A factor(s) in Klebsiella culture filtrates specifically modifies an HLA-B27 associated cell-surface component

Recent Developments in HLA B27 Anterior Uveitis

There has been steady progress in understanding the pathogenesis, clinical features, and effective treatment of acute anterior uveitis (AU) over the past 5 years. Large gene wide association studies have confirmed that AU is a polygenic disease, with overlaps with the seronegative arthropathies and inflammatory bowel diseases, associations that have been repeatedly confirmed in clinical studies. The role of the microbiome in AU has received increased research attention, with recent evidence indicating that human leukocyte antigen B27 (HLA B27) may influence the composition of the gut microbiome in experimental animals. Extensive clinical investigations have confirmed the typical features of acute AU (AAU) and its response to topical, regional and systemic immunosuppressive treatment. Increased understanding of the role of cytokines has resulted in studies confirming the value of anti-cytokine therapy [anti-tumor necrosis factor (anti-TNF) and interleukin 6 (IL-6) therapy] in severe and recurrent cases of AAU, particularly in subjects with an associated spondyloarthopathy (SpA) and in juvenile idiopathic arthritis (JIA)-associated AAU.

PROBIOTICS - A PROBABLE THERAPEUTIC AGENT FOR SPONDYLOARTHROPATHY

Spondyloarthropathy (SpA) or spondyloarthrosis refers to any joint disease of the vertebral column. Among the entities of SpA, ankylosing spondylitis has drawn the attention of some researchers, because of its specific mechanism of disease progression. It has been studied earlier that its progression is due to the presence of HLA (human leukocyte antigen) - B27. It shows molecular similarity and immunological cross-reactivity with some of the gut microbiome. Since SpA could be treated or its symptoms could be lessen by medications, but medications itself show many side effects and other complications. Probiotic- being the natural product has been found to be effective against many SpA entities, including Ankylosing Spondylitis. It alters gut microflora somehow in such a way that it helps in reducing the predisposition of any factor to SpA. Here we consider the complex relationship between SpA pathogenesis and gut microbes; with discussion that how use of probiotics as an alternative drug therapy may treat or reduce the progression of SpA, which could be a better future target to treat SpA entities.

The role of the gut and microbes in the pathogenesis of spondyloarthritis

The intestinal microbiota is firmly implicated not only in the pathogenesis of inflammatory bowel disease (IBD) but increasingly also in the development of inflammation at extraintestinal tissue sites. Significant clinical, genetic, immunological, and microbiological overlap exists between IBD and spondyloarthritis (SpA), which indicates that pathophysiological mechanisms are shared between these diseases and may center on the intestinal microbiota. Recently, culture-independent techniques have enabled the microbiota in health and disease to be described in increasing detail. Moreover, functional studies have identified myriad host effector and regulatory pathways that shape or are shaped by this microbial community. We consider the complex relationship between SpA pathogenesis and gut microbes, with a discussion of how manipulation of the gut microbiota itself may be a promising future target for SpA therapy.

Familial occurrence of subacute thyroiditis associated with human leukocyte antigen-B35

Subacute thyroiditis (SAT) is a spontaneously remitting inflammatory disorder of the thyroid, associated with human leukocyte antigen (HLA)-B35, and may be virally induced in genetically predisposed individuals. A 57-year-old Caucasian man presented with symptoms of hyperthyroidism as well as enlargement and tenderness of the thyroid. The patient had an elevated erythrocyte sedimentation rate, low thyrotropin (TSH) and elevated thyroxine and triiodothyroinine levels with suppressed 131I thyroidal uptake. He was diagnosed to have SAT. In the patient's family three sisters and one brother also had had SAT, as probably did the deceased father. Because of the familial occurrence HLA-typing was performed. All affected family members were heterozygous for HLA-B35. The family members lived more than 50 miles apart in different regions of The Netherlands and had SAT at different time points between 1986 and 2002, which in combination with HLA-B35 seems to highlight the importance of genetic influences as a risk factor for the development of SAT in this family. In conclusion, the case described here represents the second familial incidence and largest family reported so far with occurrence of SAT in association with HLA-B35.

HLA-B27 associated spondyloarthropathy, an autoimmune disease based on crossreactivity between bacteria and HLA-B27?

Most autoimmune diseases are associated with certain HLA types. Therefore, spondyloarthropathies (SpA) strongly associated with HLA-B27, are also often classified as autoimmune diseases. This study questions whether SpA indeed fulfils the criteria of an autoimmune disease. The Medline database was searched for all reports between 1966 and April 1998 on the presence of autoimmune reactivity in SpA patients. This search yielded 45 articles on this subject. Only eight articles study T cell reactivity. Twelve reports were found on the assessment of antibodies crossreacting between bacteria and HLA-B27. In the 45 studies demonstrating autoimmune reactions in SpA patients proper controls matched for HLA-B27, sex and age were nearly always lacking. Therefore, it is concluded that the frequency of increased autoreactivity in sera from patients and controls is not significantly different, and that this lack of autoreactivity does not justify classification of SpA as an autoimmune disease. As crossreactive antibodies against bacteria and HLA-B27 were equally present in sera from patients and controls, the pathogenetic significance of molecular mimicry between various bacteria and HLA-B27 is questionable. Furthermore, the regions of the B27 molecule that are supposed to be crossreactive with bacteria, differ in one or more amino acids among the distinct B27 subtypes. Although these differences strongly influence the binding of antibodies to the B27 molecule, there was no relation between the degree of crossreactivity of certain subtypes and the association of these subtypes with SpA. In conclusion, there is no evident proof that SpA is an autoimmune disease attributable to crossreactivity between bacteria and HLA-B27.

Immunopathological mechanisms in bacterial-host interactions

The ability of bacteria to cause immunopathological damage in the host may take a variety of forms. These pathways may be conveniently grouped under three major headings: (1) organisms that can cause damage via shared antigenic determinants between host and bacterium; (2) those organisms that suppress the host’s response; and (3) organisms that release substances with specific biological properties or have receptors for specific tissue sites. The group A streptococcus is among the most versatile of these bacteria because it appears that it may use all three pathways in various streptococcal-related disease states. In rheumatic fever and chorea it appears that cross-reactive antigens play a major role in inducing immunopathological damage in that there is both a heightened humoral and cellular reaction by the host to these cross-reactive determinants. Recent evidence also indicates that rheumatic fever individuals express certain B cell antigens that may be associated with susceptibility to the disease. In the other complications of streptococcal infections, namely poststreptococcal glomerulonephritis, the bacterium uses both suppression of the host’s immune response and the excretion of a particular protein common to all nephritis-associated strains to achieve its immunopathological damage. In this context, other examples of bacterial-host interactions will be discussed as evidence for the common pathways used by microbes to cause immunopathological damage in the host.

HLA-B27 positive ankylosing spondylitis and polyarteritis nodosa: a case report

A 35-year-old man, with positive HBV and HCV markers, showed clinical and histopathological features of polyarteritis nodosa (PAN), in the course of HLA-B27 positive ankylosing spondylitis (AS). The possible occurrence of both diseases in genetically susceptible subjects is discussed. Although the role of HBV surface antigen in the pathogenesis of PAN is well established, there is still a large proportion of PAN patients with no evidence of HBV infection. In the present case, the coexistence of HCV infection led us to speculate about a possible role of this virus in the pathogenesis of PAN. In our case we were able to verify the sensitivity of single photon emission computed tomography (SPECT) in the diagnosis and the clinical evaluation of the ischaemic cerebral lesions.

Klebsiella pneumoniae-reactive T cells in blood and synovial fluid of patients with ankylosing spondylitis. Comparison with HLA-B27+ healthy control subjects in a limiting dilution study and determination of the specificity of synovial fluid T cell clones

OBJECTIVE

To study the frequency of Klebsiella pneumoniae-responsive T cells in the peripheral blood (PB) of ankylosing spondylitis (AS) patients compared with that in healthy HLA-B27+ donors, and to examine T lymphocyte clones (TLC) derived from AS patient synovial fluid (SF) for the presence of Klebsiella reactivity.

METHODS

Limiting dilution analysis of PB T cells in 8 patients with active AS and in 8 HLA-B27+ healthy subjects was used to determine the frequency of PB T cells responsive to K pneumoniae and Escherichia coli GroEL. SF T cells from a patient with active AS were cloned, and 125 TLC were characterized in proliferation assays.

RESULTS

There were fewer T cells in the PB of AS patients that reacted with K pneumoniae than in the PB of healthy HLA-B27+ subjects. The frequencies of E coli GroEL-responsive T cells were approximately 5-10 times lower in all subjects tested (healthy donors and AS patients), but without significant differences between the 2 groups. Two CD4+ TLC that recognized K pneumoniae (1 cross-reactive with E coli) as well as 3 TLC that recognized GroEL (2 CD4+, 1 T cell receptor gamma/delta+) were isolated from the SF of a patient with actige AS.

CONCLUSION

Our results indicate that there is a quantitative reduction of K pneumoniae-responsive T cells in the PB of AS patients as compared with healthy controls. This may reflect a defective peripheral T cell defense in the immune response to Klebsiella and may allow bacterial antigens to reach the synovium, where they initiate specific T cell responses.

Comparison of the antibody responses to the 77 Klebsiella capsular types in ankylosing spondylitis and various rheumatic diseases

The production of antibodies to Klebsiella capsular polysaccharides was measured in sera from either HLA-B27-positive (HLA-B27+) or HLA-B27-negative (HLA-B27-) patients with classical ankylosing spondylitis (n = 54). These sera were compared with sera from patients with various rheumatic diseases (n = 82) and HLA-B27+ or HLA-B27- healthy individuals (n = 85). All sera were analyzed by means of an enzyme-linked immunosorbent assay specific to each of the 77 Klebsiella serotypes. The sera from HLA-B27+ patients with ankylosing spondylitis showed a significantly higher antibody frequency to the capsular types K26, K36, and K50 than the sera from HLA-B27- ankylosing spondylitis patients, patients with psoriatic arthritis, systemic lupus erythematosus, rheumatoid arthritis, or reactive arthritis after Yersinia enterocolitica infection, or healthy controls (P < 0.02). The antibodies were of the immunoglobulin G type. No significant antibody response to the other 74 Klebsiella serotypes, noncapsulated mutants of K26, K36, and K50, or preparations of Citrobacter, Serratia, Hafnia, or Morganella spp. or Streptococcus pneumoniae could be detected. The results might suggest a specific association between these capsular types and HLA-B27+ ankylosing spondylitis and might imply their predominance in this disease.

Failure of the serological determination of HLA-B27 due to antigen masking in patients with ankylosing spondylitis

In patients suffering from ankylosing spondylitis (AS) HLA-B27 determination by means of the microlymphocytotoxicity test (MLCT) sometimes gives equivocal or false-negative results even though it has been performed with meticulous care. These failures of the test did not arise when the isolated mononuclear cells (MNC) were incubated in lymphocyte culture medium at 37 degrees C under sterile conditions for 24 h. To objectify these observations two methods of HLA class I typing were implemented before and after incubation of the test MNC in culture medium: a bioluminescence method based on the loss of adenosine triphosphate (ATP) in lysed cells in a modification of the usual MLCT and a flow cytometric (FC) test using direct immunofluorescence with an anti-HLA-B27 monoclonal antibody (MAB). In this study 50 patients with AS and 12 healthy volunteers were typed by the usual MLCT according to the NIH standard method and with both of the quantitative methods. In most of the AS patients the discrimination between positive and negative typing results became more distinct after 24 h incubation in culture medium. In the entire group of AS patients tested three false-negative typing results were prevented by this method. Although the MAB against HLA-B27 is cross-reactive with HLA-B7 and HLA-B22, errors in the FC analysis could be avoided by calibration of the flow cytometer with standard calibration beads. Possible explanations for masking of the HLA-B27 in AS patients are discussed.

A hypothesis for the HLA-B27 immune dysregulation in spondyloarthropathy: contributions from enteric organisms, B27 structure, peptides bound by B27, and convergent evolution

Several human rheumatic diseases occur predominantly in persons who carry the histocompatibility (HLA) class I allele B27. They have also been related to Gram-negative enteric microorganisms. In addition, the recent recovery of peptides bound to B27 has allowed an understanding of the structural requirements for their binding. Using the accumulated data base of protein sequences, we have tested a series of hypotheses. First, we have asked whether the primary amino acid sequence of the hypervariable regions of HLA-B27 shares short sequences with the proteins of Gram-negative enteric bacteria. The data demonstrate that, unique among the HLA-B molecules, the hypervariable regions of HLA-B27 unexpectedly share short peptide sequences with proteins from these bacteria. Second, we have asked whether the enteric proteins tend to satisfy the structural requirements for peptide binding to B27 in those regions of the sequence shared with B27. This hypothesis also tends to be true, especially in an allelically variable part of the B27 sequence which is predicted to bind B27 if it were to be presented as a free peptide. We conclude that HLA-B27 and enteric Gram-negative bacteria have undergone a previously unappreciated form of convergent evolution which may be important in the process leading to these rheumatic diseases. Moreover, the regions of the enteric bacterial proteins which are contiguous with the short sequences shared with B27 tend to have structures which are also predicted to bind B27. These observations suggest a mechanism for autoimmunity and lead to the prediction that the B27-associated diseases are mediated by a subset of T-cell receptors, B27, and the peptides bound by B27.

Systemic and mucosal antibodies to Klebsiella in patients with ankylosing spondylitis and Crohn's disease

Whole gut lavage fluid is a useful source of material for the study of intestinal immunity and inflammation in humans. Systemic and mucosal antibodies to Klebsiella pneumoniae were measured by enzyme linked immunosorbent assay (ELISA) in serum samples and whole gut lavage fluid from 14 patients with ankylosing spondylitis, 14 with Crohn's disease, and 16 immunologically normal controls. As the concentration of IgG in whole gut lavage fluid reflects disease activity in Crohn's disease, this approach was used to detect intestinal inflammation in patients with ankylosing spondylitis who also had disease activity and use of non-steroidal anti-inflammatory drugs (NSAIDs) recorded. Small intestinal permeability to cellobiose and mannitol was also studied. In serum samples, levels of IgA antibody to klebsiella were high in patients with Crohn's disease and in patients with active ankylosing spondylitis, and were significantly correlated with the erythrocyte sedimentation rate in patients with ankylosing spondylitis. Levels of IgG antibody to klebsiella were also high in patients with Crohn's disease. Studies of whole gut lavage fluid showed similar levels of IgA antibody to klebsiella in the three study groups, but levels of whole gut lavage fluid IgM and IgG antibodies to klebsiella were high in patients with Crohn's disease. Levels of IgG in whole gut lavage fluid were high in patients with Crohn's disease but in only one patient with ankylosing spondylitis, though the cellobiose/mannitol permeability ratio was abnormal in eight of 13 patients with ankylosing spondylitis. It is concluded that high levels of serum IgA antibody to klebsiella are not specific to ankylosing spondylitis, and that there is no evidence of an abnormal intestinal IgA antibody response to klebsiella in patients with ankylosing spondylitis.

Absence of autoantibodies to peptides shared by HLA-B27.5 and Klebsiella pneumoniae nitrogenase in serum samples from HLA-B27 positive patients with ankylosing spondylitis and Reiter's syndrome

Some microorganisms which are pathogenic in humans share amino acid sequences with human proteins (molecular mimicry). It has been suggested that molecular mimicry might be a reason for autoimmunity as a result of immunological cross reactivity. A homologous sequence of six amino acids has been found in both Klebsiella pneumoniae nitrogenase and the HLA-B27.5 molecule. In addition, (auto)antibodies to a synthetic peptide that contained the HLA-B27.5/klebsiella mimicking epitope have been detected in serum samples from HLA-B27 positive patients with ankylosing spondylitis and Reiter's syndrome. Confirmation of these data is important, because ankylosing spondylitis and Reiter's syndrome have so far been assumed to be 'seronegative' rheumatic diseases. It was, however, not possible to confirm the presence of autoantibodies against the mimicking peptide in serum samples from patients with ankylosing spondylitis and Reiter's syndrome. Serum samples from 81 patients with ankylosing spondylitis, 38 patients with Reiter's syndrome, and 81 healthy blood donors were tested against the 'mimicking peptide' in an enzyme linked immunosorbent assay (ELISA). Some of the serum samples from patients showed high but non-specific binding to the mimicking peptide. A highly significant correlation between binding to plastic coated with the mimicking peptide, to plastic coated with an irrelevant peptide, and even to non-coated plastic was observed. The nature of the serum component(s) in these patient serum samples (and some control serum samples) responsible for the high non-specific binding to plastic remains unclear. It was also shown that antibodies to the HLA-B27 peptide (containing the mimicking epitope) induced in rabbits do not cross react with the klebsiella peptide and vice versa.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.

Immune complexes in ankylosing spondylitis

Immune complexes have been reported in ankylosing spondylitis (AS) and may implicate infectious agents. Serum samples from 49 patients with AS were assayed for immune complexes by polyethylene glycol precipitation, followed by radial immunodiffusion and pepsinogen binding immunoassay. Both methods showed increases in IgA containing immune complexes, which correlated with serum IgA and with IgA rheumatoid factor concentrations, but did not show increases in other immune complex components. Increased immune complexes were associated with peripheral joint synovitis, but showed no correlation with other clinical or laboratory indices of disease activity. Immune complexes from nine AS serum samples and one AS synovial fluid were electrophoretically separated then probed with anti-Klebsiella pneumoniae, but AS specific antigens were not identified. This study did not suggest a major role for immune complexes in AS without peripheral disease, nor provide serological evidence for the involvement of klebsiella antigens.

Autoimmunity in periodontal disease

Periodontal disease in characterized by the loss of the normal supporting tissues of the teeth and a humoral and cellular immune response to bacterial antigen of dental plaque which accumulates at the dento-gingival junction. This review considers the evidence for the existence of an autoimmune component of the host immune response, the possible origin of such a response and the way in which such a host response may contribute to the changes observed in the periodontium in the disease.

Autoantibodies to the HLA-B27 sequence cross-react with the hypothetical peptide from the arthritis-associated Shigella plasmid

We previously reported elevated serum antibody levels to a peptide representing the HLA-B27 polymorphic region (B27 peptide) in HLA-B27(+) ankylosing spondylitis (AS) patients. A plasmid (pHS-2) isolated from arthritogenic Shigella flexneri strains had been shown to encode an amino acid sequence homologous to HLA-B27. Rabbit antibody to this sequence (pHS-2 peptide) strongly cross-reacted with B27 peptide and, to a much lesser extent, with Klebsiella nitrogenase peptide. Serum antibody levels to pHS-2 peptide were studied in 160 spondylarthropathy patients. 12 of 115 (10.4%) AS patients, 2 of 45 (4.4%) patients with Reiter's syndrome or reactive arthritis as well as 6 of 147 (4.1%) normal controls were shown to have elevated anti-pHS-2 peptide antibodies. Antibody levels to B27 and pHS-2 peptides were significantly correlated in 134 HLA-B27(+) patients (r = 0.333, P less than 0.001). 13 of 15 affinity-purified anti-B27 peptide antibodies from patients strongly cross-reacted with pHS-2 peptide, whereas only 3 weakly cross-reacted to nitrogenase peptide. Leucine appeared to be a critical residue for this cross-reaction. AS patients' anti-B27 peptide antibodies reacted with HLA-B27 transfected L cells. These results may suggest that pHS-2 peptide more efficiently "mimics" B27 peptide than does nitrogenase peptide. Involvement of pHS-2 in pathogenesis of spondylarthropathy through molecular mimicry mechanisms requires further study.

Guilt by association: HLA-B27 and ankylosing spondylitis

The remarkable association between HLA-B27 and ankylosing spondylitis (AS) remains an enigma. While previous reviews have discussed the controversies surrounding the involvement of bacteria in the etiology of this disease and the sequence variability between subtypes of HLA-B27, concepts of disease mechanism remain ill-defined. In this article Richard Benjamin and Peter Parham synthesize new data on the structure and function of HLA class I molecules into possible mechanisms that might underly the pathogenesis of AS.

Dysfunction of HLA-B27

Every HLA antigen, as defined by the WHO-HLA Nomenclature, is unique. The major function of these molecules is to present antigen-peptides to the T-cell receptor, thereby contributing to the immunological defence mechanism. This function is regulated for each MHC antigen by its unique structure, with the peptide-binding pockets of the three-dimensional groove of the corresponding molecules playing the critical role. However, HLA-B27 is special by virtue of its disease association(s). Various aspects which might provide an explanation for--or at least a clue to an understanding of the specific role of--B27 in its disease associations are reviewed. Since it appears that there are no published experimental data which would support either of the alternative hypothetical possibilities, the bulk of current theories must therefore be purely speculative. The only lead to a better understanding of the function of B27 in disease associations is the postinfectious reactive arthritis. If it is the B27 molecule itself which is involved, further in vivo work on B27 transgenic animals might help solve this problem with its numerous unknown factors.

The use of enzyme immunoassay (EIA) and radiobinding assay to investigate the cross-reactivity of Klebsiella antigens and HLA B27 in ankylosing spondylitis patients and healthy controls

The binding of rabbit anti-Klebsiella antibodies to tissue-typed lymphocytes obtained from 30 ankylosing spondylitis (AS) patients and 54 healthy subjects has been measured by an enzyme immunoassay method. HLA B27 positive lymphocytes obtained from either AS patients (t = 3.60; p less than 0.001) or healthy subjects (t = 3.77; p less than 0.001) were found to bind Klebsiella antibodies to a significantly greater extent than non-B27 lymphocytes obtained from healthy controls. Absorption studies demonstrated that HLA B27 positive lymphocytes absorbed out significantly more anti-Klebsiella antibodies than HLA B27-negative lymphocytes (t = 6.76; p less than 0.005). These results are compatible with cross-reactivity or molecular mimicry between HLA B27 and epitopes on some Gram-negative bacteria such as Klebsiella.

Blood lymphocytes from ankylosing spondylitis patients fail to induce disease-specific cytotoxic T lymphocytes

The intriguing observation made by Geczy et al. (1) showing the possibility of generating specific ankylosing spondylitis--cytotoxic T lymphocytes by presenting HLA-B27+AS+ cells as antigen-specific stimulator cells prompted us (by using Geczy's approach) to identify cytotoxic T lymphocytes specific for this apparent B27+AS+ target structure. Peripheral blood mononuclear cells (PBMC) of 21 healthy B27+ individuals were stimulated in primary and in short-term cultures with PBMC of an HLA-identical sibling suffering from definite AS (n = 12). In addition, PBMC in vitro modified by "Geczy bacterial products" from two healthy B27+ individuals were used to stimulate B27+ AS- lymphocytes (either autologous or from a healthy HLA-identical sibling). Effector cells raised in primary AS- versus AS+ and AS- versus "modified B27" mixed lymphocyte culture combinations showed no proliferative nor cytotoxic activity at all. The scarcely observed cytotoxic reactivity of restimulated mixed lymphocyte culture was not restricted to AS+B27+ cells. These results demonstrate that PBMC from ankylosing spondylitis patients fail to induce disease-specific cytotoxic T lymphocytes and suggest that an ankylosing spondylitis--related "modified B27" structure does not exist, at least in the patient material tested.

Cross-reactive epitope with Klebsiella pneumoniae nitrogenase in articular tissue of HLA-B27+ patients with ankylosing spondylitis

Synovial tissues from patients with ankylosing spondylitis or reactive arthritis were examined by an immunoperoxidase technique, using antisera to synthetic peptides representing antigens shared between HLA-B27.1 and Klebsiella pneumoniae nitrogenase. With either antiserum, all HLA-B27+ patients with synovial inflammation showed strong immunoperoxidase staining in synovial lining cells, vascular endothelium, and infiltrating inflammatory cells. These findings indicate that antigens showing cross-reactivity between HLA-B27.1 and Klebsiella nitrogenase epitopes are strongly expressed within inflamed synovial tissues of HLA-B27+ patients.

Polymorphonuclear leukocyte chemiluminescence response in HLA-B27 positive and negative arthritic patients

The polymorphonuclear leukocyte (PMN) chemiluminescence (CL) response to opsonized zymosan reflecting the C3b/C3bi-receptor-mediated PMN respiratory burst activation was studied in 99 arthritic patients typed for the HLA-B27 antigen. The results indicate that the B27 antigen per se is not associated with disturbances in PMN CL response. However, the erythrocyte sedimentation rate showed a correlation with CL, suggesting that the activity of arthritic disease may affect the PMN CL response.

Cross-reacting bacterial determinants in ankylosing spondylitis

The importance of the association between the human histocompatibility antigen human leukocyte antigen-B27 and ankylosing spondylitis is undisputed, but its biologic significance remains unresolved. We have demonstrated specific cross reactivity between a range of enteric bacteria and a specific determinant found only on the surfaces of cells from human leukocyte antigen-B27-positive persons with ankylosing spondylitis. We have proposed that the genetic element coding for this cross-reactive determinant is mobile and that its acquisition by B27-positive cells in vivo represents an important step in the eventual development of ankylosing spondylitis.

Genetics of the spondarthropathies

Recent investigation of the possible role of bacteria in the pathogenesis of AS has provided very interesting data. What is at present lacking is a clear demonstration that the findings point to the actual mechanisms involved in the initiation of the disorder. Rapid progress in three related areas of research gives hope that, in the relatively near future, the genetic basis for susceptibility to AS will be elucidated. These are the demonstration of the detailed structure of an HLA class I molecule, of the primary amino acid structure of B27 heavy chain with its subtypes, and of the nature of the interaction between foreign proteins and MHC molecules which leads to antibody and cytotoxic cell responses. It is just possible that the B27 molecules have a disease-promoting capability because of some structural characteristic independent of their antigen binding site. However, it may perhaps be considered more likely that it is the propensity of the specific antigen-binding site itself to bind to a particular group of antigenic peptides that will explain the susceptibility of B27-positive individuals to several clinical disorders. The ability to study the properties of antigenic epitopes which preferentially bind to the very variable binding site of different MHC molecules raises the possibility of revealing the antigenic structures which bind to B27 molecules in patients with AS. This could in turn lead to the source of these antigens in the environment. There has been a tendency to assume that one simple model will explain all the B27-associated disorders but it may be preferable to keep an open mind about the possibility that the mechanisms involved in AS, in the bacteria-induced acute arthropathies and in acute anterior uveitis may not be identical. At the same time, there is a need to continue further direct investigation of the role of microbiological agents in AS both in vitro and in vivo, as ultimately it is most likely that, by blocking the effects of such agents as may be shown to be involved, progress in our ability to influence the progress of the disease in a fundamental way will be achieved. There is still little information as to how the tissues involved in AS come to be the particular targets of the pathological process and currently proposed theories of pathogenesis have not yet provided very satisfactory answers to this problem.

Four cytotoxic human-human hybridoma antibodies that react with HLA-B27

PBMC were isolated from a multiparous woman with HLA-B27 specific Abs in her serum. The HLA type of the donor was A2,9:B7. The PBMC were EBV transformed, and four cell lines making cytotoxic Abs to HLA-B27+ cells prepared. Hybridomas were constructed by fusing the EBV lines with the human fusion partner KR4. All four mAbs were of IgM isotype. One mAb (TrBH12) reacted specifically with B27+, B37+ and Bw47+ lymphoblastoid cell lines and with all B27+ PBMC except for a rare variant so far found only in one Norwegian family. Another mAb (Tr3B6) was cytotoxic for all B27+ cells tested, including the TrBH12- variant; in addition, it showed weaker cross-reactions to Bw42, B49 and a cell line with the probable phenotype B7,38. Supernatant from the Tr3B6 hybridoma was tested in lymphocytotoxicity against a panel of 658 individuals, 141 of whom were B27+. With this panel, Tr3B6 showed perfect correlation with HLA-B27. The two last mAbs (TrCG10 and TrBF1) reacted with all B27+ cells tested, but in addition showed quite extensive cross-reactions.

Molecular mimicry revisited

The host immune response is an important line of defence against parasites. Tactics to evade this response are therefore expected in host-parasite relationships, and the clearest example is the antigenic variation displayed by African trypanosomes. But while few other parasites seem to have quite this ability, many seem to display a form of antigenic convergence with the host - allowing them a degree of molecular camouflage against the host's immune system. Ideas about such antigenic convergence were developed some 30 years ago, with, for example, John Sprent's theory of 'adaptation tolerance', John Dineen's 'selection for fitness antigens' and Raymond Damian's concept of 'antigen sharing' between host and parasite which was subsequently formulated in a now classical exposition on 'molecular mimicry'. Damian's theory, that one of the mechanisms by which parasites could avoid the host immune response was by mimicking host molecules, has greatly influenced both the theoretical and practical approaches to immunoparasitology. Earlier this year, at a UCLA Symposium, Professor Damian discussed how the theory had progressed since its original exposition. This article is based on that presentation.

An antiserum to a disease-associated factor from the cells of an HLA-B27 positive patient with ankylosing spondylitis specifically recognizes an HLA-B27 associated determinant

Antiserum raised to a factor elaborated by a lymphoblastoid cell line derived from the peripheral blood cells of an HLA-B27 positive patient with ankylosing spondylitis specifically lyses the B27 positive, but not the B27 negative, cells of ankylosing spondylitis patients. The cells of B27 positive and B27 negative normal controls are not lysed. This serum has similar specificity to antisera against cross-reactive bacteria.

Infection and arthritis

The categorization in four classes of association between infection and arthritis (namely infective, post-infective, reactive and idiopathic) seems nowadays to be inadequate to cover the extensive field of interactions between infectious agents and host response resulting in arthritis. This paper is a synthetic review of the subject with particular reference to pathogenetic mechanisms in children. An effort has been accomplished, on the basis of the most recent literature, to define the respective roles of the microbial aggression and the host response in a number of conditions: septic arthritis, viral arthritides, Lyme arthritis, rheumatic fever, Reiter's syndrome, ankylosing spondylitis and rheumatoid arthritis.

Biochemical studies on a factor isolated from Klebsiella K43-BTS1 that cross-reacts with cells from HLA-B27 positive patients with ankylosing spondylitis

A component of the cell walls of certain enteric bacteria has been identified that cross-reacts with an HLA-B27-associated cell-surface structure on lymphocytes and other cell types from patients with ankylosing spondylitis. This component, or "modifying factor," from one particular organism, Klebsiella K43-BTS1, has been studied in detail. A purification scheme has been developed using preparative electrofocusing and gel-permeation high performance liquid chromatography techniques and the purified material used in various characterization studies. A previous study demonstrated that the modifying factor has an approximate molecular weight of 30,000 and an isoelectric point of 5.4-5.5. In this study two-dimensional gel electrophoresis experiments demonstrated that the modifying factor is associated with a single protein component of the cell wall of this organism. Pronase and papain destroyed the modifying factor activity whereas trypsin and alpha-chymotrypsin degraded the factor into smaller fragments without destroying its ability to modify B27+ AS- lymphocytes. Neuraminidase did not affect the modifying factor itself but did affect B27+ AS- lymphocytes such that they became unresponsive to modification. Sugar inhibition studies suggested that sugar groups are probably not involved in the function of the modifying factor. The availability of purified modifying factor should permit more detailed chemical analyses as well as functional studies to determine the significance of this molecule to the pathogenesis of ankylosing spondylitis.

Cytotoxic T lymphocytes against disease-associated determinant(s) in ankylosing spondylitis

Cytotoxic T lymphocytes, induced by stimulating the PBMC of an HLA-B27+ normal individual (B27+, AS-) with the PBMC of an HLA-identical sibling suffering from ankylosing spondylitis (AS) (B27+, AS+), specifically lyse B27+, AS+ PBMC but not PBMC from HLA-27+ or B27-, AS- normal controls, or from HLA-B27- AS patients (B27-,AS+). CTL of similar specificity can also be raised by immunizing in vitro B27+,AS- cells with autologous cells modified by cross-reactive bacterial antigens. These results suggest that CTL can recognize certain bacterial antigens in association with HLA-B27 and that this interaction may lead to an inflammatory episode during the initial stages of the disease.