Trypanolytic activity, agglutinins, and opsonins in sera from animals refractory to Trypanosoma lewisi

An examination of sera from a range of animals refractory to Trypanosoma lewisi showed that some contain trypanolytic activity and agglutinins for this trypanosome. Trypanolytic activity was demonstrated in bovine, sheep, and rabbit serum. These sera were shown to also contain agglutinins. The trypanolytic activity in all three sera was abolished by heat inactivation at 56 degrees C for 30 min. Studies with bovine serum showed that the lytic activity was totally inhibited by the addition of EDTA but was only partially inhibited by ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid-Mg2+, suggesting the involvement of both classical and alternate pathways of complement activation. Serum from the natural host, the rat but not mouse serum, was capable of inhibiting the trypanolytic activity of bovine serum. The agglutinins in bovine serum were specific, since they could be adsorbed out with T. lewisi but not T. musculi. They fractionated on gel filtration in the position expected for 19S antibodies. By using opsonization measuring techniques, it was found that mouse serum lacked opsonins to T. lewisi, although opsonic activity was detectable in human serum. The absence of agglutinins, trypanolysins, and opsonins in mouse serum suggests that other factors prevent the infection of mice by T. lewisi. From these findings, it would appear that the inability of T. lewisi to infect a range of mammals, with the exception of mice, could be due to the presence of antibodies, the ability to activate complement through the alternative pathway, or both. The absence of these recognition factors and the ability to evade the effects of alternative pathway activation may be important factors in the ability of this parasite to establish infections in rats.

Serum bactericidal and opsonic activities in patients with non-alcoholic cirrhosis

The increased susceptibility to infection suggests that patients with cirrhosis have abnormalities in host defense mechanisms. In the present study, serum bactericidal and opsonic activity were evaluated in patients with non-alcoholic cirrhosis. Seven (28 per cent) of 25 patients had diminished bactericidal activity and 14 (61 per cent) of 23 were found to have reduced opsonic activity. Serum C3, C4, and CH50 concentrations were significantly low in patients with diminished bactericidal activity. There was a strong correlation between complement levels and bactericidal activity. Deficient bactericidal and opsonic activities may explain the increased susceptibility to infections in patients with cirrhosis.

[Stage-classification of reticuloendothelial function in hepatic injuries in the rat]

The serial changes of RE function were classified into 3 stages according to changes in opsonic activity and phagocytic index in hepatectomized, CCl4-treated cirrhotic rats; enhanced stage, compensating stage and critical stage. The phagocytic index was measured by initial disappearance rate after 4 mg/kg i.v. injection of 51Cr-labelled LPS. An opsonic activity was determined by the bioassay method using cultured RE cells prepared from the normal rat liver. The enhanced stage was characterized by an enhancement in both phagocytic index and opsonic activity--3 to 21 day-70% hepatectomized, 2 to 5 day-40% hepatectomized, 3 week-cirrhotic rats. The compensating stage by increased opsonic activity and normal phagocytic index was 2 day-70% hepatectomized and 9 week-cirrhotic rats. The critical stage by decreased phagocytic index was 5 hour to 1 day-70% hepatectomized, 13 week-cirrhotic rats.

Opsonization of group B Streptococcus type III: studies using clinical strains and maternal sera

Luminol-dependent phagocytic chemiluminescence was used to measure opsonins to group B Streptococcus type III in serum samples from pregnant women. Mean levels were similar amongst patients colonized with this organism and those who were not. Values remained fairly constant for individual women during pregnancy apart from a small, but consistant fall in cord blood samples. Again using luminol-dependent chemiluminescence, 54 clinical isolates of group B Streptococcus type III were evaluated for susceptibility to serum opsonization. Six were found to be resistant and these originated from both colonized babies and babies with systemic GBS infections. Further studies demonstrated strain-to-strain variation in the degree of dependence on both heat-labile and heat-stable opsonins.

NBT-reduction for detection of specific, opsonizing antibodies against haemophilus parainfluenzae

Specific, opsonizing antibodies against Haemophilus parainfluenzae were demonstrated in serum by measuring their enhancing effect on the nitroblue tetrazolium (NBT)-reduction of normal human granulocytes, phagocytizing the homologous bacteria. Patients with septicemia and/or endocarditis and carriers of H. parainfluenzae were studied. In late phase sera of the first group such antibodies were detected in 6 of 9 cases. Opsonizing antibodies against H. parainfluenzae were not detected in any of the carrier sera. A dose-response effect was observed when a positive late phase serum was tested in serial 2-fold dilutions. The enhancement of the NBT-reduction was eliminated by absorption of serum with homologous antigen. The detection of opsonizing antibodies, essential for the immune defense against H. parainfluenzae might be helpful for evaluation of the pathogenicity of this organism, which so far is considered as a rare causative agent.

Serum opsonic activity after immunization of adults with Haemophilus influenzae type b-diphtheria toxoid conjugate vaccine

We measured the uptake of radiolabeled Haemophilus influenzae type b by human polymorphonuclear leukocytes. Haemophilus influenzae type b strains were preopsonized in individual sera from six adults immunized with type b polysaccharide vaccine (PRP) or six adults immunized with PRP covalently coupled to diphtheria toxoid (PRP-D vaccine). Serum was heat inactivated before use, and exogenous human complement was added. Of the 12 subjects, 3 had high levels of opsonic activity (greater than 40% of immune control) in their preimmunization serum. This activity did not correlate with the concentrations of anti-PRP antibody and was unaffected by absorption of anti-PRP antibody. At 1 month after vaccination, the serum of PRP-D subjects had higher opsonic activity than that from subjects who received PRP (5% serum, mean PRP-D = 86%, mean PRP = 53%, P = 0.001). After 12 months, both groups had higher serum opsonic activity than before immunization (P less than 0.02), but there was no difference between the two groups (mean PRP-D = 48%, mean PRP = 51%). In postimmunization serum, opsonic activity induced by PRP-D or PRP vaccines correlated directly with anti-PRP antibody concentrations as measured by a radioantigen binding assay. We conclude that both vaccines induce opsonic activity, opsonic activity induced by immunization of adults correlates well with the concentration of anti-PRP antibody achieved, and in preimmune sera with low concentrations of anti-PRP antibody, factors other than anti-PRP antibody contribute to opsonic activity.

A new assay for fibronectin opsonic activity and its application to plasma and plasma fractions

A homologous assay system for human plasma fibronectin opsonic activity is presented. The system utilizes peripheral leukocytes purified from leukocyte concentrates and a metabolizable, radiolabeled lipid emulsion which has been gelatin-coated. The uptake of radiolabeled lipid was shown to depend on the presence of fibronectin and was stimulated by the addition of heparin. Both polymorphonuclear leukocytes (PMNs) and monocytes were active in this system. That at least a portion of the incorporated radiolabeled lipid emulsion was phagocytosed was indicated through the use of metabolic inhibitors, trypsin, and direct electron microscopic observation. This assay was applied to the analysis of donor plasma and plasma fractions. Opsonic activity levels measured with this assay system were shown to correlate (p = 0.05) with the level of fibronectin antigen in 17 samples of dialyzed normal donor plasma. Fibronectin opsonic activity was retained by outdated liquid plasma, cryo-depleted plasma, and cryoprecipitate; however, Cohn fraction I appeared to lose considerable fibronectin opsonic activity relative to fibronectin antigen.

Impairment of opsonic function in children with hematologic malignancy during remission induction therapy

The activity of complement-mediated opsonin was measured by the whole blood chemiluminescence method in 17 children with hematologic malignancy (including 6 with ALL, 7 with ANLL and 4 with non-Hodgkin's lymphoma) during remission induction therapy. The activity of opsonin, which was at the normal level before chemotherapy, decreased in all of the children during the therapy. This phenomenon was especially marked in the children treated with L-asparaginase. Although no clear relationship was found between the decrease in opsonin activity and the susceptibility to infection, it was confirmed that in 4 children having an episode of sepsis or septic fever, the infection started when the granulocyte decreased to the nadir, and simultaneously the activity of opsonin decreased. Therefore, it may be reasonable to suspect the decrease in opsonin activity when treating children with such infections.

Monocyte function following surgery in man. Increased numbers and stimulation of migration, phagocytosis and chemiluminescence following abdominal surgery

The whole blood monocyte count (WBMC), migratory response (MMR), phagocytosis (MPI), chemiluminescence (MCL) and serum opsonic activity (SOA) were measured in patients undergoing elective surgery. The WBMC, MMR, MPI and MCL increased significantly at 24 h after operation in patients undergoing abdominal surgery with a moderate fall at 48 h and a return to normal values at 1 week; the SOA was little altered. In patients undergoing minor surgery the WBMC was also increased after surgery but the MMR was unchanged. The finding that certain monocyte functions are increased after surgery contrasts with studies showing that reticulo-endothelial clearance is depressed in the post-operative period.

Mechanisms of Action of Two New Immunomodulators

Despite antibiotics, infection remains a significant problem in surgical patients. The reasons are multiple, and include acquired immunologic deficiencies that are seen in malnutrition, sepsis, trauma, and burns. Two immunomodulators, thymopentin (TP-5) and CP-46,665, have been shown to improve survival in infectious animal models of such deficiencies. We investigated the mechanism of action in guinea pigs subjected to a burn of 30% of the total body surface area. These animals received 0.3 mg/kg of thymopentin, 0.3 mg/kg of CP-46,665, or saline solution. Neutrophils, macrophages, and serum samples were obtained from the animals and tested for their ability to phagocytose and kill Pseudomonas aeruginosa. The serum was tested for its ability to opsonize Escherichia coli. Thymopentin was found to improve neutrophil function on postburn days 2 and 4 and to improve macrophage function on postburn day 4. CP-46,665 was found to improve both macrophage function and opsonization on postburn day 2.

Opsonic activity of immunoglobulin prepared for intravenous use

The opsonic activity of two immunoglobulin preparations modified for intravenous infusion was tested against Streptococcus pneumoniae types 3, 7F, and 14 and two strains of Staphylococcus aureus by polymorphonuclear leukocyte uptake of 3H-thymidine-labeled bacteria. Reduced and alkylated immunoglobulin (Chem-IgG) and immunoglobulin prepared by chromatography with diethylaminoethyl-Sephadex (DEAE-IgG) were evaluated with and without complement and compared with the opsonic activity of immune serum globulin and heated pooled human serum. Opsonic activity of DEAE-IgG was greater than that of Chem-IgG and equivalent to the activity of immune serum globulin and pooled human serum against S. aureus 502A and type 3 pneumococcus. Both intravenous immunoglobulins had lower opsonic activity than either pooled human serum or immune serum globulin against type 14 pneumococcus. There were no differences in antibody avidity for pneumococcal antigen among the immunoglobulins tested. All four opsonins had similar opsonic activity against the protein A-deficient S. aureus Wood 46. Modification of immunoglobulin for intravenous infusion by chemical alteration may adversely affect opsonic activity by changing the Fc portion of the antibody molecule.

Preparation of antihemophilic factor and fibronectin from human plasma cryoprecipitate

Starting with human plasma cryoprecipitate, fibronectin was separated from antihemophilic factor (AHF) by fractional precipitation under mild conditions resulting in excellent recovery of AHF in the supernatant solution of the cryoprecipitate. Separation of fibronectin enabled accelerated sterile filtration of the supernatant solution containing AHF even after three- to fourfold concentration (by ultrafiltration) to desired potency. The sterile AHF concentrate, dispensed at 1000 u per vial and lyophilized, was completely dissolved within 3 minutes upon addition of 30 ml of pure water. The expected increment in circulating factor VIII and its hemostatic effects were found following intravenous infusion into factor VIII-deficient patients. Yield of AHF of five successive batches, each starting with the cryoprecipitate from some 12,000 units of fresh-frozen plasma, averaged 51 percent. The fibronectin precipitate was purified by affinity on insolubilized gelatin with chaotropic elution at pH 5.5 followed by removal of the chaotrope by diafiltration. Thermal denaturation of adventitious fibrinogen resulted in electrophoretically pure fibronectin which, following lyophilization and reconstitution with pure water, retained biological properties in an in vitro assay designed to reflect opsonic activity. The yield of fibronectin for seven successive batches, each starting with the cryoprecipitate from some 900 units of fresh-frozen plasma, averaged 10 percent.

Proteins of the cystic fibrosis respiratory tract. Fragmented immunoglobulin G opsonic antibody causing defective opsonophagocytosis

In the disease cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a common clinical complication that determines most morbidity and almost all excess mortality. We postulated that in this disease a defect in Pseudomonas-reactive IgG antibodies may contribute to chronic Pseudomonas infections. Bronchoalveolar lavages were performed upon 13 patients with CF, 7 patients with chronic bronchitis characterized by recurrent Pseudomonas infections, and 4 normal volunteers. The levels of various proteins important to host defenses and proteases were determined; enzyme inhibition studies were performed. CF respiratory immunoglobulin levels were significantly elevated when compared with both normals and patients with chronic bronchitis (P less than 0.05). Albumin and transferrin levels were decreased in the CF lung fluids. CF elastolytic activity was strikingly elevated (means = 6.02 micrograms/mg total protein) and the inhibitory profile suggested such activity resembled a serine-proteinase. Alpha-1-antitrypsin antigenic levels were not altered in CF respiratory fluids. There was a tendency for the lavage IgG to fall as elastase levels rose (r = -0.29). IgG opsonins for two Pseudomonas immunotypes were isolated with affinity chromatography for functional and immunochemical studies. Bacterial phagocytic rates in the presence of these Pseudomonas-reactive IgG opsonins derived from CF lavage fluid were depressed (0.3% uptake/unit time) when compared with similarly titered positive controls (uptake = 1.3%/unit time, P less than 0.001). Additionally, normal pulmonary macrophage intracellular killing of Pseudomonas was severely altered in the presence of opsonins derived from CF respiratory fluids. At some time points, less than 30% of the bacteria were killed. CF IgG opsonins contain a cleavage fragment (100,000 D, 5S sedimentation coefficient) with antigenic determinants similar to the Fab portion of IgG. The presence of such a fragment was inversely correlated with phagocytic functional activity. Intact IgG comprised as little as 18% of the CF lavage fluid specimens. Aliquots of intact human IgG, when mixed with the CF opsonins, augmented Pseudomonas uptake and improved intracellular killing. Conversely, peptide fragments of IgG opsonins, which are proteolytically derived in vitro, duplicated in our system the defect observed with opsonins derived from CF lung fluids; bacterial uptake was inversely related to the concentration of F(ab')2 and to a greater degree, to Fc present in the opsonic mixture. We concluded that IgG respiratory opsonins are fragmented, inhibiting phagocytosis and serving a permissive role in the chronic Pseudomonas pulmonary infection in the disease CF.

Decreased plasma fibronectin during starvation in man

This study evaluated the effect of 5 days of starvation followed by 5 days of refeeding on immunoreactive plasma and serum fibronectin and associated opsonic activity as studied by peritoneal macrophage monolayer bioassay in 12 healthy women volunteers. The temporal alteration of fibronectin was compared with the serum albumin, total iron-binding capacity, and retinol-binding protein levels. Fibronectin concentration and opsonic activity were also determined in two cachectic patients who were 61 and 78% of their ideal body weight. Prior to starvation, plasma fibronectin was 292 +/- 20 micrograms/ml and serum fibronectin was 182 +/- 16 in all subjects. After 5 days of starvation, immunoreactive fibronectin decreased (p less than 0.05) by 20-25%. This decrease was not great enough to impair opsonic activity as tested by the in vitro macrophage assay. Starvation caused no decrease in serum albumin or total iron-binding capacity, although retinol-binding protein decreased by 35%. During refeeding, subjects were randomized to a diet with (n = 6) and without (n = 6) carbohydrate. After 5 days of refeeding, fibronectin levels were normalized on the carbohydrate-containing diet, but were still low (82% of normal) on the carbohydrate-free diet. Retinol-binding protein did not fully normalize after 5 days of refeeding. In the two cachectic patients, fibronectin levels prior to total parenteral nutrition were 25 and 75% of normal. Thus, starvation can lower fibronectin levels and this protein is rapidly restored with adequate nutrition.

[Radionuclide study of reticuloendothelial system function]

The authors propose a new method for the interpretation of the measurement data obtained during radionuclide investigations of the function of the reticuloendothelial system (RES). This method is upon the concept of a considerable effect of the blood opsonizing factor on the transport of i.v. injected radioactive colloid in the body. A non-linear compartmental model was developed that describes the binding of colloid particles with opsonins in the vascular bed followed by absorption of the particles of the colloid-opsonin complex by RES cells. The identification of the parameters of the non-linear model by the results of dynamic scintigraphy of the heart and liver makes it possible to explain some phenomena in the measurement data and to assess the relative amount of opsonins in the blood and RES phagocytic activity as a whole and its constituents. It was shown in particular in the studies on patients with hepatocirrhosis that the amount of opsonins in the blood remains almost the same as compared to the normal one whereas the phagocytic activity of RES on the whole, hepatic stellate cells and RES extrahepatic cells decreases significantly.

Opsonic deficiency of peritoneal dialysis effluent in continuous ambulatory peritoneal dialysis

Staphylococcus epidermidis peritonitis frequently complicates the clinical course of patients treated with continuous ambulatory peritoneal dialysis (CAPD). Since bacterial opsonization is critical to the effective defense of the peritoneal cavity by phagocytic cells, we prospectively evaluated the opsonic activity of peritoneal dialysis effluent obtained from 17 CAPD patients during 102 patient months. Samples of peritoneal dialysis effluent contained concentrations of opsonins against S. epidermidis that were less than 2% of that observed in serum. Moreover, heat-labile opsonic activity against Escherichia coli was absent from all dialysis effluents. During the study, there were ten episodes of peritonitis in nine CAPD patients (1 per 10.2 patient months). S. epidermidis was isolated in seven episodes, a gram-negative bacillus in one, and two episodes were culture negative. the incidence of S. epidermidis peritonitis was 1 per 62 patient months in the patients with "high" peritoneal dialysis effluent opsonic activity against S. epidermidis but was nearly tenfold greater in patients with "low" opsonic activity (1 per 6.7 patient months). We conclude that peritoneal dialysis effluent opsonic activity predicts which CAPD patients are at an increased risk to develop S. epidermidis peritonitis.

Localization on encapsulated Cryptococcus neoformans of serum components opsonic for phagocytosis by macrophages and neutrophils

Previous studies have shown that the cryptococcal capsule inhibits phagocytosis of Cryptococcus neoformans by macrophages and neutrophils. In this study, the binding sites of potential serum opsonins in immune and nonimmune sera were determined by immunoelectron microscopy, and the results were compared with the results of phagocytosis of the yeasts by mouse peritoneal macrophages and human neutrophils. Immunoglobulin G (IgG) from normal human serum showed low-density binding at the capsular surface and at sites throughout the capsule. Complement component C3 from normal serum bound heavily at the capsular surface. IgG from rabbit capsular antiserum showed relatively dense deposition at the capsular surface and at sites throughout the capsule. Cells opsonized with heat-inactivated human serum were engulfed poorly by both macrophages and neutrophils, indicating that the low-density deposition of IgG produced by normal serum was not adequate for opsonization. Yeasts opsonized with normal human serum were engulfed in large numbers by neutrophils and to a lesser extent by macrophages, indicating that neutrophils in particular were able to effectively utilize the opsonically active C3 which normal human serum deposited at the capsular surface. Yeasts opsonized with rabbit anticapsular serum were engulfed by both macrophages and neutrophils, indicating that the high density of surface IgG produced by capsular antiserum is an effective opsonin for both cells. These results suggest that the complement-neutrophil system is a possible defense mechanism in the nonimmune host.