Abdominal paracentesis drainage ameliorates severe acute pancreatitis in rats by regulating the polarization of peritoneal macrophages

AIM To investigate the role of peritoneal macrophage(PM) polarization in the therapeutic effect of abdominal paracentesis drainage(APD) on severe acute pancreatitis(SAP).METHODS SAP was induced by 5% Na-taurocholate retrograde injection in Sprague-Dawley rats. APD was performed by inserting a drainage tube with a vacuum ball into the lower right abdomen of the rats immediately after the induction of SAP. To verify the effect of APD on macrophages, PMs were isolated and cultured in an environment, with the peritoneal inflammatory environment simulated by the addition of peritoneal lavage in complete RPMI 1640 medium. Hematoxylin and eosin staining was performed. The levels of pancreatitis biomarkers amylase and lipase as well as the levels of inflammatory mediators in the blood and peritoneal lavage were determined. The polarization phenotypes of the PMs were identified by detecting the marker expression of M1/M2 macrophages via flow cytometry, qPCR and immunohistochemical staining. The protein expression in macrophages that had infiltrated the pancreas was determined by Western blot.RESULTS APD treatment significantly reduced the histopathological scores and levels of amylase, lipase, tumor necrosis factor-α and interleukin(IL)-1β, indicating that APD ameliorates the severity of SAP. Importantly, we found that APD treatment polarized PMs towards the M2 phenotype, as evidenced by the reduced number of M1 macrophages and the reduced levels of proinflammatory mediators, such as IL-1β and L-selectin, as well as the increased number of M2 macrophages and increased levels of anti-inflammatory mediators, such as IL-4 and IL-10. Furthermore, in an in vitro study wherein peritoneal lavage from the APD group was added to the cultured PMs to simulate the peritoneal inflammatory environment, PMs also exhibited a dominant M2 phenotype, resulting in a significantly lower level of inflammation. Finally, APD treatment increased the proportion of M2 macrophages and upregulated the expression of the anti-inflammatory protein Arg-1 in the pancreas of SAP model rats.CONCLUSION These findings suggest that APD treatment exerts antiinflammatory effects by regulating the M2 polarization of PMs, providing novel insights into the mechanism underlying its therapeutic effect.

Hsp70 confines tumor progression of rat histiocytoma and impedes the cytotoxicity induced by natural killer cells and peritoneal macrophages

Objective:To study the role of inducible form of heat shock protein 70(Hsp70) in the host tumor regression of rat tumor model.Methods:We examined the role of Hsp70 in host tumorigenicity and in vitro cellular cytotoxicity using a rat histocytoma.The differential tumor growth and regression kinetics were studied and correlated with the expression of Hsp70,activation of macrophages and natural killer(NK) cells,and circulating or tumor infiltrating immune molecules in the host system.Results:The sub cuteaneous(s.c.) tumor regression was correlated with increased serum cytokines such as IL-12,TNF P,IFNγand Hsp70.Despite of similar increase of Hsp70 in intraperitoneal(i.p.) tumor implanted animals,animals succumb to tumor growth,further,evidently,no immune molecule activation was observed.The viral promoter driven Hsp70 over expression in these tumor cells restrained solid tumor growth,however,failed to inhibit ascites growth.The NK cells from s.c.immunized animals induces cytotoxicity in the presence of anti-tumor antibody,which necessitated CD40-L expression,conversely,NK cells from i.p.immunized animals failed to induce cytotoxicity.The NK cells from s.c.or i.p.implanted animals with Hsp70 positive tumor cells failed to induce such cytotoxicity.The peritoneal macrophages isolated from s.c.tumor implanted animals when co-cultured with parental BC-8 cells lyses tumor cells,nevertheless entail macrophage specific TNFαexpression.On the contrary,Hsp70 expressing BC-8 tumor cells were resistant to peritoneal macrophage induced cytolysis.Conclusions:This study brings out that Hsp70 possibly involved in regulating the host tumor response and cellular cytotoxicity.

THE EFFECTS OF RADIX SALVIAE MILTIORRHIZAE ON LIPID ACCUMULATION OF PEROXIDIZED LOW DENSITY LIPOPROTEIN IN MOUSE PERITONEAL MACROPHAGES ?LIPID ANALYSIS AND MORPHOLOGICAL STUDIES

Mouse peritoneal macrophages were incubated in DMEM with pox-LDL and Rradlx Salviae Miltiorrhizae (RSM) to investigate the effects of RSM on the internalization of peroxidized low density lipoprotein (pox-LDL) by using lipid analysis and electron microscopy. Lipid peroxide (LPO) concentrations were increased slightly in the medium after incubation of macrophages with normal LDL (n-LDL), while decreased significantly in the media after incubation of macrophages with pox-LDL. In the three groups with pox-LDL, it could be found that there was a dose-dependent decrease of concentrations of LPO and total cholesterol (TCH) in the two RSM groups, and the decrease in the two RSM groups was much greater than in the group without RSM. RSM accelerated a more decrease of LPO than cholesterol contents in the media containing pox-LDL. The ultrastructural studies also showed that RSM induced the accumulation of lipid droplets in the cytoplasm of mouse peritoneal macrophages. The results suggested that RSM could accelerate the phagocytosis and degradation of pox-LDL by macrophages.

Recent insights into the characteristics and role of peritoneal macrophages from ascites of cirrhotic patients

Macrophages are a diverse myeloid cell population involved in innate and adaptive immune responses,embryonic development,wound repair,and regulation of tissue homeostasis.These cells link the innate and adaptive immunities and are crucial in the development and sustainment of various inflammatory diseases.Macrophages are tissue-resident cells in steady-state conditions;however,they are also recruited from blood monocytes after local pathogen invasion or tissue injury.Peritoneal macrophages vary based on their cell complexity,phenotype,and functional capabilities.These cells regulate inflammation and control bacterial infections in the ascites of decompensated cirrhotic patients.Our recent work reported several phenotypic and functional characteristics of these cells under both healthy and pathological conditions.A direct association between cell size,CD14/CD16 expression,intracellular level of GATA-6,and expression of CD206 and HLA-DR activation/maturation markers,indicate that the large peritoneal macrophage CD14^(high)CD16^(high)subset constitutes the mature phenotype of human resident peritoneal macrophages during homeostasis.Moreover,elevated expression of CD14/CD16 is related to the phagocytic capacity.The novel large CD14^(high)CD16^(high)peritoneal subpopulation is increased in the ascites of cirrhotic patients and is highly sensitive to lipopolysaccharide(LPS)-induced activation,thereby exhibiting features of inflammatory priming.Thus,phosphorylation of ERK1/2,PKB/Akt,and c-Jun is remarkably increased in response to LPS in vitro,whereas that of p38 MAPK is reduced compared with the monocyte-derived macrophages from the blood of healthy controls.Furthermore,in vitro activated monocyte-derived macrophages from ascites of cirrhotic patients secreted significantly higher levels of IL-6,IL-10,and TNF-αand lower amounts of IL-1βand IL-12 than the corresponding cells from healthy donor’s blood.Based on these results,other authors have recently reported that the surface expression level of CD206 can be used to identify mature,resident,inflammatory peritoneal macrophages in patients with cirrhosis.Soluble CD206 is released from activated large peritoneal macrophages,and increased concentrations in patients with cirrhosis and spontaneous bacterial peritonitis(SBP)indicate reduced odds of survival for 90 d.Hence,the level of soluble CD206 in ascites might be used to identify patients with SBP at risk of death.In conclusion,peritoneal macrophages present in ascites of cirrhotic patients display multiple phenotypic modifications characterized by reduced ratio of cells expressing several membrane markers,together with an increase in the ratios of complex and intermediate subpopulations and a decrease in the classiclike subset.These modifications may lead to the identification of novel pharmaceutical targets for prevention and treatment of hepatic damage.

Studies on the Electron Microscopic Localization of Con A and WGA Receptors in Human Peritoneal Macrophages

The electron microscopic topology of Con A and WGA receptors was investi-gated in human peritoneal macrophagcs by utilizing avidin-gold colloids.Our observa-tions confirmed that both the receptors were distributed on the cell membranes,yet thereceptor expression showed variations among the individual cells.Some cells had abun-dant receptors,while others had only few receptors.The data obtained in the presentstudy indicate that human peritoneal macrophages may be a functionally andbiochemically heterogenous population,and the study may also serve as a theorcticalreference for future clinical exploitation of human peritoneal macrophages.

Lipopolysaccharide enhances the inhibition of NF-κB expression in NNK-mediated peritoneal macrophages

Objective： The aim of the study was to investigate the effect of lipopolysaccharide （LPS） on the expression of nuclear factor kappa B （NF-κB） in 4-（methylitrosamino）-1-（3-pyridyl）-1-butanone （NNK）-mediated primary mouse peritoneal macrophages in vitro. Methods： The activity of peritoneal rnacrophages treated with different concentrations of LPS was detected by MTT assay in rider to find the optimal concentration. Peritoneal macrophages were also treated with NNK （100-500 μM）, with or without LPS for 9 h. The expression of NF-κB was demonstrated via immunocytochemistry （ICC） and Western- blot, respectively. Results： The concentration of LPS at 25 μg/mL was found to be the optimal concentration to improve the activity of peritoneal macrophages （P 〈 0.01）. Simultaneously, LPS （25 μg/mL） increased the expression of NF-κB in both the nucleus and cytoplasm and facilitated transfer of NF-κB to the nucleus. NNK treatment significantly inhibited the expression of NF-κB in a concentration-dependent manner, among the LPS-stimulated or unstimulated peritoneal macrophages, especially when cotreated with LPS （25 μg/mL, P 〈 0.01 ）. Furthermore, NNK treatment （500 μM） with LPS yielded a significant decrease in NF-κB translocation to nucleus and inhibited the expression of NF-κB （P 〈 0.005）. Conclusion： LPS enhances the suppression of NF-κB expression in NNK-mediated mouse peritoneal macrophages, which may provide a theoretical basis for the inhibition of cancer.

Inhibiting Effect of Lobenzarit Disodium on the Inter-leukin-1 Activity in Normal and in Adjuvant ArthritisKats and on the H_2O_2 Release from Rat Peritoneal Macro-phages

The effects of Lobenzarit disodium (CCA) upon the activity of interleukin-1(IL-1) of peritoneal macrophages(PMΦ)in normal and in adjuvant arthritis AA) rats and on the release of hydrogen peroxide(H_2O_2)of rat peritoneal macrophages were studied. CCA 10～200 μg/ml could inhibit IL-1activity in normal rat in vitro;CCA 10 and 50 mg/kg could depress the level of increased IL-1 in AA rats in vivo;CCA 5～100μg/ml could inhibit the release of H_2O_2 from rat PMΦin vitro.The results suggest that these effects could be one of the mechanisms of anti-inflammatory action of CCA.

Essential role of monocytes and macrophages in the progression of acute pancreatitis

Acute pancreatitis(AP) is an inflammatory condition of the pancreas caused by an imbalance in factors involved in maintaining cellular homeostasis.Earliest events in AP occur within acinar cells accompanied by other principal contributors to the inflammatory response i.e.the endothelial cells,immunocytes(granulocytes,monocytes/macrophages,lymphocytes) and neutrophils.Monocytes/macrophages are important inflammatory mediators,involved in the pathophysiology of AP,known to reside in the peritoneal cavity(in the vicinity of the pancreas) and in peripancreatic tissue.Recent studies suggested that impaired clearance of injured acini by macrophages is associated with an altered cytokine reaction which may constitute a basis for progression of AP.This review focuses on the role of monocytes/macrophages in progression of AP and discusses f indings on the inflammatory process involved.

Specific function and modulation of teleost monocytes/macrophages: polarization and phagocytosis

Macrophages exist in most tissues and play a variety of functions in vertebrates.Teleost fish species are found in most aquatic environments throughout the world and are quite diverse for a group of vertebrate animals.Due to whole genome duplication and en vironme ntal adaptati on,teleost monocytes/macrophages possess a variety of different functions and modulations compared with those of mammals.A deeper understanding of teleost monocytes/macrophages in the immune system will not only help develop teleost-specific methods of disease prevention but will also help improve our understanding of the various immune mechanisms in mammals.In this review,we summarize the differences in polarizati on and phagocytosis of teleost and mammalian macrophages to improve our understanding of the various immune mechanisms in vertebrates.

Spi1 regulates the microglial/macrophage inflammatory response via the PI3K/AKT/mTOR signaling pathway after intracerebral hemorrhage

Preclinical and clinical studies have shown that microglia and macrophages participate in a multiphasic brain damage repair process following intracerebral hemorrhage.The E26 transformation-specific sequence-related transcription factor Spi1 regulates microglial/macrophage commitment and maturation.However,the effect of Spi1 on intracerebral hemorrhage remains unclear.In this study,we found that Spi1 may regulate recovery from the neuroinflammation and neurofunctional damage caused by intracerebral hemorrhage by modulating the microglial/macrophage transcriptome.We showed that high Spi1expression in microglia/macrophages after intracerebral hemorrhage is associated with the activation of many pathways that promote phagocytosis,glycolysis,and autophagy,as well as debris clearance and sustained remyelination.Notably,microglia with higher levels of Soil expression were chara cterized by activation of pathways associated with a variety of hemorrhage-related cellular processes,such as complement activation,angiogenesis,and coagulation.In conclusion,our results suggest that Spi1 plays a vital role in the microglial/macrophage inflammatory response following intracerebral hemorrhage.This new insight into the regulation of Spi1 and its target genes may advance our understanding of neuroinflammation in intracerebral hemorrhage and provide therapeutic targets for patients with intracerebral hemorrhage.

Influence of whole peptidoglycan of bifidobacterium on cytotoxic effectors produced by mouse peritoneal macrophages

INTRODUCTIONBifidobacteria are physiologically beneficial bacteria which are perdominant in human intestine ,and possess the most important functions .They play an important role in maintaining microbial balance of the intestine .Furthermore , their presence is thought to be an important indication of health of the body [1-4].Whole peptidoglycan ( WPG) is the major component in the cell wall of bifidobacterium ,which is also a biological responsemodifier with nontoxic side dffcets.

Interferon-γ acts as a regulator in the trade-off between phagocytosis and production performance in dwarf chickens

Background: Interferon-γ(IFN-γ) is critical for innate and adaptive immunity against viral and bacterial infections. IFN-γ reportedly affects the phagocytic ability of monocytes and macrophages as well as regulates pituitary function in humans and mice. The present study analyzed the impact of IFN-γ on monocyte and macrophage phagocytosis, production performance, and pituitary function in vivo and in vitro(in dwarf chickens). IFN-γ was injected into dwarf chickens through a vein, and then, the laying rate, average egg weight, and levels of follicle-stimulating hormone(FSH) and IFN-γ were measured in treatment and control groups. For the in vitro experiment, the pituitary tissues were supplemented with IFN-γ, and the m RNA expression levels of follicle-stimulating hormone beta subunit(FSH-β), interferon gamma receptor 1(IFNGR1),and interferon gamma receptor 2(IFNGR2) in the pituitary were assessed.Results: Monocyte and macrophage phagocytosis product(PP) was decreased by IFN-γ treatment in a dose-dependent manner in vitro. In the in vivo experiment, the level of IFN-γ in the treatment group was higher than that in the control group at 7 d(P < 0.05), 14 d(P < 0.01), and 21 d(P < 0.01) post-injection.Compared with the control group, monocyte and macrophage PP was lower in the treatment group after injection(P < 0.01). The laying rate was higher in the treatment group than in the control group at 2 and3 wk post-injection(P < 0.05). There was a significant difference between the treatment and control groups in the levels of FSH at 1, 3, 7, and 14 d post-injection(P < 0.01). In the in vitro experiment, increased m RNA expression levels of FSH-β, IFNGR1, and IFNGR2 were observed in the treatment group after stimulation with100 U/m L IFN-γ for 24 h compared to those in the control group(P < 0.05).Conclusions: IFN-γ inhibited the phagocytosis of monocytes and macrophages; up-regulated the m RNA expression levels of the FSH-β, IFNGR1, and IFNGR2; enhanced the secretion of FSH; and improved the laying rate. IFN-γ might be an important regulator in the trade-off between the immune effect and production performance in dwarf chickens.

THE EFFECT OF DIALYSIS ON THE RELEASE OF TNF-α FROM PERITONEAL MACROPHAGE IN VIVO

Objective To investigate the consistent inhibitory effect olperitoneal dialysate on the capacity ofperitoneal macrophage release of TNF- α and the inhibition associated with different glucose concentration invivo. Methods We compared the peritoneal macrophage activity obtained from the irrigation solution of theuremia patients (n=2) immediately after inserting the catheter and with those from the long - dwell time dialysate(≥10h) of peritoneal dialysis patients (n= 7). The capacity of peritoneal macrophage to release TNF - x was assayedby L929 cytotoxicity. At the same time, we compared TNF- 7 activity among different glucose concentration (1.5%,2.5% and 4.25% dextrose) of dialysate. Results The levels of TNF- a in CAPD and control group were 170 and517 pg/106 respectively (P<0.01). The patients who were using dialysate containing higher glucose concentrationhad lower TNF- x level (P<0.05, P<0.01). Conclusion It is suggested that the inhibitory effect of peritonealdialysate on peritoneal macrophages might continue at least 10h in vivo. The higher glucose concentration ofdialysate may have worse effect on peritoneal macrophage activity.

Mechanism of Elevated Vascular Endothelial Growth Factor Levels in Peritoneal Fluids from Patients with Endometriosis

In order to investigate the mechanism of elevated vascular endothelial growth factor (VEGF) in peritoneal fluids from patients with endometriosis, macrophages were recovered from peritoneal fluids obtained at the time of diagnostic laparoscopy from infertile women with endometriosis (EMT group, n=20) and without endometriosis (control group, n=20). Macrophages were cultured in vitro. The VEGF levels of peritoneal fluid and the supernatant of macrophages culture were determined by enzyme linked immunoassay (ELISA). Meanwhile, the eutopic (n=20) and ectopic endometrium (n=20) from endometriosis patients, and normal edometrium (n=20) from non-endometriosis patients were obtained for the analysis of VEGF expression by labeled Streptavidin Biotin (LSAB). It was found that VEGF levels in peritoneal fluid and macrophages culture supernatant were significantly higher in EMT group than in control group (P<0.01). In normal endometrium, VEGF showed a cyclic changes and similar in eutopic and ectopic endometrium from patients with endometriosis. There was no difference in the intensity of VEGF in endometrium between two groups within each menstrual phase. It is suggested that altered VEGF production by peritoneal macrophages and ectopic endometrium secretion may contribute to the elevated VEGF levels in the peritoneal fluid of patients with endometriosis.

Effects of quercetin on hepatocyte stimulating factor production by mouse peritoneal macrophages

Objective: To study the effects of quercetin on hepatocyte stimulating factor production from mouse peritoneal macrophages. Methods: Hepatocyte stimulating factor was evaluated by the amount of fibrinogen synthesized in Hep3B cells. Interleukin-6 activity was measured by B9 cell proliferation methyl thiazolyl tetrazolium colorimetric method. Hep3B cell supernatant fibrinogen was quantitated with ELISA. Results: LPS induced the synthesis of hepatocyte stimulating factor in mouse peritoneal macrophages, and hepatocyte stimulating factor promotes the synthesis of fibrinogen from Hep3B cells. Quercetin(5 to 40μmol/ L) inhibited the synthesis of hepatocyte stimulating factor stimulated by LPS. Quercetin(5 to 20μmol/ L) inhibited release of interleukin-6 from mouse peritoneal macrophages induced by 0. 5 g/ L fibrin fibrinogen degradation products. Conclusion: Quercetin inhibits the synthesis of hepatocyte stimulating factor in macrophages.

Molecular cloning, pathologically-correlated expression and functional characterization of the colony- stimulating factor 1 receptor （CSF-1R） gene from a teleost, Plecoglossus altivelis

Colony-stimulating factor 1 receptor （CSF-1R） is an important regulator of monocytes/macrophages （MO/MФ）. Although several CSF-1R genes have been identified in teleosts, the precise role of CSF- 1R in ayu （Plecoglossus altivelis） remains unclear. In this study, we characterized the CSF-1R homologue from P. altivelis, and named it PaCSF-1R. Multiple sequence alignment and phylogenetic tree analysis showed that PaCSF-1R was most closely related to that of Japanese ricefish （Oryzias latipes）. Tissue distribution and expression analysis showed that the PaCSF-1R transcript was mainly expressed in the head kidney-derived MO/MФ, spleen, and head kidney, and its expression was significantly altered in various tissues upon Vibrio anguillarum infection. After PaCSF-1R neutralization for 48 h, the phagocytic activity of MO/MФ was significantly decreased, suggesting that PaCSF-1R plays a role in regulating the phagocytic function of ayu MO/M（P.

Aqueous extract of Ocimum gratissimum Linn and ascorbic acid ameliorate nicotine-induced cellular damage in murine peritoneal macrophage

Objective:To test the in vitro protective role of aqueous extract of Ocimum gratissimum Linn. (0.gratissimum) and ascorbic acid against nicotine-induced murine peritoneal macrophage. Methods:Peritoneal macrophages from mice were treated with nicotine(10 mM),nicotine (10 mM) with aqueous extract of O.gratissimum(1 to 25μg/mL),and nicotine(10 mM) with ascorbic acid(0.01 mM) for 12 h in cell culture media,while the control group was treated with culture media.Levels of free radical generation,lipid peroxidation,protein carbonyls,oxidized glutathione levels and DNA damage were observed and compared.Results:Phytochemical analysis of aqueous extract has shown high amount of phenolics and flavonoids compound present in it.The significantly increased free radical generation,lipid peroxidation,protein carbonyls,oxidized glutathione levels and DNA damage were observed in nicotine-treated group as compared to the control group:those were significantly reduced in aqueous extract of O. gratissimum and ascorbic acid supplemented groups.Moreover,significantly reduced antioxidant status in nicotine exposed murine peritoneal macrophage was effectively ameliorated by these two products.Among the different concentration of aqueous extract of O.gratissimum,the maximum protective effect was observed at 10μg/mL which does not produce any significant change in the normal cell.Conclusions:These findings suggest the potential use and beneficial role of O.gratissimum as a modulator of nicotine-induced cellular damage in murine peritoneal macrophage.

Alteration of some cellular function in amikacin resistant Pseudomonas aeruginosa transfected macrophages:a time dependent approach

Objective:To evaluate the free radical generation and antioxidant enzymes status in murine peritoneal macrophage during in vitro amikacin resistant Pseudomonas aeruginosa(ARPA) treatment with different time interval.Methods:Peritoneal macrophages were treated with 1× 10~2 CFU/mL ARPA cell suspension in vitro for different time interval(1,2,3,6,12,and 24 h) and super oxide anion generation,NO generation,reduced glutathione level and antioxidant enzymes status were analyzed.Results:Super oxide anion generation and NO generation got peak at 12 h,indicating maximal free radical generation through activation of NADPH oxidase in murine peritoneal macrophages during ARPA transfection.Reduced glutathione level and antioxidant enzymes status were decreased significantly(P【0.05) with increasing time of ARPA transfection. All the changes in peritoneal macrophages after 12 h in vitro ARPA transfection had significant difference(P【0.05).Conclusions:From this study,it may be summarized that in vitro ARPA infection not only generates excess free radical but also affects the antioxidant system and glutathione cycle in murine peritoneal macrophage.

Proposal for a new evaluation of phagocytosis using different sizes of fluorescent polystyrene microspheres

To investigate phagocytosis, peritoneal-resident and J774.1 macrophages were incubated with fluorescent polystyrene microspheres measuring 1.0 μm in diamter at 200 particles per cell. The amount of phagocytized microspheres increased with incubation time, and both cell types had similar phagocytic activity. Further, we investigated the phagocytosis of different sizes of microspheres by J774.1 macrophages. To adequately evaluate phagocytosis, varying amounts of different sizes of microspheres were added to J774.1 cells, and their phagocytic activities were evaluated. When the microspheres were added at a density of 20 particles per cell, few small microspheres (<1.0 μm in diameter) were phagocytized. This result suggested that their low amount caused difficulty in evaluating phagocytosis. In contrast, when the same variety of microspheres was added at a density of 200 particles per cell, phagocytosis of large microspheres (>3 μm in diameter) could not be evaluated because of cytotoxicity. Thus, the amount of different sizes of microspheres added is important for precisely evaluating phagocytic activity. When the amount of different sizes of microspheres added was standardized to provide a set amount of total surface area, phagocytosis of these microspheres could be adequately evaluated and compared. To determine the effects of phagocytosis on cell viability and proliferation, cells incubated with different sizes of microspheres were assayed using a cell counting kit. We found that phagocytosis had no effect on cell viability or proliferation and was independent of particle size. Furthermore, cells already phagocytized microspheres retained their phagocytic activity.

Changes of tumorigenicity of the B16 melanoma cells transfected with MIP-1α gene

Macrophage inflammatory protein-l, a recentlycharacterized chemokine, consists of two chains (αand β). MIP-lα has been shown to exert strongchemotactic effect on neutrophils, monocytes and Tlymphocytes. In the present study, the B16 melanomacells were transfected with recombinant adenoviruscontaining MIP-lα gene. The biological characteri-zation of the MIP-1α gene transfected B16 melanomacells was investigated. The level of MIP-1α in thesupernatant of gene-transfected melanoma cells was368±24 ng/ml/10~6/24hr.. By using Boyden chambersystem, this supernatant showed strong chemotacticactivity for NK cells, CD4^+ T cells, CD8^+ T cells orthe freshly isolated peritoneal macrophages in vitro.Though the in vitro growth of the gene-transfected B16 melanoma cclls was not aftered, the in vivogrowth of the tumor cells subcutaneously inoculatedwas significantly inhibited. The infiltration ofinflammatory cells into the tumor mass formed bygene-transfected B16 cells was much more obviousthan that by