Cetuximab has an inhibitory effect on cell motility in SCC-4 oral squamous cell carcinoma cell line.

Cetuximab is a chimeric monoclonal antibody that acts as a competitive antagonist, by binding to EGFR. This cell signalling pathways regulates tumor progression. The oral squamous cell carcinoma undergoes to regional spreading and distant metastasis. This study aimed to evaluate the effect of treatment with Cetuximab on cell migration and invasion in OSCC cells, by using the SCC-4 cell line. Cell migration and cell invasion assay were performed and actin cytoskeleton of control and treated with Cetuximab cells were evaluated. Differences were considered significant when p<0.05.Cetuximab inhibited the migration of SCC-4 cells at three concentrations: 1 µg/mL, 50 µg/mL and 100 µg/mL (p<0.0001) in a dose-dependent manner. The number of SCC-4 treated cells with 1 µg/mL that migrated through the membrane was statistically different from 50 µg/mL (p<0.001) and 100 µg/mL (p<0.0001), and between 50 µg/mL and 100 µg/mL (p<0.01). Cetuximab 50 µg/mL inhibited cell invasion through the MatrigelTM compared with SCC-4 control cells (p<0.01). Cetuximab 50 µg/mL affected the organization of the actin cytoskeleton. Cetuximab has an inhibitory effect on actin cytoskeleton organization, cell migration and invasion, suggesting that Cetuximab treatment can be important to avoid oral squamous cell carcinoma metastasis.

Role of Intracystic Cytokines and Nitric Oxide in Ovarian Neoplasms.

The development of new biomarkers for the diagnosis and prognosis of ovarian cancer may provide an opportunity for new therapies. In this study, we aimed to compare cytokines (interleukin [IL]-2, IL-5, IL-6, IL-8, IL-10 and tumour necrosis factor [TNF]-α) and nitric oxide (NO) metabolite levels in non-neoplastic tumours, benign primary ovarian tumours and malignant primary ovarian neoplasms. The secondary aim was to relate cytokine and intracystic NO metabolite levels to clinical, laboratory and pathologic characteristics for patients with primary ovarian malignancies. We evaluated 110 patients with adnexal masses. Cytokine concentrations were quantified by enzyme-linked immunosorbent assay and nitrate concentrations by enzymatic reduction of nitrite by nitrate reductase. Patients with malignant neoplasms had higher IL-6, IL-8 and NO levels compared to patients with benign neoplasms. Histologic grade 1 tumours were associated with elevated IL-2 levels, whereas anaemia was associated with elevated IL-6 levels. On average, those patients with elevated IL-8 levels also had a neutrophil/lymphocyte ratio (NLR) greater than 2.6 and less than 36 months of disease-free survival (DFS). Patients with normal CA 19-9 levels had elevated IL-10 levels. TNF-α was elevated in patients with two carcinogenesis and those with a platelet/lymphocyte ratio (PLR) less than 300. NO levels were higher in patients with an NLR less than 2.6 and CA 19-9 greater than 35 U/ml. Elevated intracystic cytokine levels, especially IL-6 and IL-8, are associated with worse prognosis in ovarian cancer.

Parameters of blood count and tumor markers: a retrospective analysis and relation to prognostic factors in ovarian cancer.

PURPOSE OF INVESTIGATION: The aims of study were to evaluate potential prognostic laboratory factors in ovarian cancer (blood count parameters and tumor markers) and to relate these parameters with prognostic factors. MATERIALS AND METHODS: The authors evaluated patients that underwent surgical treatment and with confirmed histopathologic diagnosis of ovarian cancer. Age, FIGO stage, type of surgery, serum levels of tumor markers, parameters of blood count, disease-free and overall survival were recorded. Mann-Whitney test was performed. The significance level was less than 0.05. RESULTS: Higher levels of CA 125, CA 15.3, and platelets were found in the group with Stage hII/I, since hemoglobin levels were higher in stage I/II (p < 0.05). CEA levels were higher in the group of non-serous neoplasms (p < 0.05). Higher levels of CA125, CAIl5.3 and platelets were seen in the group histological grade 2/3 (p < 0.05). CONCLUSION: CA 125, CA 15.3, hemoglobin, and platelets can be related prognostic factors in ovarian cancer.

Analysis of the cytogenetic response in peripheral blood lymphocytes from breast cancer patients following chemotherapy.

The presence of chromosomal aberrations induced in circulating lymphocytes from breast cancer patients during chemotherapy was analyzed. Ten breast cancer patients undergoing neoadjuvant chemotherapy and ten healthy women (controls) were evaluated. Metaphases were obtained from cultures of peripheral lymphocytes stimulated with phytohemaglutinin and metaphase blockage was achieved with colchicine. One hundred metaphases were analyzed for chromosomal aberrations and 1,000 cells for the mitotic index. No significant differences were observed regarding the frequency of chromosomal aberrations, number of cells with chromosomal aberrations and mitotic index between the controls and patients before chemotherapy. However, after the first chemotherapy cycle, the numbers of chromosomal aberrations and cells with them was greater. After the third cycle, the mitotic index was lower, but the fifth cycle produced an increase in relation to the third and fourth cycles. The results suggest that chemotherapy raises the number of chromosomal aberrations and favors persistence of stable chromosomal abnormalities.

Neutrophil count is not associated with infection episodes in breast cancer patients treated with anthracycline-based chemotherapy.

The aim was to evaluate the impact of anthracycline-based chemotherapy on neutrophil count and infections in breast cancer women. The medical records of patients were retrospectively and prospectively reviewed (8-year period). Patients were grouped according to anthracyclines at different doses: (1) Scheme 1 (n = 56, 224 courses): 50-60 mg/m(2); and (2) Scheme 2 (n = 25, 100 courses): 65-75 mg/m(2), associated to cyclophosphamide and 5-fluorouracil, at 21-day intervals between courses. Neutrophil count was performed on diagnosis and 48-72 h before each chemotherapy course. Patients were followed up for neutrophil count and infection episodes for three consecutive courses. Multivariate analysis was used to determine independent factors for infection. After the first course, neutrophil count was reduced than baseline (P < 0.001) and maintained during the subsequent courses, without differences between courses or groups. There were 49 infection episodes (63.2% urinary, 18.4% neutropenic fever and 18.4% diverses), mainly between course 1-2 (39%) and course 3-4 (38%) of chemotherapy. Patients evaluated as presenting or not with infection episodes did not differ in neutrophil count. The number of chemotherapy courses (P < 0.05), but not age, neutrophil count or chemotherapy regimen, was associated with infection. We concluded that progressive chemotherapy, but not neutrophil count, was an independent factor for infection.

Relationship between risk factors and tumor stage in breast cancer patients in a university hospital--Brazil.

PURPOSE: To verify the relationship between clinical variables and tumor stage in breast cancer. METHODS: This retrospective study (1998 to 2001) analyzed data of 176 women with breast cancer attending a university hospital. Patients were divided into groups according to the clinicopathological variables studied. RESULTS: The disease had a similar frequency at age under 50 years (44.3%) or above (55.7%) 50 years. Stage II was more frequent. Most patients were white (69.9%), non-smokers (69.3%) and were not using oral contraceptives (71%). Stages 0-II were mainly detected in the white (74.8%) vs non-white (60.4%) group. Monthly breast self-exams were performed by 62.5% of women, in which earlier stages (0, I) were more frequently detected than in those who did not perform self-exams (27.3% vs 12.1%, p = 0.01). CONCLUSION: Breast cancer occurred mainly in white women in Stage II, and with similar frequency at age under or over 50 years. Breast self-exam was associated with early detection of the disease.

Acute-phase protein alpha-1-acid glycoprotein mediates neutrophil migration failure in sepsis by a nitric oxide-dependent mechanism.

The reduction of circulating neutrophil migration to infection sites is associated with a poor outcome of severe sepsis. alpha-1-Acid glycoprotein (AGP) was isolated from the sera of severely septic patients by HPLC and acrylamide gel electrophoresis and identified by mass spectrometry. Both the isolated protein and commercial AGP inhibited carrageenin-induced neutrophil migration into the rat peritoneal cavity when administered i.v. at a dose of 4.0 microg per rat (95 pmol per rat). Analysis by intravital microscopy demonstrated that both proteins inhibited the rolling and adhesion of leukocytes in the mesenteric microcirculation. The inhibitory activity was blocked by 50 mg/kg aminoguanidine, s.c., and was not demonstrable in inducible nitric oxide synthase (iNOS) knockout mice. Incubation of AGP with neutrophils from healthy subjects induced the production of NO and inhibited the neutrophil chemotaxis by an iNOS/NO/cyclic guanosine 3,5-monophosphate-dependent pathway. In addition, AGP induced the l-selectin shedding by neutrophils. The administration of AGP to rats with mild cecal ligation puncture sepsis inhibited neutrophil migration and reduced 7-day survival from approximately 80% to 20%. These data demonstrate that AGP, an acute-phase protein, inhibits neutrophil migration by an NO-dependent process and suggest that AGP also participates in human sepsis.

Circulating neutrophils may play a role in the host response in cervical cancer.

Neutrophil migration is a key event in the inflammatory response of any origin, and neutrophils may present antitumor activity. We investigated the number and function of circulating neutrophils obtained from patients with cervical neoplasia at different stages. Patients with preinvasive (cervical intraepithelial neoplasia, CIN3, n= 6) or microinvasive ([MICRO] stage IA1, n= 4) neoplasia were evaluated together as CIN/MICRO group (n= 10), while patients at stages II-IV were evaluated as invasive group (INV, n= 12). Healthy women served as controls (n= 15). For patients, analysis of leukogram on diagnosis showed a significant elevated neutrophil count in INV group compared with that in CIN/MICRO group. A neutrophil/lymphocyte ratio >/=5 was observed in 67% patients from INV group compared with only 10% from CIN/MICRO group. Neutrophil migration, assayed in a microchemotaxis chamber in response to the chemoattractants (10(-7) M) N-formyl-l-methionyl-l-leucyl-l-phenylalanine, leukotriene B(4), or interleukin-8, was reduced in INV group than in controls or CIN/MICRO group. Surgical treatment in randomly selected patients from CIN/MICRO group (four CIN, one MICRO) increased neutrophil migration to all chemoattractants compared with time on diagnosis. The serum levels of nitric oxide (NO) metabolites, assayed by the Griess reaction, were higher in patients (n= 19) than in controls (n= 15), without differences related to tumor stage, but were reduced in patients after surgery compared with pretreatment (n= 10). Taken together, the results suggest that neutrophils play a role in the host response in cervical cancer. Soluble circulating mediators released by tumor cells, such as NO, could interfere early in the capacity of neutrophils to migrate, thus impairing host immune response.

Neutrophil function in severe sepsis.

Sepsis and septic shock continue to be a major cause of morbidity and mortality in critically ill patients. During the onset of sepsis, several inflammatory mediators, including cytokines, chemokines and nitric oxide are released systemically and mediate most of the pathophysiological events present in sepsis and septic shock, such as cardiovascular dysfunction and target-organ lesions. Polymorphonuclear leukocytes are critical effector cells during the inflammatory process and their migration to the infection focus is extremely important for the local control of bacterial growth and consequently for the prevention of bacterial dissemination. In experimental models and in human sepsis a profound failure of neutrophil migration to the infection focus is observed. It seems that the failure of neutrophil migration is dependent on toll-like receptor 4 (TLR4) and mediated by cytokines and chemokines, which induce the production of nitric oxide that inhibits neutrophil adhesion to venular endothelium and also the neutrophil chemotactic ability.

Ultrasonographic criteria and tumor marker assay are good procedures for the diagnosis of ovarian neoplasia in preselected outpatients.

PURPOSE OF INVESTIGATION: To identify parameters for the diagnosis of ovarian neoplasia using ultrasonography (US) and serum tumor marker (TM: CA125, CA19.9, CA15.3, AFP, CEA and estradiol) assay. METHODS: Prospective study which included 373 women with increased ovarian volume (> 18 cm3 in premenopause and > 8 cm3 in postmenopause). US criteria (> or = 1) for surgery were: persistent (> 4 months) or increased cyst, cysts with > 1 thick septum or > or = 2 thin septa, cyst diameter > or = 7 cm, vegetation, calcification or cystic predominance (> 50%), solid tumor (> 50%). Doppler with a resistance index (RI) < 0.4 was considered abnormal. RESULTS: Laparotomy was performed in 164 (44%) patients with 66 (40.2%) benign neoplasias and 19 (11.6%) malignant cases (73.6% at Stage I or II). Two hundred and nine patients were maintained on clinical follow-up. The sensitivity for neoplasia and malignant neoplasia was, respectively, for RI: 17 and 63.6 and RI plus TM: 53.1 and 90.9. CONCLUSION: Ultrasound criteria and TM assay were indicated for the diagnosis of ovarian neoplasia.

Nitric oxide mediates the inhibition of neutrophil migration induced by systemic administration of LPS.

To investigate the role of NO in the inhibition of neutrophil migration by circulating endotoxin, mice were pretreated with NO synthase inhibitors or with a free radical scavenger (D-penicillamine), before intravenous LPS injection. LPS dose-dependently inhibited the thioglycollate-induced neutrophil migration into the peritoneal cavities. Aminoguanidine, a selective inducible NO synthase inhibitor, abolished the inhibition of neutrophil migration and the increase in serum nitrate levels induced by a nonlethal dose of LPS. During lethal endotoxemia aminoguanidine partially abolished the neutrophil migration inhibition. Additionally, D-penicillamine prevented the inhibition of neutrophil migration caused by LPS. However, Nitro-L-Arginine, a selective constitutive NO synthase inhibitor, did not prevent neutrophil migration inhibition. Aminoguanidine treatment did not affect the systemic increased levels of TNF-alpha, IL-1beta, and IL-10, suggesting that NO is the final mediator involved in the inhibition of neutrophil migration. Our results suggest that NO released by the inducible NO synthase mediates the inhibition of neutrophil migration mediated by circulating LPS.

The relationship of host immune cells, cytokine and nitric oxide production to tumor cells in ovarian carcinoma.

AIMS: This brief review focuses on the current understanding of the complex relationship of tumor-associated mononuclear cells (TAMs) with neoplastic cells, summarizing their immunological efficiency, cytokine profile and production of nitric oxide (NO) in the tumor microenvironment, with current insights on how this might affect tumor growth. DATA SOURCE: Data was obtained through Medline from articles indexed during the last 10 years. The main key words used in the research were: cancer, ovarian cancer, cytokine, nitric oxide (NO), mononuclear cell, lymphocyte, macrophage. SELECTION OF STUDIES AND DATA COLLECTION: 30 studies were reviewed, which contained data regarding the production of cytokines and NO by TAMs or malignant cells, and tried to establish a correlation between these mediators and tumor growth, especially in ovarian carcinoma. DATA SUMMARY: TAMs consist mainly of macrophages and T lymphocytes which present lower proliferative indices and cytotoxicity compared to autologous blood monocytes, although they are able to release various cytokines. The profile of cytokine expression could help to explain both the immunological impairment observed in patients with advanced carcinoma diseases and the potential of TAMs to exert antitumor activity, which makes these cells an attractive target for therapeutic intervention. NO is also produced in the tumor microenvironment. Several reports in animals suggest a tumoricidal role for NO, but in human tumors its role has not been well-established and may change during tumor progression.

The intravenous administration of tumor necrosis factor alpha, interleukin 8 and macrophage-derived neutrophil chemotactic factor inhibits neutrophil migration by stimulating nitric oxide production.

1. The i.v. administration of tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8) and the recently described macrophage-derived neutrophil chemotactic factor (MNCF) inhibits the recruitment of neutrophils to the inflammatory site. 2. Pretreatment of mice with the NO synthase antagonist, NG-monomethyl-L-arginine (L-NMMA, 15-60 mg kg(-1)), but not the inactive enantiomer D-NMMA (30 mg kg(-1)), prevented in a dose-dependent manner the TNF-alpha, IL-8 and MNCF-mediated inhibition of neutrophil migration into thioglycollate-challenged peritoneal cavities. 3. Treatment of the neutrophils with TNFalpha (10(-7) M), IL-8 (10(-7) M) or MNCF blocked their migration towards FMLP in the chemotaxis assay. The pretreatment of the neutrophils with L-NMMA (50-200 microM) prevented in a dose-dependent manner the inhibition of FMLP-induced chemotaxis by IL-8, but did not alter the inhibition caused by TNF-alpha or MNCF. Different concentrations of the NO donors, S-nitroso-N-acetylpenicillamine (SNAP) or 3-morpholino-sydnonimine (SIN-1), did not alter this chemotaxis. 4. Preincubating the neutrophils with L-NMMA (200 microM) significantly increased the TNF-alpha (10(-7) M) and MNCF-mediated neutrophil adhesion to unstimulated endothelial cells, but had no effect on IL-8 (10(-7) M)-mediated adhesion. 5. Although NO donors did not directly affect the mechanisms of neutrophil motility, NO is involved in the in vitro inhibitory action of IL-8 on chemotaxis. The TNF-alpha and MNCF-mediated inhibition of neutrophil migration seems to be indirect, by affecting the mechanisms of adhesion. It was concluded that TNF-alpha-, IL-8- and MNCF-mediated inhibition of neutrophil migration is associated with the stimulation of NO production.

Differential production of nitric oxide by endotoxin-stimulated rat and mouse neutrophils.

There is controversy regarding the evidence for the production of nitric oxide (NO) by neutrophils (PMNs). The present study investigates NO production, as assessed by the biosynthesis of the end products, nitrite and nitrate, in the pellets and supernatants of rat and mouse peripheral blood neutrophils obtained during endotoxemia and of peritoneal carrageenin-elicited PMNs stimulated in vitro with E. coli lipopolysaccharide (LPS). We also investigated the induction of NO synthase by rat and mouse peritoneal cells. The intraperitoneal (ip) administration of LPS to mice (10 mg/kg) and rats (5 mg/kg) significantly increased plasma nitrate concentration by six and 23-fold, respectively. In vivo pretreatment with L-NGmonomethyl arginine (L-NMMA) significantly inhibited this production. Compared to animals injected with PBS, the cell pellets of blood PMNs obtained from mice, but not rats, 2 or 6 h after LPS administration produced significant amounts of nitrite (14 +/- 3 and 18 +/- 2 nmol/mg protein, respectively). Little or no nitrite was found in the incubating medium. In contrast, 6 h after a carrageenin challenge (700 micrograms) peritoneal neutrophils obtained from rats, but not mice, released high concentrations of nitrite into the supernatant during a 24-h period of incubation (34 +/- 0.8 microM). The nitrite concentration of the pellet of these cells was negligible. In contrast to the lack of increase in the amount of nitrite released into the supernatants, the in vitro stimulation of rat PMNs with LPS (10 micrograms/ml) for 24 h did increase intracellular nitrite concentration (from 0.8 +/- 0.07 to 8 +/- 0.3 nmol/mg protein). In mouse PMNs, LPS treatment caused only a small release of nitrite into the incubation medium (14 +/- 1 microM). There was no significant change in nitrite concentration in the cell pellets. These data suggest that rat and mouse neutrophils differ in their ability to produce nitric oxide following stimulation with endotoxin.

Differential production of nitric oxide by endotoxin-stimulated rat and mouse neutrophils

There is controversy regarding the evidence for the production of nitric oxide (NO) by neutrophils (PMNs). The present study investigates NO production, as assessed by the biosynthesis of the end products, nitrite and nitrate, in the pellets and supernatants of rat and mouse peripheral blood neutrophils obtained during endotoxemia and of peritoneal carrageenin-elicited PMNs stimulated in vitro with E. coli lipopolysaccharide (LPS). We also investigated the induction of NO synthase by rat and mouse peritoneal cells. The intraperitoneal (ip) administration of LPS to mice (10 mg/kg) and rats (5 mg/kg) significantly increased plasma nitrate concentration by six and 23-fold, respectively. In vivo pretreatment with L-NGmonomethyl arginine (L-NMMA) significantly inhibited this production. Compared to animals injected with PBS, the cell pellets of blood PMNs obtained from mice, but not rats, 2 or 6 h after LPS administration produced significant amounts of nitrite (14 ñ 3 and 18 ñ 2 nmol/mg protein, respectively). Little or no nitrite was found in the incubating medium. In contrast, 6 h after a carrageenin challenge (700 mug) peritoneal neutrophils obtained from rats, but not mice, released high concentrations of nitrite into the supernatant during a 24-h period of incubation (34 ñ 0.8 muM). The nitrite concentration of the pellet of these cells was negligible. In contrast to the lack of increase in the amount of nitrite released into the supernatants, the in vitro stimulation of rat PMNs with LPS (10 muglml) for 24 h did increase intracellular nitrite concentration (from 0.8 ñ 0.07 to 8 ñ 0.3 nmol/mg protein). In mouse PMNs, LPS treatment caused only a small release of nitrite into the incubation medium (14 ñ I muM). There was no significant change in nitrite concentration in the cell pellets. These data suggest that rat and mouse neutrophils differ in their ability to produce nitric oxide following stimulation with endotoxin.

Macrophage-derived neutrophil chemotactic factor is involved in the neutrophil recruitment inhibitory activity present in the supernatants of LPS-stimulated macrophages.

In a previous study, we demonstrated the presence of a neutrophil recruitment inhibitory factor (NRIF) in the supernatants of LPS-stimulated macrophages. Recently, the purification of a 54 kDa protein, identified as the macrophage-derived neutrophil chemotactic factor (MNCF) was reported. Since NRIF and MNCF are obtained under the same conditions, and, since the intravenous administration of TNF-alpha and IL-8 inhibits neutrophil migration, we have investigated whether MNCF could be responsible for this inhibitory activity. After affinity chromatography of the macrophage supernatants on a D-galactose column, the inhibitory activity was recovered in both the unbound (D-gal(-)) and bound (D-gal(+)) fractions, with MNCF being found in the D-gal(+) fraction. Further gel filtration of the latter on Superdex 75 yielded a single peak containing both activities. In a cytotoxicity assay, most of the TNF found in the crude supernatants was recovered in the D-gal(-) fraction. Furthermore, the incubation of the D-gal(-) fraction with anti-TNF-alpha plus anti-IL-8 antisera partially prevents its inhibitory effect on neutrophil migration, but had no effect on the D-gal(+) activity. Overall, these results suggest that the D-gal(-) inhibitory effect is partially mediated by TNF-alpha and IL-8, and that MNCF accounts for the inhibition of neutrophil migration in vivo by the D-gal(+) fraction.

Interference of a neutrophil recruitment inhibitory factor upon the accumulation of inflammatory cells and airway hyperreactivity in sensitized guinea-pigs after intranasal antigen challenge.

1. A neutrophil recruitment inhibitory factor (NRIF) recovered from the crude supernatant of lipopolysaccharide (LPS)-stimulated macrophages inhibited neutrophil migration following both intratracheal and intravenous administration of LPS, but did not alter the pattern of leukopenia/leucocytosis induced by intravenous LPS. 2. The correlation between airway infiltration by inflammatory cells and hyperreactivity in lungs from actively sensitized and challenged guinea-pigs was investigated by use of NRIF. 3. Increased eosinophil counts were found in the bronchoalveolar lavage fluid from guinea-pigs sensitized with 10 micrograms ovalbumin and challenged at day 14 by the intranasal administration of the antigen. The increase was evident 5 h after challenge and persisted at 24 h. Neutrophil numbers were also increased at this time. Pretreatment with NRIF suppressed the leucocyte increase in the bronchoalveolar lavage fluid. 4. Bronchoconstriction and histamine release induced by 3 ng PAF injected into the isolated lungs were increased in challenged guinea-pigs as compared to sensitized but unchallenged controls. Pretreatment of the animals with NRIF did not interfere with this response, but significantly reduced the bronchoconstriction induced by ovalbumin injection. 5. Even though the increased number of inflammatory cells in bronchoalveolar lavage and airway hyperresponsiveness were concomitant, NRIF inhibited cellular infiltration but failed to alter airway hyperreactivity to PAF, demonstrating that these events may occur independently. Conversely, the inhibition of antigen-induced bronchoconstriction by NRIF suggests that this response is dependent upon the emigration of granulocytes.

Neutrophil recruitment inhibitory factor: a possible candidate for a novel cytokine.

Inhibitory effect upon neutrophil migration to the inflammatory focus was previously detected in the cell-free incubation fluid of lipopolysaccharide (LPS)-stimulated macrophage monolayers. In the present study we showed that the neutrophil recruitment inhibitory activity from this supernatant was mainly detected in a fraction (P2) obtained by gel filtration chromatography on Sephacryl S-300. P2 fraction was able to inhibit 'in vivo' neutrophil emigration induced by different inflammatory stimuli, but it did not affect 'in vitro' neutrophil chemotaxis induced by FMLP. When injected intravenously, P2 inhibited oedema induced by carrageenin or immunological stimulus but not the oedema induced by dextran, thus affecting cell-dependent inflammatory responses. It was observed that P2 also induced neutrophil migration when injected locally in peritoneal cavities. This activity was significantly reduced by pretreatment of the animals with dexamethasone. Cytokines, such as IL-8 and TNF-alpha that are known to exhibit inhibitory effect upon neutrophil migration, were not detected in P2 fraction by highly sensitive assays. Overall the results suggest the existence of a novel cytokine exhibiting 'in vivo' neutrophil inhibitory activity, referred as NRIF.