Production of cytokines at the operation site.

BACKGROUND AND AIM: Cytokines are part of a family of molecules involved in the initiation, control and termination of the events that occurs in wound healing process. Aim of this study was to evaluate the production of some cytokines [interleukin (IL)-6, IL-10, IL-1alpha, IL-1ra, interferon (IFN)-gamma] in the drainage wound fluid from patients undergoing incisional hernia repair. METHODS: Ten female patients with abdominal midline incisional hernia undergoing to surgical repair were included in this study. In all cases a closed suction drain was placed in the wound below the fascia and it was removed on the 4th postoperative day. Wound fluid was collected on the 1st, 2nd, 3rd and 4th day and its amount in each time was recorded. The production of IL-6, IL-10, IL-1alpha, IL-1ra and IFN-gamma were evaluated as quantity produced in 24 hour. RESULTS: In all patients the amount of drain fluid from surgical wound was highest on the 1st day after surgery, afterwards there is a significant reduction. The production of all cytokines evaluated was highest on the 1st day decreasing on the 2nd day except for IL-1alpha that not show any modification. The produciton of IL-1ra, IL-6, IL-1alpha and IL-10 was significantly reduced on the 3rd and 4th postoperative day in comparison with the respectively values recorded on the 1st day, whereas IFN-gamma levels were similar. CONCLUSIONS: The dosage of cytokines in the drain fluid led us to better evaluated the events that follow surgical wound and their analysis offers further information in the role of cytokines in healing process, with the goal to get supportive treatments to promote the best evolution.

Interleukin-15, as interferon-gamma, induces the killing of Leishmania infantum in phorbol-myristate-acetate-activated macrophages increasing interleukin-12.

The potential leishmanicidal activity of interleukin-15 (IL-15) was examined while priming with the cytokine phorbol-myristate-acetate (PMA)-activated macrophages and infecting them with Leishmania infantum parasites. The activation of macrophage cultures with IL-15 determined a significant anti-leishmanial activity, comparable with that induced by interferon-gamma (IFN-gamma). The killing of Leishmania in macrophages primed with IL-15, as well as with IFN-gamma, was followed by an increase in the IL-12 synthesis. The neutralization of IL-15 or IFN-gamma, by specific monoclonal antibodies (MoAb) caused a significant reduction in leishmanicidal activity. Furthermore, in PMA-activated macrophages, the neutralization of IL-12 production by a specific anti-IL-12 MoAb reduced leishmanicidal activity induced by IL-15 and IFN-gamma. Data indicate that IL-15 could have a role as an activator of leishmanicidal activity, directly or indirectly, by inducing IL-12 production.

Matrix metalloproteinases production in malignant pleural effusions after talc pleurodesis.

In this study we have evaluated the modifications of matrix metalloproteinases (MMPs) in malignant pleural fluids taken from patients suffering from lung cancer and treated with intrapleural talc instillation to induce pleurodesis. Furthermore, we have analysed the variations of some inflammatory mediators (C-reactive protein, alpha-1 antitrypsin) and of a protein (plasminogen) involved in MMP activation. In all patients the clinical improvement after talc pleurodesis was followed by a reduction in MMP-1, TIMP-1, C-reactive protein, alpha-1 antitrypsin and plasminogen activity. Furthermore, MMP-9 levels were variable; in fact, in some patients they were high at the beginning of treatment, in others they increased a few days after pleurodesis induction. These inhibitory effects of talc on MMP-1 and inflammatory mediators associated with the reduction of pleural effusion could constitute an effective means to evaluate the evolution of the treatment.

Anti-inflammatory effects of chemically modified tetracyclines by the inhibition of nitric oxide and interleukin-12 synthesis in J774 cell line.

We investigated the effects of chemically modified tetracyclines (CMTs) on the production of nitric oxide (NO) and on the synthesis of some cytokines: tumour necrosis factor alpha (TNF-alpha), interleukin(IL)-10 and IL-12 in lipopolysaccharide (LPS)-treated J774 cell line. Furthermore, we studied the ability of these drugs to modify the viability in LPS-stimulated J774 macrophages. CMTs decreased, in a dose-dependent manner, inducible NO synthase (iNOS) activity and, consequently, nitrite formation in J774 cultures. The CMT-induced decrease in NO production is due to the inhibition of enzyme activity rather than to a direct effect on enzyme expression. The absence of the inhibition in mRNA accumulation indicates that the inhibiting activity is mainly post-transcriptional. CMTs were unable to modulate TNF-alpha and IL-10 synthesis and they were not effective in modifying the transcription of relative mRNA in J774 macrophages. On the contrary, IL-12 mRNA expression was significantly increased by CMT-1 and CMT-8 with LPS activation. Since IL-12 protein secretion was inhibited by CMTs, these compounds interfere in the blocking of post-transcriptional events. The studies on cell viability showed that various CMTs induced a dose-dependent decrease in J774 macrophage viability. The cytotoxic activity was present even though NO production was inhibited by CMTs. These compounds appear to be able to activate apoptosis in aNO-independent way. Altogether, these results indicate that CMTs can exert anti-inflammatory effects by inhibiting NO synthesis, and they are able to modify cell viability by exerting a strong apoptotic activity.

Cytokine modifications after tension-free hernioplasty or open conventional inguinal hernia repair.

BACKGROUND: The purpose of this study was to evaluate the involvement of proinflammatory cytokines (interferon-gamma [INF-gamma], interleukin [IL]-6) and anti-inflammatory cytokines (IL-4, IL-l0, IL-13) in patients undergoing Lichtenstein tension-free hernioplasty (LH) using polypropylene prosthetic materials or conventional Bassini hernia (BH) repair. METHODS: Thirty-five male patients (age range 25 to 60 years) with unilateral inguinal hernia without complications or recurrence were included in this study. Randomly, patients underwent conventional operation and had their inguinal hernia repair performed with polypropylene mesh. Peripheral venous blood samples were collected 24 hours prior to surgery and then 6, 24, 48, and 168 hours postoperatively. Fifteen healthy controls were included. RESULTS: We present evidence that LH patients showed both an increased serum level of Thelper 1 (Th1)-like cytokines (IFN-gamma) and an increase in Thelper 2 (Th2)-like cytokines (IL-6 and IL-l0), associated with a slight reduction of peripheral blood mononuclear cells (PBMC) producing IL-6 and a normal level of PBMC producing IFN-gamma, IL-l0, IL-13, and IL-4. Whereas BH patients showed in part an amplification of Th2-like cells, characterized by the sustained serum production of IL-6 and IL-l0, associated with an increase in IL-l0 secreted by in vitro stimulated PMBC. CONCLUSIONS: Our data show that LH is associated with a higher production of inflammatory cytokines (IFN-gamma and IL-6) compared with BH, likely induced by the presence of the polypropylene prostheses.

Effects of chemically modified tetracyclines (CMTs) in sensitive, multidrug resistant and apoptosis resistant leukaemia cell lines.

Recently discovered chemically modified tetracyclines (CMTs) have shown in vitro and in vivo anti-proliferative and anti-tumour activities. Here, we evaluated in vitro the anti-proliferative and apoptotic activity of six different dedimethylamino chemically modified tetracyclines (CMT-1, CMT-3, CMT-5, CMT-6, CMT-7 and CMT-8) in sensitive and multidrug resistant myeloid leukaemia cells (HL60 and HL60R) in vitro. Three of these compounds (CMT-5, CMT-6, CMT-7) showed low cytotoxic activity both in sensitive and in resistant cells, CMT-3 was endowed with a high anti-proliferative activity only in sensitive cells and was moderately effective as apoptosis inducing agent, with an activity similar to that shown by doxycycline. On the contrary, CMT-1 and CMT-8 were very effective as programmed cell death inducing agents. The apoptotic pathway activated by these compounds involved the activation of caspases, especially caspase-9 and, for CMT-1, also the activation of FAS: Interestingly CMT-8, but not CMT-1, was able to induce apoptosis in multidrug resistant HL60R and in Fas-ligand resistant HUT78B1 cell lines. These properties, together with others previously described (e.g. anti-metastatic and anti-osteolytic activities), suggest that CMT-8 may have important applications in the clinical management of cancer. The comparative analysis of structure-activity relationship of CMT-8 and doxycycline suggests that the C-5 hydroxy moiety may play an important role in conferring activity in multidrug resistant cells. These findings appear to support the hypothesis that CMT-8 may represent an interesting lead for the development of a new class of potent apoptosis inducer agents active in multidrug resistant and Fas-ligand resistant malignancies.

The acute phase response in Sicilian patients with boutonneuse fever admitted to hospitals in Palermo, 1992-1997.

OBJECTIVES: To study the modifications of some components of the acute phase response (APR) in Sicilian patients with boutonneuse fever (BF) caused by Rickettsia conorii. METHODS: Sera from 500 Sicilian patients with confirmed BF were studied at the time of diagnosis and every week after treatment, and after recovery for the presence of various inflammatory mediators. Tumour necrosis factor alpha (TNFalpha), interleukin(IL)-6, IL-1alpha, IL-8, soluble TNF receptors (sTNF-R) and sIL-6R were assayed by commercially ELISA kits. C3, C4, factor B, C-reactive protein (CRP), fibrinogen, ceruloplasmin (Cp) and alpha(1)-antitrypsin (AAT) were assayed by a rate nephelometry. RESULTS: Interferon gamma (IFNgamma), IL-6, TNFalpha, and IL-10 cytokines were significantly modified, whereas IL-1 and IL-8 were not detectable in the blood in any phase of infection. sTNF-RI, sTNF-RII and sIL-6 were significantly increased in the first 2 weeks of infection, but sTNF-R levels were not related to the plasma levels of TNFalpha, whereas sIL-6 was directly related to serum IL-6 concentrations. C3, C4, factor B and CRP were significantly increased in the first 2 weeks of infection, but afterwards returned to the normal range, even though CRP was still high in the third week and C3 persisted high after the fourth week. Fibrinogen was high only in the first week in relation to the injury to the endothelial cells (ECs). The anti-inflammatory proteins, Cp and AAT, were extremely high in the first 2 weeks of infection acting as a buffer of APR activation. CONCLUSIONS: These results suggest that R. conorii is able to elicit, after invasion and proliferation in the ECs, the activation of APR. Further work is required to establish if active inhibitory mechanisms are operating during APR, or if there is a spontaneous decay in the initiation events.

Inflammatory response in open and laparoscopic cholecystectomy.

The modifications of IL-6. CRP, ceruloplasmin, alpha 1 antitrypsin, fibrinogen, transferrin, albumin and leukocytes counts have been evaluated after traditional open cholecystectomy (OC) or laparoscopic cholecystectomy (LC). Forty-two patients were included in this study, 20 underwent to OC and 22 underwent to LC. Serum samples were performed before surgery and at distance of 6, 24, 48 and 168 hours. The results show a more significant increase in acute phase inflammatory response after OC compared with LC as attested by highest values of leukocytosis, IL-6, CRP, fibrinogen and alpha 1 antitrypsin and lower levels of albumin. In conclusion, after LC, the phase acute response is attenuate and it can explain the reduced period of convalescence of patients treated with LC.

Th1-like and Th2-like cytokines in patients undergoing open versus laparascopic cholecystectomy.

The advantages of laparoscopic (LC versus, open cholecystectomy (OC) seems to be related to minimal invasive procedure and to the moderate inflammatory response. The aim of this study is to define the involvement of Th1 (IFN-gamma) and Th2 (IL-4, IL-6, IL-10, IL-13) cytokines production in vivo and in vitro in patients undergoing OC or LC. In 42 patients undergoing LC (n = 22) and OC (n = 20) Th1-like and Th2-like was evaluated before operation and at 6, 24 and 48 hours after operation for white blood cell counting and cytokines (IL-4, IL-6, IL-10, IL-13, IFN-gamma, TNF-alpha) in the sera and in the supernatants from circulating mononuclear cells stimulated with phytohemagglutinin or lipopolysaccharide. The acute phase response cytokine, IL-6, appeared significantly increased following OC than after LC. All other cytokines did not very significantly. In vitro data shows a reduction of IFN-gamma and increase in Th2-like cytokines in OC patients compared with the basal value. In LC subjects we observed an high production of IFN-gamma associated to an increase of Th2-like cytokines, like IL-10 and IL-13, even though IL-4 and IL-6 were unmodified. In contrast to OC, LC did not significantly affect immunocompetence, maintaining a moderate inflammatory response and an adequate balance between Th1 and Th2 cytokine. Furthermore, the strong activation of cells producing Th1-like cytokines in LC patients following mitogen activation indicated a consistent anti-microbial activity, that was not detectable in OC patients, that showed after activation only a Th2 response.

Tension-free hernia repair is associated with an increase in inflammatory response markers against the mesh.

BACKGROUND: The purpose of this study was to evaluate the involvement of inflammatory mediators in patients undergoing Lichtenstein tension-free hernioplasty (LH) using polypropylene prosthetic materials or conventional Bassini hernia repair (BH). METHODS: Thirty patients male with unilateral inguinal hernia without complications or recurrence were included in this study. Randomly, patients underwent LH or BH. Peripheral venous bloods samples were collected 24 hours prior to surgery and then 6, 24, 48 and 168 hours postoperatively. RESULTS: We present evidences that LH patients showed a higher increased serum level of fibrinogen, C-reactive protein, alpha-1-antitrypsin, and interleukin-6 than BH patients. Postoperative visual analogue scales for pain were reduced on mobilization for patients undergoing LH compared with BH. Neutrophils were significantly increased only in LH compared with baseline. Ceruloplasmin, transferrin, and albumin levels were unmodified after BH or LH. CONCLUSIONS: In conclusion our data show that although LH induces less pain and more rapid postoperative recovery, it is associated with an higher inflammatory response compared with BH, likely due to polypropylene mesh.

Tetracycline inhibits the nitric oxide synthase activity induced by endotoxin in cultured murine macrophages.

Here we investigate the effects of tetracycline base and of a semi-synthetic tetracycline derivative, doxycycline, on the induction of inducible nitric oxide synthase and, hence, on the production of nitric oxide (NO) by lipopolysaccharide in J774 macrophage cultured in vitro. The treatment of J774 line with tetracycline base (6.25-250 microM) or doxycycline (5-50 microM) dose-dependently decreased the lipopolysaccharide-stimulated (1 microg/ml) inducible NO synthase activity and, consequently, nitrite formation. For instance, the inhibition was 70% for tetracycline base at 250 microM and 68% for doxycycline at 50 microM. The inhibitory effect of tetracyclines was due neither to a reduction in the viability of the cells, studied as colorimetric 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) reduction assay, nor to an indiscriminate inhibition of total protein synthesis, but to a specific decrease in inducible NO synthase protein content in the cells, as attested by the significant reduction of the expression of inducible NO synthase, assayed by sodium-dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. However, no effect of tetracyclines on inducible NO synthase mRNA accumulation could be demonstrated in lipopolysaccharide-stimulated macrophage line, suggesting that the inhibitory effect of tetracyclines on NO synthesis involves post-transcriptional events. The reduction in lipopolysaccharide-stimulated nitrite accumulation produced by tetracyclines was significantly less when they were applied 6 h after lipopolysaccharide and absent 12 h after lipopolysaccharide, indicating that tetracyclines modify an early event in inducible NO synthase activation operating after mRNA transcription. The findings presented in this study indicate that the modulation of NO synthesis is another possible pathway by which tetracyclines may function as anti-inflammatory compounds.

Doxycycline reduces mortality to lethal endotoxemia by reducing nitric oxide synthesis via an interleukin-10-independent mechanism.

It was demonstrated that doxycycline protected BALB/c mice injected intraperitoneally with bacterial lipopolysaccharide (LPS) against lethal septic shock. Doxycycline (at 1.5 mg/kg) exerted its protective effect by inhibiting nitrate production by an interleukin-10-independent mechanism. Experiments carried out in vitro also indicated that doxycycline inhibited NO synthesis by LPS-activated macrophages without inducing any significant modification in interleukin-10 release. These data suggest that the direct inhibition of nitrate release is the main mechanism of the antiinflammatory activity of doxycycline in septic shock.

Modulation of nitric oxide production by tetracyclines and chemically modified tetracyclines.

Chemically modified tetracyclines (CMTs) dose-dependently decreased inducible nitric oxide synthase (iNOS) and, consequently, nitric oxide (NO) formation by the lipopolysaccharide (LPS)-stimulated J774 line. The inhibitory effect was due to a specific reduction in the iNOS protein content in the cells, as attested by Western blot analysis and by the inhibition of iNOS mRNA accumulation. Furthermore, CMTs cause a dose-dependent increase in cell death in the J774 line mediated by the NO-independent apoptotic mechanism.

Effect of partially modified retro-inverso analogues derived from C-reactive protein on the induction of nitric oxide synthesis in peritoneal macrophages.

1. The ability of three modified tetrapeptides, representing fragments of the C-reactive protein (CRP) sequence and stabilized in the first peptide bond by retro-inverso modification, to affect the secretion of nitric oxide (NO) was studied in macrophages of BALB/c mice. 2. These tetrapeptides, resembling the aminoacid sequence of tuftsin (CRP 1, H-gThr-(R,S)mLys-Pro-Leu-OH, ITF 1192; CRP II, H-gGly-(R, S)mLys-Pro-Arg-OH, ITF 1127; CRP III, H-gThr-(R,S)mLys-Pro-Gln-OH. ITF 1193), were able to induce NO synthesis by peritoneal macrophages in a dose-dependent manner; the most stimulating dose was 1000 ng ml-1 for CRP II and 100 ng ml-1 for CRP I and CRP III. NO synthesis was not strictly dependent on lipopolysaccharide (LPS) activation. 3. The enhanced effect of retro-inverso CRP-related analogues on the expression of iNOS (inducible NO synthase) was confirmed by higher levels of iNOS activity in the cytosol and by the increase in iNOS protein, as evaluated by Western blot analysis, in macrophages stimulated by CPR compared with untreated ones. 4. The production of NO by retro-inverso CRP-peptide analogues was significantly inhibited by dexamethasone (20 microM), NG-monomethyl-L-arginine (L-NMMA) (500 microM) and pyrrolidine dithiocarbamate (PDTC) (100 microM). 5. Retro-inverso CRP-peptide analogues stimulated macrophages to produce high levels of interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha) in the presence of LPS. 6. Retro-inverso CRP-peptide analogues stimulated NO synthesis by the enhancement of endogenously produced IL-1 and TNF-alpha, as the treatment of peritoneal macrophages with LPS in the presence of neutralizing anti-IL-1 and anti-TNF monoclonal antibodies (mAbs) reduced retro-inverso analogue-induced NO secretion. Data indicate a predominant role for IL-1 alpha in the induction of NO secretion by retro-inverso analogues. 7. These results suggest that retro-inverso CRP derived analogues act as costimulators of NO and cytokine synthesis in macrophages. The mechanisms by which they cause iNOS induction appear to be strongly dependent on the activation of nuclear factor-kappa B (NF-kappa B).

Intraperitoneal injection of tetracyclines protects mice from lethal endotoxemia downregulating inducible nitric oxide synthase in various organs and cytokine and nitrate secretion in blood.

We have tested whether tetracyclines (TETs) are able to protect mice from lipopolysaccharide (LPS)-induced shock, a cytokine-mediated inflammatory reaction. Mice, injected with a single dose of tetracycline base (TETb; 1.5, 10 and 20 mg/kg of body weight) or doxycycline (DOXY; 1.5 mg/kg), were significantly protected from a lethal intraperitoneal injection of LPS (500 micrograms per mouse). TETs acted in early events triggered in response to LSP; in fact, they were no longer significantly protective if injected more than 1 h after the injection of endotoxin. LPS-treated mice protected by TETs showed a significant inhibition of tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha), and nitrate secretion in the blood, events that were directly related with the survival. In mice treated with TETs a significant decrease of inducible nitric oxide synthase (iNOS) activity was observed in spleen and peritoneal cells compared with that detected in mice treated with LPS alone. Furthermore, TETs were found to inhibit NO synthesis by peritoneal macrophages stimulated in vitro with LPS. On the contrary, TETs were unable to decrease the ability of the macrophages to synthesize IL-1 alpha and TNF-alpha in vitro. These results indicate that TETs are not able to act directly on the synthesis of these cytokines, but they may modulate other pathways that could in turn be responsible for the inhibition of IL-1 alpha and TNF-alpha synthesis. Altogether, these results indicate that TETs are advantageous candidates for the prophylaxis and treatment of septic shock in mice, having both antimicrobial activity and the ability to inhibit endogenous TNF-alpha, IL-1 alpha, and iNOS, hence, exerting, potent anti-inflammatory effects.

Depression of CD4 T cell subsets and alteration in cytokine profile in boutonneuse fever.

Interferon (IFN)-gamma, interleukin (IL)-10, IL-6, and tumor necrosis factor (TNF)-alpha were significantly increased in sera from Sicilian patients with acute boutonneuse fever (BF) compared with those of healthy controls. IFN-gamma levels dropped sharply within the second week after infection. IL-6, IL-10, and TNF-alpha levels gradually declined; in convalescent patients only were they in the normal range. In contrast, peripheral blood mononuclear cells (PBMC) stimulated in vitro with phytohemagglutinin (PHA) produced low levels of IL-10 and IFN-gamma in acute BF that were compatible with the reduction in the levels of CD4+, CD4+/CD45RO+, and CD4+/CD45RA+ cells. In vitro production of TNF-alpha and IL-6 from PBMC stimulated with PHA was not significantly modified during the various phases of the infection compared with control PBMC, which could be due to the persistence of high levels of CD14+ monocytes compensating for the decrease in CD20+ B cells.

Ex vivo evidence for PGE2 and LTB4 involvement in cutaneous leishmaniasis: relation with infection status and cytokine production.

Ex vivo culture of spleen cells from BALB/c mice infected with 2 x 10(6) Leishmania major (L. major) promastigotes were cultured with ConcanavalinA (ConA) or leishmanial antigen (L. Ag) and tested for prostaglandin E2 (PGE2) and for leukotriene B4 (LTB4), in order to study their involvement in the evolution of cutaneous leishmaniasis and the connexion with lymphokine-mediated responses. The data were compared with those obtained in BALB/c mice protected against L. major by sublethal irradiation (550 rad; cured mice). In the unprotected BALB/c mice the levels of PGE2 that were responsible for the depression of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF alpha) Th1-associated cytokines and for the relative increase in the interleukin-4 (IL-4) became higher and higher as the lesion progressed. On the contrary, the cured mice produced levels of PGE2 similar to normal uninfected controls, high levels of TNF alpha and IFN-gamma and low levels of IL-4. Elevated levels of LTB4 were detected in the early stage of infection in the unprotected mice compared to cured ones, a sign of more intense inflammation and a stimulus for the recruitment of inflammatory cells. The observation that exogenous LTB4 was able to enhance in vitro both Th1 cytokines in cured mice and Th2 cytokines in unprotected ones suggests that LTB4 could act in the recruitment of the T cells already committed to Th1 or Th2 phenotype.

Prostaglandin E2 regulates inducible nitric oxide synthase in the murine macrophage cell line J774.

We have evaluated the role of prostaglandin E2 (PGE2) in the synthesis of nitric oxide (NO) by the activation of the inducible form of nitric oxide synthase (NOS) in the murine macrophage cell line, J774, stimulated with different doses of lipopolysaccharide (LPS). The stimulation of the J774 line with suboptimal doses of LPS (0.1 microgram/mL) caused a production of endogenous PGE2 that was capable of stimulating NOS activity inducing an increase in the NO synthesis, as attested by the fact that cyclooxygenase enzyme inhibitor, indomethacin, significantly reduced NO secretion. On the contrary, a higher dose of LPS (1 microgram/mL) produced high levels of PGE2 that reduced the levels of NOS and, subsequently, NO production. Experiments carried out with exogenous PGE2 indicated that concentrations between 1 and 10 ng/mL are able to stimulate the expression of NOS and the release of NO, while higher concentrations (> 50 ng/mL) are inhibitory. Furthermore, our data indicate that there is a network of interaction which involves NO, PGE2, and tumor necrosis factor. High levels of PGE2 inhibited TNF alpha secretion, which in turn could exert inhibitory effects on NO synthesis.

The macrophage-activating tetrapeptide tuftsin induces nitric oxide synthesis and stimulates murine macrophages to kill Leishmania parasites in vitro.

The macrophage-activating tetrapeptide tuftsin was able to activate, in a dose-dependent manner, murine macrophages to express nitric oxide (NO) synthase and to produce NO. Tuftsin required lipopolysaccharides for the optimal induction of NO production and synergized with gamma interferon in the induction of NO synthesis. Tuftsin-dependent NO production was sensitive to inhibition by dexamethasone and the NO synthase specific inhibitor LGN-monomethylarginine (L-NMMA). Murine peritoneal macrophages activated by tuftsin were able to kill the amastigotes of the intracellular protozoan parasite Leishmania major in vitro.