Mg Of Zymosan Research Articles

Does Training Innate Immunity Confer Broad-spectrum Protection Against Bone and Joint Infection in a Mouse Model?

The innate immune system can recall previous immunologic challenges and thus respond more effectively to subsequent unrelated challenges, a phenomenon called trained immunity. Training the innate immune system before surgery might be a potential option to prevent bone and joint infection. (1) Does the training process cause adverse effects such as fever or organ injury? (2) Does training the innate immune system confer broad-spectrum protection against bone and joint infection in a mouse model? (3) Does trained immunity remain effective for up to 8 weeks in this mouse model? After randomization and group information blinding, we trained the innate immune system of C57BL/6 mice (n = 20 for each group) by intravenously injecting them with either 0.1 mg of zymosan (a toll-like receptor 2 agonist), 0.1 mg of lipopolysaccharide (a toll-like receptor 4 agonist), or normal saline (control). For assessing the host response and possible organ injury after training and infection challenge, we monitored rectal temperature, collected blood to determine leukocyte counts, and performed biochemical and proinflammatory cytokine analyses. After 2 weeks, we then assessed whether trained immunity could prevent infections in an intraarticular implant model subjected to a local or systemic challenge with a broad spectrum of bacterial species (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Streptococcus pyogenes, or Pseudomonas aeruginosa) in terms of culture-positive rate and colony counts. The proportion of culture-positive joint samples from trained and control groups were compared after 4 weeks. Finally, we increased the interval between training and bacterial challenge up to 8 weeks to assess the durability of training efficacies. Training with zymosan and lipopolysaccharide caused mild and transient stress in host animals in terms of elevated rectal temperature and higher blood urea nitrogen, creatinine, alanine aminotransferase, and aspartate aminotransferase levels. Trained mice had fewer culture-positive joint samples after local inoculation with S. aureus (control: 100% [20 of 20]; zymosan: 55% [11 of 20], relative risk 0.55 [95% CI 0.37 to 0.82]; p = 0.001; lipopolysaccharide: 60% [12 of 20], RR 0.60 [95% CI 0.42 to 0.86]; p = 0.003) and systemic challenge with S. aureus (control: 70% [14 of 20]; zymosan: 15% [3 of 20], RR 0.21 [95% CI 0.07 to 0.63]; p = 0.001; lipopolysaccharide: 15% [3 of 20], RR 0.21 [95% CI 0.07 to 0.63]; p = 0.001) than controls. We observed similar patterns of enhanced protection against local and systemic challenge of E. coli, E. faecalis, S. pyogenes, and P. aeruginosa. Zymosan-trained mice were more effectively protected against both local (control: 20 of 20 [100%], zymosan: 14 of 20 [70%], RR 0.70 [95% CI 0.53 to 0.93]; p = 0.02) and systemic (control: 70% [14 of 20]; zymosan: 30% [6 of 20], RR 0.43 [95% CI 0.21 to 0.89]; p = 0.03) challenge with S. aureus for up to 8 weeks than controls. Trained immunity confers mild stress and broad-spectrum protection against bone and joint infection in a mouse model. The protection conferred by immunity training lasted up to 8 weeks in this mouse model. The results of the current research support further study of this presurgical strategy to mitigate bone and joint infection in other large animal models. If large animal models substantiate the efficacy and safety of presurgical immunity training-based strategies, clinical trials would be then warranted to translate this strategy into clinical practice.

Evaluation of the articular cartilage in the knees of rats with induced arthritis treated with curcumin.

This study was designed to evaluate the anti-inflammatory effects of a curcumin treatment on the knee of rats with induced osteoarthritis. Fifteen adult rats were used and divided in three groups: the osteoarthritis group (OAG), control group (CG-without induction of osteoarthritis), and curcumin-treated osteoarthritis group (COAG). Osteoarthritis was induced in the right knee of rats in the OAG and COAG by administering an intra-articular injection of 1 mg of zymosan. Fourteen days after induction, 50 mg/kg curcumin was administered by gavage daily for 60 days to the COAG. After the treatment period, rats from all groups were euthanized. Medial femoral condyles were collected for light microscopy and immunohistochemical staining. The expression of SOX-5, IHH, MMP-8, MMP-13, and collagen 2 (Col2) was analyzed. The COAG exhibited an increase in the number of chondrocytes in the surface and middle layers compared with that of the OAG and CG, respectively. The COAG also showed a decrease in the thicknesses of the middle and deep layers compared with those of the OAG, and an increase in Col2 expression was observed in all articular layers (surface, middle, and deep) in the COAG compared with that in the OAG. SOX-5 expression was increased in the surface and deep layers of the COAG compared with those in the OAG and CG. Based on the results of this study, the curcumin treatment appeared to exert a protective effect on cartilage, as it did not result in an increase in cartilage thickness or in MMP-8 and MMP-13 expression but led to increased IHH, Col2, and SOX-5 expression and the number of chondrocytes.

GM-CSF- and IRF4-Dependent Signaling Can Regulate Myeloid Cell Numbers and the Macrophage Phenotype during Inflammation.

Studies have demonstrated the importance of a GM-CSF→IFN regulatory factor 4 (IRF4)→CCL17 pathway, first identified in monocytes/macrophages, for arthritic pain and disease development. In this study, we further investigated the involvement of this new pathway in shaping the inflammatory response using the zymosan-induced peritonitis (ZIP) model. ZIP (8 mg of zymosan, i.p., day 0) was induced in C57BL/6 wild-type (WT), GM-CSF-/- , Irf4-/- , and Ccl17E/E mice. In comparison with WT mice, GM-CSF-/- and Irf4-/- mice had a reduced ZIP response, as judged by a reduced number of neutrophils and macrophages in the peritoneal cavity. Moreover, the phenotype of the ZIP macrophages was altered by a lack of GM-CSF or IRF4 (increased IL-10 secretion and Arg1 mRNA expression), with IRF4 levels being lower in GM-CSF-/- ZIP macrophages than in the WT cells. In addition, GM-CSF ̶IRF4 signaling upregulated MHC class II expression in ZIP macrophages and bone marrow-derived macrophages. Although Ccl17 mRNA expression was reduced in ZIP macrophages in the absence of either GM-CSF or IRF4, thus supporting the presence of the new pathway in inflammatory macrophages, CCL17 did not modulate the inflammatory response, both in terms of number of myeloid cells or the macrophage phenotype. Thus, during an inflammatory response, both macrophage numbers and their phenotype can depend on GM-CSF- and IRF4-dependent signaling independently of CCL17.

The impact of acute inflammation on progression and metastasis in pancreatic cancer animal model

BackgroundThe impact of acute inflammation on cancer is unclear. Therefore, we evaluated the impact of acute inflammation on cancer progression in an animal model concerning morphological change as well as molecular features. Material and methodsMurine pancreas ductal adenocarcinoma cell line (Panc-02) and zymosan were used for the induction of cancer and acute inflammation respectively, in C57/BL6 mice. In the C group (n = 10), 2 × 107Panc02 cells were injected into the tail of the pancreas. In the Z1 (n = 10) and Z2 (n = 10), 3 mg of zymosan was injected intraperitoneally once and twice respectively, after tumor cell injection. All of the mice were sacrificed 4 weeks after tumor cell injection. ResultsThe degree of inflammation was more severe in the Z2 group than in the other two groups. The tumor volume of the Z2 group was larger than that of the C group (P = 0.032) and the presence of liver metastasis was significantly more common in the Z2 group than in the C and Z1 groups (P = 0.025). Confocal microscopy analysis revealed significantly more expression of Snail, EpCAM, Muc1, NLRP3 and miR-155 in the liver and pancreas in the Z2 group than in the other two groups. EpCAM and Muc1 were detected in blood samples in the Z2 group by flow cytometry, but not in the other two groups. In the Z2, expression of E-Cadherin was weaker and vimentin, snail1 were stronger compared to the C and Z1 group in the PCR and western blot. ConclusionPresent results suggest that acute inflammation accompanied with cancer promotes cancer progression by the epithelial-to-mesenchymal transition (EMT) and circulating tumor cells (CTC) process.

A New Strategy for the Identification of Novel Molecules with Targeted Proresolution of Inflammation Properties

As our understanding of inflammatory resolution increases, drugs that trigger proresolution pathways may become significant in treating chronic inflammatory diseases. However, anti-inflammatory drugs are traditionally tested during the first hours of onset (i.e., to dampen leukocyte and edema formation), and their ability to trigger proresolution processes has never been investigated. Moreover, there is no model available to screen for putative proresolving agents. In this study, we present a new strategy to identify therapeutics for their ability to switch inflammation off and restore homeostasis. Injecting 1.0 mg of zymosan i.p. causes transient inflammation characterized by polymorphonuclear neutrophil clearance and dominated by recently described resolution-phase macrophages along with an innate-type lymphocyte repopulation, the latter being a marker of tissue homeostasis. In contrast, 10 mg of zymosan elicits an aggressive response characterized by classically activated macrophages leading to systemic inflammation and impaired lymphocyte repopulation. Although this latter model eventually resolves, it nonetheless represents inflammation in the clinically relevant setting of polymorphonuclear neutrophil/classically activated macrophage dominance driving a cytokine storm. Treating such a reaction therapeutically with proresolution drugs provides quantifiable indices of resolution--polymorphonuclear neutrophil/macrophage clearance, macrophage phenotype switching (classically activated to resolution phase), and repopulation with resolution-phase lymphocytes--cardinal signs of inflammatory resolution and homeostasis in the peritoneum. As an illustration, mice bearing peritonitis induced by 10 mg of zymosan were given ibuprofen, resolvin E1, a prostaglandin D(2) receptor 1 agonist, dexamethasone, rolipram, or azithromycin, and their ability to trigger resolution and homeostasis in this new inflammatory setting was investigated. We present the first model for testing drugs with targeted proresolution properties using quantifiable parameters of inflammatory resolution and homeostasis.

Characterization and pharmacological evaluation of febrile response on zymosan-induced arthritis in rats

The present study investigated the febrile response in zymosan-induced arthritis, as well as the increase in PGE(2) concentration in the cerebrospinal fluid (CSF), along with the effects of antipyretic drugs on these responses in rats. Zymosan intra-articularly injected at the dose of 0.5 mg did not affect the body core temperature (Tc) compared with saline (control), whereas at doses of 1 and 2 mg, zymosan promoted a flattened increase in Tc and declined thereafter. The dose of 4 mg of zymosan was selected for further experiments because it elicited a marked and long-lasting Tc elevation starting at 3 1/2 h, peaking at 5 1/2 h, and remaining until 10 h. This temperature increase was preceded by a decrease in the tail skin temperature, as well as hyperalgesia and edema in the knee joint. No febrile response was observed in the following days. In addition, zymosan-induced fever was not modified by the sciatic nerve excision. Zymosan increased PGE(2) concentration in the CSF but not in the plasma. Oral pretreatment with ibuprofen (5-20 mg/kg), celecoxib (1-10 mg/kg), dipyrone (60-240 mg/kg), and paracetamol (100-200 mg/kg) or subcutaneous injection of dexamethasone (0.25-1.0 mg/kg) dose-dependently reduced or prevented the fever during the zymosan-induced arthritis. Celecoxib (5 mg/kg), paracetamol (150 mg/kg), and dipyrone (120 mg/kg) decreased CSF PGE(2) concentration and fever during zymosan-induced arthritis, suggesting the involvement of PGE(2) in this response.

Discovery and Validation of Novel Peptide Agonists for G-protein-coupled Receptors

G-protein-coupled receptors (GPCRs) represent an important group of targets for pharmaceutical therapeutics. The completion of the human genome revealed a large number of putative GPCRs. However, the identification of their natural ligands, and especially peptides, suffers from low discovery rates, thus impeding development of therapeutics based on these potential drug targets. We describe the discovery of novel GPCR ligands encrypted in the human proteome. Hundreds of potential peptide ligands were predicted by machine learning algorithms. In vitro screening of selected 33 peptides on a set of 152 GPCRs, including a group of designated orphan receptors, was conducted by intracellular calcium measurements and cAMP assays. The screening revealed eight novel peptides as potential agonists that specifically activated six different receptors in a dose-dependent manner. Most of the peptides showed distinct stimulatory patterns targeted at designated and orphan GPCRs. Further analysis demonstrated a significant in vivo effect for one of the peptides in a mouse inflammation model.

NADPH Oxidase-dependent Generation of Lysophosphatidylserine Enhances Clearance of Activated and Dying Neutrophils via G2A

Exofacial phosphatidylserine (PS) is an important ligand mediating apoptotic cell clearance by phagocytes. Oxidation of PS fatty acyl groups (oxPS) during apoptosis reportedly mediates recognition through scavenger receptors. Given the oxidative capacity of the neutrophil NADPH oxidase, we sought to identify oxPS signaling species in stimulated neutrophils. Using mass spectrometry analysis, only trace amounts of previously characterized oxPS species were found. Conversely, 18:1 and 18:0 lysophosphatidylserine (lyso-PS), known bioactive signaling phospholipids, were identified as abundant modified PS species following activation of the neutrophil oxidase. NADPH oxidase inhibitors blocked the production of lyso-PS in vitro, and accordingly, its generation in vivo by activated, murine neutrophils during zymosan-induced peritonitis was absent in mice lacking a functional NADPH oxidase (gp91phox-/-). Treatment of macrophages with lyso-PS enhanced the uptake of apoptotic cells in vitro, an effect that was dependent on signaling via the macrophage G2A receptor. Similarly, endogenously produced lyso-PS also enhanced the G2A-mediated uptake of activated PS-exposing (but non-apoptotic) neutrophils, raising the possibility of non-apoptotic mechanisms for removal of inflammatory cells during resolution. Finally, antibody blockade of G2A signaling in vivo prolonged zymosan-induced neutrophilia in wild-type mice, whereas having no effect in gp91phox-/- mice where lyso-PS are not generated. Taken together, we show that lyso-PS are modified PS species generated following activation of the NADPH oxidase and lyso-PS signaling through the macrophage G2A functions to enhance existing receptor/ligand systems for optimal resolution of neutrophilic inflammation.

Efeito de inibidores da sintase de óxido nítrico na dor inflamatória articular e influxo celular da artrite induzida por zymosan em ratos

OBJETIVO: Investigar o papel do oxido nitrico (NO) no influxo celular (IC) e a incapacitacao articular (IA) na artrite por zymosan (AZy). METODOS: Ratos Wistar receberam injecao de Zy (1mg) no joelho direito. Grupos-controles receberam salina. A IA foi avaliada pelo Teste de incapacitacao articular para ratos. Apos sacrificio, o IC e a liberacao de PGE2 foram avaliados no lavado articular. Avaliou-se o edema pela diferenca peso umido/peso seco do tecido articular. Grupos foram tratados i.p. com L-NAME - inibidor de sintases de NO (NOS) (LN=30-300mg/kg) ou aminoguanidina (AG= 30-300mg/kg) - inibidor seletivo de iNOS 30 min antes ou 2 h apos o Zy. RESULTADOS: O pre-tratamento com L-NAME ou AG inibiu de forma dose-dependente a IA e o IC, mas nao o edema ou a liberacao de PGE2, sendo maximo para LN ou AG (100mg/kg). L-arginina (1g/kg) co-injetada com LN (100mg/kg) reverteu a inibicao da IA e do IC. D-NAME (100mg/kg) nao teve efeito. Co-injecao de naloxona (antagonista opioide) reverteu o efeito de LN e AG sobre a IA. A pressao arterial media elevou-se (p<0,01) apos LN (100mg/kg), mas nao com AG (100mg/kg). LN e AG (100mg/kg) dados 2 h apos Zy nao tiveram efeito. Azul de metileno (inibidor de GMPc), e nao hemoglobina (scavenger de NO), reduziu IA e IC (p<0,01). Nitroprussiato de sodio (doador de NO) dado 2 h apos Zy, reduziu a IA, mas nao o IC (p<0,01). CONCLUSOES: A antinocicepcao na AZy por inibicao da iNOS so ocorre como pre-tratamento, por efeito antiinflamatorio via GMPc, independentemente de NO exogeno ou de PGE2, associada a liberacao de opioides endogenos. Um doador de NO produz analgesia na AZy. Enfim, o trabalho demonstra efeito analgesico de um doador de NO em um modelo de periartrite, abrindo a perspectiva do uso dessas substâncias em humanos.

A low-morbidity murine model of peritonitis.

Peritonitis continues to be a major source of mortality and morbidity in patients undergoing abdominal surgery. The aim of this study was to develop a nonfatal model of bacterial peritonitis in mice so that we could study aspects of the pathobiology and treatment of peritonitis in an in vivo model. Mice were inoculated via a midline laparotomy with 0.5 mg of zymosan in 0.1 ml of saline into the subomental space. At 24, 48, and 96 hours after treatment, animals were killed, and analysis was performed to determine the degree of peritoneal inflammation. End points included intraperitoneal cellular influx, tumor necrosis factor-alpha concentrations, and myeloperoxidase activity. In addition, peritoneal lavage fluid was plated onto blood agar for analysis of bacterial colony-forming units. There were 40 mice in each group. There were no deaths in either group. Facultative Gram-negative bacteria were cultured from the peritoneal cavities of zymosan-treated animals at 24 and 48 hours after insult (colony-forming unit counts of 92+/-11 vs. 0 in control animals). In the zymosan-treated animals, there were significantly increased numbers of inflammatory cells (especially neutrophils) in the peritoneal cavity at 24 and 48 hours after treatment; these numbers returned to control levels by 96 hours. Myeloperoxidase activity was also elevated both in the peritoneal fluid (2.4 X 10(-4) units/ml compared with 1.6 x 10(-4) units/ml, P < 0.05) and in remote organs (i.e., lung, P < 0.05; liver, P < 0.001; and kidney, P < 0.05) at 24 hours after treatment. There was no significant difference in tumor necrosis factor-alpha levels between zymosan-treated and control mice in either serum or peritoneal fluid at any time point investigated. There was no mortality in either the zymosan-treated or control animals. In this model of bacterial peritonitis in mice, we have demonstrated how the peritoneal cavity can resolve a relatively localized inflammatory insult within 96 hours of induction. This response is characterized by a cellular influx of predominantly neutrophils and macrophages and by pronounced oxidative activity. We will use this in vivo model to characterize aspects of the pathobiology and treatment of peritonitis.

Bacterial translocation in a non-lethal rat model of peritonitis.

Bacterial translocation from the gut may occur under a variety of different clinical circumstances and has been implicated in the development of multiple organ failure. The aim of this study was to determine the distribution of bacterial translocation occurring in a model of chemically induced peritonitis. We also sought to document the degree of the associated immune and inflammatory response. Though a midline laparotomy, rats were injected with 5 mg of zymosan (in 0.2 ml of saline) into the subomental space. After 4, 18, 24, 48 and 96 h, a number of endpoints evaluated: intraperitoneal cellular influx, TNF-alpha and interleukin-6 concentrations and myeloperoxidase activity. Bacterial cultures were initiated from the free peritoneal fluid, mesenteric lymph nodes, liver, lung, and kidney. Imprints were also made of the peritoneal mesothelial surface to determine its integrity. When comparing rats injected with zymosan with the controls, there was evidence of a peritoneal inflammatory response within 4 hours. Facultative gram negative bacteria were found to be growing in the mesenteric lymph nodes and in the peritoneal fluid at 48 h. Anaerobic organisms were also cultured from the peritoneal fluid at 48 h. No organisms were cultured from the liver, lung or kidneys. In addition there was a significant increase in intraperitoneal cell numbers (predominantly neutrophils, P < 0.05), myeloperoxidase activity (P < 0.05) and TNF-alpha and IL-6 concentrations (P < 0.05). There was extensive loss of the peritoneal mesothelial cells. The peritoneal inflammatory changes and bacterial translocation had resolved by 96 h. Bacterial translocation can be induced by the presence of an acute inflammatory focus in the peritoneal cavity. The translocation and inflammatory changes were associated with extensive loss of mesothelial cells. Nonetheless, these changes all resolved, indicating that the peritoneal cavity has a significant capacity to deal with such insults. A clearer understanding of the cellular and molecular events involved in the resolution phase could lead to improvements in the treatment of peritonitis.

Promoting detachment of neutrophils adherent to murine postcapillary venules to control inflammation: effect of lipocortin 1.

In this study we investigated, using intravital microscopy, how neutrophil extravasation across mouse mesenteric postcapillary venules is inhibited by the glucocorticoid-regulated protein lipocortin (LC; also termed annexin) 1. Intraperitoneal injection of 1 mg of zymosan into mice induced neutrophil rolling on the activated mesenteric endothelium followed by adhesion (maximal at 2 hr: 5-6 cells per 100-micrometers of vessel length) and emigration (maximal at 4 hr: 8-10 cells per high-powered field). Treatment of mice with human recombinant LC1 (2 mg/kg s.c.) or its mimetic peptide Ac2-26 (13 mg/kg s.c.) did not modify cell rolling but markedly reduced (>/=50%) the degree of neutrophil adhesion and emigration (P < 0.05). Intravenous treatment with peptide Ac2-26 (13 mg/kg) or recombinant human LC1 (0.7-2 mg/kg) promoted detachment of neutrophils adherent to the endothelium 2 hr after zymosan administration, with adherent cells detaching within 4.12 +/- 0.75 min and 2.36 +/- 0.31 min, respectively (n = 20-25 cells). Recruitment of newly adherent cells to the endothelium was unaffected. The structurally related protein LC5 was inactive in this assay, whereas a chimeric molecule constructed from the N terminus of LC1 (49 aa) attached to the core region of LC5 produced cell detachment with kinetics similar to LC1. Removal of adherent neutrophils from activated postcapillary endothelium is a novel pharmacological action, and it is at this site where LC1 and its mimetics operate to down-regulate this aspect of the host inflammatory response.

Regulation of Lysophospholipase Activity of the 85-kDa Phospholipase A2 and Activation in Mouse Peritoneal Macrophages

The regulation of the lysophospholipase activity of the 85-kDa cytosolic phospholipase A2 (PLA2) was studied in vitro and in stimulated macrophages. Bovine serum albumin was found to inhibit lysophospholipase activity of the recombinant 85-kDa PLA2 when assayed at a relatively low substrate concentration. Inhibition could be reversed if the substrate concentration was increased or if Ca2+ was present in the assay. Incubation of recombinant enzyme with macrophage membranes and lipid extracts from macrophage membranes resulted in the release of arachidonic acid, as well as, stearic acid, which is enriched at the sn-1 position of macrophage phospholipids. This suggests that with a bilayer substrate the PLA2 can sequentially deacylate the sn-2 then sn-1 acyl groups. This was verified by demonstrating that the phospholipids, phosphatidylcholine and phosphatidylinositol, were hydrolyzed to glycerophosphocholine and glycerophosphoinositol by incubation with recombinant 85-kDa PLA2. The 85-kDa enzyme was identified as the main lysophospholipase activity in mouse peritoneal macrophage cytosols. Addition of Ca2+ to the assay enhanced activity, but this effect decreased as the substrate concentration was increased. Incubation of macrophages with zymosan increased the lysophospholipase activity of the 85-kDa PLA2 in cytosols. Phosphorylation of recombinant PLA2 with mitogen-activated protein kinase resulted in an increase in lysophospholipase, as well as, PLA2 activity. In macrophages stimulated with zymosan release of stearic acid (18:0) and palmitic acid (16:0) was observed in addition to arachidonic acid (20:4). These results are consistent with a role of the 85-kDa PLA2 in regulating lysophospholipid levels in macrophages during zymosan stimulation.

Selective decontamination of the digestive tract prevents secondary infection of the abdominal cavity, and endotoxemia and mortality in sterile peritonitis in laboratory rats

This study was undertaken to find out whether translocation of bacteria to the abdominal cavity and endotoxemia in rats with sterile peritonitis could be prevented by selective decontamination of the digestive tract. Sterile peritonitis was caused by the intraperitoneal injection of either 100, 150, 200, or 300 mg of zymosan suspended in paraffin. The frequency of infection of the abdominal cavity depended on the dose of zymosan given, ranging from 20% in rats receiving 100 mg to 89% in rats receiving 300 mg of zymosan. In rats not receiving antibiotics for selective decontamination of the digestive tract (the control group). Gram-negative bacilli were isolated from the digestive tract in all rats, and Gram-negative bacilli were isolated from the abdominal cavity in ten of 19 rats. In rats receiving antibiotics for selective decontamination of the digestive tract, Gram-negative bacilli were isolated from the digestive tract in none of the 14 rats, and likewise, Gram-negative bacilli were isolated from the abdominal cavity in none of the 14 rats (p < .005). Moreover, in rats receiving antibiotics for selective decontamination of the digestive tract, endotoxin levels in feces and plasma were significantly lower, as compared with rats not receiving antibiotics for selective decontamination of the digestive tract. Selective decontamination of the digestive tract prevents translocation of Gram-negative bacilli to the abdominal cavity, and endotoxemia and mortality in rats with sterile peritonitis.

Study of the optimal reaction conditions for assay of the mouse alternative complement pathway

The optimal reaction conditions for hemolytic assay of alternative complement pathway activity in mouse serum were investigated. A microtiter system was used, in which a number of 7.5×10 6 rabbit erythrocytes per test well appeared to be optimal. Rabbit erythrocytes were superior as target cells over erythtocytes from a number of other animal species. The optimal conditions were as follows: an incubation temperature of 39°C, an ionic strength of about 200 mM, and a magnesium concentration of 2.5 mM. Incubation during 60 min was not sufficient for an end-point titration. Addition of 1 mg of zymosan A per test well, however, enhanced and accelerated the hemolytic activity of mouse serum via the alternative pathway resulting in a maximum value after 45 min. This, most probably, proceeded by a mechanism involving the formation of a zymosan-C5-convertase and bystander lysis of the target cells. In contrast to the normal alternative pathway assay the zymosan-potentiated test did, most probably, not involve natural antibodies. Cobra venom factor was more efficient in enhancing the sensitivity of the assay for the mouse alternative complement pathway than zymosan. This makes this factor very useful for testing C-pour body fluids.