Nonopsonic antibodies in cystic fibrosis. Pseudomonas aeruginosa lipopolysaccharide-specific immunoglobulin G antibodies from infected patient sera inhibit neutrophil oxidative responses

Pseudomonas aeruginosa in chronic lung disease: untangling the dysregulated host immune response

Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen capable of exploiting barriers and immune defects to cause chronic lung infections in conditions such as cystic fibrosis. In these contexts, host immune responses are ineffective at clearing persistent bacterial infection, instead driving a cycle of inflammatory lung damage. This review outlines key components of the host immune response to chronic P. aeruginosa infection within the lung, beginning with initial pathogen recognition, followed by a robust yet maladaptive innate immune response, and an ineffective adaptive immune response that propagates lung damage while permitting bacterial persistence. Untangling the interplay between host immunity and chronic P. aeruginosa infection will allow for the development and refinement of strategies to modulate immune-associated lung damage and potentiate the immune system to combat chronic infection more effectively.

Mucosal Immunity in Cystic Fibrosis

The highly complex and variable genotype-phenotype relationships observed in cystic fibrosis (CF) have been an area of growing interest since the discovery of the CF transmembrane conductance regulator (CFTR) gene >30 y ago. The consistently observed excessive, yet ineffective, activation of both the innate and adaptive host immune systems and the establishment of chronic infections within the lung, leading to destruction and functional decline, remain the primary causes of morbidity and mortality in CF. The fact that both inflammation and pathogenic bacteria persist despite the introduction of modulator therapies targeting the defective protein, CFTR, highlights that we still have much to discover regarding mucosal immunity determinants in CF. Gene modifier studies have overwhelmingly implicated immune genes in the pulmonary phenotype of the disease. In this context, we aim to review recent advances in our understanding of the innate and adaptive immune systems in CF lung disease.

Mechanisms of humoral immune response against Pseudomonas aeruginosa biofilm infection in cystic fibrosis

P. aeruginosa chronic lung infection is the major cause of morbidity and mortality in patients with cystic fibrosis (CF), and is characterized by a biofilm mode of growth, increased levels of specific IgG antibodies and immune complex formation. However, despite being designed to combat this infection, such elevated humoral response is not associated with clinical improvement, pointing to a lack of anti-pseudomonas effectiveness. The mode of action of specific antibodies, as well as their structural features, and even the background involving B-cell production, stimulation and differentiation into antibody-producing cells in the CF airways are poorly understood. Thus, the aim of this review is to discuss studies that have addressed the intrinsic features of the humoral immune response and provide new insights regarding its insufficiency in the CF context.

Immunization of young African green monkeys with OprF epitope 8-OprI-type A- and B-flagellin fusion proteins promotes the production of protective antibodies against nonmucoid Pseudomonas aeruginosa

There is currently no approved vaccine against Pseudomonas aeruginosa, the major cause of morbidity and mortality in cystic fibrosis (CF) patients and a major pathogen in ventilated and burn patients. In a previous study, we demonstrated the immunization of mice with OprF(311-341)-OprI-type A- and B-flagellin fusion proteins dramatically enhanced clearance of nonmucoid P. aeruginosa. The goal of the current study was to evaluate the ability of OprF(311-341)-OprI-flagellins to elicit the production of protective IgG in young (4-6 months old) African green monkeys. Intramuscular immunization of African green monkeys with 1, 3, 10, or 30mug of OprF(311-341)-OprI-flagellins generated robust antigen-specific IgG responses. In addition, immunization with OprF(311-341)-OprI-flagellins elicited high-affinity anti-flagellins, OprI, and OprF IgG that individually promoted extensive deposition of complement component C3 on P. aeruginosa and synergized to facilitate maximal C3 deposition. Passive immunization of mice with plasma from OprF(311-341)-OprI-flagellins immunized monkeys significantly reduced lung bacterial burden three days post-challenge compared to mice that received pre-immunization plasma. Based on our results, OprF(311-341)-OprI-A- and B-flagellin fusion proteins are highly effective in mice and nonhuman primates and thus merit additional development as a potential vaccine for use in humans.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Cathepsin-G interferes with clearance of Pseudomonas aeruginosa from mouse lungs

The cystic fibrosis airway is susceptible to Pseudomonas aeruginosa infection, which stimulates an intense inflammatory response leading to airway obstruction and bronchiectasis. Neutrophils migrate into the airway, and once there, release high concentrations of neutral serine proteases during phagocytosis and in death. In particular, neutrophil elastase is central to progression of bronchiectasis by interfering with bacterial clearance and directly perpetuating the inflammatory response in the airway. Using a murine model of endobronchial inflammation, we found that a different neutrophil-derived serine protease, cathepsin G, inhibited the host's ability to clear Pseudomonas from the lung, based on a 1-log reduction in bacteria recovered from cathepsin G-deficient mice. Higher antibody concentrations were found in respiratory epithelial lining fluid from mice lacking cathepsin G, but there was no difference in other opsonins, such as surfactant proteins A and D. Chemokine levels measured in the lung correlated with bacterial burden and not the animal's genotype, indicating that airway inflammation was not affected by the presence (or absence) of specific serine proteases. These findings suggest that cathepsin G interferes with airway defenses, showing that proteases other than neutrophil elastase have roles in the pathogenesis of suppurative airway diseases.

Safety and immunogenicity of an oral inactivated whole-cell pseudomonas aeruginosa vaccine administered to healthy human subjects

This study examines the safety and immunogenicity of an oral, whole-cell Pseudomonas aeruginosa vaccine administered to healthy volunteers. Thirty subjects received an oral dose of Pseudostat in two timed, measured doses with serological follow-up to 56 days postvaccination. Following vaccination, several individuals were identified as antibody responders for all three immunoglobulin (Ig) isotypes tested, specifically against whole-cell P. aeruginosa extract and outer membrane proteins F and I. The mean pooled lipopolysaccharide antigen-specific IgA showed the most significant and constant increases in titer postdose, with a similar increase in titer for whole-cell P. aeruginosa extract-specific IgA. The results demonstrated an increased phagocytic ability of the selected macrophage cell line in post vaccination sera. Furthermore a significant increase in intracellular macrophage killing of opsonized P. aeruginosa was also demonstrated (82% on day 14 postdose) in the presence of the postvaccination sera. The safety component of the study did not show any vaccine-attributable adverse effects in any of the subjects, as documented by clinical evidence, hematology, and biochemistry profiles. We conclude that Pseudostat is safe and immunogenic in humans at this dose and that further studies to determine the appropriate dosage and efficacy are needed. In our study, we have shown that the most significant and sustained responses to oral vaccination in human adult volunteers were serum IgA levels and that pooled sera collected postimmunization have an increased capacity to promote opsonophagocytotic killing of P. aeruginosa.

Cystic fibrosis lung disease: genetic influences, microbial interactions, and radiological assessment

Cystic fibrosis (CF) is a multiorgan disease caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. Obstructive lung disease is the predominant cause of morbidity and mortality; thus, most efforts to improve outcomes are directed toward slowing or halting lung-disease progression. Current therapies, such as mucolytics, airway clearance techniques, bronchodilators, and antibiotics, aim to suppress airway inflammation and the processes that stimulate it, namely, retention and infection of mucus plaques at the airway surface. New approaches to therapy that aim to ameliorate specific CFTR mutations or mutational classes by restoring normal expression or function are being investigated. Because of its sensitivity in detecting changes associated with early airway obstruction and regional lung disease, high-resolution CT (HRCT) complements pulmonary function testing in defining disease natural history and measuring response to both conventional and experimental therapies. In this review, perspectives on the genetics and microbiology of CF provide a context for understanding the increasing importance of HRCT and other imaging techniques in assessing CF therapies.

Effects of beta-carotene supplementation for six months on clinical and laboratory parameters in patients with cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) have significantly decreased plasma concentrations of nutrient antioxidant vitamins, especially of beta-carotene, which is thought to result from fat malabsorption and chronic pulmonary inflammation. The aim of this double blind, placebo controlled study was to investigate the effect of oral beta-carotene supplementation for six months on clinical parameters.

METHODS

Twenty four patients with CF were randomised to receive beta-carotene 1 mg/kg/day (maximum 50 mg/day) for three months (high dose supplementation) and 10 mg/day for a further three months (low dose supplementation) or placebo. At monthly follow up visits the plasma beta-carotene concentration, total antioxidant capacity, malondialdehyde (MDA) as a marker of lipid peroxidation, and clinical parameters (Shwachmann-Kulczycki score, body mass index (BMI), height, and lung function (FEV(1))) were assessed. The number of pulmonary exacerbations requiring antibiotic treatment (in days) three months before and during the study were evaluated.

RESULTS

The plasma concentration of beta-carotene increased significantly to the normal range during the three months of high dose supplementation (baseline 0.08 (0.04) micromol/l to 0.56 (0.38) micromol/l; p<0.001) but decreased to 0.32 (0.19) micromol/l in the period of low dose supplementation. Initially raised plasma levels of MDA fell to normal levels and the total antioxidant capacity showed a non-significant trend towards improvement during high dose supplementation. Antibiotic treatment decreased significantly in the supplementation group from 14.5 (14.9) days/patient during the three months before the study to 9.8 (10.3) days/patient during high dose supplementation (p=0.0368) and to 10.5 (9.9) days/patient during low dose supplementation, but increased in the placebo group. The Shwachmann-Kulczycki score, lung function, and BMI did not show any changes in either of the treatment groups. No adverse events were observed during the study period.

CONCLUSION

Oral beta-carotene supplementation in a dose of 1 mg/kg/day only was effective in normalising the plasma concentration of beta-carotene and resulted in a decrease in pulmonary exacerbations. These data suggest that patients with CF may benefit clinically from supplementation with beta-carotene and further studies are warranted.

Avidity of anti-P aeruginosa antibodies during chronic infection in patients with cystic fibrosis

BACKGROUND

In order to study the impact on the lung function of patients with cystic fibrosis of the avidity of antipseudomonal antibodies, the avidity of antibodies against the chromosomal beta-lactamase of Pseudomonas aeruginosa (a beta ab) and against the 60-65 kDa heat shock protein of P aeruginosa (anti-GroEL) were measured in serum samples collected longitudinally during chronic infection with P aeruginosa from a group of patients with poor and good lung function.

METHODS

The thiocyanate elution method in which the molarity of potassium thiocyanate required to elute 50% bound antibody under conditions of antigen excess in ELISA was used to measure the relative avidity.

RESULTS

All patients developed increasing levels of a beta ab and anti-GroEL antibodies during the follow up period but no maturation of the avidity of these antibodies was observed. In patients with good lung function the avidity of a beta ab was higher than in patients with poor lung function (p = 0.018). No significant difference in the avidity of the anti-GroEL antibodies was observed between the two groups of patients.

CONCLUSION

In patients with cystic fibrosis a high avidity of a beta ab could contribute to a more efficient inhibition of the beta-lactamase by these antibodies, resulting in the better lung function seen in this group. The immunopathological implication of the failure in avidity maturation of antibodies in chronic infection is discussed.

Production and characterization of a set of mouse-human chimeric immunoglobulin G (IgG) subclass and IgA monoclonal antibodies with identical variable regions specific for Pseudomonas aeruginosa serogroup O6 lipopolysaccharide

The heavy- and light-chain variable regions from a murine monoclonal antibody that recognize Pseudomonas aeruginosa serogroup O6 lipopolysaccharide (LPS) were used to generate a series of chimeric mouse-human monoclonal antibodies with identical variable regions. The murine variable-region gene segments were cloned into an immunoglobulin (Ig) cDNA expression vector that contained the human kappa light-chain and IgG1 constant regions. The IgG1 heavy-chain constant region was then replaced with the human IgG2, IgG3, IgG4, or IgA1 heavy-chain constant region. The five different expression vectors were transfected into Chinese hamster ovary cells for antibody production. The chimeric antibodies exhibited immunoreactivity and affinity similar to that of the parental murine IgG antibody toward whole cells of a serogroup O6 strain. In vitro complement deposition assays demonstrated that the chimeric IgG4 and IgA antibodies did not mediate the deposition of complement component C3 onto the surface of either purified LPS or whole bacteria. The chimeric IgG1 and IgG3 antibodies were similar in their ability to deposit C3 onto the surface of both bacteria and LPS, while IgG2 antibody was more effective at depositing C3 onto the surface of bacteria than onto purified LPS. The pattern of opsonophagocytic activity of the chimeric monoclonal antibodies was similar to that of complement deposition onto bacterial cells in that the chimeric IgG1 and IgG3 had the highest opsonic activity. Although IgG2 deposited more C3 onto the bacterial surface than did IgG4 or IgA, all three of these isotypes had low opsonic activity against the serogroup O6 target strain. This series of related antibodies will help reveal functional differences in efficacy among protective antibodies to P. aeruginosa and will be critical for defining the optimal formulation of either a vaccine for active immunization or a polyclonal intravenous IgG or monoclonal antibody cocktail for passive immunotherapy.

Amount and Avidity of IgG Antibodies to Pseudomonas Aeruginosa Exotoxin A Antigen in Cystic Fibrosis Patients

Amount and avidity of serum IgG antibodies to Pseudomonas aeruginosa exotoxin A in sera of 31 patients with cystic fibrosis (CF) was studied. Eight patients had P. aeruginosa isolated from the sputum on multiple occasions, while from 23 patients no P. aeruginosa was isolated. Amount of IgG antibodies to P. aeruginosa exotoxin A were significantly increased in the serum of patients with P. aeruginosa pulmonary colonization (p<0.0001). On the contrary, serum IgG avidity in the colonized and in the non-colonized CF patients was low (<10) and was statistically different when compared to the 30 age-matched healthy controls (p<0.0001). There was no change in IgG avidity in six chronically infected CF patients from whom we obtained serum samples after half a year period (p=0,55).

Effect of high-affinity anti-Pseudomonas aeruginosa lipopolysaccharide antibodies induced by immunization on the rate of Pseudomonas aeruginosa infection in patients with cystic fibrosis

Patients with cystic fibrosis (CF; N = 26) and with no prior history of infection with Pseudomonas aeruginosa were immunized with an octavalent O-polysaccharide-toxin A conjugate vaccine. During the next 4 years, 16 patients (61.5%) remained free of infection and 10 (38.5%) became infected. Total serum antilipopolysaccharide (LPS) antibody levels induced by immunization were comparable in infected and noninfected patients. In contrast, 12 of 16 noninfected versus 3 of 10 infected patients (p = 0.024) mounted and maintained a high-affinity anti-LPS antibody response. When compared retrospectively with the rate in a group of age- and gender-matched, nonimmunized, noncolonized patients with CF, the rate at which P. aeruginosa infections were acquired was significantly lower (p < or = 0.02) among all immunized versus nonimmunized patients during the first 2 years of observation. Subsequently, only those immunized patients who maintained a high-affinity anti-LPS antibody response had a significant reduction (p < or = 0.014) in the rate of infection during years 3 and 4. Smooth, typeable strains of P. aeruginosa predominated among immunized patients; rough, nontypeable strains were most frequently isolated from nonimmunized patients. Mucoid variants were isolated from one immunized patient versus six nonimmunized patients. These results indicate that the induction of a high-affinity P. aeruginosa anti-LPS antibody response can influence the rate of infection in patients with CF.

Effects of interferon gamma on the antibody response to Pseudomonas aeruginosa lipopolysaccharide in mice

Different strains of mice were examined for the capacity to produce an Ig subclass-specific antibody response to purified Pseudomonas aeruginosa lipopolysaccharide (PALPS). With the exception of the AKR strain, the predominant isotype for most of the strains tested was IgG3 whereas the least frequent isotype expressed was either IgG2b or IgG1. AKR mice were unique in that the predominant isotype produced was IgG2a, rather than IgG3; however, the administration of anti-interferon gamma antibody, at the time of immunization with PALPS caused a substantial decrease in the IgG2a antibody response. Selected B10 congenic strains were used to assess the relationship between the antibody responses and the major histocompatibility complex (MHC) genes. Here, the isotype-patterns for the antibody responses were essentially the same regardless of the MHC haplotype. Interestingly, an increase in IgG2a, with a concomitant decrease in IgM and IgG1 antibody was noted when C3H mice were given interferon gamma at the time of immunization. These studies indicate that, in general, the antibody response to PALPS consists of IgG3 antibody as the predominant isotype, and that the antibody response can be modified by interferon gamma.

Eosinophilic activation in cystic fibrosis

BACKGROUND

The neutrophil is a potent contributor to pulmonary destruction in cystic fibrosis. Since eosinophils also possess destructive potential the involvement of eosinophils in cystic fibrosis has been investigated.

METHODS

Eosinophil numbers and levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, were determined in the serum of 42 patients with cystic fibrosis and in the sputum of 10 of them. To determine neutrophil activation levels of myeloperoxidase (MPO) were also measured.

RESULTS

In cystic fibrosis increased serum levels of ECP were detected compared with healthy non-atopic subjects. Serum ECP levels were not related to the peripheral blood eosinophil count. A strong correlation with ECP concentrations in sputum indicated that the level of ECP in serum was representative of its pulmonary level. Levels of MPO were also increased in cystic fibrosis. A strong correlation was found between MPO and pulmonary function. In addition, ECP was related to arterial oxygen and carbon dioxide tensions. Antibiotic treatment reduced neutrophil activation without effect on ECP levels.

CONCLUSIONS

Until now Pseudomonas aeruginosa and neutrophils were held to be primarily responsible for progressive tissue damage in cystic fibrosis. The results of this study suggest that eosinophils might also participate in such pulmonary destruction.

Eosinophilic activation in cystic fibrosis

BACKGROUND

The neutrophil is a potent contributor to pulmonary destruction in cystic fibrosis. Since eosinophils also possess destructive potential the involvement of eosinophils in cystic fibrosis has been investigated.

METHODS

Eosinophil numbers and levels of eosinophil cationic protein (ECP), a marker of eosinophil activation, were determined in the serum of 42 patients with cystic fibrosis and in the sputum of 10 of them. To determine neutrophil activation levels of myeloperoxidase (MPO) were also measured.

RESULTS

In cystic fibrosis increased serum levels of ECP were detected compared with healthy non-atopic subjects. Serum ECP levels were not related to the peripheral blood eosinophil count. A strong correlation with ECP concentrations in sputum indicated that the level of ECP in serum was representative of its pulmonary level. Levels of MPO were also increased in cystic fibrosis. A strong correlation was found between MPO and pulmonary function. In addition, ECP was related to arterial oxygen and carbon dioxide tensions. Antibiotic treatment reduced neutrophil activation without effect on ECP levels.

CONCLUSIONS

Until now Pseudomonas aeruginosa and neutrophils were held to be primarily responsible for progressive tissue damage in cystic fibrosis. The results of this study suggest that eosinophils might also participate in such pulmonary destruction.

Correlation between specific IgG subclass antibodies to Pseudomonas aeruginosa and opsonic activity in serum from patients with cystic fibrosis

Heat-stable opsonins from sera of patients with cystic fibrosis (CF) non-CF patients with chronic Pseudomonas aeruginosa infection, healthy children, and adults were investigated for their ability to promote phagocytosis of 35S-labeled P. aeruginosa by human polymorphonuclear neutrophils. Healthy children had significantly lower levels of opsonic activity than adults. Sera from patients with CF without chronic P. aeruginosa lung infection showed significantly higher levels of opsonic activity compared to healthy children. Sera from patients with CF in the early stage of chronic infection had similar opsonic activity as non-CF patients with chronic infection. Sera from patients with CF in the late stage of chronic infection had higher opsonic activity than other infected patients, but not different from adult controls. An inverse correlation was found between levels of specific antibodies to P. aeruginosa and opsonic activity in the group of patients in a late stage of infection. An inverse correlation was also found between levels of IgG1 and IgG3 to P. aeruginosa St-Ag and opsonic activity during the late stage of infection. Infection with P. aeruginosa in CF did not induce significantly increased opsonic activity. It seems that antibodies to P. aeruginosa may have inhibitory opsonic activity.

Anti-Pseudomonas aeruginosa IgG subclass titers in patients with cystic fibrosis: correlations with pulmonary function, neutrophil chemotaxis, and phagocytosis

To explore possible mechanisms for the association between elevated immunoglobulin levels and lower pulmonary function in cystic fibrosis patients, we measured serum IgG subclass levels and anti-P. aeruginosa IgG subclass titers and correlated levels with neutrophil phagocytosis and chemotaxis. Serum was obtained from 13 cystic fibrosis patients colonized with the same serotype of P. aeruginosa, 12 noncolonized patients, and 12 normal volunteers. All anti-P. aeruginosa IgG subclass titers were elevated in serum from colonized patients. IgG3 level and anti-P. aeruginosa IgG3 titer were inversely correlated with pulmonary function. Phagocytosis of P. aeruginosa by neutrophils correlated with serum IgG3 level and was increased by opsonization with serum from colonized patients. Chemotactic index was increased in serum from colonized patients and inversely correlated with pulmonary function chest roentgenogram score. Chemotactic index directly correlated with anti-P. aeruginosa IgG3 titer and serum IgG3. These data demonstrate that cystic fibrosis patients with increased IgG3 levels are in poorer clinical condition and that their serum enhances neutrophil function. Such patients may have increased pulmonary inflammation with subsequent lung damage.

Effects of IL-4 depletion on the antibody response to Pseudomonas aeruginosa lipopolysaccharide in mice

These studies were done to examine the role of interleukin-4 (IL-4) in the generation of isotype specific antibody responses of mice to Pseudomonas aeruginosa lipopolysaccharide (PALPS) by neutralization of IL-4 in vivo using anti-IL-4 antibody (11B11). We found that the administration of anti-IL-4 antibody (11B11) 24 h before immunization with PALPS resulted in a decreased PALPS-specific antibody response for all isotypes examined (IgM, IgG1, IgG2a, IgG2b, IgG3). By contrast, we observed that the non-antigen-specific (polyclonal) IgM response of mice following treatment with 11B11 antibody and PALPS was increased while the polyclonal responses for the other isotypes were unaffected. When mice were given recombinant IL-10 at the time of immunization with PALPS there was a decrease in the PALPS-specific antibody response but an increase in the polyclonal IgM, IgG2a, IgG2b, IgG3 response whereas the polyclonal IgG1 response was decreased by a five-fold margin. The results of these studies suggest that both the antigen-specific and the polyclonal response can be influenced in a different manner by IL-4 or by IL-10.

Complement activation by polyclonal immunoglobulin G1 and G2 antibodies against Staphylococcus aureus, Haemophilus influenzae type b, and tetanus toxoid

To obtain information on effector functions of human immunoglobulin G2 (IgG2), we have measured the complement-activating properties of polyclonal IgG subclass antibodies against bacterial antigens. IgG1 and IgG2 were purified from serum samples from five healthy individuals, and complement activation was measured with different bacterial antigens. We used Staphylococcus aureus Wood 46 (STAW), which is a common antigen, Haemophilus influenzae type b (Hib), which is a common pathogenic microorganism in children, and formaldehyde-inactivated tetanus toxin (TT). Bacteria were incubated with antibodies and then incubated with sera from agammaglobulinemic patients as a complement source, and C3c deposition was measured by enzyme-linked immunosorbent assay. We found that anti-STAW IgG2 activated complement to a level similar to that of anti-STAW IgG1. Anti-Hib IgG1 complement activation was as much as seven times higher than that of anti-Hib IgG2 in four individuals. In one individual, anti-Hib IgG2 was more effective in complement activation than anti-Hib IgG1. Anti-TT antibodies showed patterns similar to those of anti-Hib. Our results indicate that IgG2 antibodies may contribute significantly to antibacterial defense. Also, individual differences in antibody effector functions should be taken into account when evaluating the immune status of patients and during early phase 1 studies of new vaccines.

IgG subclass antibody responses to alginate from Pseudomonas aeruginosa in patients with cystic fibrosis and chronic P. aeruginosa infection

Chronic bronchopulmonary infection with alginate-producing, mucoid Pseudomonas aeruginosa is characteristically associated with cystic fibrosis (CF). A significant correlation between the antibody response to alginate and poor lung function has been reported. Enzyme-linked immunosorbent assays were developed for the quantitation of human IgG1, IgG2, IgG3, and IgG4 antibodies to P. aeruginosa alginate. We investigated the pattern of IgG subclass antibodies against P. aeruginosa alginate in serum of patients with CF, others with chronic P. aeruginosa infection, and healthy controls. Healthy controls and patients with CF, before they acquired P. aeruginosa infection, had no or very low titers of antibodies against P. aeruginosa alginate. The latter with chronic infection had significantly higher antibody levels than all others groups, including patients with chronic P. aeruginosa infection but no CF. CF with chronic P. aeruginosa infection led to an inverse correlation between lung function parameters and levels of IgG3 and IgG4. Fifty-seven patients with CF have been followed for an average of 12 years with multiple antibody assays covering the preinfection, early, and late stage of chronic infection. All of them developed IgG1 and IgG3 antibodies to alginate at the start of infection. IgG2 antibodies developed later and showed only a slow increase during the chronic infection. Patients who died had significantly higher IgG2 anti-alginate antibody levels than other investigated groups. Elevated levels of IgG2 and IgG3 antibodies to P. aeruginosa alginate are a sign of poor prognosis in CF.

Cystic fibrosis. 1. Pseudomonas aeruginosa infection in cystic fibrosis and its management

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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.