Transformation from SAA2-fibrils to AA-fibrils in amyloid fibrillogenesis: in vivo observations in murine spleen using anti-SAA and anti-AA antibodies

PCR in combination with SSO probes was used to analyze the polymorphism in exons 2 and 3 of HLA-B27 subtypes and HLA-C-related alleles in two genetically distant Caucasian groups: Spanish and Jewish populations. AS patients and healthy B27 donors from both populations were analyzed in order to ascertain B27-Cw haplotypes. Three different ancestral haplotypes were found to be represented in both populations: B*2705/Cw*0102, B*2705/Cw*02022, and B*2702/Cw*02022. The B*2705 (92.5%) was the most frequent allele found in the Spanish population, carried by B*2705/Cw*0102 (60.9%) and B2705/Cw*02022 (30.4%) haplotypes. In contrast, B*2702 (59.4%) was the most prevalent allele found in the Jewish population and was carried by the B*2702/Cw*02022 (63.3%) haplotype. No different allelic and haplotypic distributions were among healthy and AS patients in either Spanish or Jewish populations. The differences found in the distribution of B27 haplotypes among Spanish and Jewish Caucasian populations are consistent with the genetic distance of these ethnic groups. When the Jewish population was subdivided into Ashkenazi (A) and non-Ashkenazi (NA) groups, no significant differences were observed in the distribution of B*2702/Cw*02022 haplotype. Minor differences were observed in the underrepresented B*2705 haplotypes. The present results reflect the ancestral affinities of A and NA Jewish populations. A possible HLA-B27 evolutive pathway in Caucasians is proposed according to the data available for the B27/Cw ancestral haplotypes in Spanish and Jewish groups.     

Routine molecular genotyping of HLA-B27 in spondyloarthropathies overcomes the obstacles of serological typing and reveals an increased B *2702 frequency in ankylosing spondylitis

OBJECTIVE: To evaluate the reproducibility and reliability of polymerase chain reaction (PCR) in HLA-B27 typing compared to the conventionally used microlymphocytotoxicity test (MLCT). To determine the HLA-B27 subtype frequencies (B*2701-B*2709) in patients with HLA-B27 associated disease and healthy persons using sequence specific oligonucleotides (SSO). METHODS: 398 consecutive patients were HLA-B27 typed by MLCT and PCR. Subtyping by SSO was performed in 142 patients with HLA-B27 associated disease [ankylosing spondylitis (AS) n = 38, reactive arthritis 44, undifferentiated spondyloarthropathy (uSpA) 45, psoriatic arthritis 15] and 125 healthy HLA-B27 controls. RESULTS: MLCT identified 61 HLA-B27 positive patients (15.3%); PCR identified 78 positive patients (19.6%). MLCT gave false negative results for 8 patients (2.0%) and false positives for a further 7 (1.8%). Only subtypes B*2702 and B*2705 were present in patients and controls. Overall frequencies of B*2702 in patients and controls were 14.1 and 9.6%, respectively. The B*2702 frequency was significantly (pcorr. < 0.04) higher in AS (23.7%) and lower in uSpA (6.7%) patients. CONCLUSION: HLA-B27 typing by PCR is reliable and reproducible and therefore recommended for routine typing. It overcomes the obstacles of serological typing, i.e., equivocal results and cross-reactivity. In addition, subtype frequencies (B*2702 and B*2705) are equally distributed among patients and controls, although subtype B*2702 seems to be more frequent in AS and less so in uSpA.     

Evaluation of a corporate-sponsored health care program for retired employees

Five HLA-B27 subtypes, B*2701, B*2703, B*2704, B*2705, and B*2706, were tested for direct binding with twenty-six synthetic nonapeptides carrying the primary anchor residue motifs (combination of amino residues at positions 2 and 9) relevant to B*2705. The peptide sequences were derived from human HSP89 alpha, P53 and MBP. The alpha chains were immunospecifically isolated from LH (B*2701), CH (B*2703), WE1 (B*2704), BTB (B*2705), and LIE (B*2706) cells and their peptide binding was measured by the HLA class I alpha chain refolding assay. The data obtained indicated that the B27 subtypes tested can bind a common set of peptides carrying several different anchor residue motifs. The motifs, R-K and R-R, reported for B*2705 and a new motif H-R were accepted by B*2703, B*2704, and B*2706, but not by B*2701. However, other motifs, including known B*2702 and/or B*2705 motifs, R-H, R-L, R-A, and R-F, and a new motif found here, R-G, were apparently accepted by all B27 subtypes tested. The observed cross-peptide binding in the B27 subgroup is compatible with the so-called arthritogenic peptide hypothesis in the pathogenesis of ankylosing spondylitis.     

Overlapping peptide-binding specificities of HLA-B27 and B39: evidence for a role of peptide supermotif in the pathogenesis of spondylarthropathies

OBJECTIVE: Previous studies indicated the increase of HLA-B39 among HLA-B27 negative patients with spondylarthropathies (SpA). This study was performed to examine whether the natural ligands of HLA-B27 are capable of binding to HLA-B39. METHODS: Peptides were synthesized according to the sequences of known natural ligands of HLA-B27 or B39 and were tested for their binding to HLA-B*3901 and B*2705 by quantitative peptide binding assay, using a TAP-deficient RMA-S cell line transfected with human beta2-microglobulin and HLA class I heavy chain genes. RESULTS: Four of the 10 HLA-B27 binding peptides significantly bound to HLA-B*3901. All 4 peptides had hydrophobic/aromatic amino acids (Leu or Phe) at the C-terminus. In contrast, peptides with basic residues (Lys, Arg) or Tyr at the C-terminus did not bind to B*3901. In parallel experiments, 1 of the 2 natural ligands of HLA-B*3901 was found to bind to B*2705. CONCLUSION: A subset of natural HLA-B27 ligands was capable of binding to B*3901. In addition to Arg at position 2 (Arg2), hydrophobic/aromatic C-terminal residues, such as Leu or Phe, seemed to be crucial for the cross-specificity. These results suggested that HLA-B27 and B39 recognize overlapping peptide repertoires, supporting the hypothesis that the peptides presented by both of these class I antigens play a role in the pathogenesis of SpA.     

Stenotic origin of an aberrant left subclavian artery from a right-sided aortic arch. A case report

OBJECTIVE: To refine the algorithms governing peptide presentation by HLA-B*2705 by analyzing: (i) the specificity of the human transporter associated with antigen processing (TAP) for HLA-B27 binding peptides; and (ii) the peptide binding affinity to HLA-B*2705. METHODS: TAP-translocation was measured with a labeled reporter peptide containing an N-linked glycosylation acceptor site in Streptolysin O-permeabilized cells for a panel of HLA-B27 binding peptides. Peptide binding affinity was determined by peptide-induced stabilization of empty HLA-B*2705 expressed by the TAP-deficient cell line T2-B27. RESULTS: Human TAP preferentially translocated analogues with residues leucine, isoleucine, methionine and arginine as the carboxy-terminal amino acids, whereas analogues with aspartic acid and serine were translocated poorly. The binding affinity to HLA-B*2705 of the poorly translocated aspartic acid and serine analogues was about 100-fold less compared to the parent HLA-B27 binding peptide. CONCLUSIONS: Human TAP shows considerable specificity for the C-terminus of potential HLA-B27 ligands. Nonamer peptides with aspartic acid and serine at the C-terminus are poorly translocated by the TAP and have low binding affinity for HLA-B*2705, and are therefore unlikely to become presented by HLA-B*2705.     

Binding of peptides naturally presented by HLA-B27 to the differentially disease-associated B*2704 and B*2706 subtypes, and to mutants mimicking their polymorphism

B*2704 and B*2706 are closely related HLA-B27 subtypes of which the former but not the latter is associated to ankylosing spondylitis. Their peptide specificity relative to other disease-associated subtypes was analyzed by testing binding of self-peptides naturally presented by B*2705 or B*2702, and synthetic analogs, to B*2704, B*2706, and site-specific mutants mimicking their changes. Peptides with basic, aliphatic or aromatic C-terminal residues bound to B*2705 with similar affinity. In B*2704 C-terminal aliphatic/ aromatic residues were preferred. B*2706 discriminated drastically between polar and nonpolar C-terminal residues, showing strong preference for Leu and Phe, and less than B*2704 for basic and Tyr residues. Loss of single acidic charges (D > S77, D > Y116) increased preference for C-terminal Leu and Phe, but allowed efficient binding of peptides with basic residues or Tyr. Their gain (V > E152, H > D114) maintained wide C-terminal specificity, but severely impaired binding, presumably by disrupting interactions with internal peptide residues. This was compensated by Y116 in the double D114Y116 mutant. The specificity of B*2704 and B*2706 was explained only partially by the separate effects of single mutations, indicating that novel properties arise from concomitant changes at various positions. For instance, specificity of B*2706 for nonpolar C-terminal residues required simultaneous removal of Asp77 and Asp116. B*2706 differed from B*2705, B*2702, and B*2704 in its lower suitability for C-terminal Tyr, suggesting that this feature might be relevant for HLA-B27 association to spondyloarthropathy.     

The same natural ligand is involved in allorecognition of multiple HLA-B27 subtypes by a single T cell clone: role of peptide and the MHC molecule in alloreactivity

The human alloreactive CTL clone 27S69, raised against B*2705, cross-reacts with B*2702 and B*2703, but not with B*2701, B*2704, B*2706, or B*2710. Its natural epitope was identified by electrospray/ion trap mass spectrometry, as the proteasome-derived RRFFPYYV octamer. This is the first HLA-B27 ligand shown to be immunogenic in alloreactivity. The RRFFPYYVY nonamer, also found in the B*2705-bound peptide pool, was recognized much less efficiently, demonstrating that an alloreactive CTL distinguishes between very similar natural ligands. Molecular modeling suggested that this was due to the different conformation of each peptide in complex with B*2705. B*2702- and B*2703-RMA-S cells were lysed by CTL 27S69 when sensitized with the octamer, demonstrating that cross-reaction with these subtypes is through recognition of the same peptide as in B*2705. B*2704-, B*2706-, and B*2710-RMA-S cells were not sensitized for lysis, in spite of efficient binding of the octamer, indicating that polymorphism in these subtypes directly impairs allorecognition. B*2701-RMA-S and -C1R cells were sensitized for lysis by the octamer, suggesting lack of the endogenous peptide epitope on this subtype. Absence of the octamer in the B*2701-bound peptide pool further suggested that B*2701 polymorphism impairs the generation of this peptide.     

The naturally occurring polymorphism Asp116-->His116, differentiating the ankylosing spondylitis-associated HLA-B*2705 from the non-associated HLA-B*2709 subtype, influences peptide-specific CD8 T cell recognition

HLA-B27 molecules are interesting because of their strong association with ankylosing spondylitis (AS) and reactive arthritis (ReA). A pathogenetic role for these molecules has been postulated in presenting a putative "arthritogenic" peptide to CD8 T cells. The HLA-B*2709 subtype, although differing by a single amino acid (His116-->Asp116) from the widespread and strongly AS-associated subtype HLA-B*2705, is not found in patients. Since residue 116 interacts with the C terminus of the peptide, it is possible that the two subtypes differ in their antigen-presenting features. We show here that CD8 T cells can distinguish the two HLA-B27 subtypes when presenting a same epitope derived from Epstein-Barr virus-latent membrane protein 2. Moreover, alanine scanning mutagenesis analysis revealed that the peptide residues relevant for such recognition are different depending on whether HLA-B*2705 or -B*2709 molecules present the epitope. These results give support to the belief that functional differences determined by subtype-specific polymorphisms can have a pathogenetic relevance and open up a new scenario where subtle modifications within the peptide/HLA ligand might be responsible for the differential association between HLA-B27 subtypes and spondyloarthropathies.     

HLA-B27 (B*2701) specificity for peptides lacking Arg2 is determined by polymorphism outside the B pocket

B*2701 differs from B*2705-by three amino acid changes: D-->Y74, D-->N77, L-->A81, and from B*2702 only by two: D-->Y74 and T-->I80. Tyr74 is located in the C/F cavity of the peptide-binding site, and is unique to B*2701 among HLA-B27 subtypes. Binding of natural B*2705 and B*2702 ligands to B*2701, and to mutants mimicking subtype changes, was analyzed. In addition, sequencing of the peptides bound in vivo by B*2701 and the Y74 mutant was carried out. The main distinctive feature of B*2701 was its presentation of peptides with Gln2. Synthetic analogs bound in vitro similarly as the corresponding ligands with Arg2. Moreover, both Gln2 and Arg2 were dominant upon pool sequencing of B*2701-bound peptides, and 2 of 8 natural ligands contained Gln2. Suitability of Gln2 was largely determined by the Y74 change, as indicated by: 1) binding of Gln2 analogs to this mutant, and 2) detection of Gln2 by pool sequencing of Y74-bound peptides. B*2701 bound peptides with C-terminal aromatic or Leu residues, and interacted with these motifs more strongly than B*2702. The Y74 mutation alone was not responsible for poor binding of peptides with C-terminal basic residues to B*2701, since they bound efficiently and at least one was presented in vivo by this mutant. Most peptides bound to the A81 mutant worse than to B*2705, but frequently better than to B*2701 or B*2702, suggesting that other subtype changes were compensatory. The peptide specificity of B*2701 suggests that this subtype may determine susceptibility to spondyloarthropathy.     

HLA-B27-restricted antigen presentation in the absence of tapasin reveals polymorphism in mechanisms of HLA class I peptide loading

Tapasin is a resident ER protein believed to be critical for antigen presentation by HLA class I molecules. We demonstrate that allelic variation in MHC class I molecules influences their dependence on tapasin for peptide loading and antigen presentation. HLA-B*2705 molecules achieve high levels of surface expression and present specific viral peptides in the absence of tapasin. In contrast, HLA-B*4402 molecules are highly dependent upon human tapasin for these functions, while HLA-B8 molecules are intermediate in this regard. Significantly, HLA-B*2705 like HLA-B*4402, requires tapasin to associate efficiently with TAP (transporters associated with antigen processing). The unusual ability of HLA-B*2705 to form peptide complexes without associating with TAP or tapasin confers flexibility in the repertoire of peptides presented by this molecule. We speculate that these properties might contribute to the role of HLA-B27 in conferring susceptibility to inflammatory spondyloarthropathies.     

HLA-B27 molecular subtypes and spondylarthropathies

The close association between HLA-B27 and spondyloarthropathies remains unexplained. Twelve HLA-B27 subtypes designated B*2701 to B*2712 have been described in various populations. Variations in the ability of these alleles to carry susceptibility to spondyloarthropathies may exist, and may be ascribable to differences in endogenous peptide presentation. This hypothesis was evaluated by a study of peptide-binding motifs of endogenous peptides extracted from various HLA-B27 alleles. A peptide motif with a tyrosine residue at the C-terminus was not characteristic of HLA-B27 subtypes carrying susceptibility, consistent with the known lack of association of B*2707 with spondyloarthropathies. However, at the level of the individual, differences may exist between endogenous peptides presented by subtypes that do and do not confer susceptibility.     

Binding of the pili of Pseudomonas aeruginosa to a low-molecular-weight mucin and neutral cystatin of human submandibular-sublingual saliva

The HLA-B*27 group of alleles has been extensively studied due to the association of particular B*27 alleles with ankylosing spondylitis (AS). We describe here an HLA-B*27 allele (B*2712) encoding an antigen that lacks reactivity with B27 monoclonal antibodies (moabs) and alloantisera but reacts with some B40/B60 moabs and alloantisera and expresses the Bw6 public epitope. This allele was discovered by the segregation of an HLA-B allele undetectable by PCR-SSP within a Caucasian family from the British population referred for routine bone marrow transplant HLA typing and found in the haplotype A*29; B*2712; Cw*1203; DRB1*13; DQB1*0603. Serological typing showed a lack of reactivity with four B27 moabs and four alloantisera but positive reactivity with moabs and alloantisera specific for B40/B60 and Bw6 public epitopes. Subsequent sequencing showed the closest homology was with B*2708 with three mismatches in exon 2 at positions 204, 209 and 210. The intron 2 sequence was identical with other B*27 lineage alleles including a 2 base pair deletion at positions 95 and 96. The relationship between HLA-B*2712 and reported B60 associations with susceptibility to AS remains to be determined.     

Antinuclear antibody and HLA-B27 positive uveitis: combination of two diseases?

AIMS/BACKGROUND: Anterior uveitis associated with juvenile chronic arthritis concerns two different clinical entities: firstly, antinuclear antibody (ANA) positive patients who have a chronic anterior uveitis with severe complications and often a poor visual prognosis; secondly, usually HLA-B27 positive children, predominantly boys, with unilateral recurrent anterior uveitis. Three patients are described who had a combination of clinical and laboratory features of both diseases. METHODS: Retrospective clinical and laboratory analysis of three patients. RESULTS: Ocular features in the three patients combined the clinical picture of ANA positive chronic anterior uveitis during early childhood with the clinical features of HLA-B27 unilateral acute anterior uveitis during adolescence. The patients fulfilled the diagnostic criteria of juvenile chronic arthritis, and they had no ankylosing spondylitis. All three patients had the HLA-B*2705 subtype. CONCLUSIONS: Whether the association of ANA positive chronic anterior uveitis and HLA-B27 unilateral acute anterior uveitis is a coincidence or represents a distinct clinical entity is not yet clear.     

HLA-DRB1*08 influences the development of disease in Mexican Mestizo with spondyloarthropathy

OBJECTIVE: HLA class II encoded factors may influence the phenotype of ankylosing spondylitis (AS). These include HLA DRB1*07 for peripheral arthritis, and polymorphism of the HLA-linked LMP2 locus and HLA DRB1*08 for acute anterior uveitis (AAU). We studied the relationship between DRB1*08 and disease phenotype in additional populations of individuals with AS. METHODS: The patient population included 385 unrelated HLA-B27 positive individuals with AS. These included 204 Caucasians and 2 populations of Mexican Mestizo with AS: 106 with predominately adult onset disease from Guadalajara and 75 with predominately juvenile onset disease from Mexico City. The control population of 428 individuals included 210 random and 36 HLA-B27 positive unrelated Canadian Caucasians and 173 random and 9 HLA-B27 positive Mexican Mestizo from Mexico City. DRB1*08 typing was by sequence specific polymerase chain reaction. RESULTS: A significantly higher prevalence of DRB1*08 was observed in Mexican patients with juvenile onset disease (44.9%) and especially those with undifferentiated spondyloarthropathy (55.6%) compared to normal unrelated Mexican Mestizo (25.4%) (p < 0.01 for both) and in patients with undifferentiated spondyloarthropathy versus B27 controls (11.1%) (p = 0.03), although no significant differences were observed in within patient group comparisons based on phenotypic features of disease such as AAU and age at onset. No significant relationship between DRB1*08 and disease phenotype was evident in Caucasian individuals. CONCLUSION: Our data suggest DRB1*08 may influence the phenotype of spondyloarthritis in Mexican Mestizo, but do not support the view that DRB1*08 influences the development of AAU, as reported in a Japanese population.     

Choosing the best abdominal closure by meta-analysis

A novel HLA-B allele (B*5002), detected as a discrepancy between serological and PCR-SSP HLA-A and B phenotyping of bone marrow panel donors, was identified by nucleotide sequencing of exons 2 and 3. Titration studies on 39 HLA-B12/B21 cross-reactive antisera showed that the serological specificity of HLA-B*5002 was HLA-B45. PCR-SSP testing of 287 serologically defined HLA-B45-positive subjects from a panel of 12,411 donors, together with HLA-B*45 and B*5002 frequency data on 4,342 PCR-SSP typed subjects, indicated that 4.53% of serologically defined HLA-B45-positive subjects possess HLA-B*5002 and not HLA-B*4501. The phenotype frequency of HLA-B*5002 was 0.08954%; gene frequency was 0.00045 (n=16,753). In 73.3% of instances B*5002 appeared to be present on a haplotype with DRB1*0406 and DQB1*0402, 54.6% of which possessed A*2301. The B*5002, DRB1*0406, DQB1*0402 haplotype represents 52.4% of all haplotypes with DRB1*04 and DQB1*04 and 78.6% of haplotypes possessing DRB1*0406 and DQB1*0402.     

Alteration of HLA-B27 peptide presentation after infection of transfected murine L cells by Shigella flexneri

Shigella flexneri is a triggering agent for reactive arthritis in HLA-B27-susceptible individuals. Considering the intracellular multiplication of bacteria, it seems likely that bacterial peptides may be presented by the major histocompatibility complex (MHC) class I pathway. To examine this hypothesis, we infected HLA-B*2705- and/or human beta2-microglobulin-transfected murine L-cell lines with M90T, an invasive strain of S. flexneri. Bacterial infection induced no detectable modifications in the biosynthesis and expression level of HLA-B27, as assessed by immunoprecipitation, Northern blot analysis, and flow cytometry. Using confocal microscopy, we observed that bacterial infection induced a clustering of HLA-B27 molecules during macropinocytosis and before bacterial dissemination from cell to cell. Peptides naturally bound to HLA-B27 molecules were acid eluted from infected cells and separated by high-performance liquid chromatography. Major differences were observed in high-performance liquid chromatography profiles and in the nature of peptides presented following bacterial infection. Although most of the antigens presented were not accessed by Edman degradation, we obtained two sequences partially homologous to bacterial proteins. These peptides lacked the major HLA-B27 peptide anchor (Arg) at position 2, and one had an unusual length of 14 amino acids. These data suggest that alterations in the peptide presentation by HLA-B27 occur during infection, which could be relevant to the pathogenesis of HLA-B27-related arthritis.     

Characterization of natural peptide ligands for HLA-B*4402 and -B*4403: implications for peptide involvement in allorecognition of a single amino acid change in the HLA-B44 heavy chain

This study describes the characterization of endogenous peptides associated with the two major subtypes of HLA-B44. The two subtypes differ for a single amino acid substitution from Asp (HLA-B*4402) to Leu (HLA-B*4403) in position 156 of the alpha 2 domain, causing strong alloreactivity in vivo. In order to study the involvement of peptides in this phenomenon, the peptide motifs of the two subtypes were determined from natural peptide pools using Edman degradation. The motif was found to be essentially identical for HLA-B*4402 and -B*4403, with a strong predominance for Glu at position 2, Tyr or Phe at positions 9 and 10 and hydrophobic residues, especially Met, at position 3. Two individual naturally processed ligands of HLA-B*4403 were sequenced and shown to be derived from intracellularly expressed proteins found in protein sequence databases. The sequence of these natural peptide ligands conform well to the determined motif. These data will allow the prediction of HLA-B44 restricted peptide epitopes from viral and tumor antigens of known amino acid sequences. Moreover, they indicate that the peptide repertoire presented by HLA-B*4402 and -B*4403 is very similar, suggesting that the strong alloresponse between these two subtypes is not due to presentation of a different set of self peptides.     

Fetal growth velocity in the prediction of intrauterine growth retardation in a low risk population

Assignment of HLA-B types can be hampered by ambiguous reactivity of the typing sera resulting in inaccurate HLA-B assignments. In this study, 19 Korean samples exhibiting ambiguous serologic reactivities were characterized by DNA sequencing. Alleles identified from 7 samples were previously undetected in this population (B*1517, B*4101, B*4701, B*5001, and B*5106) and from 9 samples were common alleles in this population (B*4002, B*4003, B*4006, B*1501, B*1401, B*67012, and B*5401). Three samples were putative HLA-B homozygotes. Three major factors causing serologic ambiguity were identified: weak or false negative reactivity of typing sera (52.4%); cross or false positive reactivity of the sera (38.1%); and absence of information on the reaction patterns due to the lack of appropriate sera in the typing kit (e.g. B*4101 encoded molecule) or to the presence of recently characterized molecules (e.g. B*5106 encoded molecule) (9.5%). Overall, sequencing was helpful in clarifying ambiguous serologic reaction patterns improving the HLA typing for the Korean population.     

Computational determination of side chain specificity for pockets in class I MHC molecules

We show that a rapidly executable computational procedure provides the basis for a predictive understanding of antigenic peptide side chain specificity, for binding to class I major histocompatibility complex (MHC) molecules. The procedure consists of a combined search to identify the joint conformations of peptide side chains and side chains comprising the MHC pocket, followed by conformational selection, using a target function, based on solvation energies and modified electrostatic energies. The method was applied to the B pocket region of five MHC molecules, which were chosen to encompass the full range of specificities displayed by anchors at peptide position 2. These were a medium hydrophobic residue (Leu or Met) for HLA-A*0201, a basic residue (Arg or Lys) for HLA-B*2705; a small hydrophobic residue (Val) for HLA-A*6801, an acidic residue (Glu) for HLA-B*4001 and a bulky residue (Tyr) for H-2K(d). The observed anchors are correctly predicted in each case. The agreement for HLA-B40 and H-2K(d) is especially promising, since their structures have not yet been determined experimentally. Because the experimental determination of motifs by elution is difficult and these calculations take only hours on a high speed workstation, the results open the possibility of routine determination of motifs computationally.     

Caring for the individual

AIM: Investigation of associations of reactive arthritis (ReA) with histocompatibility antigens class I and II and determination of new approaches to assessment of association ReA with antigen HLA B27. MATERIALS AND METHODS: 118 ReA patients with associated intestinal and 82 ReA patients with associated urogenital infection were studied. The infection was identified bacteriologically, with agglutination reaction, enzyme immunoassay, direct and indirect immunofluorescence, culturing. HLA-antigens were studied in lymphocytotoxic test: locus A, B and C in all the patients, DR in 65 patients. RESULTS: ReA triggers were intracellularly parasite bacteria: facultative parasites in the enterocolitic variant (Yersinia, as a rule), obligate parasite in the urogenital (Chlamidia, as a rule). HLA B27 antigen was discovered in 77.5% of patients (RR 45.8), HLA DR1--in 48.4% of patients (RR 3.3). In urogenital variant HLA B27 antigen occurred more frequently than in enterocolitic: 87.8% (RR 95.6) versus 70.3% (RR 31.5); p < 0.01). In HLA-B27-positive patients compared to HLA-B27-negative ones there were higher ESR (p < 0.001), leukocyte count (p < 0.05), concentrations of CRP and alpha-2-globulins (p < 0.001). CONCLUSION: In HLA-B27-subjects optimal conditions exist for generalization of obligate parasites and favorable for production of facultative ones. The degree of association of ReA with HLA B27 antigens is dependent on adaptive features of microorganisms appearing in the process of evolution--obligaty and facultativeness of their internal parasitivity.