E-cadherin-dependent adhesion of dendritic and Langerhans cells to keratinocytes is defective in cervical human papillomavirus-associated (pre)neoplastic lesions

Although human papillomavirus (HPV) DNA is detected in the majority of squamous intraepithelial lesions (SILs) and squamous cell carcinomas (SCCs) of the uterine cervix, the persistence and progression of cervical lesions suggest that viral antigens are not adequately presented to the immune system. This hypothesis is reinforced by the observation that most SILs show quantitative and functional alterations of Langerhans cells (LCs). The aim of this study was to determine whether modulation of E-cadherin-mediated homophilic and heterotypic interactions between keratinocytes and LCs is involved in these abnormalities of LCs in (pre)neoplastic cervical epithelium. Cell membrane expression of E-cadherin and the density of CD1a+ LCs were low in the epithelium of SILs and SCC biopsy specimens, compared with normal exocervical epithelium. Dendritic cells (DCs) and LCs generated in vitro were randomly distributed throughout the full thickness of organotypic cultures of E-cadherin- HPV-transformed cells. In contrast, these cells rapidly adhered to the keratinocyte cell layers when HPV-transformed cells transfected with E-cadherin were used. These data suggest that the E-cadherin-mediated contact between keratinocytes and LCs is potentially important for initiating or maintaining the immune response during chronic HPV infection.     

Preoperative granulocyte/macrophage colony-stimulating factor (GM-CSF) increases hepatic dendritic cell numbers and clustering with lymphocytes in colorectal cancer patients

Despite surgery with curative intent, approximately 30% of colorectal carcinoma patients will develop liver metastases during follow-up. Synchronous occult micrometastases, tumor cell shedding into the portal circulation and postoperative immune impairment have all been suggested to facilitate outgrowth of liver metastases. In experimental models, increases in both number of resident macrophages of the liver, the so-called Kupffer cells (KC), and tumoricidal capacity of KC were observed after pretreatment with granulocyte/macrophage colony-stimulating factor (GM-CSF), a potent immuno-stimulatory agent. Following perioperative recombinant human GM-CSF (rhGM-CSF), we previously showed activation of the systemic immune response in the postoperative period, which is normally transiently down-modulated after surgery. Therefore, in this pilot study, effects of preoperative rhGM-CSF administration on the composition of human liver immune cell population were evaluated in patients undergoing surgery for colorectal cancer. No difference in KC numbers of rhGM-CSF-treated patients was observed. Importantly, however, a 6-fold increase in dendritic cell (DC) numbers was observed compared to control patients, as quantified by immunohistochemistry of liver biopsies, taken during laparotomy. Furthermore, direct contact between liver CD8+ cells and DC was significantly enhanced in rhGM-CSF-treated patients. Both increases in DC numbers and DC interaction with CD8+ T cells suggest enhanced immunological activation, which may reduce liver metastases formation and ultimately improve survival after initial colorectal surgery.     

The influence of granulocyte/macrophage colony-stimulating factor on dendritic cell levels in mouse lymphoid organs

To ascertain whether the development of dendritic cells (DC) in mouse lymphoid organs is dependent on granulocyte/macrophage colony-stimulating factor (GM-CSF), we determined the number of DC in the thymus, spleen and lymph nodes of normal mice, of mice with the genes coding for GM-CSF or its receptor inactivated, and of transgenic mice with excessive levels of GM-CSF. DC were extracted from the tissues and enriched prior to flow cytometric analysis. The total DC level and the incidence of DC expressing lymphoid-related markers (CD8^hiCD11b^lo) and myeloid-related markers (CD8^loCD11b^hi) were monitored. Both in GM-CSF null mice, and GM-CSF receptor null mice, DC of all surface phenotypes were present in all lymphoid organs; only small decreases in DC levels were recorded, except for the lymph nodes of GM-CSF receptor null mice which showed a more pronounced (threefold) decrease in DC numbers. Since the GM-CSF receptor null mice lacked the β chain common to the GM-CSF, interleukin (IL)-3 and IL-5 receptors, the development of DC in the absence of GM-CSF was not due to common β chain mediated developmental signals elicited by IL-3 or IL-5. In GM-CSF transgenic mice, there was only a 50 % increase in DC numbers in thymus and spleen, paralleling an increase in overall cellularity, but a more pronounced (threefold) increase in DC numbers in lymph nodes. There was no evidence that GM-CSF had a selective effect on any particular DC subpopulation defined by CD8 or CD11b expression. We conclude that the development of most lymphoid tissue DC can proceed in the absence of GM-CSF, although this cytokine can produce some elevation of DC levels. It is not clear whether the enhancing effect of GM-CSF is direct or an indirect effect mediated by other cytokines.     

Feasibility to generate monocyte-derived dendritic cell from coculture with melanoma tumor cells in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin-4

OBJECTIVE: We investigated how melanoma cells and membrane-bound granulocyte/macrophage colony stimulating factor (mbGM-CSF) melanoma cell lines affect the differentiation of dendritic cells (DC) from CD14+ monocytes. METHOD OF STUDY: The malignant melanoma cell lines (Conley and Jorp) and mbGM-CSF-positive cell lines (Conley B-F8 and Jorp C-E6) were cultured and cell-free supernatants were collected from each cell line cultures to assess the GM-CSF level. Adherent monocytes were cocultured for 6-7 days with irradiated mbGM-CSF and wild type melanoma cells (50 Gy) at each 1:1 and 0.1:1 ratio in six-well culture plates in ex vivo culture medium containing interleukin (IL)-4. Immunophenotyping was performed by triple color immunofluorescence staining with flow cytometry analysis. RESULTS: GM-CSF was detected at low levels in the culture supernatants of Conley B-F8 (0.48 ng/10(6) cells/24 hr), whereas there was no detectable GM-CSF in that of Conley melanoma cell line. Monocytes cultured with GM-CSF/IL-4 generated the expression of high levels of HLA DR, CD1a and CD86, while the expression of CD14 and CD83 were in low amounts. However, the addition of GM-CSF to these cultures resulted in an increased expression of these markers and decreased that of CD14. Monocytes cocultured with Jorp C-E6 illustrated similar expression pattern of CD1a, HLA DR and CD14 in the presence or absence of GM-CSF as Conley B-F8 melanoma cell line. Monocytes cocultured with Conley B-F8 melanoma cells at 1:1 and 0.1:1 ratio showed no significant difference in expression of CD1a, CD14 and CD83 between the two ratios. CONCLUSION: Our results illustrate the feasibility to generate monocyte-derived DC from coculture with melanoma tumor cells in the presence of GM-CSF and IL-4. However, mbGM-CSF tumor cells did not significantly enhance the DC differentiation through juxtacrine stimulation unless soluble GM-CSF was added in the culture media.     

Telomerase in (pre)neoplastic cervical disease

This study was performed to determine upregulation of the human telomerase RNA component (hTR) and mRNA of the catalytic subunit of telomerase (hTERT) in (pre)malignant cervical lesions, to analyze possible intralesional heterogeneity of hTR expression, and to relate hTR and hTERT mRNA levels to telomerase activity levels and human papillomavirus (HPV) typing. hTR expression was determined by in situ hybridization (ISH) on paraffin-embedded sections, obtained from patients with cervical intraepithelial neoplasia (CIN) I-III or cervical cancer and from normal controls. hTR and hTERT mRNA expression were determined by semiquantitative rt-PCR on frozen samples from the same lesions. Data on telomerase activity and HPV were obtained from a previous study. hTR expression as determined by ISH was observed in 0 of 8 normal cervices, 1 of 14 CIN I, 15 of 28 CIN II, 21 of 30 CIN III, and 16 of 18 cervical cancer specimens. In general, hybridization patterns for hTR expression were homogeneous throughout the lesion. Frequency of hTR expression was related to grade of CIN/cervical cancer (P<.001). hTR expression, as determined by rt-PCR, was detected in 8 of 8 normal cervices, 2 of 2 CIN I, 12 of 14 CIN II, 23 of 23 CIN III, and 16 of 17 cervical cancer specimens. hTERT mRNA was detected in 1 of 8 normal cervices, 1 of 2 CIN I, 5 of 14 CIN II, 14 of 23 CIN III, and 11 of 17 cervical cancer specimens. hTR as determined by rt-PCR was not related to grade of CIN/cervical cancer, whereas hTERT mRNA expression was related to grade of CIN/cervical cancer (P<.01). hTR expression, as determined by ISH and hTERT mRNA expression by rt-PCR, were related to telomerase activity levels (P<.001, P<.05, respectively) and presence of oncogenic types of HPV (both P<.05). Our data show frequent upregulation of hTR and hTERT mRNA expression in CIN lesions, which appear to occur earlier than induction of telomerase activity. The fact that semiquantitative hTERT mRNA as well as hTR levels are related to telomerase activity levels illustrates that in (pre)malignant cervical lesions upregulation of both telomerase components may be important for functional telomerase.     

Neutrophilic differentiation induced by human upper airway fibroblast-derived granulocyte/macrophage colony-stimulating factor (GM-CSF).

We have established primary lines of fibroblasts from nasal polyp (NP) tissues as well as from normal nasal (NN) mucosa and have examined the ability of these cells to release hormone-like peptide messenger molecules (cytokines). Our results show that human upper airway fibroblasts release granulocyte/macrophage colony-stimulating factor (GM-CSF), granulocyte-CSF (G-CSF), and macrophage-CSF (M-CSF) in vitro. We also show that fibroblasts derived from NP tissue express the gene for GM-CSF at a higher level, and release the GM-CSF product in greater amounts, than NN fibroblasts. In addition, we have examined the ability of these fibroblasts and their conditioned medium (CM) to induce differentiation of human hemopoietic progenitor cells. After 7 d, cultures of these cells in RPMI-10% fetal bovine serum contained 5 +/- 2.5% (mean +/- SD) neutrophils. In contrast, culture of progenitor cells with fibroblasts resulted in significantly greater neutrophilic differentiation (18 +/- 4%). Culture in fibroblast-CM induced a similar degree of differentiation, and fibroblast-CM from NP fibroblasts elicited greater differentiation compared to CM from NN fibroblasts (17.5 +/- 3 versus 12 +/- 3%). The neutrophilic differentiation induced by fibroblast-CM can be fully inhibited by preincubating this CM with a monoclonal neutralizing antibody to human GM-CSF. Thus, our results demonstrate: (1) the ability of human upper airway fibroblasts to release GM-, G-, and M-CSF in vitro; (2) that fibroblasts derived from NP tissues express the gene and release the product GM-CSF at greater levels compared to NN fibroblasts; and (3) that fibroblast-derived GM-CSF causes neutrophilic differentiation of human hemopoietic progenitors.     

Effect of recombinant human granulocyte/macrophage colony-stimulating factor on neutrophil superoxide production.

Recombinant human granulocyte/macrophage colony-stimulating factor (GM-CSF) induced significant superoxide production in human neutrophils within 30 minutes after addition of stimulus and the response was complete within 2 hr. Other agents known to prime neutrophils, including LPS and tumor necrosis factor-alpha, lacked activity under the experimental conditions employed. Using a panel of pharmacologic inhibitors, we sought to compare GM-CSF-induced neutrophil superoxide to that produced by cells exposed to N-formyl methionyl-leucyl-phenylalanine (fMet-Leu-Phe) and phorbol 12-myristate 13-acetate (PMA). Each stimulant displayed a different profile. Rolipram, a peak IV phosphodiesterase inhibitor, specifically inhibited neutrophil activation by GM-CSF and fMet-Leu-Phe, while superoxide production stimulated by PMA was unaffected. Staurosporine, a protein kinase C (PK-C) inhibitor, suppressed superoxide production induced by all three neutrophil stimulants. Cytochalasin B totally inhibited superoxide induced by GM-CSF under conditions that promote the fMet-Leu-Phe-induced response. Cytochalasin B did not markedly affect PMA-induced superoxide. The results are consistent with the hypothesis that intact PK-C activity is essential for neutrophil superoxide production, but that differences exist in the initial pathways induced by these neutrophil activators. Superoxide secretion from GM-CSF-treated neutrophils appears to be a direct, delayed response that requires assembly of microfilaments during exposure to the cytokine.     

Immunohistochemical detection of granulocyte/macrophage colony-stimulating factor in Langerhans' cell histiocytosis

Granulocyte/macrophage-colony stimulating factor (GM-CSF) induces in vitro activation of Langerhans' cells. The association of GM-CSF and tumour necrosis factor α (TNFα) induces the differentiation of Langerhans' cells from CD34 positive haematopoietic progenitors. Intradermal administration of recombinant GM-CSF is associated with local accumulation of Langerhans' cells. We investigated the presence of GM-CSF in tissue samples of 10 patients with Langerhans' cell histiocytosis. Four patients had skin involvement, three had bone and three had diffuse disease. Eight normal skin samples were analysed as controls. Immunohistochemistry was performed on frozen tissue samples with two specific monoclonal antibodies directed against two different epitopes of GM-CSF. We detected GM-CSF in all the histiocytosis tissue samples. The GM-CSF was detected within the cytoplasm of all the tumoral Langerhans' cells. We did not find GM-CSF in any other cell type. These results suggest that GM-CSF may be implicated in the pathogenesis of Langerhans' cell histiocytosis.     

Epithelial cells are the major source of biologically active granulocyte macrophage colony-stimulating factor in human endometrium

Granulocyte macrophage colony-stimulating factor (GM-CSF) hasemerged as an important growth factor for trophoblast and otherplacental cells, leading to improved placental functioning andfetal survival. Recent observations have indicated that GM-CSFis synthesized by epithelial cells in the murine pregnant andnon-pregnant uterus. In this study, the production of GM-CSFby cells derived from human endometrium is assessed using asensitive bioassay and specific neutralization of the cytokinebioactivity with a monoclonal antibody to GM-CSF. Originally,GM-CSF was assayed in the culture supernatants of explant culturesof human endometria. Concentrations of GM-CSF up to 4440 pg/mlwere detected. Subsequently, enriched epithelial cell cultureswere prepared from glands isolated from human endometrium. Thepurity of epithelial cultures was demonstrated by the expressionof cytokeratin, a weak immunoreactivity for vimentin and a lackof immunoreactivity for leukocyte common antigen, CD68, a macrophage-specificprotein and endothelial marker (factor VIH-related antigens).Detected concentrations of GM-CSF were as high as 18 800 pg/ml.Furthermore, pure epithelial cells of a neoplastic endometrialcell line ECC1 secreted GM-CSF, confirming the ability of endometrialepithelial cells to secrete this cytokine. The immunostainingof dated endometria from proliferative and secretory phasesshowed primarily that epithelial cells, and to a lesser extentstromal cells, exhibited immunoreactivity for GM-CSF. A Westernblot analysis, performed to validate the immunohistochemicaldata, confirmed the presence of an immunoreactive gene productfor GM-CSF in human endometrium throughout the menstrual cycle.These findings indicate that human endometrium synthesizes GM-CSFand that epithelial cells are a major contributor to its production.     

Role of granulocyte/macrophage colony-stimulating factor in zymocel-induced hepatic granuloma formation

To examine the role of granulocyte/macrophage colony-stimulating factor (GM-CSF) in inflammatory granuloma formation, we injected GM-CSF-deficient (GM-CSF(-/-)) mice and wild-type (GM-CSF(+/+)) mice intravenously with 2 mg of zymocel, and mice were killed at various intervals for examination. In GM-CSF(-/-) mice, we demonstrated a marked delay of zymocel-induced hepatic granuloma formation until 5 days after zymocel injection with a rapid reduction in numbers of granulomas at 10 days until their disappearance. In the early phase of granuloma formation, monocyte infiltration and differentiation of monocytes into macrophages were impaired in GM-CSF(-/-) mice compared with GM-CSF(+/+) mice. The percentages of [(3)H]thymidine-labeled macrophages at 2 days after zymocel injection were lower in the GM-CSF(-/-) mice than in the GM-CSF(+/+) mice. The DNA nick-end-labeling method demonstrated increased numbers of apoptotic cells in and around hepatic granulomas of GM-CSF(-/-) mice from 8 days after zymocel injection, and electron microscopy detected apoptotic bodies. Granuloma macrophage digestion of glucan particles and activation of macrophages were similar in the two types of mice. In situ hybridization demonstrated expression of GM-CSF mRNA in the endothelial cells, hepatocytes, and some granuloma cells in the GM-CSF(+/+) mice but not in the GM-CSF(-/-) mice. These results provide evidence that GM-CSF is important for the influx of monocytes into hepatic granulomas, for differentiation of monocytes into macrophages, and for proliferation and survival of macrophages within hepatic granulomas.     

Protein phosphorylations in granulocyte/macrophage colony-stimulating factor-stimulated human peripheral blood eosinophils]

Peripheral blood eosinophils from normal healthy subjects were isolated on a Percoll gradient and were incubated with [32P] orthophosphoric acid. 32P-labeled eosinophils were washed and stimulated with GM-CSF under different conditions. After reaction was stopped, SDS/PAG electrophoresis was performed along with autoradiographs to determine the incorporation of 32P into proteins. GM-CSF-stimulated eosinophils produced an increase of 32P incorporation into the bands in the 31 kDa and 35 kDa areas after 30 sec and 1 min of stimulation. The increase of 32P incorporation was dependent on Mg2+ concentration and temperature, suggesting that proteins in the eosinophils with apparent molecular weights of 31 kDa and 35 kDa can be phosphorylated with the stimulation of GM-CSF.     

Role of granulocyte macrophage colony-stimulating factor during gram-negative lung infection with Pseudomonas aeruginosa

Granulocyte macrophage colony-stimulating factor (GM-CSF) stimulates survival, proliferation, differentiation, and function of myeloid cells. Recently, GM-CSF has been shown to be important for normal pulmonary homeostasis. We report that GM-CSF is induced in lung leukocytes during infection with Gram-negative bacteria. Therefore, we postulated that deficiencies in GM-CSF would increase susceptibility to Gram-negative infection in vivo. After an intratracheal inoculum with Pseudomonas aeruginosa, GM-CSF-/- mice show decreased survival compared with wild-type mice. GM-CSF-/- mice show increased lung, spleen, and blood bacterial CFU. GM-CSF-/- mice are defective in the production of cysteinyl leukotrienes, prostaglandin E2, macrophage inflammatory protein, and keratinocyte-derived chemokine in lung leukocytes postinfection. Despite these defects, inflammatory cell recruitment is not diminished at 6 or 24 h postinfection, and the functional activity of polymorphonuclear leukocytes from the lung and peritoneum against P. aeruginosa is enhanced in GM-CSF-/- mice. In contrast, alveolar macrophage (AM) phagocytosis, killing, and H2O2 production are defective in GM-CSF-/- mice. Although the absence of GM-CSF has profound effects on AMs, peritoneal macrophages seem to have normal bactericidal activities in GM-CSF-/- mice. Defects in AM function may be related to diminished levels of IFN-gamma and TNF-alpha postinfection. Thus, GM-CSF-/- mice are more susceptible to lung infection with P. aeruginosa as a result of impaired AM function.     

Interleukin-1 binds to specific receptors on human bronchial epithelial cells and upregulates granulocyte/macrophage colony-stimulating factor synthesis and release.

Cultured human bronchial epithelial cells constitutively produce granulocyte/macrophage colony-stimulating factor (GM-CSF). An upregulation of the synthesis and release of GM-CSF from those cells might contribute to the persistence of infiltration and local activation of inflammatory cells in some inflammatory diseases of the airways, such as asthma. Increased levels of immunoreactive and biologically active interleukin-1 (IL-1) have been identified in the airway secretions of asthmatic patients, together with an increase in GM-CSF contents. As IL-1 is known to upregulate GM-CSF production in many cell populations, in this study we investigated the ability of IL-1 to bind to specific receptors on bronchial epithelial cells and promote GM-CSF synthesis and release. Bronchial epithelial cells possessed specific single-class surface receptors for recombinant IL-1. The addition of exogenous IL-1 led to a dose-dependent increase in the accumulation of GM-CSF mRNA and release of immunoreactive GM-CSF to the culture medium. Release of IL-1 in the bronchial mucosa during allergic and nonallergic responses may lead to enhanced GM-CSF synthesis and release by epithelial cells, thus promoting airway inflammation.     

Human monocyte-derived dendritic cells produce macrophage colony-stimulating factor: enhancement of c-fms expression by interleukin-10

Human monocyte-derived dendritic cells (DC) generated with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 express c-fms (CD115), the receptor for macrophage-CSF (M-CSF). Expression of c-fms on monocyte-derived DC has been interpreted as the susceptibility of these cells to M-CSF-induced macrophage development. We show here that homogenous cultures of CD14⁻ DC constitutively produced large amounts of M-CSF. However, presence of M-CSF neither induced macrophage development nor did it prevent terminal maturation into CD83⁺ DC. M-CSF production by DC was driven by GM-CSF and inhibited by the specific phosphatidylinositol 3-kinase inhibitor wortmannin. M-CSF synthesis was rapidly induced during the first 24 h of DC culture and then declined during the 5-day culture period. Replating of the cells, which was associated by a transient adherence, always induced a strong up-regulation of M-CSF synthesis. Addition of recombinant IL-10 to DC cultures enhanced c-fms expression and induced macrophage development as measured by the strong up-regulation of CD14 expression as well as by enhanced expression of the Fcγ receptors I, II, and III (CD64, CD32, CD16). Our data demonstrate that immature monocyte-derived DC produce M-CSF which does not induce macrophage development, despite the surface expression of c-fms on DC. IL-10 appears to induce macrophage development by up-regulating c-fms and, thereby, enhancing the sensitivity of the cells to endogenously produced M-CSF.     

Effects of IL-5, granulocyte/macrophage colony-stimulating factor (GM-CSF) and IL-3 on the survival of human blood eosinophils in vitro.

The mechanisms that could affect the lifespan of eosinophils after they have left the bone marrow, and their capacity to respond to activation factors were studied by examining the effects of IL-5, GM-CSF and IL-3 on purified human blood eosinophils in culture. All three cytokines prolonged the lifespan of the majority of blood eosinophils. This effect was dose-dependent: IL-5 greater than GM-CSF greater than IL-3. Light density eosinophils from most patients had a longer lifespan in culture than did normal density eosinophils, with or without the three cytokines. Eosinophil death in the absence of these cytokines occurred by apoptosis. Eosinophils from two patients did not survive when cultured with IL-5, although they survived in the presence of IL-3 or GM-CSF. IL-5, GM-CSF and IL-3 induced the expression of the activation epitope on the eosinophil ribonucleases recognized by monoclonal antibody EG2. We conclude that small amounts of IL-5, GM-CSF and IL-3 prevented programmed cell death in human blood eosinophils and induced the expression of the activation forms of eosinophil ribonucleases. We suggest that differences in the capacity of normal and light density eosinophils to survive in culture, and in the ability of eosinophils from some patients to respond to IL-5 could account for variations in the severity of disease seen in patients with persistent eosinophilia.     

A randomized trial comparing the combination of granulocyte-macrophage colony-stimulating factor plus granulocyte colony-stimulating factor versus granulocyte colony-stimulating factor for mobilization of dendritic cell subsets in hematopoietic progenitor cell products.

The ability of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) administration to increase the content of blood leucocytes and hematopoietic progenitor cells (HPCs) is well established, yet the effect of these cytokines on immune function is less well described. Recent data indicate that plasmacytoid dendritic cells (DC2) may inhibit cellular immune response. We hypothesized that administration of the combination of G-CSF and GM-CSF after chemotherapy would reduce the type 2, or plasmacytoid, DC2 content of the autologous blood HPC grafts compared with treatment with G-CSF alone. To test this hypothesis, 35 patients with lymphoma and myeloma were randomized to receive either G-CSF or the combination of G-CSF plus GM-CSF after chemotherapy, and blood HPC grafts were collected by apheresis. Cytokine-related adverse events between the 2 groups were similar. More than 2 x 10(6)CD34 + cells per kilogram were collected by apheresis in 14 of 18 subjects treated with G-CSF and in 16 of 17 subjects treated with GM-CSF plus G-CSF ( p = not significant). There were minor differences between the 2 groups with respect to the content of T cells and CD34 + cells in the apheresis products. However, grafts collected from recipients of the combination of GM-CSF plus G-CSF had significantly fewer DC2 cells and similar numbers of DC1 cells compared with recipients treated with G-CSF alone. A third cohort of patients received chemotherapy followed by the sequential administration of G-CSF and the addition of GM-CSF 6 days later. Grafts from these patients had a markedly reduced DC2 content compared with those from patients treated either with G-CSF alone or with the concomitant administration of both cytokines. These data, and recent data that cross-presentation of antigen by DC2 cells may induce antigen-specific tolerance among T cells, suggest that GM-CSF during mobilization of blood HPC grafts may be a clinically applicable strategy to enhance innate and acquired immunity after autologous and allogeneic HPC transplantation.     

Size fractions of ambient particulate matter induce granulocyte macrophage colony-stimulating factor in human bronchial epithelial cells by mitogen-activated protein kinase pathways

Environmental pollutants, including ambient particulate matter (PM), increase respiratory morbidity. Studies of model PM particles, including residual oil fly ash and freshly generated diesel exhaust particles, have demonstrated that PM affects inflammatory airway responses. Neither of these particles completely represents ambient PM, and therefore questions remain about ambient particulates. We hypothesized that ambient PM of different size fractions collected from an urban environment (New York City air), would activate primary culture human bronchial epithelial cells (HBECs). Because of the importance of granulocyte-macrophage colony-stimulating factor (GM-CSF) on inflammatory and immunomodulatory processes, we focused our studies on this cytokine. We demonstrated that the smallest size fraction (ultrafine/fine; < 0.18 micro m) of ambient PM (11 micro g/cm(2)), upregulated GM-CSF production (2-fold increase). The absence of effect of carbon particles of similar size, and the day-to-day variation in response, suggested that the chemical composition, but not the particle itself, was necessary for GM-CSF induction. Activation of the extracellular signal-regulated kinase and the p38 mitogen-activated protein kinase was associated with, and necessary for, GM-CSF release. These studies serve to corroborate and extend those on model particles. Moreover, they emphasize the role of the smallest size ambient particles in airway epithelial cell responses.