Decrease In Complement Activity Research Articles

Torque Teno Virus Control by the Classical Pathway of Complement Activation-A Retrospective Analysis From a First-in-Human Trial Utilizing Sutimlimab.

Torque Teno virus (TTV) load is linked with the functionality of its host's immune system and has been proposed as a potential monitoring tool for immune-modulating therapy. However, the immunological mechanisms of TTV control are incompletely understood. To assess the effect of the classical complement pathway on TTV, 64 healthy volunteers and 10 kidney transplant recipients treated with the anti-C1s antibody sutimlimab were analyzed for serum TTV copy numbers (c/mL) by qPCR. Overall, a correlation was observed between the decrease in complement activity caused by sutimlimab and the TTV load increase (ρ = -0.367, p < 0.001). Subgroup analysis indicated a trend toward TTV load increase in healthy volunteers following the highest sutimlimab dose compared to baseline (100 mg/kg body weight; median 3.5 log10 c/mL, interquartile range [IQR] 2.8-4.4 vs. 2.9 log10 c/mL, 0.8-3.5; p = 0.063). Administering multiple lower doses (30 mg/kg) also showed a trend toward TTV load increase in healthy volunteers (1.8 log10 c/mL, 0-2.3 vs. 1.9, 1.3-2.8; p = 0.054) and a significant increase in transplant recipients (3.5 log10 c/mL, 3.0-6.1 vs. 4.1, 3.5-6.4; p = 0.004). This report suggests a role for the classical complement pathway in controlling TTV load.

State of local immune in phegmon of the maxillofacial region and neck on the background local photodynamic therapy

Objective. To study the effect of local photodynamic therapy (PDT) on local immunity in patients with maxillofacial region and neck phlegmonas.Materials and methods. The study included 62 patients with phlegmon of the maxillofacial region and neck. Two groups of patients were formed. Patients of the 1st group were treated locally according to the traditional methods. Patients of the second group additionally underwent local PDT on the background of the complex of traditional therapeutic measures.Results. Under the influence of local PDT with the preparation «Fotolon» in patients with maxillofacial region phlegmonomas in the postoperative wound we observed activation of phagocytosis, an increase in the population of CD3 + T-lymphocytes, subpopulation CD4 + T-helper, immunoregulatory index (IRI) with a simultaneous decrease in the level of CD8 + T-lymphocytes, The decrease of CD25+ activated Tand B-lymphocytes carrying the receptor for interleukin 2, and CD95+ activated Tand B-lymphocytes carrying the Fas-receptor, the decrease of complement activity, circulating immune complexes (CIC), IgM, IgA levels with an increase of IgG.Conclusion. Local PDT activates local immunity in patients with maxillofacial and neck phlegmons. Exposure to PDT causes a more balanced immune system response by increasing the innate immune response in patients and a pronounced immunological reactivity in the region of the postoperative wound.

Profile of antiphospholipid antibodies and complement system in COVID-19 patients of different severity

COVID-19, a severe acute respiratory syndrome caused by SARS-CoV-2, may predispose to thrombotic events, especially when combined with antiphospholipid antibodies (aPL). However, there are limited data on prevalence and antigenic specificity of aPL in COVID-19. Complement activation is assumed to play an important role in pathogenesis of COVID-19-associated coagulopathy. During the SARS-CoV-2 pandemic, it is necessary to identify important biomarkers for predicting severe course of COVID-19 and risk of thrombotic complications. Our objective was to evaluate the aPL profile, quantitative content and activity of complement and its components in COVID-19 patients graded by severity in the course of time. IgM and IgG antibodies to cardiolipin (CL), phosphatidylserine (PS), β2-glycoprotein-I (β2-GP-I), prothrombin (PT), annexin V (An V), as well as C1q complement component, content of its C3 and C4 components and total complement activity were determined in blood serum using ELISA approach. 141 patients with COVID-19 were included in the study. Group 1 consisted of 39 patients with mild form, group 2 (65 patients) presented with moderate form, and group 3 included 37 patients with severe form of COVID-19. Blood samples were obtained on day 3-7 of the disease (1st point) and after 14-28 days (2nd point). The results were as follows: aPL were detected in 29.1% of the total COVID-19 cohort, frequency of aPL detection by the severity grade did not differ (33.3%, 24.6% and 32.4%). In 8.5% of the patients, aPL were detected only at the 1st time point; in 14.2%, only at the 2nd point; and in 6.4% of the cases, at the both time points. Antibodies to PT (16.3%) and An V (11.3%) were revealed more frequently. The detection frequency of antibodies to PT was significantly higher than antibodies to CL and PS (7.1%), β2-GP-I (7.8%). The prevalence of aPL in groups 1 and 3 did not differ. At the 1st point in group 3, increased levels of C4 (89.2%) and C3 (24.3%) in blood, and a decrease in complement activity (35.1%) were more often observed than in group 1. At the 2nd time point in group 3, a decrease in complement activity was often detected (59.5%). The C3 levels exceeding 720 μg/ml were found to predict a 2.6-fold increased risk of severe COVID-19, and this risk became 3.3 times higher at C4 levels of &gt; 740 μg/ml. The antibodies to PT and An V are often detected in COVID-19 patients, along with low prevalence of antibodies to CL and β2-GP-I. These antibodies can be involved in pathogenesis of COVID-19-associated coagulopathy, being detectable at the late stage of the disease, and they may trigger APS in predisposed patients and reconvalescents. Although presence of aPL antibodies is not associated with COVID-19 severity, their persistence over the period of convalescence may be an additional risk factor for thromboembolic complications. The COVID-19 patients are characterized by activation of the complement system, which increases in severe cases, and manifests with increased or decreased levels of C3 complement component, increased levels of C4 component in blood, and a decreased total complement activity. Quantitative determination of C3 and C4 complement components over the period of COVID-19 progression is of prognostic value, with respect to severity of the disease.

Adipose tatty acid composition and gene expression in obesity, and response to chronic marine omega-3 fatty acid supplementation.

AbstractIntroduction:Obesity is an excess of adipose tissue (AT) and is linked with increased inflammation that enhances risk of type-2 diabetes and cardiovascular disease. The BIOCLAIMS study assessed the effect of obesity on AT fatty acid composition and gene expression, and the responses of these to chronic omega-3 FA supplementation.Materials and methods:AT biopsies were collected pre- and post-12 week supplementation with 1.1 g EPA + 0.8 g DHA/day or corn oil. The composition of FA in the total lipid extract of AT from 37 normal-weight and 44 obese subjects was assessed by gas chromatography, whole AT transcriptome from 10 normal-weight and 10 obese subjects was assessed by RNA-Sequencing, and selected gene expression in AT of 27 normal-weight and 38 obese subjects was assessed by qRT-PCR.Results:789 AT genes were differentially expressed (623 upregulated, 175 downregulated) in obesity compared to normal-weight (FC &gt; 2, P &lt; 0.05). Differentially expressed genes included EGFL6, MMP-7 and -9, 5-LOX, WNT3 and WNT10B, DACT2, CNR1, SLC27A2 and PLA2G7, and were associated with immune and inflammatory response, cell proliferation, activation and movement, Wnt signalling, remodelling and expansion, and lipid incorporation and degradation.Chronic supplementation with EPA + DHA increased the concentration of AT EPA, DPA and DHA in normal-weight subjects (P &lt; 0.01), and EPA in obese subjects (P = 0.006). EPA + DHA modulated the expression of 26 genes (14 upregulated, 12 downregulated) in normal-weight subjects and 7 genes (3 upregulated, 5 downregulated) in obese subjects (FC &gt; 2, P &lt; 0.05). Of note, EPA + DHA downregulated IGLV1-44, IGLV1-51, PROK2, and TREM1 in normal weight subjects (P &lt; 0.05), and IGLV1-44, IGLV1-47, DACT2 and IDO1 obese subjects (P &lt; 0.05). Genes of note upregulated by EPA + DHA included KCNH2, GCGR, SLC36A2 and FOXC2 in normal-weight subjects, and MAB21L1, LRRTM4, and COX-2, in obese subjects. Differentially expressed genes were associated with a decrease in complement activation and immunoglobulin secretion, negative regulation of cell proliferation, and positive regulation of remodelling, amino acid and glucose transport, and COX pathway metabolite synthesis.Discussion:These data indicate an altered AT transcription profile and gene expression in obesity suggesting enhanced immune and inflammatory response, tissue expansion and remodelling, and changes to lipid metabolism, as well as dysregulation in response to supplementary EPA + DHA at a gene expression level. EPA + DHA are able to modulate AT gene expression predominantly associated with reducing immune response, but obesity may involve resistance to the effects on tissue remodelling and nutrient transport.

The profile of adsorbed plasma and serum proteins on methacrylic acid copolymer beads: Effect on complement activation.

Polymer beads made of 45% methacrylic acid co methyl methacrylate (MAA beads) promote vascular regenerative responses in contrast to control materials without methacrylic acid (here polymethyl methacrylate beads, PMMA). Invitro and invivo studies suggest that MAA copolymers induce differences in macrophage phenotype and polarization and inflammatory responses, presumably due to protein adsorption differences between the beads. To explore differences in protein adsorption in an unbiased manner, we used high resolution shotgun mass spectrometry to identify and compare proteins that adsorb from human plasma or serum onto MAA and PMMA beads. From plasma, MAA beads adsorbed many complement proteins, such as C1q, C4-related proteins and the complement inhibitor factor H, while PMMA adsorbed proteins, such as albumin, C3 and apolipoproteins. Because of the differences in complement protein adsorption, follow-up studies focused on using ELISA to assess complement activation. When incubated in serum, MAA beads generated significantly lower levels of soluble C5b9 and C3a/C3adesarg in comparison to PMMA beads, indicating a decrease in complement activation with MAA beads. The differences in adsorbed protein on the two materials likely alter subsequent cell-material interactions that ultimately result in different host responses and local vascularization.

AB0088 Activity of Cationic Proteins in Neutrophils, Complement Activity Fnd Circulating Immune Complexes in Systemic Lupus Erythematosus, Rheumatoid Arthritis and Systemic Sleroderma

BackgroundCationic proteins (CP) of neutrophils are characteristically detected in patients with rheumatoid arthritis (RA), and growing evidence suggest that they are involved in disease pathogenesis.ObjectivesWe investigated the concentration of the...

Effect of Transgenic hCD46 Expression During Ex Vivo Xenoperfusion of hCD46/HLA-E Double Transgenic Pig Limbs with Human Blood

Background: To overcome rejection of pig-to-human xenografts, a new founder line with overexpression of human CD46 and HLA-E was analyzed in ex vivo perfusion experiments with respect to complement activation and cytokine responses. Methods: Six forelimbs (2 wild type and 4 hCD46/HLA-E transgenic pigs) were ex vivo perfused with whole, heparin-anticoagulated human blood. Blood samples were analyzed for production of porcine and/or human (p/h) cytokines and complement activation. Total complement activity was assessed by CH50 assay. Tissue samples were stained for deposition of human IgM, MBL, C3b/c, C4b/c, C6 and co-localization of MBL with IgM and C4b/c to determine the role of the lectin pathway of complement activation in xenotransplantation. Results: No hyperacute rejection was observed in this model and extremity perfusions lasted for up to 18 h, irrespective of the presence of the transgenes. Serum levels of p/h cytokines IL1b, IL-6, IL-8, IL-10, as well as sC5b-9 and sC4d were significantly lower in blood perfused through transgenic as compared to wild type limbs. CH50 results revealed early (1h) decrease of complement activity in all limb perfusions. Deposition of hIgM, MBL, C3b/c, C4b/c, and C6 were observed in tissue of wild type limbs, but no C6 deposition was found in transgenic limbs. Co-localization of MBL with IgM and C4b/c was also observed. Conclusion: The terminal pathway of complement activation was down-regulated by transgenic expression of CD46 and was associated with decreased cytokine production. In addition, deposition of MBL and it's co-localization with IgM and C4b/c suggested a role of antibodydependent activation of the lectin pathway of complement activation in xenotransplantation. Overall, this ex vivo perfusion system represents a powerful tool to study the basic mechanisms occurring in the setting of vascularized xenotransplantation and to evaluate the protection from early rejection mechanisms in tissues originating from transgenic pigs.

Microflora of the seminal fluid of healthy men and men suffering from chronic prostatitis syndrome

Chronic prostatitis syndrome (CPS) is a common urologic condition that many clinicians find difficult to diagnose and treat effectively. The information about the composition of the flora of the seminal fluid in healthy men and patients with CPS is limited. The aim of this study was to define the microbial communities present in the seminal fluid of healthy men and patients with CPS and at in vitro detection of decomplementary activity (DCA) phenotypes of isolates along with their comparison with isolates from patients with or without CPS. The bacteriological study was carried out to 48 healthy men and 60 men with CPS. Culture specimens were spread on various selective media. Bacterial DCA was tested by measuring the decrease in complement activity (CH(50)) under the influence of culture supernatants. The most common isolates in both groups were coryneforms, lactobacilli, coagulase-negative staphylococci, micrococci and streptococci. Enterobacteriaceae, enterococci and Staphylococcus aureus were isolated only from the CPS group. The organisms from seminal fluid of healthy men exerted DCA at 3.56 +/- 2.15; 2.47 +/- 1.23 and 4.36 +/- 2.2 anti-CH(50) for staphylococci, micrococci and diphtheroids respectively. The DCA of staphylococci, coryneforms, Enterobacteriaceae, enterococci and micrococci from CPS group were 12.8 +/- 2.1 (p < 0.05), 4.4 +/- 3.6 (p > 0.05), 16.8 +/- 2.1, 7.2 +/- 1.9 and 11.6 +/- 3.3 (p < 0.05) anti-CH(50) respectively. The data obtained in this study testify the microecological disorders in microbiota of seminal fluid in CPS.

Complement activation by diesel exhaust particles (DEP).

The effect of diesel exhaust particles (DEP) on the hemolytic activity of human serum complement was investigated. Previous treatment of human serum with DEP extracts at 37 degrees C decreased the hemolytic activity of human serum complement dose dependently, to 20% of its original value. This decrease in complement activity by DEP extracts was observed with previous incubation at 37 degrees C but not at 4 degrees C. A decrease in complement activity was observed after previous incubation at 37 degrees C in the presence of EGTA/Mg but not in the presence of EDTA, indicating that the alternative pathway of the complement system had been activated by DEP extracts. Activation of the complement system by DEP extracts was further demonstrated by observation of the cleavage of the third component of the complement (C3) in serum to C3b with immunoelectrophoresis using goat anti-human C3 antiserum. This cleavage of C3 was similarly observed in the presence of EGTA/Mg, indicating the activation of the alternative pathway of the complement system by DEP extracts. These results indicate that DEP can activate the alternative pathway of the complement system, resulting in a decrease in the hemolytic activity of complement and in the production of biologically active degradation products of complement proteins such as C3a. The biological significance of the activation of the complement by DEP in the alveolus is discussed in relation to the influx of neutrophiles.

Efficacy of subcutaneous application of live infectious bursal disease vaccine in young chickens with maternally derived antibody.

The infectivity of neutralized IBDV by normal chicken serum (NCS) was detected in day-old and 3-week-old chicken spleen adherent (CSA) cells, and that of neutralized IBDV by maternal antibody (MN-Ab) was detected in 3-week-old CSA cells. Moreover, CSA cells from day-old chickens had complement receptor (CR), and CSA cells from 1-week-old had both CR and Fc receptor (FcR). However, the infectivity of neutralized IBDV by MN-Ab was confirmed on CSA cells which were blocked for FcR on CSA cells by heat-aggregated NCS (56 degrees C, 60 min). These results indicated that infection of neutralized IBDV by NCS on CSA cells occurred via CR, and neutralized IBDV by MN-Ab was infected via FcR. In day-old specific pathogen free (SPF) chickens, the antibody level in NCS treated and non-treated IBD live vaccine subcutaneously inoculated groups was higher than the levels in the MN-Ab-treated IBDV inoculated group, and detected until 28 days old. Moreover, subcutaneously inoculated chickens were protected against the challenge of wild IBDV at 21 days old, whereas subcutaneously inoculated chickens were infected with MN-Ab-treated IBD live vaccine. In commercial layers which had MN-Ab, antibody levels of subcutaneously vaccinated group were higher than both the non-vaccinated and orally vaccinated groups, and virus isolation and viral antigen were positive with high detection rates on peripheral lymphocytes of each subcutaneously vaccinated group of SPF and commercial chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of porcine endothelial cell determinants recognized by human natural antibodies

Abstract: Organs transplanted from pigs to primates are subject to hyperacute rejection. This immunologic reaction is initiated by the recipient's natural antibodies that bind to endothelial cell antigens of the organ, resulting in the activation of the complement system and rapid destruction of the graft. Various lines of evidence, particularly blocking studies, using purified carbohydrates have suggested that the endothelial cell determinant recognized by human natural antibodies is a terminal galactose in an α configuration (α‐Gal). Although these studies are compelling, they fall short of proof because xenoreactive natural antibodies, being polyreactive, might bind to structures other than those used for blocking. Moreover, in vivo evidence that anti‐α‐Gal antibodies participate in hyperacute rejection has not been reported. Here we report that an enzyme specific for α‐Gal, α‐galactosidase, removes α‐galactose residues from both intact porcine aortic endothelial cells and immobilized porcine aortic endothelial cell membrane extracts and that as a result of this, xenoreactive natural antibody binding is lowered by 70 to 80%. This decrease in binding of human IgM causes a corresponding decrease in complement activation. Similar results were obtained using the sera of other Old World primates. Digestion of immobilized porcine aortic endothelial cell membrane extracts with α‐galactosidase produced a similar reduction in human IgM binding to gp 115/135. These results indicate that a terminal α‐galactose is an important component of the gp 115/135 porcine endothelial cell antigen. We also report that perfusion of porcine organs I with primate serum removes anti‐α‐Gal IgM from the serum.

Chemical modification of cellulose membranes with improved blood compatibility

Cellulose membranes markedly promote the complement activation during haemodialysis treatment. The polysaccharide structure with the special arrangement of hydroxyl groups at the anhydroglucose unit can be postulated as a trigger for activation. Therefore the hydroxyl groups localised at the surface of the membrane were masked by heterogeneous derivatisation and grafting with reactive polymers, especially by introduction of polar and/or ionic groups bound covalently on the membrane surface. The chemical treatment, the resulting physico-chemical properties and the blood compatibility of the modified surface are discussed. Membranes modified by the introduction of sulphate, sulphonate and carboxylic groups demonstrated a clear decrease in complement activation (C3a des Arg) in comparison to pure cellulose.

特異的Ｔｈｒｏｍｂｏｘａｎｅ（ＴＸ）Ａ２合成酵素阻害剤（Ｅ）‐３‐〔ｐ‐（１Ｈ‐ｉｍｉｄａｚｏｌ‐１‐ｙｌｍｅｔｈｙｌ）ｐｈｅｎｙｌ〕‐２‐ｐｒｏｐｅｎｏｉｃ ａｃｉｄ（ＯＫＹ‐０４６）の抗アレルギー作用 （第２報） ＩＩ〜ＩＶ型アレルギー反応に対する作用

We studied the effects of OKY-046 on types II, III and IV allergic reactions, as classified by Coombs and Gell. In Type II, OKY-046 at 30-100 mg/kg intraduodenally (i.d.) and at 1-30 mg/kg intravenously (i.v.) inhibited the bronchoconstriction in a dose-dependent manner after Forssman antigen injection. Aspirin (3 mg/kg, i.v.) also suppressed it. OKY-046 (30-100 mg/kg, i.d.) suppressed the increase of TXB2 level in the plasma in a dose-dependent manner. However, there was no effect of OKY-046 and aspirin on the decrease in complement activity (CH50), platelets and leukocytes. Additionally, OKY-046 (300 mg/kg, p.o.) prolonged the survival time following Forssman antigen injection. However, the immune hemolysis reaction was not prevented by OKY-046 (10(-6)-10(-3) M). FUT-175 protected against the Forssman shock at 1 mg/kg, i.v. and the in vitro immune hemolysis reaction at 10(-5) M. In Type III, OKY-046 (300 mg/kg, p.o.) significantly suppressed the direct passive Arthus reaction and immune complex nephritis in rats. There was no effect of OKY-046 on the delayed-type hypersensitive response to picryl chloride in mice. We think that OKY-046 should be a beneficial drug for the treatment of types II and III allergic reactions.

Experimental Bacteroides fragilis Bacteremia in a Primate Model

Experimental Bacteroides fragilis bacteremia was studied in subhuman primates. Following intravenous infusion of viable B. fragilis there was an exponential clearance of organisms from the bloodstream. The major clearance organ was the liver, which accumulated 68.2% of the total inoculum. The most efficient clearance was exhibited by the spleen, with uptake of 1.16% gm tissue. Hemodynamic studies revealed no significant changes in heart rate, mean arterial pressure, or cardiac output following B. fragilis infusion. Complement activity as measured by CH50, alternative pathway hemolytic activity, granulocyte aggregometry, C4, C3, properdin, and Factor B levels were similarly unaffected by infusion of B. fragilis. In contrast, profound hemodynamic changes and a consistent decrease in complement activity was noted after challenge with S. minnesota. The results of this study suggest that B. fragilis bacteremia has a minor role in producing the acute hemodynamic changes associated with the septic shock syndrome.

Nonparticipation of C1q in the decrease of complement activity in the cold in sera of patients with chronic liver diseases.

Serum and plasma samples taken simultaneously from 560 patients with various diseases were examined for hemolytic complement activity (CH50) after incubation at 4 degrees C for 20 h. Serum CH50 titers less than 20 U/ml were observed in 39 cases and among them, a difference between serum and plasma CH50 of more than 5 U/ml were observed in 16 cases. Diagnosis of most of them were chronic liver diseases. To analyze the dissociation of CH50 titers between serum and plasma, sequential estimations of CH50 were performed on serum and plasma samples which showed the dissocation incubated at 4 and 37 degrees C. Marked decrease in CH50 titers was obtained in sera but not in plasma incubated at 4 degrees C. In such sera, however, no significant decrease of protein amount and agglutinating activity of C1q was observed. The result could indicate that C1q would not participate in the decrease of serum hemolytic activity in the cold, suggesting an activation of complement other than the classical pathway.

Changes in activity of some mechanisms of specific and nonspecific immunity in vitamin B1 deficiency

The effect of thiamine deficiency on the immune response and activity of certain mechanisms of natural immunity was studied in adult rats. Thiamine deficiency was simulated experimentally by a single injection of hydroxythiamine, a vitamin B1 antagonist. Administration of hydroxythiamine caused a marked decrease in complement activity, phagocytic activity of the peripheral blood leukocytes, bactericidal activity of the serum, and antibody production in response to immunization with sheep's red blood cells. Conversely, lysozyme activity increased. In vitamin B1 deficiency the intensity of incorporation of [14C]leucine into liver protein synthesis was reduced.

Radiographic contrast media infusions: Measurement of histamine, complement, and fibrin split products and correlation with clinical parameters

To further an understanding of the effects of radiographic contrast media (RCM) infusions, 43 patients underwent clinical evaluation, including allergy history and skin testing, at least 48 hr before receiving a bolus of Renografin-60 (meglumine diatrizoate [52] and sodium diatrizoate [8]) for intravenous pyelography. Venous plasma samples were obtained serially before and at 2, 4, 10, 30, and 60 min after the infusion. Each sample was assayed for histamine by isotopic enzyme assay, for complement by total hemolytic activity, and for fibrin split products by radioimmunoassay. Immediate generalized reactions occurred in 6 of the patients. Each of the 43 patients had a change in at least 1 of the mediators measured. Plasma histamine rose in 40% of the patients (mean, 3.1 ± 1.62 ng/ml). Plasma complement hemolytic activity decreased in 63% (mean, 29 ± 19%). Fibrin split products were detected in 41%. In comparing the 6 patients who experienced reactions to the 37 who did not, there were no statistically significant differences in rise in plasma histamine, decrease in complement activity, presence of fibrin split products, personal history of allergy, prior exposure or reaction to RCM, skin tests to RCM, and histamine or saline. Although histamine levels, complement activity, and fibrin split products changed in a substantial number of patients undergoing RCM infusions, these changes did not correlate with immediate generalized reactions or with the previously described clinical parameters. It is probable that other modulating factors play significant roles in determining whether or not a reaction occurs.

An Investigation of Some of the Factors Determining the Decrease in Complement Activity in Anaphylactic Shock

Summary Guinea pigs actively sensitized to egg albumin mixed with adjuvants developed more acute symptoms of shock and showed a more pronounced and rapid fall in complement titer when challenged intravenously 6 weeks later than did similar groups sensitized to egg albumin without adjuvants. The change in C′ titer tended to be greatest in the guinea pigs exhibiting very severe respiratory symptoms. Fatal protracted shock followed the intraperitoneal injection of large amounts of antigen in highly sensitized guinea pigs, but the decrease in complement activity was usually less pronounced than in the intracardially-challenged animals dying within a 10-minute interval. Actively and passively sensitized guinea pigs in which fatty livers and a marked fall in C′ titer had been induced previously through repeated injection of ethionine, exhibited respiratory symptoms as acute as the sensitized controls. Less severe respiratory symptoms were recorded on challenge in actively-sensitized guinea pigs that had been treated with gum acacia for several weeks to induce low C′ titers; symptoms of initial excitement with subsequent weakness were more conspicuous. In both groups of sensitized guinea pigs, complement titers declined further on challenge. In passively sensitized guinea pigs, challenged soon after intraperitoneal injection of antiserum, the change in C′ titer was negligible, even though some of these animals developed symptoms of slight to moderate shock. A rapid and striking fall in C′ titer occurred in guinea pigs of the same groups that experienced acute shock following intravenous challenge 18 hours to 7 days after injection of antiserum.

Parallel studies of complement and coagulation. IV. Effect of carbon tetrachloride.

To determine whether liver injury would result in a parallel decline in the complement titer and coagulative properties of the blood, groups of guinea pigs were given series of injections of the liver poison, carbon tetrachloride. Marked fatty degeneration of the liver, a decline in total serum protein and albumin, a decrease in complement activity, and a prolongation of coagulation time was observed in the treated animals. A general relationship was noted between the albumin-globulin ratio and the complement titer of the serum and between the complement titer and the coagulation time of the plasma.

Loss of Hemolytic-Complement Activity and of Granulocytes Following Reinjection of an Antigen into the Rabbit

Summary and Conclusions The data obtained in this study support the following conclusions: An abrupt and pronounced reduction of complement follows in 30 to 60 minutes after the reinjection of an antigen into a rabbit. This decrease of complement-activity is probably due to fixation of complement by the complex of extracellular antibody and extracellular antigen in vivo.A similar mechanism possibly is involved in the loss of complement in anaphylaxis and also in serum sickness.The antigen-antibody union may also account for the loss of hemolytic complement in the course of various infectious diseases.The granulocytopenia which generally accompanies the reduction of complement after the reinjection of an antigen appears to be related to anaphylactic and anaphylactoid reactions as well as to an in vivo antigen-antibody reaction. This reaction may however occur in the apparent absence of extracellular antibody.The complement-reduction reaction is well suited for the study of antigen-antibody and hapten-antibody reactions in vivo. It may be used for the detection of extracellular antigen or antibody. It is highly specific and sensitive, apparently not affected by an excess of antigen or antibody, and may require little antigen for its appearance. At present, however, it is not a quantitative method.The granulocytopenic reaction may be useful for the early detection of an anaphylactic type of sensitivity to a given antigen.The granulocytopenic reaction has been observed often in the absence of any cardinal signs of anaphylactic shock.Further study is required to determine the practical significance of the losses of antibodies, complement, and granulocytes during the early part of the so-called negative phase in immunization.