Skin testing with Mycobacterium avium sensitin to identify infection with M. avium complex in patients with cystic fibrosis

We sought to determine if patients with cystic fibrosis and sputum cultures positive for Mycobacterium avium complex (MAC) have delayed-type hypersensitivity to an M. avium sensitin. Seventeen (33%) of 51 selected patients had MAC isolated from at least one sputum culture. Skin tests with purified protein derivative and M. avium sensitin demonstrated that five (10%) of 51 patients were anergic, and anergy was correlated with use of systemic steroids. Sixteen (35%) of 46 nonanergic patients had M. avium-dominant skin test reactions. Twelve (75%) of these 16 patients with cultures positive for MAC had M. avium-dominant skin tests; the specificity of skin testing was 87%. These data suggest that most patients with cystic fibrosis and sputum cultures positive for MAC have infection rather than colonization with MAC. Skin testing with M. avium sensitin is a sensitive and specific method for screening these infections.

Direct assessment of gastrointestinal inflammation and mucosal immunity in children with cystic fibrosis

Fibrosing colonopathy is a recently described complication of cystic fibrosis, of unknown aetiology but possibly related to treatment with high-dose pancreatic enzyme supplements. We have used a whole gut perfusion technique to study subclinical gut inflammation in cystic fibrosis patients; concentrations of haemoglobin, IgG, albumin, alpha-1-antitrypsin, granulocyte elastase, IL1 beta, and IL8 were measured in whole gut lavage fluid: 23 tests were performed in 17 children with cystic fibrosis (20 elective tests, three lavages to treat distal intestinal obstruction syndrome (DIOS)). None has had fibrosing or haemorrhagic colitis. There were 12 tests in control children with constipation or precolonoscopy. Moderately abnormal results were obtained for many of the parameters studied, in specimens from all the cystic fibrosis children; however there were no significant differences between tests on high-dose and low-dose enzyme supplements of the same brand in the five children who had duplicate tests performed electively. The lavage fluid specimens from two cystic fibrosis children were strikingly abnormal in all tests apart from haemoglobin and alpha-1-antitrypsin. These were two of the three children with DIOS, and were also the only cases in the series taking Nutrizym 22. These data suggest that the majority of cystic fibrosis children, including those on high-dose enzyme supplements, do not have clinically significant colitis, but that there is subclinical mucosal inflammation in a minority (two of 17 in this series), for which DIOS and/or Nutrizym 22 treatment may be risk factors. Alternatively, inflammation and dysmotility in the proximal colon may be directly produced by a drug or other agent, producing a clinical syndrome indistinguishable from DIOS. Tests for indices of inflammation in gut lavage fluid offer a new approach to the detection and measurement of iatrogenic intestinal and colonic injury.

Interferon-gamma (IFN-gamma) treatment decreases the inflammatory response in chronic Pseudomonas aeruginosa pneumonia in rats

In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis (CF), we studied whether the inflammatory response could be altered by intraperitoneal treatment with recombinant rat interferon-gamma (rrIFN-gamma). Rats were treated either before or after intratracheal challenge with P. aeruginosa embedded in alginate beads. Rats treated after challenge had a significant reduction in the severity of macroscopic lung inflammation compared with rats treated before challenge (P = 0.004) and controls (P = 0.003). The histopathology in controls was dominated by numerous polymorphonuclear leucocytes (PMN) (> or = 90%) surrounding the alginate beads like in CF. This could be caused by a Th2-like response. In contrast, a complete shift to a chronic-type inflammation dominated by mononuclear leucocytes (> or = 90% lymphocytes and plasma cells) and granulomas was observed in both rrIFN-gamma-treated groups of rats. This could be caused by a Th1-like response. There was no significant difference in lethality between the groups, and the antibody titres against P. aeruginosa sonicate and alginate were similar in the treated rats and controls. Since the ongoing lung tissue damage in CF patients has been shown to be caused by elastase secreted by PMN, which dominate the P. aeruginosa lung infection, our findings offer a possible new strategy of modifying the inflammatory response in CF patients.

Humoral and cellular immune responses of nonhuman primates to long-term repeated lung exposure to Ad2/CFTR-2

To evaluate the host immune response to long-term repeat administration of adenovirus vector, rhesus monkeys were treated at intervals of approximately 3 weeks with up to 18 instillations of Ad2/CFTR-2, a second generation vector encoding the cystic fibrosis transmembrane conductance regulator (CFTR). All monkeys instilled with Ad2/CFTR-2 developed a significant humoral immune response against adenovirus but not CFTR. Antibodies with virus neutralizing activity were detected in the serum and bronchoalveolar lavage (BAL) of all vector-treated monkeys and included both IgG and secretory IgA. Virus-specific T cells capable of proliferating in response to stimulation with adenovirus antigen were detected in all vector-treated monkeys. No CFTR-specific proliferation of peripheral blood lymphocytes was detected. An increase in the proportion of CD8+ T cells was noted in the BAL of virus-treated monkeys but cells from the BAL displayed little or no cytolytic activity against infected autologous fibroblasts when tested under a variety of culture conditions. However, MHC-restricted cytolytic activity was detected in the tracheobronchial lymph nodes and spleen of one of three virus-treated monkeys tested. MHC-unrestricted killing of infected fibroblasts was also observed with spleen cells from all animals tested. From these results, it appears that both the humoral and cell-mediated arms of the immune response were stimulated by repeated administration of high doses of Ad2/CFTR-2 suggesting that effective, long-term adenovirus gene therapy may require modification of the vector or treatment of the host to allow the virus to evade host immune defenses.

Biological response of nonhuman primates to long-term repeated lung exposure to Ad2/CFTR-2

We have assessed the safety and efficacy of repeated adenovirus vector administration by exposing the left caudal lung lobe of rhesus monkeys to as many as 17 exposures of Ad2/CFTR-2. After nine doses of either 3 x 10(9) or 3 x 10(10) infectious units, the monkeys were free of adverse effects as assessed by thoracic radiographs, CBCs, clinical chemistries, arterial blood gases, and physical and clinical signs. In some animals elevated protein levels and increased numbers of cells were recovered in bronchoalveolar lavage (BAL), and in all animals there were increased proportions of lymphocytes in the BAL. After 11 doses, two animals were killed. In the lower dose animal (3 x 10(9) IU), there was little histopathology evident. In the higher dose animal (3 x 10(10) IU), histopathology was largely confined to a focal fibrotic lesion that may have been associated with treatment. At the tenth exposure, the dose was increased to 6 x 10(10) or 3 x 10(11) IU. There was evidence of lung injury by thoracic radiographs after two additional exposures and an increase in protein and number of cells in the BAL. The animals were still free of evidence of adverse effects by other parameters, but histopathologic changes were noted upon death. After 15 or 17 doses, three animals were instilled with Ad2/beta gal-2 and killed 3 days later. These animals had greatly reduced levels of transgene expression when compared with controls.

Adenovirus infection in cystic fibrosis patients: implications for the use of adenoviral vectors for gene transfer

Clinical trials using replication-deficient adenovirus as vectors for gene transfer into the airways of cystic fibrosis (CF) patients are in progress. However, little is known about the prevalence of wild-type adenovirus infections in patients with cystic fibrosis and their effect on lung function. To answer these questions, serum IgG and IgM antibody titers against adenovirus type 5 were prospectively measured by an indirect immunofluorescence assay in 199 CF outpatients and in a control group of 45 healthy children and young adults. In addition, we performed pulmonary function tests when the patients were in stable clinical condition. IgM antibodies against adenovirus were present in 104 of the 199 cystic fibrosis patients (52.3%). IgG antibodies against adenovirus were detected in 192 of the 199 cystic fibrosis patients (96.5%), and were significantly higher in cystic fibrosis patients older than 7 years than in younger patients and in age matched controls. IgG antibody titers measured a second time 11.8 months later in 143 of the 199 patients had increased in 48 (33.6%) patients. In 27 of these 48 patients, who had at least a 2-fold increase in antibody titer, FVC and FEV1 decreased by 9.8% (p < 0.05) and 8.3% (p = 0.05), respectively, over 45 months. In a comparison group matched for age, sex, and chronic Pseudomonas aeruginosa infection but no increase in antibody titers, FVC and FEV1 were unchanged. The results indicate that wild-type adenovirus infections are prevalent in cystic fibrosis patients and that wild-type adenovirus infections in cystic fibrosis patients seem to be associated with deterioration in lung function. These observations may have important implications for efficacy and safety considerations when using adenoviral vectors for gene therapy.

Biofilm disease: its clinical manifestation and therapeutic possibilities of macrolides

In the investigation of the disease manifestation of DPB from the viewpoint of biofilm disease, the important factors are an excess antigen-antibody reaction in which alginate acts as the antigen and the resulting formation of immune complex. The effects of 14- and 15-membered macrolides are inhibition of immunoreaction induced by alginate and their inhibitory effect on alginate production serving as an antigen at the GMD level. Further, the specificity of macrolides on these actions was also evidenced from the standpoint of structural activity. In my opinion, based on the similarity in pathogenic process between patients with infected cystic fibrosis and patients with Pseudomonas biofilm disease, long-term administration of 14- or 15-membered ring macrolides can be tried in patients with infected cystic fibrosis.

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.

Heat-shock proteins in host-pathogen interactions: implications for cystic fibrosis

The expression of heat-shock proteins by both pathogen and host cells during the phagocytosis of Staphylococcus aureus and Pseudomonas aeruginosa, two bacterial species that colonize the airways of patients with cystic fibrosis, probably contributes to pulmonary inflammation in cystic fibrosis. Here, we discuss the likely signals for heat-shock-protein induction within host and bacterial cells.

Immunohistologic quantification of Pseudomonas aeruginosa in the tracheobronchial tree from patients with cystic fibrosis

Pseudomonas aeruginosa has been recognized as a pathogen of major importance in the patient with cystic fibrosis (CF). However, no information is available regarding the histologic quantification of P. aeruginosa organisms in the CF tracheobronchial tree. We retrieved all formalin-fixed paraffin-embedded lung blocks from 20 consecutive autopsies of cystic fibrosis patients. Serial histologic sections were made and stained by three methods: hematoxylin and eosin, immunoperoxidase with anti-P. aeruginosa rabbit serum as the primary antibody, and immunoperoxidase with normal rabbit serum as the primary antibody. By studying the hematoxylin and eosin section, we classified five areas in the lung as bronchi, large bronchioles, small bronchioles, bronchioloectatic areas, and abscess/airways with destroyed epithelium. The areas stained by an anti-P. aeruginosa immunoperoxidase method were examined under high-power magnification, and the bacteria within random fields were counted. Pseudomonas aeruginosa organisms were identified in 14 of 20 cases, including 13 of 16 cases in which P. aeruginosa was specifically cultured at autopsy. Quantification of organisms within the lumens of all five airway types showed that the bacterial density in cystic fibrosis airways is highest in bronchi.

Normal bronchial epithelial cells constitutively produce the anti-inflammatory cytokine interleukin-10, which is downregulated in cystic fibrosis

Interleukin-10 (IL-10) is a potent regulatory cytokine that decreases inflammatory responses and T-cell stimulation. We have found that respiratory epithelial lining fluid (ELF) from patients with cystic fibrosis (CF) contains significantly less soluble IL-10 than ELF of healthy control subjects. Although macrophages from the chronically infected lungs of CF patients appear to be one source of IL-10, little or no intracellular IL-10 was found in bronchoalveolar lavage macrophages from healthy control subjects, suggesting that there must be another source of this cytokine in healthy lungs. We found that bronchial epithelial cells from healthy control subjects constitutively produce IL-10, which appears to be downregulated in CF patients. It is thus likely that the bronchial epithelium plays an important role in regulating the local immune response, producing IL-10 to decrease inflammation in the healthy lung. Conversely, downregulation of epithelial IL-10 production in CF airways may contribute to enhancing local inflammation and tissue damage.

Mucoid Pseudomonas aeruginosa growing in a biofilm in vitro are killed by opsonic antibodies to the mucoid exopolysaccharide capsule but not by antibodies produced during chronic lung infection in cystic fibrosis patients

Serum opsonophagocytic-killing titers often indicate the level of immune resistance to bacterial pathogens, yet in almost all cystic fibrosis (CF) patients that have chronic lung infections with mucoid Pseudomonas aeruginosa, high titers of opsonic-killing Abs can be measured and the infectious pathology still progresses through pulmonary failure and death. This anomalous finding may be due to the use of suspended cells of P. aeruginosa to evaluate phagocytic killing, whereas in the lungs of CF patients the organisms grow in a microcolony or biofilm, encased in mucoid exopolysaccharide (MEP, also called alginate). To determine whether the microcolony mode of growth contributes to bacterial resistance to host defenses, we evaluated opsonophagocytic killing of mucoid P. aeruginosa growing in a biofilm. Abs from infected CF patients were poorly able to mediate opsonic killing of biofilm, but not suspended, mucoid P. aeruginosa cells. Bacterial resistance to killing could be overcome by disruption of the biofilm layer with an enzyme that degrades MEP. Chronically infected CF patients also fail to produce opsonic-killing Abs specific to MEP, and when these Abs were evaluated in sera of older, noninfected CF patients and humans vaccinated with MEP, comparable killing of P. aeruginosa in biofilms and suspensions was obtained. In this case, C3 was deposited onto the MEP layer and could be visualized by fluorescence microscopy deposited throughout the biofilm. We conclude that opsonic Abs made by CF patients in response to chronic infection are ineffective at mediating phagocytic killing and elimination of bacterial cells growing as microcolonies in their lungs.

Cross-sectional and longitudinal studies of naturally occurring antibodies to Pseudomonas aeruginosa in cystic fibrosis indicate absence of antibody-mediated protection and decline in opsonic quality after infection

Most patients with cystic fibrosis (CF) develop chronic endobronchial infection with mucoid Pseudomonas aeruginosa. It has been suggested that opsonic antibodies to the mucoid exopolysaccharide of P. aeruginosa protect older CF patients (> 12 years of age) who have remained free of colonization by this organism. Serum antibodies from chronically infected CF patients had greater total complement-dependent opsonic activity than did those of older noncolonized patients (P < .02), but when bound antibody was equalized, opsonic quality was greater for the latter group (P < .03). In longitudinal studies, antibody titers to mucoid P. aeruginosa rose greatly after initial infection, but opsonic quality declined (P = .002). Twenty CF patients who passed age 12 free of P. aeruginosa colonization developed chronic P. aeruginosa lung infection at ages 14-35 years. Thus, naturally occurring antibodies do not protect CF patients from P. aeruginosa infection, and opsonic quality of serum antibodies deteriorates as infection becomes established.

High levels of complement-activation capacity in sera from patients with cystic fibrosis correlate with high levels of IgG3 antibodies to Pseudomonas aeruginosa antigens and poor lung function

Heat-stable opsonins from sera of cystic fibrosis (CF) patients were investigated for their ability to activate complement. Complement activation by Pseudomonas aeruginosa after opsonization with patient serum was examined in a complement-consumption assay. Absorption of patients' sera with formalin-treated and boiled bacteria removed specific antibodies and the complement activation decreased. We found a positive correlation between serum complement-activation ability and IgG3 antibody levels to lipopolysaccharide (LPS), alginate, and a crude mixture of P. aeruginosa antigens (sonicate) in a group of patients with high levels of anti-Pseudomonas precipitins. In the same group of patients a significant negative correlation was found between complement activation and lung function. Eighteen patients have been followed longitudinally with serum samples covering the pre-infection, the early, and the late stages of chronic infection. Patients with poor lung function showed significantly higher levels of complement-activation capacity. We conclude that patients with high levels of specific IgG3 antibodies are able to induce a high level of complement activation and then develop more aggressive pulmonary tissue damage, probably secondary to local immune complex formation.

Faecal interleukin-8 and tumour necrosis factor-alpha concentrations in cystic fibrosis

Interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-alpha) concentrations were measured in faecal samples from nine patients with cystic fibrosis and nine healthy age matched controls. The patients were assessed with Shwachman score, apparent energy absorption, pancreatic enzyme dosage, simple spirometry, and presence of pseudomonal colonisation. Median (range) wet stool IL-8 and TNF-alpha concentrations in patients were 32,113 pg/g (21,656-178,128) and 3187 pg/g (368-17,611) respectively, compared with < 43.5 pg (IL-8)/g (< 22-4079) and 99 pg (TNF-alpha)/g (< 0.26-231) in controls. IL-8 concentration was negatively correlated with Shwachman score (r = -0.79) and pancreatic enzyme dosage (r = -0.77), but not with energy absorption. Seven patients were mature enough to cooperate with spirometry. Their IL-8 concentrations correlated with percentage predicted forced expiratory volume in one second (r = -0.78). IL-8 concentration was greater in four patients with, than five without, established pseudomonal colonisation: median difference 134,583 pg/g. TNF-alpha concentration was not correlated with measures of disease severity. Faecal IL-8 concentration might reflect the severity of pulmonary inflammation in cystic fibrosis and could provide an easily obtainable marker of disease activity.

Bioactive tumor necrosis factor in the sputa of cystic fibrosis patients

Eighty sputum samples from 37 cystic fibrosis patients were assayed for tumor necrosis factor alpha (TNF-alpha) in the L929 bioactivity assay. In addition, the presence of TNF-alpha-specific mRNA in the sputum was determined by using TNF-alpha-specific DNA probes in a PCR amplification step after reverse transcription of the mRNA to cDNA. Bioactive TNF-alpha was detected in 69 (86%) of the 80 sputum samples tested and, on at least one occasion, in 35 (95%) of the 37 cystic fibrosis patients sampled. The highest levels of TNF-alpha were observed in sputa obtained from patients presenting with an exacerbation of their disease.

Role of the low zinc bioavailability on cellular immune effectiveness in cystic fibrosis

An altered cellular immune response as a secondary phenomenon has been suggested to be probably involved in the bronchopulmonary infections by Pseudomonas aeruginosa in cystic fibrosis (CF). The difficulty to eradicate with modern anti-pseudomonal antibiotics the bronchopulmonary infections has led us to further investigate the possible existence of other cellular immune defects and their cause. Alterations in zinc turnover are present in CF. Zinc is relevant for good immune functioning. In particular, zinc is required to confer biological activity to thymulin (ZnFTS), a biochemically defined thymic hormone with a modulating action on cell-mediated immunity. The zinc-unbound form (FTS) is inactive and it can be unmasked by in vitro zinc addition to the plasma samples revealing the total amount of circulating thymulin (active + inactive). Marginal zinc deficiencies may prevent peripheral biological activation of active thymulin. Total zinc-saturable thymulin fractions in CF are similar to those observed in normal subjects, whereas the active quota is strongly reduced associated with concomitant high plasma levels of inactive thymulin compared to the values of healthy children (P < 0.01). A strict correlation exists between zinc and thymic hormone-saturable fraction (r = 0.87, P < 0.01) in CF. These findings suggest that the defect is not due to a thymic failure but to a reduced peripheral saturation of thymulin by zinc ions. This defect might depend on augmented plasma concentration of alpha 2-macroglobulin, which has a higher binding affinity for zinc than thymulin. T cell subsets are normal in CF. Reduced NK cell number and activity are present. Also, plasma IL-2 levels are reduced. The existence of positive correlations between zinc and IL-2 (r = 0.79, P < 0.01) and between zinc or active thymulin and NK activity (r = 0.70, P < 0.01 and r = 0.88, P < 0.01, respectively) suggest a close link among zinc failure, impaired IL-2 activity, low thymulin level, and reduced NK activity in CF patients with both normal and growth retardation. Although the role of NK cells is unknown in CF, a zinc supplementation, in order to induce a complete saturation of thymulin molecules, to correct some cellular immune defects and to improve the growth, may be suggested.

Early pulmonary inflammation in infants with cystic fibrosis

The mechanisms underlying the initiation of lung disease and early respiratory morbidity in cystic fibrosis (CF) are poorly understood. By identifying infants with CF through a statewide neonatal screening program, we investigated whether airway inflammation was present in these infants, with the goal of furthering our understanding of the early events in this lung disease. Bronchoalveolar lavage fluid (BALF) from 16 infants with CF (mean age, 6 mo) and 11 disease control infants (mean age, 12 mo) was examined for the following inflammatory parameters: (1) neutrophil count; (2) activity of free neutrophil elastase; (3) elastase/alpha 1-antiprotease inhibitor complexes; and (4) the level of interleukin-8 (IL-8). We also quantified the spontaneous level of expression of IL-8 mRNA transcripts by airway macrophages. Each index of airway inflammation was increased in the BALF of infants with CF as compared with control infants. In addition, both the number of neutrophils and IL-8 levels were increased in infants with CF who had negative cultures (n = 7) for common bacterial CF-related pathogens, as well as for common respiratory viruses and fungi at the time of bronchoalveolar lavage (BAL). These findings suggest that airway inflammation is already present in infants with CF who are as young as 4 wks. Furthermore, although many different cell types (e.g., epithelial cells) may express IL-8, airway macrophages appear to be a source of this chemokine, and may thus play a prominent role in early neutrophil influx into the lung.

An easy microtiter assay for quantitation of cytokine induction by lipopolysaccharide (LPS) and activity of LPS-binding serum components

Lipopolysaccharide (LPS, endotoxin) is a major inducer of cytokines, such as interleukin 1 (IL1), IL6, IL8 and tumor necrosis factor (TNF). A convenient microtiter assay was developed to measure such activity. LPS coated onto a plastic surface was used to stimulate purified human mononuclear cells (MNC) in microtiter plates. Following stimulation the supernatants were assayed for presence of TNF by ELISA. Purified rough and smooth LPS from Pseudomonas aeruginosa gave a dose-dependent TNF release over a range of 0.1-1.0 microgram LPS/well. The assay was subsequently used to investigate the biological activity of anti-LPS antibodies and other LPS-specific serum components in sera from patients with cystic fibrosis (CF). As a group, sera from 10 CF patients chronically infected with P. aeruginosa did not affect the LPS-induced TNF release, while sera from normal controls inhibited this biological activity. When individual CF patients with or without chronic lung infection are considered, the antibodies appear to either enhance or inhibit the LPS-stimulated TNF release (range: 73-120%), while all antibodies from healthy controls inhibit the activity of LPS (range: 76-97%). Only a weak correlation (rho = 0.491, p = 0.037, n = 19) was found between the antibody titer in ELISA and the biological activity of sera. This new assay is suggested for convenient measurement of interference with cytokine induction from human MNC by patient or therapeutic anti-LPS antibodies and other LPS-specific serum components.

Serum IgG response to Burkholderia cepacia outer membrane antigens in cystic fibrosis: assessment of cross-reactivity with Pseudomonas aeruginosa

Burkholderia cepacia (Pseudomonas cepacia) is now recognised as an important pathogen in cystic fibrosis patients, and several reports have suggested that sputum-culture-proven colonisation occurs despite the presence of specific antibody. In an attempt to establish the use of antibody studies as diagnostic and prognostic indicators of B. cepacia infection, we have examined the IgG response to B. cepacia outer membrane proteins and lipopolysaccharide in patients also colonised with P. aeruginosa. The B. cepacia strains were grown in a modified iron-depleted chemically defined medium and outer membrane components examined by SDS-PAGE and immunoblotting. IgG antibodies were detected against B. cepacia outer membrane antigens, which were not diminished by extensive preadsorption with P. aeruginosa. The response to B. cepacia O-antigen could be readily removed by adsorption of serum either with B. cepacia whole cells or purified LPS, whereas we were unable to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells. The inability to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells maybe due to non-exposed surface epitopes. Several B. cepacia sputum-culture negative patients colonised with P. aeruginosa had antibodies directed against B. cepacia outer membrane protein. this study suggests that there is a specific anti-B. cepacia LPS IgG response, which is not due to antibodies cross-reactive with P. aeruginosa. Our studies indicate that much of the B. cepacia anti-outer membrane protein response is specific and not attributable to reactivity against co-migrating LPS.

Cloning and nucleotide sequence comparison of the groE operon of Pseudomonas aeruginosa and Burkholderia cepacia

By alignment of GroEL amino acid sequences from four distantly related bacteria two highly conserved domains were identified. Two oligonucleotides complementary to the conserved domains were designed based on the preferred Pseudomonas aeruginosa codon usage. The primers were used in the PCR to amplify a 900-base fragment of the P. aeruginosa groEL gene. The fragment was sequenced and the partial GroEL sequence was expanded by vectorette PCR upstream and downstream to cover the complete P. aeruginosa groE operon. The same technique was used to sequence the Burkholderia cepacia (formerly Pseudomonas cepacia) groE operon and the region immediately upstream of groES. The B. cepacia groE operon is preceded by typical -10 and -35 heat shock expression signals. A total of 2041 and 2139 bp was sequenced from P. aeruginosa and B. cepacia respectively. Each revealed two open reading frames encoding two proteins with a predicted molecular mass of 10 and 57 kDa, corresponding to GroES and GroEL respectively. The GroEL proteins show an interspecies amino acid homology of 71%, and 73% with E. coli GroEL. Both GroEL proteins are 52% homologous to the corresponding human mitochondrial GroEL protein. The sequence data confirm the existence of highly conserved structures, which could be functionally important for the concerted action of GroEL and GroES in the folding and assembly of other proteins, and possibly in the initiation of autoimmune diseases.