Secretory IgA: immune defence pattern in ankylosing spondylitis and klebsiella

Galactooligosaccharide Mediates NF-κB Pathway to Improve Intestinal Barrier Function and Intestinal Microbiota

The use of antibiotics to treat diarrhea and other diseases early in life can lead to intestinal disorders in infants, which can cause a range of immune-related diseases. Intestinal microbiota diversity is closely related to dietary intake, with many oligosaccharides impacting intestinal microorganism structures and communities. Thus, oligosaccharide type and quantity are important for intestinal microbiota construction. Galactooligosaccharides (GOS) are functional oligosaccharides that can be supplemented with infant formula. Currently, information on GOS and its impact on intestinal microbiota diversity and disorders is lacking. Similarly, GOS is rarely reported within the context of intestinal barrier function. In this study, 16S rRNA sequencing, gas chromatography, and immunohistochemistry were used to investigate the effects of GOS on the intestinal microbiota and barrier pathways in antibiotic-treated mouse models. The results found that GOS promoted Bifidobacterium and Akkermansia proliferation, increased short-chain fatty acid levels, increased tight junction protein expression (occludin and ZO-1), increased secretory immunoglobulin A (SIgA) and albumin levels, significantly downregulated NF-κB expression, and reduced lipopolysaccharide (LPS), interleukin-IL-1β (IL-1β), and IL-6 levels. Also, a high GOS dose in ampicillin-supplemented animals provided resistance to intestinal damage.

Relationship between Gut Microbiota and Bone Health

Gut microbiota (GM) are microorganisms that live in the host gastrointestinal tract, and their abundance varies throughout the host's life. With the development of sequencing technology, the role of GM in various diseases has been increasingly elucidated. Unlike earlier studies on orthopedic diseases, this review elucidates the correlation between GM health and bone health, and discusses the potential mechanism of GM effects on host metabolism, inflammation, and ability to induce or aggravate some common orthopedic diseases such as osteoarthritis, osteoporosis, rheumatoid arthritis, etc. Finally, the prospective methods of GM manipulation and evaluation of potential GM-targeting strategies in the diagnosis and treatment of orthopedic diseases are reviewed.

Raised incidence of ankylosing spondylitis among Inuit populations could be due to high HLA-B27 association and starch consumption

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis mainly affecting the spinal joints. It would appear that the most likely causative agent in the development of AS is an environmental factor in the genetically susceptible, HLA-B27 positive, individuals. Extensive data from several countries support the notion that Klebsiella pneumonia bacteria are the most likely culprit in the causation of AS. These microbes possess antigens which resemble HLA-B27 and spinal collagens. Increased intake of high-starch diet is directly proportional to the gut-associated bacterial load, especially in the large intestine, and among these microbial agents, Klebsiella is considered as one of the main constituting components. Therefore, a low-starch diet intake alongside the currently used medical therapeutic modalities could be beneficial in the management of patients with early AS. It is suggested that a change in the dietary habits from high protein, low-starch marine components to the Westernized high-starch diet among the Inuit peoples of Alaska and Canada could be considered as one of the main contributing factors in the increased prevalence of AS during the last few decades within this genetically unmixed native population.

The link between ankylosing spondylitis, Crohn's disease, Klebsiella, and starch consumption

Both ankylosing spondylitis (AS) and Crohn's disease (CD) are chronic and potentially disabling interrelated conditions, which have been included under the group of spondyloarthropathies. The results of a large number of studies support the idea that an enteropathic pathogen, Klebsiella pneumoniae, is the most likely triggering factor involved in the initiation and development of these diseases. Increased starch consumptions by genetically susceptible individuals such as those possessing HLA-B27 allelotypes could trigger the disease in both AS and CD by enhancing the growth and perpetuation of the Klebsiella microbes in the bowel. Exposure to increased levels of these microbes will lead to the production of elevated levels of anti-Klebsiella antibodies as well as autoantibodies against cross-reactive self-antigens with resultant pathological lesions in the bowel and joints. Hence, a decrease of starch-containing products in the daily dietary intake could have a beneficial therapeutic effect on the disease especially when used in conjunction with the currently available medical therapies in the treatment of patients with AS and CD.

Elevation of serum IgA in spondyloarthropathies and IgA nephropathy and its pathogenic role

Ankylosing spondylitis and IgA nephropathy share some immunologic features, eg, elevated serum IgA and IgA-immune complex levels. These entities are frequently found as being associated. IgA and IgA immune complex catabolism involves asialoglycoprotein receptors and specific IgA Fc receptors (FcalphaR or CD89) on tissue and blood cells. Recent studies revealed impaired CD89 expression in both diseases. These abnormalities, which are associated with receptor saturation, might generate the increase in serum IgA and IgA immune complex levels by either altered recycling or failure of degradation. This article reviews the literature on IgA abnormalities and discusses the potential role of FcalphaR in IgA nephropathy and AS and the consequences of its similar defect in the two diseases.

Enhanced jejunal production of antibodies to Klebsiella and other Enterobacteria in patients with ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE

To measure gut immunity directly in jejunal fluid in patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA).

METHODS

Antibodies against three different Enterobacterias were measured in jejunal perfusion fluids (collected by a double balloon perfusion device) of 19 patients with AS, 14 patients with RA, and 22 healthy controls using enzyme linked immunosorbent assay.

RESULTS

The AS patients had significantly increased jejunal fluid concentrations of IgM, IgG, and IgA class antibodies against Klebsiella pneumoniae, and IgM and IgA class antibodies against Escherichia coli and Proteus mirabilis compared with healthy controls. When compared with the patients with RA, the AS patients had higher concentrations of IgA and IgG class antibodies only against K pneumoniae. The RA patients had higher IgM class antibody concentrations against all three studied Enterobacterias, when compared with the healthy controls, suggesting an enhanced mucosal immune response in these patients. A three month treatment with sulphasalazine did not decrease enterobacterial antibody concentrations in the 10 patients with AS.

CONCLUSION

There is strong direct evidence for an abnormal mucosal humoral immune response particularly to K pneumoniae in patients with AS.

Serum secretory immunoglobulins in ankylosing spondylitis

Humoral mucosal immunity may be implicated in pathophysiology of ankylosing spondylitis (AS). The aim of the study was to evaluate serum levels of IgA, IgM and secretory IgA (sIgA), secretory IgM (sIgM) as well as free secretory component (FSC) in patients with AS compared to controls and rheumatoid arthritis (RA) patients. Levels of sIgA, sIgM and FSC were measured with a specific ELISA in 37 AS patients, 45 controls and 27 RA. The results were as follows: Serum levels of IgA were higher in AS vs controls and in RA vs controls (p = 0.01). Levels of sIgA were higher in AS vs controls (p = 0.01), but higher in RA vs AS (p = 10(-4)). There was no difference of sIgM in AS vs controls, FSC levels were higher in AS vs controls, and higher in AS patients with elevated CRP. In view of elevated FSC, this increase of sIgA in AS may have been due to excessive production of mucosal IgA after bacterial stimulation according to the current hypothesis of the disease.

Increased IgA antibodies to cytokeratins in the spondyloarthropathies

OBJECTIVES

Increased levels of IgA antibodies to cytokeratin-18 (CK-18) and epidermal keratins (EpK) in the sera of patients with rheumatoid arthritis (RA) have been demonstrated previously. In the present study investigations were carried out to determine whether levels of these autoantibodies were also raised in the spondyloarthropathies, and whether there was any association with particular disease manifestations.

METHODS

Using specific enzyme linked immunosorbent assays (ELISA) measurements were taken of IgA, IgG and IgM antibodies to EpK and to CK-18 in the sera of patients with psoriatic arthropathy, ankylosing spondylitis (AS), Reiter's syndrome, psoriasis and in normal subjects.

RESULTS

IgA antibodies to both EpK and CK-18 were significantly increased in sera from patients with psoriasis and psoriatic arthropathy but not in the sera from the patients with AS or Reiter's syndrome, or in the controls. In psoriatic arthritis, however, these levels were significantly higher only in those patients with peripheral joint disease and not in those with axial arthritis alone. There was no significant increase in antibody levels in patients with AS or Reiter's syndrome. There were no differences in the levels of IgG or IgM antibodies to CK-18 or EpK between the patient groups and controls.

CONCLUSIONS

Raised levels of IgA antibodies to CK-18 and EpK in psoriatic arthropathy and psoriasis probably reflect exposure of intracellular cytokeratin antigens to the immune system after damage to cytokeratin containing cells, and suggests a common pathogenic mechanism in these conditions which involves production of cytokeratin autoantibodies. In patients with psoriatic arthropathy, such a mechanism appears only to be operating in patients with peripheral joint involvement and not in those with axial arthritis.

[Spondylarthropathies and the IgA system]

The spondyloarthropathies (SA) implicate bacterial infections of mucosal origin. IgA synthesis capacity in vitro is normal in AS. IgA increase is secondary to a specific immune response to the bacterial antigens implicated in the disease's pathogenesis. IgA participate to immune complex formation, which may lead to some extraarticular features of the disease (e.g. renal, cutaneous or vascular). There is also an increase of secretory IgA reflecting the activation of the two compartments of this humoral immune response, part of a coherent pathophysiological scheme of the disease. In a practical point of view, IgA serum levels may be considered as a biological parameter of SA activity.

Serum levels of secretory IgA in ankylosing spondylitis

An ELISA test was performed in order to measure the serum levels of secretory IgA (sIgA) in 51 patients with ankylosing spondylitis (AS) and 30 healthy controls. Raised values of sIgA were found in AS patients compared to controls. Patients with active disease, defined by clinical criteria, showed a significant elevation of serum sIgA compared to healthy controls (p = 0.03) or to patients with inactive disease (p = 0.02). A positive correlation between total serum IgA and sIgA was found (p = 0.001). Our findings further support the role of the mucosal stimulation in the pathogenesis of AS.

Sulfasalazine in the treatment of ankylosing spondylitis. A twenty-six-week, placebo-controlled clinical trial

Eighty-five patients with active ankylosing spondylitis (AS) were randomized to receive either sulfasalazine (less than or equal to 3 gm/day, mean 2.5) or placebo for 26 weeks. There was a statistically significant improvement, compared with baseline, in most of the clinical variables in patients receiving the active drug. Laboratory parameters (erythrocyte sedimentation rate, C-reactive protein, IgG, IgM, and IgA) also improved during the active treatment, suggesting a beneficial effect of sulfasalazine on AS. At the end of the treatment, significant differences between the sulfasalazine and placebo groups were observed in morning stiffness, chest expansion, erythrocyte sedimentation rate, and in all immunoglobulin classes. Two patients in each treatment group discontinued the trial because of side effects. Enteric-coated sulfasalazine seemed to be effective and well tolerated in patients with active AS.

Raised titres of anti-klebsiella IgA in ankylosing spondylitis, rheumatoid arthritis, and inflammatory bowel disease

Serum titres of IgA are raised in ankylosing spondylitis and increased titres of antibodies to klebsiella have also been reported. The humoral response was investigated in ankylosing spondylitis and other inflammatory disorders. IgA antibodies to klebsiella pneumoniae K43 were measured in patients with ankylosing spondylitis, Crohn's disease, ulcerative colitis, and rheumatoid arthritis and in controls. Significantly raised median titres of anti-klebsiella IgA, measured as optical density at 405 nm with an enzyme linked immunosorbent assay (ELISA), were seen among the patients with ankylosing spondylitis (0.7), Crohn's disease (0.8), rheumatoid arthritis (0.6), and ulcerative colitis (0.8) compared with controls (0.4). Activity of disease in ankylosing spondylitis and titres of anti-klebsiella IgA were not correlated. In contrast, titres of anti-klebsiella IgM were significantly lower in patients with ankylosing spondylitis and ulcerative colitis. The increase in the titres of anti-klebsiella IgA may be due to increased permeability of the gut to bacterial antigens, leading to an increased IgA response in the gut mucosa and permitting the release of IgA into the circulation. As the increased antibody titres were seen in Crohn's disease and rheumatoid arthritis as well as in ankylosing spondylitis the response may be nonspecific, occurring because of possible underlying inflammatory bowel disease in these conditions.

Phagocyte function in reactive arthritis

The pathogenesis of reactive arthritis is multifactorial. The possible pathogenetic mechanisms include the role of microbial antigens which cross-react with the host tissue or trigger cytotoxic immune response. In addition an exaggerated inflammatory response of the host may contribute to the clinical picture of the acute arthritis and its late sequels. In this review, we present data showing that HLA-B27 positive subjects show enhanced neutrophil (PMN) migration and their sera support PMN migration more than HLA-B27 negative sera. Enhanced PMN function is persistent in patients with previous severe reactive arthritis or with late inflammatory sequels. In addition to hyperreactive PMNs, monocytes from patients with previous yersinia arthritis, but also from healthy HLA-B27 positive subjects, respond to stimulation with lipopolysaccharide by enhanced production of inflammatory monokines compared with HLA-B27 negative healthy controls. Thus, hyperreactive phagocytes can contribute to the severe inflammatory complications seen in patients with reactive arthritis. The primed phagocytes can also respond vigorously when stimulated either with endogenous mediators of inflammation or with endotoxin released during a new infection or as a sequel of change in the mucosal permeability described in patients with spondyloarthropathy.

Chlamydia trachomatis serology in ankylosing spondylitis

Demonstration of chlamydial antibodies in patients with ankylosing spondylitis (AS) could show an etiological role of Chlamydia trachomatis in this condition. We studied serum specimens from 50 HLA-B27 positive patients with AS (Group I), 34 HLA-B27 positive patients with other rheumatic diseases (Group II), 67 HLA-B27 positive healthy blood donors (Group III) and 37 healthy untyped blood donors. (Group IV). Measured by an immunoperoxidase assay (IPA) chlamydial IgA (titre greater than or equal to 1:20) was more prevalent in the HLA-B27 positive persons than in the healthy controls not selected for HLA-group (Groups I + II + III vs IV : p less than 0.02). Chlamydia trachomatis IgA-IPA containing sera also had specific IgG-IPA antibodies (greater than or equal to 1:80) in 29 (96%) out of 30 sera from HLA-B27 positive individuals and controls. Conversely, 45% of specific IgG-positive (greater than or equal to 1:80) AS sera, 27.7% sera in Group II, 39.4% Group III sera vs. 11.1% of sera in Group IV had concomitant chlamydial IgA (greater than or equal to 1:20). The differences in the prevalence of specific IgA were statistically significant: Group I vs. IV : p less than 0.01; Group III vs. IV :p less than 0.05 and Gr. I + II + III vs. IV: p less than 0.05. Our data suggest an enhanced antibody production against Chlamydia trachomatis among the HLA-B27 positive individuals whether they have AS or are healthy.

Correlation of immunoglobulin and C reactive protein levels in ankylosing spondylitis and rheumatoid arthritis

Serum C reactive protein (CRP), IgG, and IgA levels were measured in 22 patients with ankylosing spondylitis (AS) and in 20 patients with rheumatoid arthritis (RA) to study the regulation of these proteins in inflammatory disease states. In both RA and AS the mean CRP, IgG, and IgA levels were raised above normal values. Although IgA and CRP levels showed a significant positive correlation in RA (r = 0.53, p = 0.02), there was no correlation between these values in AS (r = 0.24, p = 0.29). The difference in correlation coefficients between the AS and RA groups was significant at a p = 0.05 level. In RA the raised IgA levels may be another manifestation of the acute phase response, as shown by the good correlation between IgA and CRP in that disease. In AS, however, the IgA levels, although raised, do not correlate with CRP levels, suggesting that the mechanism of increase of IgA in the two diseases is different. Gut mediated immune stimulation has been proposed as a cause of raised IgA levels in AS.

IgA antibodies to gram-negative bacteria in the serum and saliva of patients with ankylosing spondylitis

The concentration of IgA and titre of IgA antibodies to several Gram-negative bacteria were measured in the serum and parotid saliva of patients with AS and normal tissue-typed individuals. Salivary IgA and antibody levels in the patients were identical with the control population. The serum antibody level against Yersinia enterocolica 0:3 was slightly raised in patients but there was no difference in the reactions to Klebsiella oxytoca strain MX100 or Escherichia coli 0111.B4. The serum IgA level was elevated in patients with AS, irrespective of HLA B27. We conclude that this approach is unlikely to provide convincing evidence of a link between Gram-negative bacteria and ankylosing spondylitis.

IgA-anti-yersinia antibodies in yersinia triggered reactive arthritis

Patients who develop reactive arthritis after yersinia enteritis are characterised by high and persisting IgA-anti-yersinia antibodies. We have further analysed the humoral immune response to yersinia in this condition. Total concentrations of IgM, IgG, IgA, and secretory IgA in the serum and specific anti-yersinia antibodies belonging to IgA1, IgA2, or secretory IgA were compared in patients with or without reactive arthritis. In the former group the serum concentration of secretory IgA and of yersinia specific antibodies in all categories studied was raised compared with the level in patients without joint symptoms; the difference was most significant for the IgA-anti-yersinia antibodies with secretory piece or with J chain. The findings suggest that the strong antibody response in the patients developing reactive arthritis is due to a chronic stimulation of the intestinal lymphoid tissue.

Absence of IgA nephropathy in patients with ankylosing spondylitis

In 40 patients with ankylosing spondylitis (AS) no evidence for IgA nephropathy was obtained. This conclusion was based on the absence of hematuria and on the inability to find an increased incidence of IgA-containing immunoglobulin deposits in skin biopsies. Increased Clq binding assay was only found in those AS patients with anterior uveitis. In 26% of the skin biopsies perivascular mononuclear cell infiltrates were observed, and immunoglobulin deposits were seen in 65%. These facts suggest that the immunologic system is involved in the pathogenesis of this disease.

Immunological variables and acute-phase reactants in patients with ankylosing spondylitis (Bechterew's syndrome) and their relatives

Serum and EDTA blood from 120 patients with ankylosing spondylitis (Bechterew's syndrome) and serum from 138 first-degree relatives of patients and from 42 adult blood donors were investigated. Increased serum concentrations of IgA and IgG and complement factors C3 and C4 were found in total groups of HLA B27-positive male or female patients compared with controls or relatives. The men had higher serum concentration of IgA and complement factors than the women, whereas IgM concentration was higher in the women. These patterns were found in controls, in relatives and in patients. Increased concentrations of IgA and of C4 were characteristic of all patients whereas IgG and IgM and C3 concentrations were likewise elevated in patients with peripheral joint arthritis/arthropathy. Increased levels of circulating immune complexes (CIC) were associated with peripheral joint arthritis and were strongly correlated with IgG or CRP concentrations in serum. Total haemolytic complement activity in serum was negatively correlated with concentrations of CIC or CRP indicating complement activation in patients with such complexes. No differences in serum concentrations of Ig or complement factor concentrations were seen between HLA B27-positive and negative relatives with normal sacro-iliac joints or between relatives and controls. Strong mutual correlations were seen among IgG, IgM, complement factors, CRP, SAA, sedimentation rate and alpha 2-macroglobulin. When the present findings were combined with our previous results it turned out that AS, and psoriasis with or without arthropathy, and acute anterior uveitis (AAU) in combination with sacro-iliitis, may be described as IgA-related conditions and that increased serum C4 was related to sacro-iliitis in all these disorders.

IgM, IgG, and IgA synthesis in vitro in persons suffering from yersinia arthritis and in patients with ankylosing spondylitis

In ankylosing spondylitis (AS) and in yersinia arthritis the main findings in serum immunoglobulin (Ig) studies have been raised IgA in AS and a high anti-yersinia IgA and IgG response and the persistence of IgA class antibodies in yersinia arthritis. In order to study predisposition to high IgA response in AS and yersinia arthritis we measured the in-vitro Ig production in patients with AS and in persons who have once had yersinia arthritis, and we compared it with the Ig production in persons who have had yersiniosis but recovered without getting arthritis and with that in healthy controls. IgA secretion by peripheral blood lymphocytes stimulated by pokeweed mitogen was the same in all 4 groups, and no signs of higher IgA production in AS patients could be found. In AS patients lymphocyte activation by whole yersinia bacteria resulted in higher total IgG production than in healthy controls. The total number of plaque-forming cells in yersinia-stimulated cultures was significantly higher in persons who have had yersiniosis without arthritis than in persons who have suffered from yersinia arthritis or in persons in other groups. AS patients had low IgM production, which reverted to normal when hydrocortisone was added to the culture. The in-vitro Ig production in general did not correlate with the presence of the HLA B27 antigen but rather with the clinical history of the subjects studied.

HLA-B27 and the immune response to enterobacterial antigens in ankylosing spondylitis

Total serum immunoglobulins and class specific serum antibodies to Klebsiella pneumoniae, Salmonella typhimurium, Yersinia enterocolitica and Pseudomonas aeruginosa were measured in 107 patients with ankylosing spondylitis (AS) and 110 healthy tissue typed controls by enzyme linked immunosorbent assay (ELISA). The specificity of this technique was confirmed by the use of specific bacterial murine antisera and by cross-absorption of human sera by specific bacteria. Total serum IgA in AS patients correlated with both erythrocyte sedimentation rate (ESR) (P less than 0.001) and C-reactive protein (P less than 0.05) and was significantly elevated compared to healthy individuals (P less than 0.001). A significant elevation of IgA antibodies to K. pneumoniae was detected in the serum of AS patients with active disease when compared to healthy controls (P less than 0.01). These studies support the involvement of an enterobacterial micro-organism in the pathogenesis of AS and further relate to the role of HLA-B27 in this disease.

Serum and secretory IgA immune response to Klebsiella pneumoniae in ankylosing spondylitis

Serum and salivary IgA antibodies to Klebsiella pneumoniae were estimated by enzyme-linked immunosorbent assay (ELISA) in 53 patients with ankylosing spondylitis (AS) and 30 healthy controls. The concentrations of total serum IgA, salivary secretory component (SC) and serum C-reactive protein (CRP) were also measured. In the serum of AS patients there was a positive correlation between Klebsiella IgA antibodies and the CRP. Salivary anti-Klebsiella IgA was elevated in 39% of AS patients although this was not associated with disease activity. Serum and secretory IgA antibodies to E. coli and Pseudomonas aeruginosa were similar in patients and controls irrespective of disease activity. We conclude that part of the increase in salivary and serum IgA in AS may be due to a specific immune response to Klebsiella in the gastrointestinal tract and that serum antibodies reflect more closely those events associated with active inflammatory disease.

Acute-phase proteins and serum immunoglobulins in ankylosing spondylitis

The erythrocyte sedimentation rate (ESR) and the serum acute-phase proteins (APP), C-reactive protein (CRP), fibrinogen, 9th component of complement (C9), and alpha, antitrypsin were measured on 231 occasions in 80 patients with ankylosing spondylitis and compared with those in 30 controls. APP levels did not correlate with clinical assessment of disease activity. However, there were significant correlations between CRP, C9, and fibrinogen (p = less than 0.01), suggesting that these APP may be more reliable indicators of disease activity. The mean values of the APP in those patients with a peripheral arthritis were significantly higher than in those with pelvospondylitis alone for ESR (p less than 0.01), CRP (p less than 0.01), and fibrinogen (p less than 0.05). The only significant difference between those patients with an iritis and those with only pelvospondylitis was an elevated CRP in the iritis group (p less than 0.01). This suggests that a peripheral arthritis is the most important cause of an elevated ESR or APP in ankylosing spondylitis. Serum immunoglobulins were also measured and they showed a significant elevation of IgA in all 3 patients groups, there being no difference between each group. Serum IgG was raised only in those patients with an iritis or peripheral arthritis, the IgM levels being within the normal range for all patient groups.

IgA antibodies to Klebsiella pneumoniae in ankylosing spondylitis

Serum IgA antibodies to Klebsiella pneumoniae were measured in 65 patients with ankylosing spondylitis (AS) during different phases of disease activity and compared with the antibody level in 21 psoriatic arthritis (PsA) patients, 43 rheumatoid arthritis (RA) patients and 57 healthy controls. The mean IgA antibody to Klebsiella in AS patients with an erythrocyte sedimentation rate (ESR) greater than or equal to 15 mm/h was significantly higher than the antibody level in patients with an ESR less than 15 mm/h (p less than 0.02) and tended to increase with rising ESR. There was a significant difference in anti-Klebsiella antibody levels between AS patients with an elevated ESR and antibody levels in PsA patients (p less than 0.001), RA patients (p less than 0.001) and healthy controls (p less than 0.005). There was no difference between healthy controls and patients with PsA, RA or AS patients with a low ESR. The IgA anti-Klebsiella antibody was specifically absorbed out from sera with inactivated klebsiella pneumoniae organisms. Antibody levels to Candida albicans and Escherichia coli did not differ in patients vis-à-vis control subjects. The mean serum anti-Klebsiella IgA level was found to be higher in patients who were either clinically active or had positive faeval cultures, when compared with patients with inactive disease and negative cultures, but these differences were not statistically significant, although when both parameters were examined together a significant additive effect was detected (p less than 0.001). It is concluded that patient with AS exhibit a specific elevation of serum IgA antibody to Klebsiella antigen.

Reactive arthritis--infectious agents and genetic susceptibility in the pathogenesis of sero-negative arthritis

In this review we discuss the role of genetic and infectious factors in the aetiology of ‘reactive’ arthritis. Two broad categories of reactive arthritis are considered—the sero-negative HLA B27 related spondarthritides, and a miscellaneous group of reactive arthritides occuring after bacterial infection but which are not HLA B27 related.