Time-dependent changes in opsonin amount associated on nanoparticles alter their hepatic uptake characteristics

The relationship between the time-dependent change in serum proteins adsorbed on nanoparticles and their disposition to the liver was investigated by employing lecithin-coated polystyrene nanosphere with a size of 50 nm (LNS-50) as a model nanoparticle in rats. The total amount of proteins adsorbed on LNS-50 increased and the qualitative profile of serum proteins adsorbed on LNS-50 changed during the incubation with serum up to 360 min. The liver perfusion study indicated that the hepatic uptake of LNS-50 incubated with serum for 360 min was significantly larger than those of LNS-50 incubated for shorter period. It was suggested that the increase in the hepatic uptake of LNS-50 with the increase in incubation time would be ascribed mainly to the increase in the opsonin-mediated uptake by Kupffer cells. Semi-quantification of major opsonins, complement C3 (C3) and immunoglobulin G (IgG), and in vitro uptake study in primary cultured Kupffer cells demonstrated that the increase in C3 and IgG amounts adsorbed on LNS-50 was directly reflected in the increased disposition of LNS-50 to Kupffer cells. These results indicate that the amounts of opsonins associated on nanoparticles would change over time and this process would be substantially reflected in the alteration of their hepatic disposition characteristics.

Lung fluid immunoglobulin from HIV-infected subjects has impaired opsonic function against pneumococci

BACKGROUND

The incidence of pneumococcal pneumonia is greatly increased among human immunodeficiency virus (HIV)-infected subjects, compared with among non-HIV-infected subjects. Lung fluid levels of immunoglobulin G (IgG) specific for pneumococcal capsular polysaccharide are not reduced in HIV-infected subjects; therefore, we examined immunoglobulin subtypes and compared lung fluid IgG opsonic function in HIV-infected subjects with that in healthy subjects.

METHODS

Bronchoalveolar lavage (BAL) fluid and serum samples were collected from 23 HIV-infected and 26 uninfected subjects. None of the subjects were receiving highly active antiretroviral therapy, and none had received pneumococcal vaccination. Pneumococcal capsule-specific IgG levels in serum and BAL fluid were measured by enzyme-linked immunosorbent assay, and IgG was concentrated from 40 mL of BAL fluid. Opsonization and opsonophagocytosis of pneumococci with serum, BAL fluid, and BAL IgG were compared between HIV-infected subjects and healthy subjects.

RESULTS

The effect of type 1 pneumococcal capsular polysaccharide-specific IgG in opsonizing of pneumococci was significantly less using both serum and BAL IgG from HIV-infected subjects, compared with serum and BAL IgG from healthy subjects (mean level, 8.9 fluorescence units [95% confidence interval, 8.1-9.7 fluorescence units] vs. 12.1 fluorescence units [95% confidence interval, 9.7-15.2 fluorescence units]; P=.002 for lung BAL IgG). The opsonophagocytosis of pneumococci observed using BAL IgG from HIV-infected subjects was significantly less than that observed using BAL IgG from healthy subjects (37 fluorescence units per ng of IgG [95% confidence interval, 25-53 fluorescence units per ng of IgG] vs. 127 fluorescence units per ng of IgG [95% confidence interval, 109-145 fluorescence units per ng of IgG]; P<.001).

CONCLUSION

HIV infection is associated with decreased antipneumococcal opsonic function in BAL fluid and serum.

Development and validation of a fourfold multiplexed opsonization assay (MOPA4) for pneumococcal antibodies

Opsonophagocytic killing assays (OPAs) are essential for developing and improving pneumococcal vaccines. There is a need for a high-throughput, reliable, standardized, and fully characterized OPA for pneumococcal antibodies. To meet the need, we have developed and characterized a fourfold multiplexed OPA (MOPA4) against 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) of pneumococci. Thirteen target bacteria were made resistant to only one of the following antibiotics: optochin, streptomycin, spectinomycin, and trimethoprim. Following optimization of assay conditions, accuracy of MOPA4 was determined by testing 30 sera from old adults in the MOPA4 and the single-serotype assays. The opsonization titers obtained with both assays agreed well (r(2) > 0.95). Although 22 (out of 390; approximately 6%) results differed more than twofold, the differences were not reproducible. The assay was specific: preabsorbing test sera with homologous polysaccharide (PS) completely abrogated opsonic activity, but a pool of unrelated PS (5 mug/ml of each) had no effect. Intra- and interassay coefficients of variation were 10 and 22%, respectively. MOPA4 results were unaffected by having different target pneumococcal serotypes in each assay group. Also, HL60 cell-to-bacteria ratios could be varied twofold without affecting the results. We conclude that MOPA4 is sensitive, accurate, specific, precise, and robust enough for large-scale clinical studies. Furthermore, MOPA4 should allow evaluation of multivalent pneumococcal vaccines with the limited volume of serum typically available from young children.

Priming of immunological memory by pneumococcal conjugate vaccine in children unresponsive to 23-valent polysaccharide pneumococcal vaccine

Pneumococcal polysaccharide vaccine (PPV) is of limited immunogenicity in infants and immunocompromised patients. Our prospective randomized controlled trial investigated whether priming with pneumococcal conjugate vaccine (PCV) induced specific immunological memory in previously nonresponders to PPV. Of a total of 33 children (2 to 18 years) with polysaccharide-specific immunodeficiency (PSI), group A (n = 16) received two doses of 7-valent PCV in a 4- to 6-week interval, and a booster dose of 23-valent PPV after one year. Group B (n = 17) received two doses of PPV in a 1-year interval exclusively. Specific antibody concentrations for serotypes 4, 5, 6B, 9V, 14, 18C, 19F, and 23F were determined (enzyme-linked immunosorbent assay) before and at 7 and 28 days after administration of the PPV booster and compared to an opsonophagocytosis assay. Of group A, 64 to 100% had antibody concentrations of > or = 1 microg/ml on day 28 after the booster versus 25 to 94% of group B. Group A had significantly higher antibody concentrations for all PCV-containing serotypes already on day 7, indicating early memory response. Antibody concentrations were in accordance with functional opsonic activity, although opsonic titers varied among individuals. Pneumococcal vaccination was well tolerated. The incidence of airway infections was reduced after priming with PCV (10/year for group A versus 15/year for group B). Following a PPV booster, even patients primarily not responding to PPV showed a rapid and more pronounced memory response after priming with PCV.

Multiplex opsonophagocytosis assay (MOPA): a useful tool for the monitoring of the 7-valent pneumococcal conjugate vaccine

Pneumococcal conjugate vaccination is highly efficacious against invasive diseases in young children. Since host protection is mainly mediated by opsonin-dependent phagocytosis, the in vitro measurement of opsonophagocytic activity of the anti-capsular antibodies is assumed to be a reliable correlate of protection to monitor vaccine efficacy. Unfortunately, the methods used so far are all tedious to perform and material-consuming. Therefore, we modified the multi-specificity opsonophagocytosis killing assay (MSOPKA) into a high-throughput method, which simultaneously measures the opsonophagocytosis against the seven serotypes covered by the current conjugate vaccine in a single assay. In the so-called multiplex opsonophagocytosis assay (MOPA), a mixture containing equal numbers of colony forming units (CFUs) of chloramphenicol-resistant serotype 4, spectinomycin-resistant serotype 6B, streptomycin-resistant serotype 9V, erythromycin-resistant serotype 14, rifampicin-resistant serotype 18C, tetracycline-resistant serotype 19F, and trimethoprim-resistant serotype 23F pneumococci was used as a target mixture and incubated with serial dilutions of test serum. After opsonophagocytosis by differentiated HL-60 cells in the presence of complement, the samples were spotted onto different blood agar plates containing the seven selective antibiotics, respectively. Opsonophagocytosis was calculated as the highest serum dilution resulting in 90% or more reduction in CFUs. The data obtained by this assay correlated well with the data obtained by the MSOPKA. In conclusion, the MOPA simultaneously measures opsonophagocytosis capacity of serum against the capsular serotypes included in the 7-valent pneumococcal conjugate vaccine in a high-throughput fashion, requiring low volumes of patient sera.

Safety and immunogenicity of a booster dose of Staphylococcus aureus types 5 and 8 capsular polysaccharide conjugate vaccine (StaphVAX®) in hemodialysis patients

StaphVAX, an unadjuvanted, bivalent vaccine composed of Staphylococcus aureus (S. aureus) capsular polysaccharides (CPS) types 5 and 8 bound to the mutant non-toxic recombinant Pseudomonas aeruginosa exotoxin A (rEPA) conferred approximately 60% protection for 10 months against bacteremia caused by this pathogen in hemodialysis patients. A protective level of 80 microg/ml was estimated based upon geometric mean (GM) antibody levels at the end of the efficacy period. To extend the duration of protection conferred by StaphVAX in hemodialysis patients, recipients of the vaccine were reinjected in a randomized double-blinded, placebo-controlled study. Vaccinees received StaphVAX and a saline placebo injection 14 days apart according to the randomization schedule. The booster dose of StaphVAX was administered an average of 958 days (753-1167 days) after the first injection. There were no serious adverse reactions. Antibody levels at day 14, 28, 92, and 182 post-injection were measured by ELISA. Maximal levels of IgG anti-CPS were observed at the 28-day interval. For type 5, GM antibody levels increased from 73 microg/ml at day 0 to 162 microg/ml (P < 0.001) and for type 8 from 59 microg/ml to 133 microg/ml (P < 0.001). Anti-CPS antibody levels of approximately 80 microg/ml to type 5 and type 8 were achieved in 72.4 and 74.3% of vaccinees, respectively. There was excellent correlation between the level of anti-CPS and opsonic titer (r = 0.93). Moreover, the decline of anti-CPS antibody levels at six months was significantly less rapid than that observed from the first immunization (P < 0.001). We conclude that a booster immunization to maintain protective levels of specific antibodies for an extended period of time is feasible for patients at continuous risk for S. aureus bacteremia.

Low complement levels and opsonic activity in hepatic hydrothorax: its relationship with spontaneous bacterial empyema

GOALS

To analyze the pleural fluid factors that might cause spontaneous bacterial empyema (SBEM) in patients with cirrhotic hydrothorax.

BACKGROUND

Pathogenic mechanism of SBEM of cirrhotic patients is probably similar to that of spontaneous bacterial peritonitis, but local factors affecting pleural fluid have not been studied.

STUDY

Determination of C3, C4, and opsonic activity levels of pleural fluid in a cohort of patients with pleural effusions of different causes.

RESULTS

Forty-eight patients had hepatic hydrothorax; 8, heart failure and 45, exudates (9, tuberculosis; 21, malignancies; 10, other). Of the 48 cirrhotic patients, 15 developed SBEM on admission. The pleural fluid of cirrhotic patients showed significantly lower levels of total protein, complement, and opsonic activity than did the fluids of patients with other causes of SBEM. Patients who developed SBEM had lower concentrations of pleural fluid total protein and C3 and had a higher Child-Pugh score than patients who did not develop the infection.

CONCLUSION

Cirrhotic patients with hepatic hydrothorax have lower pleural fluid opsonic activity and C3 levels than those found in the pleural fluid of patients with other causes. Patients who develop SBEM have lower levels of pleural fluid C3, pleural fluid total protein, and a higher Child-Pugh score than those who do not develop SBEM.

The use of 7-amino-actinomycin D in the analysis of Candida albicans phagocytosis and opsonization

We describe the use of 7-amino-actinomycin D (7AAD) to measure phagocytosis and the opsonizing capacity of serum. Heat-inactivated Candida albicans was previously stained with 7AAD and incubated with resident peritoneal macrophages. The samples were analyzed by flow cytometry and phagocytic cells were identified by their bright red fluorescence. This is a rapid, reproducible and reliable one-step procedure and provides a means of evaluating low levels of phagocytosis.

Receptors involved in the phagocytosis of senescent and diamide-oxidized human RBCs

BACKGROUND

Senescent RBCs bear IgG and C3 opsonins that are three to four times less than required for similar phagocytosis of experimentally opsonized RBCs.

STUDY DESIGN AND METHODS

Studies were performed to determine the phagocyte receptors involved in phagocytosis in vitro. The effect of clustering of opsonins and oxidative damage in the sequestration of RBCs was studied by exposing RBCs to BS3 (bis[sulfosuccinimidyl]-suberate) and diamide (azodicarboxylic acid bis[dimethyl-amide]).

RESULTS

Sequestration of senescent RBCs was inhibited by the treatment of lymphokine-activated monocytes with N-acetyl-D-galactoseamine (GalNAc), arginine-glycine-aspartic acid (RGD), or antibodies to CR3, FcgammaRI, FcgammaRII, leukocyte response integrin (LRI), and integrin-associated protein (IAP). Exposure to BS3 alone did not enhance phagocytosis. The addition of serum resulted in opsonin binding. The level of opsonization required for sequestration was higher than on senescent RBCs and was only marginally inhibited by blocking CR3, FcgammaRI and FcgammaRII. Diamide treatment alone did not lead to sequestration. Diamide-treated RBCs exposed to serum bound opsonin much as did senescent RBCs, and sequestration was inhibited by GalNAc, RGD, and antibodies to CR3, FcgammaRI, FcgammaRII, LRI, and IAP.

CONCLUSION

Membrane alterations resulting in the binding of opsonins and the sequestration of senescent RBCs may be similar to those that occur on diamide-oxidized RBCs. They suggest the need for cooperative events among oxidation, clustering and cross-linking, and serum opsonization.

Fc(alpha) receptor I (CD89) on neutrophils in periodontal lesions

AIMS

In this study, we have examined the occurrence of FcalphaRI-bearing cells in gingival tissue, gingival fluid and blood, in search for possible roles of IgA and FcalphaRI in periodontal lesions.

METHODS

Gingival biopsies from inflamed and healthy sites were obtained from patients with chronic marginal periodontitis. Sections of inflamed gingiva were examined by immunofluorescence techniques and compared to sections from healthy sites. Smears were made from blood and gingival crevicular fluid and similarly studied.

RESULTS

Dense infiltrates of neutrophils with strong expression of FcalphaRI (and FcgammaRIII) were found in connective tissue and epithelium of the apical part of periodontal pockets from diseased sites. In contrast, only few such cells were found in healthy gingiva from the same patients. Neutrophils in gingival fluid, tissue and blood expressed FcalphaRI with similar intensity, whereas the expression of FcgammaRIII was significantly decreased in gingival crevicular fluid. Considerable numbers of bacteria from gingival plaque were found to be covered by IgA.

CONCLUSION

It is suggested that FcalphaRI on neutrophils may play an important rôle in elimination of IgA-opsonized bacteria, both in periodontal tissue and the adjacent pockets.

Assessment of phagocytic capacity and opsonic activity in blood and mammary secretions during lactation in sows

The objective of this study was to determine whether phagocytic capacity and opsonic activity in blood and mammary secretions of sows are impaired at parturition compared with later on during lactation. The study comprised eight primiparous sows (Landrace x Yorkshire) free from clinical signs of disease. Blood and mammary secretion samples were collected within 48 h of parturition and 7 and 16 days after parturition. Numbers and proportion of polymorphonuclear neutrophils (PMN) were determined in blood and mammary secretions. Phagocytic capacity was assessed in whole blood and in a cell suspension derived from mammary secretions. Opsonic activity was assessed in serum and i cell-depleted, skimmed mammary secretions. The two assays were based on chemiluminescence, both having zymosan and Escherichia coli as target particles. Numbers and proportion of PMN in mammary secretions were higher (P < 0.05) at parturition than later on during lactation. A parturition, phagocytic capacity in cell suspensions derived from mammary secretions was higher for both (P < 0.05) and E. coli (P < 0.1). However, when phagocytic capacity was related to the number of PMN in the suspension no such difference was observed. The opsonic activity in cell-depleted, skimmed mammary secretions at parturition was lower (P < 0.05) for zymosan but not for E. coli. None of the described variations were reflected in blood or serum. The findings of this study do not unequivocally support the theory that an immune suppression at parturition in the sow can help explain the increased incidence of coliform mastitis at that time.

The effect of mannan-binding lectin on opsonophagocytosis of Neisseria meningitidis

Mannan-binding lectin (MBL), an acute phase protein with a structure and a function very similar to that of C1q, is known to act as an opsonin binding to a number of microorganisms. In order to investigate the effect of MBL on the phagocytic killing of meningococci, a serogroup B meningococcal strain (H44/76) and its unencapsulated variant v24, as well as a serogroup A meningococcal strain were opsonized with MBL (purified from normal human plasma at the State Serum Institute, Denmark) and used in a phagocytic killing assay at a density of 7 x 10(3) CFU/ml. Polymorphonuclear cells (PMNs) from one healthy donor were isolated by density gradient centrifugation over Percoll and added to the system (7 x 10(6) cells/ml). In a first set of experiments without addition of serum or complement, no influence of MBL was observed on the killing of any of these strains. Addition of MBL to non-opsonized bacteria of the serogroup A strain did not result in enhanced killing either; on the contrary, the growth of this strain increased significantly when a high MBL concentration (40 micrograms/ml) was used in the presence of PMNs. Further investigations were performed using sera of five individuals with late complement component deficiency (LCCD) and a concomitant MBL deficiency, vaccinated with a tetra-valent (ACYW135) meningococcal capsular polysaccharide vaccine. Pre- and post-vaccination sera (50% final concentration) were tested against a group A strain opsonized or not with MBL. In only one patient was there a moderate increase of killing of the opsonized bacteria after vaccination compared to pre-vaccination serum. Our results suggest that MBL may not play a significant role in the opsonophagocytosis of meningococci, irrespective of its binding to unencapsulated and serogroup A strains.

Occurrences, immunoglobulin classes, and biological activities of antibodies in normal human serum that are reactive with Cryptococcus neoformans glucuronoxylomannan

Serum obtained from normal human subjects contains antibodies reactive in an enzyme-linked immunosorbent assay with the glucuronoxylomannan (GXM) of Cryptococcus neoformans. The frequency of occurrence of class-specific antibodies among normal subjects was 28% for immunoglobulin G (IgG), 98% for IgM, and 3% for IgA. Anti-GXM antibodies with kappa light chains occurred in 98% of normal subjects, while the occurrence of lambda light chains was 28%. Each of five subjects with high levels of anti-GXM IgG antibodies had readily detectable antibodies of the IgG2 isotype; two of the five subjects had readily detectable IgG1 antibody. An examination of sera from human immunodeficiency virus-infected patients showed that human immunodeficiency virus infection was accompanied by a significant decrease in the occurrence of IgM antibodies and anti-GXM antibodies with kappa light chains; these decreases occurred early in infection when CD4 counts were still > or = 500 cells per microliter. A slight but not statistically significant decrease in the occurrence of anti-GXM IgG antibodies was seen only in patients with CD4 levels of < 200 cells per microliter. Sera from normal subjects with high levels of anti-GXM IgG antibodies were examined to identify any contribution of the antibodies to complement activation or to opsonization of the yeast cells. An analysis of the kinetics for activation and binding of C3 to the yeast cell showed no pattern of quantitative or qualitative differences between sera with high or low levels of anti-GXM IgG antibodies. Phagocytosis studies showed that the naturally occurring IgG antibodies did not contribute to opsonization of the yeast cells.

Opsonic activity of sera and blister fluid from severely burned patients evaluated by a chemiluminescence method

Burn wound sepsis is the most common and severe complication in the patients with severe burn. To know the systemic and local defect in immunity of burned patients, we measured the luminol-enhanced chemiluminescence (CL) response of normal polymorphonuclear leukocytes (PMNs) upon exposure to zymosan particles, bacteria or Candida albicans that were opsonized with any of patient's serum, blister fluid of burn wound or pooled normal serum (blood type AB). Sera from patients exhibited lower opsonic activities than those of pooled normal serum in the early postburn days. The levels of serum immunoglobulins, complement components and plasma fibronectin were found to correlate well with opsonin-index (OI), which was determined based on the CL response data obtained during the course of infusion therapy with fresh frozen plasma. Furthermore, patient's blister fluid showed much lower opsonic activity against bacteria such as Pseudomonas aeruginosa than patient's own serum. These results indicate that blister fluid is also not effective to opsonize bacteria because of the marked depression of the levels of immunoglobulins and complement components. Destruction of the skin barrier by thermal injury and impairment of systemic or local humoral immunity may predispose these patients to burn wound sepsis.

Diuretics vs. paracentesis followed by diuretics in cirrhosis: effect on ascites opsonic activity and immunoglobulin and complement concentrations

Ascitic fluid opsonic activity and ascitic fluid C3 concentrations are important protective factors against spontaneous bacterial peritonitis. This randomized controlled study was performed to compare the effect of diuretic administration alone vs. single large-volume therapeutic paracentesis followed by administration of diuretics on ascitic fluid opsonic activity and on ascites and serum immunoglobulin and complement concentrations in patients with alcoholic cirrhosis and tense ascites. Twenty-one patients were randomly allocated to two groups: group 1 included 11 patients who were treated with diuretics alone, and group 2 included 10 patients who were treated with single large-volume therapeutic paracentesis (5 to 6 L of ascites removed) followed by diuretics. Ascitic fluid opsonic activity and serum and ascites immunoglobulin and complement concentrations were measured at the beginning and at the end of treatment. The ascitic fluid opsonic activity increased significantly in patients treated with diuretics alone (p < 0.05), whereas in the group of patients treated with therapeutic paracentesis followed by diuretics, the ascites opsonic activity remained stable. Although ascitic fluid IgG, IgA and C3 concentrations increased significantly in patients treated with diuretics alone (p < 0.05), ascitic fluid C3 concentration significantly decreased in patients from group 2 (p < 0.05), whereas IgG and IgA concentrations remained unchanged. However, in both groups of patients serum immunoglobulin and complement concentrations remained unchanged. This study suggests that in cirrhotic patients with tense ascites, treatment with diuretics alone may have the potential advantage over single large-volume therapeutic paracentesis followed by the administration of diuretics of providing better protection from spontaneous bacterial peritonitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of group B streptococcal hyperimmune globulin and standard intravenously administered immune globulin in neonates

Standard intravenously administered immune globulin (IVIG) contains varying amounts of group B streptococcus (GBS) antibody. A GBS hyperimmune IVIG was produced by immunizing plasma donors. The GBS type-specific opsonic activity was > or = 90% in the hyperimmune IVIG at a 1280 dilution-1 versus at a 10 dilution-1 in standard IVIG. Suckling rat survival after GBS type-specific infection was 100% when the rats were treated with hyperimmune IVIG versus < or = 20% with standard IVIG. To evaluate the effect of this product on GBS antibody levels and clinical toxic effects, we randomly administered either GBS hyperimmune IVIG, 500, 250, or 100 mg/kg, or standard IVIG, 500 mg/kg, to 20 neonates with suspected sepsis. No adverse effects were observed. Total and subclass serum IgG levels reflected only the dose; serum GBS type-specific IgG and opsonic activity reflected both the product and dose of IVIG administered. Standard IVIG did not significantly increase serum GBS type-specific IgG, whereas hyperimmune IVIG, 500 mg/kg, produced a fourfold rise for > 6 weeks; more variable increases were observed after 250 and 100 mg/kg doses were given. Serum GBS type-specific opsonic activity correlated with serum GBS type-specific IgG levels (R2 = 0.74; p < 0.0001). Further studies of this or similar products will be necessary to determine whether GBS type-specific antibody improves the outcome of GBS-infected neonates.

[Evaluation of antimicrobial system of polymorphonuclear leukocytes and opsonic activity in patients with congenital biliary atresia]

Postoperative ascending cholangitis (AC) is a serious problem in patients with biliary atresia (BA). It was reported that this complication was due to impaired functions of polymorphonuclear leukocytes (PMNs). We investigated the oxygen-dependent bactericidal activities including the ability to generate O2-, Myeloperoxidase (MPO) activity and opsonic activity using chemiluminescence method. The serum complement level and fibronectin level were also examined. O2- generating ability was 30.7 +/- 4.5 x 10(4) counts/min (cpm) in BA and 37.4 +/- 4.4 x 10(4) cpm in controls (p < 0.01). There was a significant difference in serum C4 between these two groups. No difference was found in opsonic activity, MPO activity, C3A, C3 and fibronectin. The O2- generating ability of the PMNs in BA was decreased but the opsonic and MPO activity were not depressed. From these results it is suggested that the frequent occurrence of AC in BA is not caused by low opsonic activity but may be associated with decreased O2- generation. Because of low C4 concentration, activation of classical pathway may also be impaired in BA.

Immunization against serogroup B meningococci. Opsonin response in vaccinees as measured by chemiluminescence

One hundred and thirteen healthy volunteers were immunized twice (six weeks apart) with four different doses (12.5, 25, 50 and 100 micrograms, measured as protein content) of an outer membrane vesicle vaccine from a serogroup B meningococcal strain (44/76, B:15:P1.16) complexed to serogroup C meningococcal polysaccharide and/or Al(OH)3 i.e. 12 different vaccines. Serum opsonic activity against the serogroup B strain was measured using a chemiluminescence method. A significant rise in serum opsonic activity was demonstrated in 84 volunteers (74%) six weeks after the first injection and in 97 (86%) six weeks after the second. All vaccinees with low preimmunization values (less than 25 mVs) experienced a significant increase in opsonic activity. A dose-related response was most evident for the vaccines containing adjuvant, and these vaccines were associated with a maximum response six weeks after the second injection, while the vaccines without Al(OH)3 induced a peak response six weeks after the first injection. The postimmunization opsonic activity was similar to that found in convalescent sera, indicating that the vaccines may protect against serogroup B meningococcal disease.

Immunoglobulin-coated bacteria in effusions from secretory and chronic suppurative otitis media

Samples of middle ear effusions from 10 children with secretory otitis media and from 10 children with chronic suppurative otitis media were subjected to qualitative and quantitative bacteriologic analysis. In addition, secretory immunoglobulin A (SlgA)- and IgG-coated bacteria were evaluated using the immunofluorescence technique. Secretory otitis media effusions harbored few, if any, immunoglobulin-coated bacteria, whereas chronic otitis media effusions as a rule had heavily IgG- and SlgA-coated bacteria. However, those chronic otitis media effusions that were culture positive for Pseudomonas aeruginosa had no immunoglobulin-coated bacteria. The effusions of very young children were completely devoid of SlgA-coated bacteria. This study demonstrates that, based on the immunoglobulin coating of bacteria obtained from the middle ear cleft, one can evaluate immunologic response during otitis media.

Complement-mediated serum activities against genetically defined capsular transformants of Haemophilus influenzae

Although there are six different capsular serotypes of Haemophilus influenzae (a-f), only type b strains commonly cause systemic infections in man. The present study was performed to determine whether the propensity of the type b organism to cause invasive infections is due to a unique ability to evade complement-mediated host defenses. The ability of genetically defined capsular transformants (a-f) of an unencapsulated H. influenzae to resist the bactericidal and opsonic activities of serum was examined. The unencapsulated organism and the type f transformants were relatively susceptible to serum bactericidal activity in both adult and infant serum pools, the type a and e transformants were relatively resistant, and the types b, c and d transformants were intermediate. With respect to serum opsonic activity in both adult and infant serum pools, the unencapsulated organism and the type f transformant were relatively susceptible, the type a, b and e transformants were relatively resistant and the type c and d transformants were intermediate. Thus, although the type b capsule endows the organism with the ability to resist the bactericidal and opsonic effects of complement, this property is not unique to type b.

Chemoattractant and opsonic activity in ascitic fluid. A study in 47 patients with cirrhosis or malignant peritonitis

We studied prospectively the ascitic fluid of 47 patients. Thirty-five were cirrhotics (group A) and 12 had malignant peritonitis (group B). All ascitic fluid samples were initially uninfected. We measured opsonic activity by a chemiluminescent assay, and chemoattractant activity by the under agarose technique. We also measured ascitic concentrations of C3, C4, fibronectin, C-reactive protein, immunoglobulins G, A and M and total proteins. All patients were followed throughout the presence of ascites. None of the group B patients developed peritoneal infection, nor did 23 of the group A patients (group A2). Twelve group A patients (group A1) developed spontaneous bacterial peritonitis (SBP), four of them with recurrence. All indices except immunoglobulins A and M were significantly different between group A and group B patients. Comparing group A1 and group A2, only chemoattractant activity and concentrations of total proteins and C3 were significantly lower in group A1. Using a multivariate analysis with Cox's model, only C3 concentration had an independent predictive value for occurrence of SBP in cirrhotic patients.

Human immunoglobulins for intravenous use: comparison of available preparations for group B streptococcal antibody levels, opsonic activity, and efficacy in animal models

Currently available human immunoglobulin preparations for intravenous use (IVIGs) are being used (with antibiotics) by some physicians for therapy of sepsis in newborns. Most neonatal sepsis and/or meningitis in this country is caused by group B Streptococcus (GBS), and most of these cases are due to type III GBS (III-GBS). The killing of III-GBS in vitro is dependent on specific IgG antibody. Adequate serum levels of specific III-GBS antibody protect the exposed newborn from the development of invasive disease. Therefore, III-GBS was used as a model to evaluate the activity of three IVIG preparations available for clinical use. Specific antibody levels, in vitro opsonophagocytic killing, and protective efficacy in animal models revealed differences in activity for III-GBS between the three IVIG preparations as well as between IVIG lots from the same manufacturer. Furthermore, it was found that the effect of IVIG using one of the assay methods may not reliably predict activity obtained using the other assays. These data document the inability to predict functional activity against a specific pathogen such as GBS on the part of a lot of IVIG chosen at random. In view of these findings and of the limited data evaluating clinical efficacy, IVIG cannot be recommended at this time for use in the therapy of infectious diseases such as neonatal sepsis.

Application of luminol-dependent chemiluminescence to assay opsonizing antibodies to procyclic forms of Trypanosoma congolense in the sera of dogs experimentally infected with heterologous stocks

Luminol-dependent chemiluminescence (LCL) responses of dog granulocytes were used to assay opsonizing antibodies to procyclic culture forms of T. congolense. A high degree of sensitivity was demonstrated and LCL levels were high, when the phagocytic cells were incubated with the sera of infected dogs even at dilutions as high as 1:400 as compared to pre-infection or negative sera. The levels of opsonizing antibodies were elevated in all the dogs throughout the time of observation. The technique was sensitive, could be automated and, therefore, allows a rapid evaluation of large numbers of serum samples for Trypanosoma specific antibodies.

Pseudomonas hyperimmune globulin passive immunotherapy for pulmonary exacerbations in cystic fibrosis

We studied the effect of an intravenously administered gamma globulin [Ps-ivIG] enriched fivefold over conventional ivIG for Pseudomonas aeruginosa lipopolysaccharide [PA LPS] antibodies on ten patients with cystic fibrosis [CF] aged 19-32 years during hospitalization for pulmonary deterioration. All were colonized with greater than or equal to 1 PA phenotype resistant to all antibiotics at the time of admission and they received 500 mg/kg Ps-ivIG intravenously as a single dose in addition to conventional treatment, including antibiotics and chest physiotherapy. No adverse effects occurred. Circulating immune complexes and complement levels remained unchanged from baseline. Serum levels of anti-PA LPS IgG, as measured by ELISA for eight PA LPS immunotypes, increased to 244 +/- 65% (mean +/- SE) of baseline levels 1 hour post-infusion (P less than 0.01), remained significantly elevated during a mean hospital stay of 17 days, and returned to near baseline by follow-up 4 weeks after hospital discharge. Plasma half-life and clearance values were similar to those of other subjects receiving conventional ivIG. Sputum PA density declined from 3.0 to 1.2 x 10(8) cfu/mL 1 week post-infusion (P approximately equal to 0.05), and returned to baseline at follow-up. Serum anti-PA opsonic activity increased after infusion (P less than 0.01), but returned to baseline by 72 hours. Clinical scores improved from admission to discharge (P less than 0.005) without decline at follow-up. Forced vital capacity [FVC] and forced expiratory volume in one second [FEV1] increased from admission to discharge (P less than 0.01 and P less than 0.05, respectively) without decline at follow-up. Using autologous historical control data, standard hospital therapy without Ps-ivIG resulted in no improvement in FVC or FEV1, and a subsequent decline in these parameters (P less than 0.05 for each) during a similar follow-up period. This occurred despite the fact that half the patients did not have antibiotic-resistant PA on the control admission. We conclude that Ps-ivIG is a safe adjunctive therapy for pulmonary exacerbations in moderately ill cystic fibrosis patients colonized with resistant PA, and may be associated with both greater and more prolonged improvement in pulmonary function than standard therapy alone.

Effect of diuresis versus therapeutic paracentesis on ascitic fluid opsonic activity and serum complement

Therapeutic paracentesis has recently been reported to eliminate ascites in patients with cirrhosis more rapidly than diuresis. However, diuresis has been shown to increase ascitic fluid opsonic activity. Patients with adequate ascitic fluid opsonic activity have been reported to be protected from spontaneous bacterial peritonitis. In this randomized controlled trial, 19 patients with cirrhotic ascites were treated with diuresis versus daily therapeutic paracenteses during 20 hospitalizations. Serum and ascitic fluid complement concentrations and ascitic fluid opsonic activity were measured at the beginning and end of treatment. Although opsonic activity increased significantly (p less than 0.01) in patients treated with diuresis, this parameter was stable in the paracentesis group. The stability of the ascitic fluid opsonic activity and complement concentration in the paracentesis group were maintained at the expense of a decrease in serum complement, whereas serum and ascitic fluid complement increased in the diuresis group. Diuresis may have the advantage over therapeutic paracentesis of providing better protection from spontaneous bacterial peritonitis. Study of larger numbers of patients will determine if these changes in complement concentrations and opsonic activity translate into an increased risk of spontaneous bacterial peritonitis in vivo.

Exchange blood transfusion and on-line plasma exchange for sepsis in infants

During the last 6 years, 19 infants with sepsis have been treated with exchange blood transfusions 47 times, and 13 patients survived. However, this procedure is compromised by antibody formation against WBCs and platelets. Accordingly, a miniature system for on-line plasma exchange (PE) between septic infant and healthy parent has been developed and evaluated using a canine model. Escherichia coli, at a dose of 5 X 10(9) CFU/ml/kg, was injected intravenously into 17 puppies that were divided into 3 groups; untreated; sham treated; and PE in which 80 ml/kg of plasma in each septic puppy was replaced during 2 hr with fresh plasma simultaneously obtained from healthy adult dogs. Four of 5 puppies survived in the PE group, while all other puppies died within 24 hr. In the PE group, viable cell counts of E. coli and endotoxin decreased significantly, and opsonic activity improved. This system is effective and applicable for treatment of sepsis in infants.

[Plasma fibronectin in surgical patients]

Plasma fibronectin (PFN) was measured to clarify the role in patients who underwent major surgery. There was no statistical difference between male and female, benign and malignant disease, or more than 60 years old and less. Compared to the preoperative values of PFN, the postoperative ones showed significant decrease immediately after operation, this decrease was attributed to massive bleeding and prolonged surgical procedure. In contrast to the previous papers reporting as an opsonin, no such results were obtained. However, there was close relationship between PFN and antithrombin III, alpha 2-plasmin inhibitor, factor XIII, retinol binding protein and transferrin, which represent hemostasis, fibrinolytic system and nutritional status, respectively. To determine whether PFN acts as an opsonin, heparin (opsonin cofactor) was given to Wistar rats in various conditions. There was no significant difference between PFN in those rats and in controls. These results indicate that postoperative PFN is a good parameter of glycoprotein in hemostasis, fibrinolytic system, and rapid turnover protein, not of an opsonin.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and opsonization synergistically enhance leukotriene B4 (LTB4) synthesis induced by phagocytosis in human neutrophils

Normal human blood neutrophils were studied for their capacity to synthesize leukotriene B4 (LTB4) and its omega-oxidized metabolites after phagocytosis of zymosan. Phagocytosis of serum-opsonized particles led to a higher release of LTs than did unopsonized zymosan. The most striking effect of phagocytosis was observed when neutrophils were primed with granulocyte-macrophage colony-stimulating factor (GM-CSF): opsonization and GM-CSF synergistically increased LTB4 synthesis by neutrophils.

Opsonic activity in serum from septic infants treated with intravenous immunoglobulin

Thirteen infants with staphylococcal sepsis and reduced opsonic activity received infusions of acid treated immunoglobulin together with antibiotics. Opsonic activity (using Staphylococcus aureus (type 42D) as the test organism), haemolytic activity of complement, and concentrations of complement C3 and IgG were measured in serum prepared before and after three days of treatment with immunoglobulin at a dose of 250-300 mg/kg/day. There was increased ingestion of S aureus by normal human granulocytes in the presence of fresh serum prepared after infusion of immunoglobulin and significantly increased opsonic activity of heat inactivated serum after treatment with immunoglobulin. The haemolytic activity of complement and concentrations of complement C3 were not influenced, and serum concentrations of IgG increased as the result of receiving a total of 800-900 mg/kg immunoglobulin over a period of three days. This study shows that administration of acid treated IgG to septic infants leads to functionally increased opsonisation.

Flow cytometric assay for the measurement of serum opsonins to Neisseria meningitidis serogroup B, serotype 15

A flow cytometric phagocytosis assay has been developed for the measurement of human serum opsonins to serogroup B meningococci. Live bacteria and bacteria inactivated by heat, formalin or ethanol were labelled with fluorescein-isothiocyanate (FITC). The bacteria were opsonized with sera from patients with group B meningococcal disease and sera from healthy controls, and phagocytosis determined by combined measurements of FITC-fluorescence and forward angle light scatter. Optimal sensitivity was obtained using viable bacteria, 5% serum, 20 bacteria per leukocyte capable of phagocytosis, 7.5 min opsonization time, 5 min phagocytosis time, 37 degrees C, and continuous agitation during opsonization and phagocytosis. The opsonic activity of sera from convalescent patients was markedly higher than that of sera from patients with acute illness. Only minor day-to-day and interindividual variations were observed. The flow cytometric phagocytosis technique is a rapid and reproducible method for the measurement of serum opsonins to meningococci.

Serum opsonins to serogroup B meningococci in meningococcal disease

The opsonic activity to serogroup B meningococci (B:15:P1.16) was measured in sera from 101 patients with meningococcal disease using a chemiluminescence method. On admission to hospital the opsonic activity was lower in 12 patients who died than in survivors (p = 0.0007). A close association was observed between the opsonic activity and the duration of symptoms before admission, the severity of the disease, and the levels of IgG antibodies to the outer membrane complex (15:P1.16). The opsonic activity was low in 2 premorbid sera compared to healthy controls. The mean opsonic activity peaked 2 weeks after admission and was still high 3-5 years later. Meningococcal strains of different serogroups, serotypes and subtypes induced a similar increase in opsonic activity to B:15:P1.16 meningococci. No increase in activity was observed in sera from patients with meningitis and septicemia caused by other bacteria. Serum opsonins seem to be of significant importance in the host defence against serogroup B meningococci.

Cervicovaginal opsonic activity, immunoglobulins, complement, and soluble fibronectin in healthy women randomly assigned to tampon or napkin use

The effect of tampon use on cervicovaginal immunoglobulins, complement, fibronectin, and antistaphylococcal opsonic activity was determined in a study of 35 healthy women randomly allocated to either tampon or napkin use for three consecutive menstrual cycles. Sequential cervicovaginal washings were collected on days 3 (+/- 2), 15 (+/- 2), and 25 (+/- 2) of the menstrual cycle before randomization and that 3 months afterward. Prior to randomization, no statistically significant differences were noted for any parameter (with correction for total protein content) between regular tampon users and exclusive napkin users. Following randomization, total opsonic activity during tampon use increased significantly over that in the same women during napkin use (P = .04, Wilcoxon matched-pairs signed-ranks test, two-tailed). This difference was observed only in menstrual samples and not at other sampling times. These data indicate that tampon use has minimal effects on cervicovaginal mucosal immunity and is not associated with aberrations of opsonophagocytosis in the lower female genital tract.

[Neutrophil chemiluminescence in pneumoconiosis]

Neutrophilic phagocytic activity and serum opsonic activity were examined in pneumoconiosis patients. One hundred patients aged 43 to 81 were classified into four types (types 1 to 4) according to the degree of chest X-ray findings. A simultaneous multiple measurement system for luminol-dependent chemiluminescence was used. Neutrophilic phagocytic activity and serum opsonic activity were shown by the time length to reach peak chemiluminescence (PT) and the height of peak chemiluminescence (PH). There were no significant differences of neutrophilic phagocytic activities and serum opsonic activities between normal persons and type 1 cases of mild disease. However, these activities were elevated in cases with more severe disease, and the most severe type 4 type cases tended to show lower activities than type 2 and type 3 cases. PT of total chemiluminescence was influenced by both neutrophilic phagocytic activity and serum opsonic activity, but PH only by neutrophilic phagocytic activity. Statistically significant correlation was observed between serum opsonic activity and serum CH50 levels.

[A study of the effects of fresh frozen plasma to improve host defense against bacterial infection and levels of coagulation factors after hepatectomy]

Intraperitoneal infection and massive bleeding after hepatectomy often lead to liver failure. A possible cause of these complications may be the debasement of coagulation factors and opsonins in plasma after hepatectomy. The effects of fresh frozen plasma (FFP) to prevent these complications were investigated. 1) In the patients administered with more than 10 units/day of FFP after major hepatectomy, postoperative plasma opsonic activity was higher and the frequency of the intraperitoneal infection was lower than in the patients administered with smaller volume. In the former group, the activity of coagulation factors tended to increase postoperatively except for factor VII. But even the activity of factor VII was above critical level, and actually postoperative bleeding caused by coagulative insufficiency was not observed. 2) In the 70%-hepatectomized dogs, disappearance curve of intravenously injected Escherichia coli was biexponential. So two compartment model composed of circulating blood and phagocytic system was applied and velocity constants of the each phases of sequestration, reflux, and ingestion were calculated. The administration of FFP and opsonization of bacteria by normal plasma did not influence the phases of sequestration and reflux, but significantly accelerated the ingestion phase. The administration of FFP also increased survival rate after bacterial injection. These results suggest that FFP is effective on improving host defense against bacterial infection.

Spontaneous M6 protein size mutants of group A streptococci display variation in antigenic and opsonogenic epitopes

Deletions of highly, but not entirely, homologous intragenic sequence repeats result in amino acid sequence and conformational changes in the M proteins of spontaneous M protein-size variants of group A streptococci. To determine if antigenic changes occurred as a result of these deletion mutations, monoclonal and polyclonal antibodies with defined epitopes were used in competition assays. Competing antigens were either purified pepsin-derived fragments (representing the amino-terminal half of the molecule) of parent and mutant M proteins or were intact bacterial cells. These assays showed that antigenic variation occurred at the site(s) of these deletions but not at adjacent or distant epitopes. Once cleaved from the bacterium by pepsin, the M molecules also underwent conformational changes, which were reflected in their ability to compete. A monoclonal antibody opsonic for M6 streptococci lost its ability to completely opsonize one of the size mutants in this study. Therefore, spontaneous intragenic events between repeats within emm-6, the structural gene for the M6 protein, do result in structural variations within the mutant M molecules. This variation alters the ability of certain antibodies, originally produced in response to sequences in the parental M molecule, to bind to the mutant M molecules or opsonize the mutant organisms. Group A streptococci have evolved a mechanism for generating antigenic diversity that differs from currently known mechanisms in other bacterial species.

The three different phases of reticuloendothelial system phagocytic function in rats with liver injury

In the present study, reticuloendothelial system (RES) phagocytic function of rats with partial hepatectomy or experimentally induced liver cirrhosis was investigated by determining the phagocytic index, the opsonic index, and uptake rate in liver, spleen, and lung of a 51Cr-labeled endotoxin-injected rat. In both the partially hepatectomized and the cirrhotic rats, all three indicators varied markedly according to the elapsed period since liver injury. The changes in RES phagocytic function were classified into three different phases: compromised, compensatory, and enhanced. The compromised phase, consisting of a decrease in the phagocytic index, was observed during the first 24 hr after 67% hepatectomy and in advanced liver cirrhosis. This represented the failure of RES phagocytic function. The compensatory phase, in which the phagocytic index was maintained at nearly normal levels mainly by a compensatory enhancement in the opsonic index, was seen during the first to second postoperative day and in moderate liver cirrhosis. The enhanced phase, with a high phagocytic index, was observed from Day 4 to approximately Day 14 after surgery, and in the cases of mild liver damage. In the compromised and compensatory phases, the liver uptake rate was significantly decreased compared with the control. However, the uptake in the spleen and lung were markedly increased. In conclusion, the phagocytic function of the RES was significantly affected to a degree which changed with the extent of liver damage.

Response of CAPD patients with a high incidence of peritonitis to intraperitoneal immunoglobulin therapy

This study has demonstrated that in the majority of high-peritonitis-incidence (PI) CAPD patients the defective opsonic activity levels in the peritoneal dialysis effluent (PDE) are restored for 3 weeks by a 12 g IP injection of immunoglobulins (Ig). Further studies showed that in a minority of high-PI CAPD patients who also had low PDE IgG and opsonic activity levels, IP Ig therapy did not significantly reduce the PI. To evaluate this phenomenon we utilized this therapy in 20 high-PI CAPD patients undergoing IP Ig therapy for an average of 24 months daily for 3 weeks (12 g every 3 weeks) and analyzed: 1) PDE IgG levels; 2) PDE opsonic activity; 3) peritoneal macrophage (PM0) membrane-bound IgG; 4) PDE Interleukin-1 (IL-1) levels; 5) PM0 membrane Fc receptor number. The results showed that in the 15 patients in whom Ig therapy reduced PI, there were long-lasting increases in the PDE IgG, opsonic activity and IL-1 levels, as well as a normal PM0 Fc receptor number and PM0 reversibly bound infused Ig. Conversely, the five patients in whom the IP Ig did not reduce the PI showed only transient increases in PDE IgG and opsonic activity levels, no PDE IL-1 increase, and the PM0 were deficient in Fc receptors and, therefore, unable to take up the infused Ig. We conclude that in high-PI CAPD patients there are different peritoneal immune defense abnormalities and that their identification is, therefore, important for the correct choice of therapy to improve these defects.

Patients with deficient ascitic fluid opsonic activity are predisposed to spontaneous bacterial peritonitis

To assess the risk of development of spontaneous bacterial peritonitis in relation to ascitic fluid opsonic activity, routine admission abdominal paracentesis was performed on 119 patients during 141 hospitalizations. Paracentesis was repeated if evidence of peritonitis developed during the hospitalization. The ascitic fluid opsonic activity (0.2 +/- 0.5 log kill) of 24 spontaneously infected specimens was significantly (p less than 0.001) lower than that of the group with sterile portal hypertension-related ascites (0.8 +/- 1.1 log kill), and significantly lower than the group with ascites of miscellaneous type (2.4 +/- 1.0 log kill, p less than 0.001). The C3 and C4 concentrations of the spontaneous peritonitis specimens were also significantly lower than in the specimens from the other groups. Of the 55 patients whose initial sterile ascitic fluid opsonic activity was less than 0.2 log kill, 8 (14.5%) developed spontaneous bacterial peritonitis during the hospitalization; whereas none of the 70 patients with sterile ascitic fluid opsonic activity greater than or equal to 0.2 log kill developed spontaneous peritonitis. This difference in the risk of development of peritonitis was significant (p less than 0.01). Patients with deficient ascitic fluid opsonic activity are predisposed to spontaneous bacterial peritonitis.

[Postoperative debasement of the host-defense system and wound healing in elderly patients, and nutritional support as a therapeutic implication]

Plasma opsonic activity and several kinds of plasma protein levels in each pre- and post-operative days were compared between older 25 cases (70 years or older) and 31 younger cases (59 years or younger) which both underwent elective abdominal surgery. The activity to opsonize E. coli 075 as a host-defense capacity was reduced on postoperative days 1,3 and returned gradually in either young or elderly. But opsonic activity levels in elderly patients in each postoperative days were significantly lower than in younger group. Plasma albumin level and rapid turnover protein levels in elderly patients tended to be lower than those in younger group through the postoperative period but statistically not significant. Plasma levels of C3 and fibronectin overshot the each preoperative value on days 5-7, after sharp reduction on day 1 in younger patients, but those in elderly didn't. Opsonic activity levels were closely correlated with plasma protein levels. Based on these clinical results, the experiments were designed to evaluate the effect of nutritional support in the early postoperative period on opsonic activity and protein synthesis in aged rats. These studies elucidated that early nutritional support brought beneficial effects on opsonic activity and plasma protein levels on postoperative days 7, but not on days 3 in aged rats. This may be because in aged animals, protein synthetic function has not fully recovered in the early postoperative period.

Neutrophil-mediated killing, opsonization, and serum-mediated killing of Escherichia coli K1 by neonatal rats

Neonates are particularly susceptible to infection with Escherichia coli K1. To investigate the mechanisms which lead to this susceptibility, we examined: (a) the bactericidal activity of neutrophils; (b) opsonization, and (c) the bactericidal activity of serum in developing rats. Neutrophils from adult rats killed E. coli K1 more efficiently than did neutrophils from young animals. Opsonization of E. coli by serum of prematurely delivered rats was poor. Serum from prematurely delivered and term rats promoted growth of E. coli K1, while serum from adult rats killed greater than 95% of the organisms within 90 min. However, the mixture of heat-inactivated serum from adult rats plus serum from prematurely delivered rats killed E. coli K1.

Immunity to malaria in young Gambian children after a two-year period of chemoprophylaxis

A cohort of 48 Gambian children was protected against malaria by fortnightly administration of Maloprim (pyrimethamine and dapsone) for 2 years between their 3 and 5 birthdays. A matched cohort of 47 children received placebo. During the year following the termination of prophylaxis there was no increase in the frequency of clinical attacks of malaria in the protected children compared with the control children. Antibody levels to circumsporozoite protein were measured by a radioimmunoassay and that to blood-stage antigens by a variety of techniques including an ELISA to whole blood-stage Plasmodium falciparum antigen, immunofluorescent assays (IFAT) to acetone fixed, glutaraldehyde fixed and unfixed parasites, a merozoite inhibition test and an opsonizing assay. Antibody levels were, in general, lower in protected than in control children and several differences between the two groups were statistically significant. When antibody levels were measured by ELISA and IFAT at the end of the following rainy season, when malaria transmission was intense, those in protected children had increased to comparable levels to those found in control children. Our findings suggest that chemoprophylaxis given for 2 years lowers malaria antibody levels but that it does not interfere with the development of protective immunity.

Reticulo-endothelial function in obstructive jaundice

A study of reticulo-endothelial function was performed in 30 patients with obstructive jaundice. Reticulo-endothelial phagocytic function, measured by the clearance of intravenous human micro-aggregated albumin, was significantly depressed in jaundiced patients compared with non-jaundiced controls (P less than 0.001). There was a significant correlation (P less than 0.001) between phagocytic function and plasma bilirubin level but not with transaminase or bile salt level. Phagocytic function was not related to the presence of malignancy, but was markedly reduced in patients with cholangitis. There was no reduction in hepatic sinusoidal blood flow, opsonin levels (fibronectin, IgG, complement) or serum opsonic activity to account for the reticulo-endothelial dysfunction.

Correlation of serum opsonic activity in cystic fibrosis with colonization and disease state: measurement of opsonins to Pseudomonas aeruginosa by neutrophil superoxide anion generation

Serum from patients with cystic fibrosis and normal controls was used to opsonize mucoid and nonmucoid Pseudomonas aeruginosa particles. Opsonic activity was then determined by measuring the production of superoxide anion (O2-) from normal neutrophils stimulated with the opsonized particles. Without any opsonization, mucoid P. aeruginosa stimulated significantly more O2- than nonmucoid P. aeruginosa. Responses to nonmucoid P. aeruginosa observed with heat-inactivated serum from patients with cystic fibrosis were significantly higher (p = 0.008) than those observed with heat-inactivated control sera. Comparisons made between patients who were colonized with P. aeruginosa and those who were not showed that heat activated serum from colonized patients had significantly higher levels of opsonic activity than heat inactivated serum from patients who were not colonized. These differences were observed with either mucoid or nonmucoid P. aeruginosa. A negative correlation was also observed between opsonic activity and clinical status measured by Schwachman scores of colonized patients. These data indicate that in patients colonized with P. aeruginosa the deterioration of their clinical status correlated with increased opsonic activity reflected in the oxidative burst response of neutrophils.

Standardization of a chemiluminescence method for the measurement of meningococcal opsonins using ethanol fixed meningococci

A chemiluminescence (CL) method using polymorphonuclear leukocytes (PMNLs) and an automatic photoluminometer was used to measure serum opsonins to viable and inactivated group B meningococci. Continuous mixing at 37 degrees C both during opsonization and phagocytosis was essential for optimal CL responses. The CL response increased rapidly during an opsonization time up to 7.5 min, and with PMNL and bacteria concentrations up to 37.5 X 10(5) and 3.8 X 10(7) cells/ml, respectively. Opsonized ethanol fixed meningococci gave CL responses similar to those of viable meningococci, but had a better reproducibility. Using the ethanol fixed bacteria, the variation of PMNLs from different donors, the day-to-day variation, and the coefficient of variation of the CL responses, were all less than 10%. The opsonic activity of convalescent sera from 10 patients with meningococcal disease was markedly higher than that of sera obtained during the acute phase of the disease. Thus, this standardized CL assay using ethanol fixed bacteria is a highly reproducible and sensitive method for measuring serum opsonins to meningococci.

Rhodococcus equi: equine neutrophil chemiluminescent and bactericidal responses to opsonizing antibody

The opsonic capacity of serum containing R. equi-specific antibody was compared with antibody-deficient sera using luminol-dependent chemilumenscence (LDCL) and bactericidal assays. These assays incorporated peripheral blood polymorphonuclear neutrophilic leukocytes (PMNL) exposed to R. equi opsonized with neonatal equine pre-colostral serum (control) or serum from foals with R. equi infections (principal). All sera were complement inactivated at 56 degrees C for 30 min. Bacteria were obtained from the lung of a foal with R. equi pneumonia. Neutrophils were obtained from one adult horse for LDCL and another for bactericidal assays. Chemiluminescence of PMNL exposed to R. equi opsonized with control or principal sera was measured in a liquid scintillation counter. Mean peak LDCL within 1 h was significantly (P less than 0.01) higher with principal sera (2.4 X 10(5) cpm) than with control sera (0.018 X 10(5) cpm). A radioisotope bactericidal assay was used to determine the effect of control or principal sera on PMNL capacity to kill R. equi. Mean peak percent kill of R. equi by PMNL within 2 h was significantly (P less than 0.01) higher with principal sera (95.2%) than with control sera (54.6%). Enzyme-linked immunosorbent assay (ELISA) values for R. equi-specific antibody were determined on all sera. Mean ELISA values were significantly (P less than 0.01) higher for principal sera (71.8) than for controls (0.0). This investigation documents the presence and biological effectiveness of opsonic activity in complement-inactivated sera from foals with R. equi infections and R. equi-specific antibody.