity against leukemic cells.

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) after chemotherapy in patients with non-Hodgkin's lymphoma; a placebo-controlled double blind phase III trial

To assess the clinical and hematopoietic effects of rhGM-CSF, a placebo-controlled double blind multicenter phase III study was undertaken in patients with non-Hodgkin's lymphoma receiving cytotoxic chemotherapy. Sixty-two patients who had granulocytopenia (< 1 x 10(3)/microliters) after the first cycle of chemotherapy with cyclophosphamide, adriamycin, vincristine, and prednisolone were enrolled. After the second cycle of chemotherapy with the same regimen, patients randomly received either rhGM-CSF (125 micrograms/m2/day) or placebo for 14 days (rhGM-CSF; 31 patients and placebo; 31 patients). Administration of rhGM-CSF induced a significant increase in granulocytes mainly with neutrophils, eosinophils and monocytes, but elevation of lymphocytes, platelets, and reticulocytes was not induced. Median days of granulocytes less than 1 x 10(3)/microliters in patients receiving rhGM-CSF were significantly shorter than in patients receiving placebo (p = 0.001). Adverse reactions encountered with rhGM-CSF, and observed in 58% of the patients were never life-threatening and always rapidly reversible. They included fever, nausea and vomiting, diarrhea, skin eruption, and malaise. These results suggest that rhGM-CSF can be safely administered to prevent neutropenia after chemotherapy in patients with non-Hodgkin's lymphoma.

Functional dichotomy of mouse microglia developed in vitro: differential effects of macrophage and granulocyte/macrophage colony-stimulating factor on cytokine secretion and antitoxoplasmic activity

After differentiation either with exogenous macrophage (M) or with granulocyte/macrophage (GM) colony-stimulating factor (CSF) microglial cells were isolated from neonatal mouse brain cell cultures and were comparatively tested for secretory immune effector cell functions. Both factors obviously do not promote the development of cells with biased growth requirement; however, the two microglia populations displayed distinct potentials to produce inflammatory cytokines. Upon gradual stimulation by lipopolysaccharide, the cells harvested from M-CSF-driven culture released more interleukin-1 and tumor necrosis factor activity, GM-CSF-grown cells on the contrary proved superior in interleukin-6 secretion. This pattern was paralleled by corresponding different kinetics of cytokine release in both types of microglial cells. When infected with Toxoplasma gondii only GM-CSF-differentiated cells were able to restrict the intracellular multiplication of tachyzoites in the absence of external stimuli. As described for interferon-gamma-treated macrophages, the antiparasitic activity of this microglia population is due to the synthesis of reactive nitrogen intermediates, since it was antagonized by NG-monomethyl-L-arginine, a competitive inhibitor of the arginine-dependent metabolic pathway. Complementary to previous data which attest an intrinsic capability for antigen presentation to GM-CSF-grown microglia, the functional state of the cells elicited by M-CSF and GM-CSF, respectively, may correspond to the resting and an activated form of microglia as distinguished in vivo.

Practical aspects of cytokine therapy

Biological therapy with cytokines and growth factors represents a completely new approach in cancer therapy and forces us to adapt our research procedures originally tailored to cytotoxic agents. The lack of reliable predictive in vitro systems or animal models for biological agents and the fact that promising candidates must proceed rapidly to the clinic implies that a drug's therapeutic potential can only be assessed following careful studies in man. Consequently, the effectiveness of clinical trials must be improved by closely relating them to research programs utilizing material from cytokine-treated patients. In clinical practice, patients with low tumor burden may profit most from therapy with immunomodulators, which requires minimally effective doses rather than maximally tolerated dosages. Hemopoiesis can be influenced either by hemopoietic growth factors or by negative regulators, which may prevent stem cell damage during chemotherapy. According to the principles of autocrine growth mechanisms, resting malignant cells may be triggered into cell cycle by their growth factor(s), thus becoming more sensitive to chemotherapy. When discussing the fascinating aspects of the cytokine network, we must be aware that we are only beginning to understand the mechanisms of biological therapy and that close cooperation among preclinical and clinical scientists is required for its rational development.

Effect of in vivo administration of cisplatin on the colony forming ability of murine bone marrow cells

In vitro colony forming ability of bone marrow cells obtained from cisplatin-treated C3H/He mice was studied. Mice were administered cisplatin in a single intraperitoneal dose of 10 mg/kg body wt, 24 h prior to the harvest of femoral bone marrow cells. Incubation of untreated bone marrow cells without any CSF in vitro showed little colony forming ability which was marginally enhanced in cisplatin-treated bone marrow cells. Presence of M-CSF (250 U/ml) or GM-CSF (250 U/ml) in the culture medium significantly augmented the colony forming ability of both untreated and cisplatin-treated bone marrow cells. In the presence of M-CSF, colony forming units-macrophage (CFU-M) were predominantly high in untreated bone marrow cells, followed with CFU-granulocyte-macrophage (CFU-GM). The number of CFU-M was significantly up-regulated in response to M-CSF in bone marrow cells obtained from cisplatin administered mice, whereas the number of CFU-GM remained unchanged, as compared to untreated mice. Both CFU-M and CFU-GM were enhanced in the presence of GM-CSF in untreated bone marrow cells. Cisplatin-treated bone marrow cells on incubation in the presence of GM-CSF showed a significant enhancement of CFU-M and GM as compared to untreated samples. IL-1 (100 U/ml) in the presence of M-CSF significantly up-regulated colony forming ability of cisplatin-treated bone marrow cells, whereas TNF (100 U/ml) inhibited the colony forming ability.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of monoclonal antibody 17-1A and GM-CSF in patients with advanced colorectal carcinoma--long-lasting, complete remissions can be induced

Antibody-dependent cellular cytotoxicity (ADCC) is considered to be one of the effector functions of unconjugated monoclonal antibodies (MAbs) in tumor therapy. The antitumor activity of MAbs might therefore be augmented if the cytotoxic capability of the effector cells could be increased. In an in vitro system, the killing capacity of MAb was significantly enhanced by pre-treatment of the effector cells with granulocyte-macrophage colony-stimulating factor (GM-CSF). Based on these findings, the therapeutic effect of the combination of mouse MAb 17-1A (IgG2a) and GM-CSF was evaluated in 20 patients with metastatic colorectal carcinoma (CRC). The patients received GM-CSF for 10 days and a single i.v. infusion of MAb 17-1A on day 3 of the cycle. Four cycles were given at 1-monthly intervals. There was a continuous increase in blood monocytes and lymphocytes during all 4 GM-CSF cycles. Neutrophils and eosinophils were also significantly augmented but in a biphasic manner and the cell counts on day 10 of cycle IV were significantly lower than in cycles I and II. GM-CSF-related side-effects were of no major clinical importance. During the third cycle, an immediate-type allergic reaction (ITAR) against MAb 17-1A occurred in most patients, necessitating reduction of the MAb dose as well as of the infusion rate. Two patients achieved complete remission. One patient had a minor response, and 3 other patients were considered to have stable disease > 3 months.

The therapeutic use of the unconjugated monoclonal antibodies (MAb) 17-1A in combination with GM-CSF in the treatment of colorectal carcinoma (CRC)

Unconjugated monoclonal antibodies (MAb) and granulocyte macrophage-colony stimulating factor (GM-CSF) may induce tumor regression in patients. Antibody-dependent cellular cytotoxicity (ADCC) is considered to be one of the effector functions of MAb. Human peripheral blood mononuclear cells (PBMC) preincubated with GM-CSF and used as effector cells in an 18h ADCC assay with SW948 (human colorectal carcinoma cell line) as target cells and MAb 17-1A induced significant increase in the lytic capacity of the effector cells. Based on these findings the therapeutic effect of the combination of mouse MAb 17-1A (IgG2a) against colorectal carcinoma (CRC) cells and GM-CSF was evaluated in 20 patients with metastatic CRC. The patients received GM-CSF (250 micrograms/m2/day s.c.) for 10 days and a single i.v. infusion of MAb 17-1A (400 mg) at day 3 of the cycle. The cycles were repeated with an interval of one month. Four cycles were given. ADCC as well as Fc-receptor bearing mononuclear cells increased significantly during therapy. Two patients achieved CR (10%). One patient had an MR (5%) and a further three patients were considered to have SD > 3 months (15%). The two CR patients are still in CR, 35+ and 30+ months respectively after initiation of therapy. Patients with an ADCC activity at start of therapy above the median value of the total patient material survived significantly longer than those patients with an ADCC reactivity below this value (p = 0.002).

Effects of interleukin-1, -2, -4, -6, interferon-gamma and granulocyte/macrophage colony stimulating factor on human vascular endothelial cells

Human vascular endothelial cells (HUVEC) exhibit various immunological functions, i.e. expression of HLA class-II antigens after incubation with IFN-gamma or antigen presenting function. It has also been reported that HUVEC are able to produce IL-1, IL-6, GM-CSF and immunologically active cleavage products of arachidonic acid. In our study we investigated whether various cytokines, namely IL-1, IL-2, IL-6, GM-CSF and IFN-gamma, do alter the proliferative capacity of HUVEC, the production of van Willebrandt factor (vWF) and the expression of MHC class-II antigens. HUVEC were prepared by the collagenase digestion of human umbilical veins. Monolayers of cells were incubated with cytokines in different concentrations for 24 and 48 h. IFN-gamma inhibits the HUVEC [3H]thymidine uptake in a dose-dependent manner. Suppression of proliferation (40.1%) could be observed after 24 h incubation with 100 U IFN-gamma/ml. IL-1 was a more effective inhibitor of HUVEC proliferation (54% at 10 U/ml and 24 h incubation and 48.4% after 48 h) than IFN-gamma. IL-6 and GM-CSF showed an increasing effect on proliferation with 226% and 151% of the control group, respectively. IFN-gamma after an incubation period of 12 h and IL-1 after 24 h reduced the vWF content by about 30%. Bright MHC class-II expression was induced only by IFN-gamma. In conclusion, some of the immunoregulative cytokines might play an important role in the control of HUVEC proliferation.

Specific immune recognition of autologous tumor by lymphocytes infiltrating colon carcinomas: analysis by cytokine secretion

Tumor-infiltrating lymphocytes (TIL) were grown in the presence of interleukin-2 from 19 colon carcinoma specimens, including 1 primary lesion and 18 metastatic lesions. These cultures showed a median proliferation of 606-fold (range 13-fold to 28,000-fold) over 49 culture days (range 26-76 days). By phenotype, mature cultures were 69%-99% CD3+ (mean 93%) and contained mixed populations of CD4+ and CD8+ cells (CD4 > CD8 in 10 of 19 cultures). Fresh cryopreserved colon tumors were not lysed by autologous TIL in short-term 51Cr-release assays, and were poorly lysed by lymphokine-activated killer cells. Ten TIL cultures were assayed for cytokine secretion in response to autologous and allogeneic tumors during a 6- to 24-h coincubation. Culture supernatants were tested by ELISA for the presence of granulocyte/macrophage-colony-stimulating factor, interferon gamma, and tumor necrosis factor alpha. Of 10 TIL, 4 secreted at least two of these cytokines specifically in response to autologous and/or HLA-matched fresh allogeneic colon carcinomas, but not to melanomas or HLA-unmatched colon carcinomas. Cytokine secretion was mediated by both CD4+ and CD8+ TIL, and could be inhibited by mAb directed against the appropriate class of MHC antigen. These data provide evidence for specific, MHC-restricted immune recognition of human colon carcinomas by T lymphocytes.

The effects of rhGM-CSF on macrophage function

Markers of monocyte/macrophage activity are numerous, and offer an insight on the potential effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). These include anti-microbial effects, anti-tumour effects, inflammation and wound healing enhancing effects, antigen presenting effects and effects on the haematopoietic microenvironment. The actions of rhGM-CSF on monocytes/macrophages relevant to enhanced antimicrobial activity include increased phagocytosis, increased oxidative metabolism, increased numbers of Fc receptors, release of chemotactic factors and stimulation of mechanisms for killing intracellular viruses, fungi, bacteria and protozoa. Markers of macrophage anti-tumour activities can be divided into two types: those associated with antitumour antibodies, antibody-dependent cell cytotoxicity (ADCC) and those associated with synthesis and secretion of cytolytic substances by activated macrophages. In addition, rhGM-CSF has actions on fibroblasts and kerotinocytes consistent with an important role in wound healing. Moreover, the clinical use of rhGM-CSF to enhance antibody responses in conditions of inadequate immunisation is currently being investigated. Furthermore, rhGM-CSF appears to have a role in stimulating haemopoietic recovery following cytotoxic chemotherapy or radiation damage to bone marrow tissue.

Differentiation driven by granulocyte-macrophage colony-stimulating factor endows microglia with interferon-gamma-independent antigen presentation function

The antigen presentation function of microglial cells was analyzed after differentiation in neonatal mouse brain cell cultures supplemented either with macrophage (M) or granulocyte/macrophage (GM) colony-stimulating factor (CSF). The cells separated from concomitant astrocytes in both culture systems turned out to exhibit cytological characteristics of macrophages and bore MAC-1 and F4/80 markers in a similar way. When comparatively tested for accessory cell function, only microglia developed with GM-CSF were able to efficiently induce antigen-directed proliferation of a series of helper T cell lines representing both the TH1 and TH2 subtype. Antigenic T cell activation by this microglia population was performed without prior stimulation and exceeded that of M-CSF-dependently grown microglial cells, even if those had been pretreated with interferon-gamma (IFN-gamma). In contrast to such difference in function, low cell surface expression of MHC class II or intercellular adhesion molecule-1 determinants proved to coincide in both populations. Correlating with the capacity for antigen presentation, expression of membrane-bound interleukin-1 (IL1)--a costimulatory signal for TH2 cells--was augmented significantly in GM-CSF-grown microglia. In parallel, the interaction only of this microglia population with a selected TH1 cell line was accompanied by maximal release of T cell-stimulating factor, a cytokine recently identified as an IL1-analogous second signal for TH1 cells. Thus, a developmental process is suggested which produces a form of microglia specialized in antigen presentation and thereby acting uncoupled from IFN-gamma.

The development of human tumor-cell resistance to TNF-alpha does not confer resistance to cytokine-induced cellular cytotoxic mechanisms

We have derived a TNF-alpha-resistant clone (RA-I) from the parental TNF-sensitive human breast-adenocarcinoma cell line (MCF-7). The acquisition of TNF-resistance was not associated with endogenous TNF production or with differential levels of TNF receptors since both MCF-7 and RA-I display comparable TNF-receptor expression. We have investigated the relationship between acquisition of resistance to TNF and susceptibility to lysis by cytokine-activated effectors. Experiments were performed using human peripheral-blood monocytes stimulated with IL-2, IFN or GM-CSF, and lymphokine-activated killer cells as effector cytotoxic cells. Our data indicate that both TNF-resistant (RA-I) and TNF-sensitive (MCF-7) cells were killed by IL-2-activated monocytes. Incubation of monocytes with IFN also resulted in the activation of their tumoricidal activity against MCF-7 and RA-I. When stimulated monocytes were pre-incubated in the presence of a TNF-specific neutralizing monoclonal antibody, prior to co-culture with target cells, no effect on their lytic capacity was observed. Thus, the monocyte killing does not appear to involve the membrane form of TNF. These observations suggest that, in our experimental system, IL-2 and IFN are able to induce non-TNF-mediated mechanisms of cytotoxicity by monocytes. Experiments performed using GM-CSF and LPS for monocyte stimulation indicate that, although both reagents were efficient in inducing the membrane form of TNF on monocytes, they did not enhance the cell-killing capacity towards MCF-7 and RA-I targets. Furthermore, using IL-2-stimulated LGL as effector cells, we show in this study that the TNF-resistant clone RA-I was as sensitive as MCF-7 to human LAK cells.

Human recombinant migration inhibitory factor activates human macrophages to kill tumor cells

A recombinant form of human migration inhibitory factor (rMIF) obtained from COS-1 cells transfected with MIF-specific cDNA is able to activate cultured human peripheral blood monocytes and monocyte-derived macrophages, in a dose-dependent manner to become cytotoxic for tumor cells in vitro. The cytotoxicity exhibited by macrophages treated with rMIF is > or = 30% above that of cells incubated with control supernatants or with media and peaks 72 hr after the addition of tumor targets. rMIF also induces macrophages to produce tumor necrosis factor (TNF-alpha) and interleukin-1 beta (IL-1 beta). These results demonstrate that rMIF is able to modulate macrophage functions and plays a role in cell-mediated immune response.

The effect of aerosolized recombinant human granulocyte macrophage colony-stimulating factor on lung leukocytes in nonhuman primates

The number and function of myeloid cells in the lungs are critical determinants of health and disease. To examine whether these cells can be modulated in vivo by a colony-stimulating factor (CSF), recombinant human granulocyte macrophage-CSF (GM-CSF) was given to cynomolgus monkeys by either continuous intravenous infusion (7,200 U/kg/day) for 2 wk or by aerosol exposure to 10(7) U on 1 or 2 consecutive days. At intervals after the initiation of GM-CSF administration, animals underwent bronchoalveolar lavage (BAL) and had peripheral blood sampled to characterize changes in lung and circulating phagocytic cells. Compared with animals exposed to bovine serum albumin, there was an increase in the total number of BAL cells retrieved. This increase was greatest in animals receiving aerosolized GM-CSF, and it was the result of more macrophages and neutrophils. Both lung macrophages and blood neutrophils from animals exposed to aerosolized GM-CSF exhibited an augmented respiratory burst in response to phorbol myristate acetate. Lung macrophages from GM-CSF-exposed animals exhibited increased capacity to bind and/or ingest opsonized and unopsonized Staphylococcus aureus. Despite functional activation of lung phagocytic cells, biochemical analyses of BAL fluid for markers of lung injury revealed an increase in only some parameters in the GM-CSF group. Intravenous administration of GM-CSF had the expected effect on augmenting the number of myeloid cells in the bloodstream. Aerosolized GM-CSF produced a transient effect on circulating myeloid cell number between 3 and 5 days after exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines in tumour therapy

Cytokines are low molecular weight proteins released by cells of the immune system that have therapeutic potential in cancer. They include the interleukins, the interferons, tumour necrosis factor and the colony-stimulating factors. Cytokines are capable of producing significant and sustained responses against a number of tumours. Clinically, the highest response rates to cytokine immunotherapy have been seen in melanoma and renal cell cancer. Current efforts aim to reduce treatment-related toxicity while maintaining the efficacy of cytokines. The therapeutic potential of these agents may be increased with genetic manipulation by introducing genes encoding cytokines into tumour-infiltrating lymphocytes and certain tumour cells. However, immunotherapy remains time consuming and expensive, and further developments are necessary before it can have a definitive role in tumour management.

Tumor growth changes the contribution of granulocyte-macrophage colony-stimulating factor during macrophage-mediated suppression of allorecognition

Tumor-bearing host (TBH) macrophages (M phi) suppress T cell alloresponses, and this study suggests granulocyte-macrophage colony-stimulating factor (GM-CSF), a molecule associated with suppressive M phi activity during tumor growth, signals more immunosuppression. In the absence of M phi, GM-CSF increased T cell proliferation in response to alloantigen. However, TBH M phi-mediated suppression of allorecogntion was further induced by GM-CSF. Allogeneic mixed lymphocyte reaction (MLR) cultures, containing normal host (NH) M phi, were either unaffected or enhanced. Prostaglandin E2 (PGE2), a highly suppressive monokine that decreases alloreactivity, did not seem to be involved in the suppression caused by the TBH M phi/GM-CSF interaction. M phi-CSF (M-CSF) addition to cultures did not reverse the suppression caused by TBH M phi and GM-CSF, and inhibition of PGE2 synthesis did not change the response to M-CSF. TBH Ia- M phi, a suppressor population that predominates among splenic M phi during tumor growth, demonstrated significantly lower reactivity in the presence of GM-CSF. In contrast, alloresponses suppressed by NH Ia- M phi demonstrated higher reactivity in the presence of GM-CSF. The data collectively suggest that TBH M phi respond differently to GM-CSF, and that tumor-induced changes in GM-CSF responsiveness affect M phi accessory ability.

Clinical uses of growth factors

The haemopoietic growth factors are a diverse group of hormones with effects on different haemopoietic cell lineages and at various points in their developmental differentiation. The biology of many of these factors is now well understood. They have entered clinical trials and have demonstrated benefits in particular clinical situations. The thrust of current phase II and III clinical investigations now is to use these factors, alone or in combinations, to modify various disease states and to ameliorate many of the side-effects of other therapeutic agents, particularly cytotoxic anticancer agents. Many other disease states also lend themselves to therapy with these growth factors. Other haemopoietic growth factors have not been as extensively studied in humans but hold great promise. In this chapter, the current status of the haemopoietic growth factors presently under clinical trial has been reviewed. In addition, several factors which have been recently described but which have not yet entered clinical trials have been discussed.

Native cytokine antagonists

Cytokines orchestrate the complex homeostasis of cells and tissues by acting in both an autocrine and paracrine fashion. The processes responsible for regulation of cytokines is not well understood. This chapter has summarized what is known about antagonism and inhibition of the action of cytokines. Several concepts have emerged from work in this area. At least two cytokines (IL-1 alpha and IL-1 beta) have an endogenous receptor antagonist, the IL-1 receptor antagonist. This is the first example of one endogenous molecule directly blocking the binding of another molecule to its receptor: most forms of regulation occur through independent receptors. Several cytokines, including TNF, IFN-gamma, IL-2 and IL-4, are inhibited by soluble receptors. Several cytokines, including IL-10, TGF-beta and MDF, act to inhibit other cytokines. It is likely that these inhibitors will be found to have pleiotropic actions in vivo. Finally, we describe antibody inhibition of cytokines. Detailed studies will be required to understand the complex interplay of the aforementioned cytokine inhibitors and the processes they regulate.

Effects of human interleukin 3, macrophage and granulocyte-macrophage colony-stimulating factor on monocyte function following autologous bone marrow transplantation

The effects of human interleukin 3 (IL-3), macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were studied on the functional activity of human peripheral blood monocytes from healthy individuals and from eight patients at 4, 8 and 12 weeks following autologous bone marrow transplantation (ABMT). Functions studied included superoxide production, phagocytosis of Candida albicans and reduction of 3-[4,5-dimethylthiazol-2-yl]-2.5-diphenyl tetrazolium bromide (MTT). IL-3 and GM-CSF significantly enhanced the oxidative metabolism of monocytes from healthy individuals, while the effect of M-CSF was moderate. A considerable variability between healthy individuals was found in both resting and cytokine-stimulated monocytes with regard to superoxide production. All three investigated CSFs, i.e. IL-3, M-CSF and GM-CSF did not affect phagocytosis of C. albicans by the cells or their metabolic activity (reduction of MTT). In ABMT patients no deficit in the functional activity of monocytes was found at any time after transplantation and all three CSFs investigated did not modulate the functional activity of the cells. These results suggest that monocytes do not have a major role in infectious complications post-ABMT.