Association between HLA-BW38 and peripheral psoriatic arthritis

Genetic markers for psoriatic arthritis among patients with psoriasis. Part II: HLA genes

Psoriatic arthritis often leads to the development of severe outcomes ankylosis, deformities of the affected joints with severe impairment of their functions and disability. Early identification of patients with psoriasis with an increased risk of developing psoriatic arthritis for the purpose of its timely diagnosis and early initiation of therapy can prevent the development of severe disease outcomes. It is believed that the genes of the HLA system make the greatest individual genetic contribution to the formation of a predisposition to hereditary diseases with polygenic inheritance. The literature review considers the polymorphisms of the genes of the HLA system, associated with the development of psoriatic arthritis, in patients with psoriasis. The HLA alleles that contribute to the development of psoriatic arthritis and its individual forms have been identified. HLA alleles have been identified, which have a protective effect against the development of psoriatic arthritis.

Managing Psoriatic Arthritis With Inflammatory Bowel Disease and/or Uveitis

Psoriatic arthritis (PsA) is a chronic inflammatory disease that presents with psoriasis (PsO), peripheral and axial arthropathy. The heterogeneity of disease presentation leads to the term "psoriatic disease (PsD)" which is thought to better encompass the range of clinical manifestations. PsA is associated with several comorbidities such as cardiovascular diseases, metabolic syndrome and other extra-articular manifestations including uveitis, and inflammatory bowel disease (IBD). While novel therapeutics are being developed following advances in our understanding of the pathogenesis of the disease, the diverse combinations of PsA with its various comorbidities still pose a clinical challenge in managing patients with PsA. This article reviews our current understanding of the pathogenesis of PsA and how various pathways in the pathogenesis lead to the two comorbid extra-articular manifestations - uveitis and IBD. We also review current evidence of treatment strategies in managing patients with PsA with comorbidities of uveitis and/or IBD.

HLA class I and II alleles in susceptibility to ankylosing spondylitis

OBJECTIVE

To examine associations of HLA class I and class II alleles with ankylosing spondylitis (AS) in three cohorts of patients of European, Asian and African ancestry.

METHODS

HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1 and HLA-DPB1 alleles were genotyped in 1948 unrelated white and 67 African-American patients with AS from the Prospective Study of Outcomes in Ankylosing Spondylitis cohort, the North American Spondylitis Consortium and Australo-Anglo-American Spondyloarthritis Consortium, 990 white and 245 African-American Controls and HLA-B alleles in 442 Han Chinese patients with AS and 346 controls from Shanghai and Gansu, China. In addition to the case:control analyses, HLA-B*27-negative patients with AS were analysed separately, and logistic regression and 'relative predispositional effects' (RPE) analyses were carried out to control for the major effect of HLA-B*27 on disease susceptibility.

RESULTS

Although numerous associations were seen between HLA alleles and AS in whites, among HLA-B*27-negative patients with AS , positive associations were seen with HLA-A*29, B*38, B*49, B*52, DRB1*11 and DPB1*03:01 and negative associations with HLA-B*07, HLA-B*57, HLA-DRB1*15:01, HLA-DQB1*02:01 and HLA-DQB1*06:02. Additional associations with HLA-B*14 and B*40 (B60) were observed via RPE analysis, which excludes the HLA-B*27 alleles. The increased frequency of HLA-B*40:01 and decreased frequency of HLA-B*07 was also seen in Han Chinese and African-Americans with AS. HLA-B*08 was decreased in whites with acute anterior uveitis.

CONCLUSIONS

These data, analysing the largest number of patients with AS examined to date in three ethnic groups, confirm that other HLA class I and II alleles other than HLA-B*27 to be operative in AS predisposition.

Clinical and immunogenetic characterization in psoriatic arthritis patients

In psoriatic arthritis (PsA), genetic factors play a substantial role in disease susceptibility as well as in its expression. This study aims to determine the distribution of class I and class II HLA antigens in PsA patients and secondly to analyze the influence of genetic factors in the clinical expression of the disease. Consecutive PsA patients (CASPAR criteria) with less than 1 year of disease duration were included. Sociodemographic and clinical data were recorded. Blood samples were obtained, DNA was extracted by polymerase chain reaction (PCR), and class I (A, B, and C) and class II (DR) HLA antigens were determined by oligotyping. A control group of 100 nonrelated healthy controls from the general population served as control. p values were corrected (pc) according to the number of alleles tested. A total of 73 patients were included, 37 were females (50.7 %) with a median disease duration of 72 months (interquartile range (IQR) 24-149). Thirty-three patients (45.2 %) had a family history of psoriasis. When analyzing all the class I and class II HLA antigens, a significantly higher frequency of B38 (odds ratio (OR) 2.95, p = 0.03) and Cw6 (OR 2.78, p = 0.009) was found in PsA patients compared to the control group. On the contrary, the HLA-A11 (OR 0.14, p = 0.04) and B7 (OR 0.31, p = 0.03) were significantly more frequent among healthy controls. Furthermore, B18 was significantly more frequent in patients with early arthritis onset (less than 40 years): seven patients (22.6 %) with early onset compared to two patients (4.8 %) with late onset (p = 0.03). No association between HLA-B27 and spondylitis or HLA-DR4 with polyarticular involvement was observed. The HLA-B38 and Cw6 alleles are associated with a greater PsA susceptibility in Argentine population.

HLA associations reveal genetic heterogeneity in psoriatic arthritis and in the psoriasis phenotype

OBJECTIVE

Rigorously ascertained cases of psoriatic arthritis in subjects presenting to a rheumatology unit were compared with cases of psoriasis in subjects presenting to a dermatology unit, where subjects with musculoskeletal features were excluded, to address 1) the extent to which the contribution of the major histocompatibility complex (MHC) to psoriatic arthritis susceptibility resembles that in psoriasis, and 2) whether MHC genes determine quantitative traits within the psoriatic arthritis phenotype.

METHODS

Separate discovery and validation subcohorts of patients recruited from a relatively homogeneous population were studied by sequence-based HLA typing, in which frequencies of the HLA-B and HLA-C alleles and haplotypes were compared.

RESULTS

In patients with psoriatic arthritis, the frequency of C*06:02 was lower than that in patients with psoriasis (28.7% versus 57.5%; P = 9.9 × 10(-12) ). Three haplotypes containing B*27:05 or B*39:01 were significantly increased in frequency in patients with psoriatic arthritis, but not in those with psoriasis. The structurally related B*39:06 allele was not increased in frequency. B*27 was associated with an interval of 0.98 years between skin and musculoskeletal disease (P = 2.05 × 10(-6) ), compared with an interval of 10.14 years for C*06. Preliminary evidence suggested that B*38:01 and B*08 may be associated with psoriatic arthritis susceptibility, and that allotypes encoding P2 pockets that bind side chains opposite in charge from those encoded by the B*27 and B*39 molecules may exert a protective role.

CONCLUSION

These findings suggest that the psoriasis phenotype results from two patterns of MHC effect. The first involves the classic psoriasis susceptibility gene C*06, which confers more penetrant skin disease with less prevalent and more time-dependent musculoskeletal phenotype development. The second pattern appears to be mediated by HLA-B alleles, notably B*27, and includes temporally more coincident musculoskeletal involvement that is nearly equivalent in penetrance to that of the skin disease.

Seronegative spondyloarthritis

Seronegative spondyloarthritis (SpA) is a group of inflammatory rheumatic diseases with common clinical and aetiological features, including axial and peripheral inflammatory arthritis, enthesitis, extra-articular manifestations and a close link to the presence of the human leucocyte antigen (HLA)-B27 epitope. Ankylosing spondylitis is the most common of the SpA diseases, with prevalence in the Caucasian population ranging between 0.15% and 1.8%, generally higher in populations with a higher background prevalence of HLA-B27 positivity. Incidence has been estimated between 0.49 (Japan) and 10 (Norway) per 100,000. The prevalence of psoriatic arthritis ranges from 0.02% to 0.2%, and the incidence in the normal population is 7.2 per 100,000 per year. In patients with existing psoriasis, the prevalence of psoriatic arthritis rises to 6-42%. The prevalence of reactive arthritis is dependent on the background incidence of gastrointestinal or genitourinary infections; incidence has been described as up to 30-40 per 100,000. SpA symptoms are present in up to 50% of patients with inflammatory bowel disease.

Investigating the role of the HLA-Cw*06 and HLA-DRB1 genes in susceptibility to psoriatic arthritis: comparison with psoriasis and undifferentiated inflammatory arthritis

Objective:

Psoriasis of early onset (type I; age of onset ⩽40 years) is associated with HLA-Cw*06 while the shared epitope (SE) is associated with rheumatoid arthritis susceptibility. Our aim was to investigate the role of HLA-Cw*06 and HLA-DRB1 genes (including SE) with psoriatic arthritis (PsA) susceptibility.

Methods:

In a case–control association study, HLA-Cw*06 phenotype frequencies were compared between patients with PsA (n = 480), psoriasis alone (n = 611) and healthy controls (n = 166). Similarly, at the HLA-DRB1 locus, phenotype and SE frequencies were compared in patients with PsA (n = 480), early undifferentiated inflammatory arthritis alone (n = 1621) and healthy controls (n = 537).

Results:

The HLA-Cw*06 phenotype was associated with type I psoriasis (OR 6.9, 95% CI 4.4, 11.1, p = 2.2×10⁻²¹) and with patients with PsA having type I psoriasis (OR 5.0, 95% CI 3.2, 7.9, p = 4.39×10⁻¹³), but not with patients with PsA having type II psoriasis (age of onset >40 years). HLA-DRB1*07, in linkage disequilibrium with HLA-Cw*06, was also associated with patients with PsA having type I psoriasis (OR 2.7, 95% CI 2.1, 3.7, p<0.00001). HLA-DRB1*04 alleles and the SE were associated with undifferentiated inflammatory arthritis but not with PsA.

Conclusions:

The SE is not a PsA susceptibility locus. HLA-Cw*06 and HLA-DRB1*07 are associated with patients with PsA having type I psoriasis, suggesting that the primary association is with age of onset of psoriasis. Patients with PsA having type I psoriasis, therefore, have a genetic background different to those with type II psoriasis, and adjustment for this is necessary in future studies that investigate the genetic susceptibility of PsA.

Early psoriatic arthritis

In the majority of patients with psoriatic arthritis (PsA), it is a chronic progressive disease, and only 12% of patients with early PsA will be in disease-modifying antirheumatic drug-free remission at 2 years. Radiologic damage occurs in the early stages of PsA; up to 47% of patients with PsA have radiologic erosions after 2 years. This article reviews the clinical features of early PsA, pathologic insights into PsA gleaned from studies of early PsA, and the current state of diagnostic imaging and therapeutics in early PsA.

Human leukocyte antigen distribution in Israeli patients with psoriatic arthritis

OBJECTIVES

This study was designed to investigate the distribution of human leukocyte antigen (HLA) classes I and II in a group of Israeli Jewish patients with psoriatic arthritis (PsA) and identify HLA markers related to disease manifestation in PsA.

PATIENTS AND METHODS

Human leukocyte antigens class I and class II (both serologically and from oligotyping) were tested in a group of 50 consecutive patients with PsA, 32 with skin psoriasis (PSO), and 255 healthy persons. Data on age, gender, disease duration, and pattern of rheumatological manifestations-oligoarthritis, polyarthritis, spinal involvement, involvement of distal interphalangeal joints (DIPs), and enthesitis-were registered.

RESULTS

Human leukocyte antigens A3, B13, and B38 alleles were found to be significantly prevalent in PsA compared with PSO patients and healthy controls. HLA-B27 was found in only two out of 50 patients with PsA. Patients with PSO and PsA had significantly increased incidence of HLA-DRB0101 and -DRB0301, while the frequency of HLA-DRB0403 was significantly higher among patients with PsA of Ashkenazi origin. We found a statistically significant association between DIP involvement and the presence of HLA-A26 and -B38, while HLA-DRB0301 was related to spinal involvement.

CONCLUSIONS

Psoriatic arthritis in Israeli patients seems to be associated with the presence of HLA-A3, -B13, -B38, -DRB0101, and -DRB0301. HLA-B27 was not a marker of PsA in this cohort of patients, including patients with psoriatic spondyloarthropathy.

Psoriatic spondyloarthropathy: a comparative study between HLA-B27 positive and HLA-B27 negative disease

OBJECTIVES

To evaluate the relative contribution of the human leukocyte antigen (HLA)-B27 to psoriatic spondyloarthropathy (PsSpA) susceptibility and to analyze whether this antigen contributes to disease expression.

METHODS

This cross-sectional study included 70 patients (mean age 48 +/- 14.5 years; 44 men and 26 women). PsSpA was defined according to radiological findings (grade 2 or more sacroiliitis), and patients were classified into 3 main subtypes: isolated axial disease (n = 16), axial plus oligoarthritis (n = 29) and axial plus polyarthritis (n = 25). All patients were studied following a standard protocol that included the collection of demographic and epidemiological data, clinical history, radiographs, complementary tests, physical examination, and HLA-B27 testing (serological method). For functional evaluation, the Health Assessment Questionnaire-Specific for spondyloarthropathy (HAQ-S) was used. Patients with and without HLA-B27 antigen were compared on the basis of the data.

RESULTS

Twenty-four patients (34%) carried the HLA-B27 antigen (RR 6.4, P <.0004). Fifty-six percent of those patients with the isolated axial pattern had this antigen, compared with 24% in the poly-arthritis axial pattern and 31% of those in the oligo-arthritis axial group (P =.016). Univariate analysis demonstrated correlations between HLA-B27 and an earlier age of onset for both psoriasis (P =.028) and arthritis (P =.006), male gender (P =.002), bilateral sacroiliitis (P =.002), and uveitis (P =.026). HLA-B27 negative patients developed more peripheral erosions than HLA-B27 positive patients (P =.05). No correlation was found between B27 and clinical symptoms of back involvement, syndesmophytes, or functional impairment.

CONCLUSIONS

The HLA-B27 antigen is not only important for PsSpA susceptibility, but also determines some clinical features. This antigen was associated with earlier age of psoriasis and arthritis onset, bilateral sacroiliitis, and male gender. However, it was not associated with either the severity or extension of the spondylitic process or with functional impairment.

Genetic epidemiology. Psoriatic arthritis

The existence of psoriatic arthritis as a distinct clinical entity remains a topic of debate; some authors propose that it is simply the co-occurrence of psoriasis and inflammatory arthritis. However, a distinct entity is likely to have distinct susceptibility factors in addition to those that contribute to psoriasis and inflammatory arthritis alone. These aetiological factors may be genetic and/or environmental, and in this review, the evidence for distinct psoriatic arthritis genetic susceptibility factors is considered.

Psoriatic arthritis joint fluids are characterized by CD8 and CD4 T cell clonal expansions appear antigen driven

The CD8 alphabetaT cell receptor repertoire in joint fluid of individuals with active psoriatic arthritis contained an average of 32 major oligoclonal expansions in many variable genes of the TCR beta chain (BV) families, as shown by beta-chain CDR3 length analysis. Interestingly, a small number of oligoclonal expansions were shared between simultaneous samples of joint fluid and blood; however, most expansions found in joint fluid were not identifiable in blood emphasizing the immunologic specificity of the clonal events for the inflamed joint at a given point of time. The CD4 T cell joint fluid repertoire contained fewer and smaller oligoclonal expansions also largely restricted to the joint, suggesting that CD4 T cells participate perhaps by interacting cognitively to generate the CD8 clones. The inferred amino acid sequence of a single CD8 oligoclonal expansion revealed that they usually are composed of one or a few structurally related clones at the amino acid sequence level with beta-chains that encode identical or highly homologous CDR3 motifs. These were not shared among patients. Moreover, several clones that encoded the same amino acid sequence were found to be structurally distinct at the nucleotide level, strongly implying clonal selection and expansion is operating at the level of specific TCR-peptide interactions. The findings support a model of psoriatic arthritis inflammation involving extensive and selective Ag, likely autoantigen, driven intra-articular CD4, and CD8 T cell clonal expansions.

The immunogenetics of the seronegative spondyloarthropathies

In none of the rheumatic diseases has the genetic contribution to pathogenesis been so well characterized as in the seronegative spondyloarthropathies. Most important has been the elucidation of the structure and effect on disease expression of HLA-B27, where 11 subtypes have been distinguished to date. These vary in frequency in different ethnic groups and seem to show differential disease associations. The high frequency of this gene in patients with the seronegative spondyloarthropathies, especially ankylosing spondylitis (AS) and Reiter's syndrome (RS)/reactive arthritis (ReA), has emerged as probably the best example of a disease association with a hereditary marker. Other HLA genes, in addition to HLA-B27, have been implicated in psoriasis and psoriatic arthritis. These include those from the HLA-C locus and from HLA-DR. In addition, recent family studies have implicated other genes outside the MHC that further enhance the susceptibility to AS.

Insights into the pathogenesis of psoriasis and psoriatic arthritis

Psoriasis and its related arthritis are chronic inflammatory disorders affecting predominantly the skin and synovium. Although their etiology remains to be established, multiple factors seem to play important roles in their pathogenesis. These environmental (eg, infectious agents and trauma), genetic, and immunologic factors are reviewed in this article.

HLA-B27 and the seronegative spondyloarthropathies

In the 25 years since the initial reports of the association of HLA-B27 with ankylosing spondylitis (AS) and subsequently with Reiter's syndrome, psoriatic spondylitis, and the spondylitis of inflammatory bowel disease, the association of HLA-B27 with the seronegative spondyloarthropathies has remained one of the best examples of a disease association with a hereditary marker. HLA-B27 has been recognized as representative of a spectrum of diseases, ranging from the majority of HLA-B27-positive individuals who have no disease at all, through those with isolated eye or skin involvement, to those with critical eye, heart, and peripheral joint compromise of full-blown AS. Yet HLA polymorphism has evolved in response to environmental stresses, and even the presence of HLA-B27 itself appears to confer advantages in certain infectious diseases, such as acquired immune deficiency syndrome (AIDS). This article will review what is currently known about HLA-B27 and disease, especially in the seronegative spondyloarthropathies. The structure-function relationship of HLA-B27 will be presented, including differences between the B27 subtypes both in their ethnic variation and possible disease implications. The disease spectrum conferred by the presence of HLA-B27 will also be discussed, and the theories of how HLA-B27 contributes to the pathogenesis of the spondyloarthropathies will be considered.

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.

Psoriatic arthritis. Genetics and HLA antigens

There is convincing evidence of a genetic basis for both psoriasis and psoriatic arthritis (PsA). Part of this genetic predisposition is due to genes within the major histocompatibility complex (MHC). In psoriasis, the primary association is with HLA-Cw6. Further work on specific nucleotide frequencies, especially those in the alpha 1 domain helix of the HLA-C molecule, will be of interest in determining whether a specific nucleotide frequency is present in all patients. The situation in PsA is considerably more complex. It is now established that there is an association between HLA-B27 and PsA, both in its peripheral arthropathy and in spinal disease in which radiological sacroiliitis is present. Spinal disease without radiological sacroiliitis is probably not associated with HLA-B27. There is some suggestion that HLA-B16 or its splits, HLA-B38 and HLA-B39, may also be associated with PsA, but there is considerable heterogeneity between the series, which prevents a firm conclusion being made. It is possible, but again not conclusive, that there is an association between HLA-DR4 and the symmetrical seronegative pattern of peripheral PsA. It is also likely that genes outwith the MHC predispose to psoriasis and PsA. It is further likely that a role will be found for environmental factors in both psoriasis and PsA. There is a tantalizing possibility of a complex interplay between a variety of environmental factors and genetic factors, both within and outwith the MHC, determining not only susceptibility but also the individual clinical pattern of disease. Further clarification of these possibilities is likely to depend primarily on understanding the role of genes within the MHC in predisposing to comparatively more homogeneous diseases, such as psoriasis and ankylosing spondylitis, before the mechanisms operating in PsA can be analysed and better understood.

The cervical spine in patients with psoriatic arthritis: a clinical, radiological and immunogenetic study

The radiological changes of the cervical spine were evaluated in 57 patients with psoriatic arthritis and were correlated with clinical, radiological, and immunogenetic features of the disease. Forty patients (70%) showed radiological evidence of the cervical spine being affected by the disease. Two patterns of cervical spine abnormalities were noted. Fifteen patients (26%) had erosive and/or subluxing cervical rheumatoid like lesions; 25 patients (44%) had a more frequently reported pattern similar to ankylosing spondylitis. Although subaxial subluxations were the most frequently observed cervical abnormalities (53%) in the inflammatory subgroup, none of the patients studied had cord compression. Ankylosing cervical spine disease was the only form of axial involvement in nine (36%) of 25 patients with the ankylosing form of psoriatic arthritis. All of these patients had peripheral disease and were B27 negative. Predictors of cervical spine disease patterns were considered using clinical, demographic, and radiological features and HLA antigens. The results of a multivariate analysis showed that the best predictors of inflammatory cervical spine disease are the presence of HLA-B39 and HLA-DR4 antigens, radiocarpal erosions, and the absence of the HLA-DR5 antigen.

Seronegative arthritis and the bowel

In this chapter we have outlined the seronegative spondarthritides associated with bowel disease, excluding those discussed in separate chapters. Although, traditionally, Crohn's disease and ulcerative colitis have been dealt with separately in any discussion of seronegative arthritides, they have been discussed together here for the following reasons. Despite being pathologically distinct they show remarkable similarity in extraintestinal manifestations including any associated arthritis. Any observed differences in prevalence rates of arthritis may be secondary to the relative difficulty in diagnosing Crohn's disease, and most of the important prevalence studies were done before the more sophisticated techniques to investigate the bowel became available. This may in part explain the dramatic increase in the world-wide incidence of Crohn's disease seen in the last 30 years, particularly through the 1970s, but which has fallen off recently (Miller et al, 1974). It would seem that the body has a limited means of expressing disease processes. The final common pathway of a number of quite distinct disease entities is the concept of the seronegative spondarthritides. Exactly how the microbiological, immunogenetic and molecular factors interact to produce a particular disease end-point is currently not clearly defined, but with the increasingly sophisticated means to investigate the body at a cellular level the explanations may soon be at hand. Further controlled family studies are also needed to define the genetic relationships more precisely. We may then be able to piece the jigsaw puzzle together.

Seronegative spondarthritides

We have attempted to review the epidemiology of a group of diseases collectively termed the seronegative spondarthritides. In discussing environmental influences on these diseases we have reviewed shared aetiological hypotheses and how these have been, and may be, manipulated to influence disease development. The socioeconomic impact of disease has been discussed, together with some of the strategies we might adopt to prevent further disability and handicap. Recent developments, particularly in the laboratory, promise imminent advances in the aetiopathogenesis of this group of chronic inflammatory disorders.

HLA antigens in psoriasis and psoriatic arthritis

HLA phenotypes were determined in 50 patients with psoriasis alone and in 50 patients with psoriasis and psoriatic arthritis. Positive associations were found in both groups with B13, B17, B37, Cw6, and DR7, and in addition with C4A6. Higher relative risks were found in respect to the patients with psoriasis alone compared with those with arthritis, and this suggests the involvement of additional genetic factors predisposing to peripheral arthritis. In patients with psoriasis only, the presence of Cw6 was associated with a significantly earlier age of onset.

Psoriasis and arthritis. III. A cross-sectional comparative study of patients with "psoriatic arthritis" and seronegative and seropositive polyarthritis: radiological and HLA aspects

In a group of patients with seronegative polyarthritis and psoriasis, the radiological features and the incidence of histocompatibility antigens were compared with those of a group of patients with seronegative polyarthritis but not psoriasis. No radiological criteria proved to be characteristic of psoriatic arthritis. In the group of patients with seronegative polyarthritis and psoriasis, erosions of the distal interphalangeal (DIP) joints were seen more frequently and were more severe than in the group of patients with seronegative arthritis without psoriasis. For the group of patients with seronegative polyarthritis and psoriasis, correlation was found between psoriatic nail lesions and erosions of the DIP joints, but this correlation was not found between the nail involvement and erosion of the adjacent DIP joint. No significant differences were found for the incidence of histocompatibility antigens between patients with seronegative polyarthritis with or without psoriasis. However, differences were found between these two groups and either the seropositive polyarthritis group or blood bank donors.

Psoriatic arthritis in children

This paper reviews the typical features of psoriatic arthritis, with emphasis on the clinical manifestations in children. The concepts of seronegative spondyloarthropathy and enthesopathy are described. Recent information is presented on genetics, possible pathophysiologic mechanisms, and treatment.

Histocompatibility antigens in psoriasis, psoriatic arthropathy, and ankylosing spondylitis

Patients with ankylosing spondylitis, psoriatic arthritis, and psoriasis alone were typed for HLA A, B, Cw, and DR antigens, and the antigen frequencies were compared with those in a normal control population and in patients with rheumatoid arthritis. Patients with psoriasis had a significantly raised frequency of Cw6. Those with arthritis in addition to their psoriasis also had raised frequencies of B27 and DR7. Patients with ankylosing spondylitis were characterised by the expected high frequency of HLA B27. Again, those with peripheral arthritis had a higher B27 and DR7 frequency than those without. DR3 is associated with the development of erosions in psoriatic arthritis.

Vascular changes in psoriatic synovium. A light and electron microscopic study

Light and electron microscopic studies were performed on the synovial membranes from the large joints of 12 patients with psoriatic arthritis. The most significant histopathologic findings were vascular changes that were characterized by endothelial cell swelling accompanied by inflammatory cell infiltration and marked thickening of the vessel wall. Fibrosis of the subsynoviocyte tissue was also prominent, especially in patients with chronic disease. Villi were not prominent, and the lining layer was not thickened. Both type A and B cells were seen; none had significant abnormalities. No electrondense deposits were observed. These findings lend further support to the theory that microvascular changes play a significant role in the pathogenesis of psoriasis and its related arthritis.

Arthritis in psoriasis

A group of 61 unselected patients with psoriasis attending a dermatology clinic were studied to determine the prevalence of psoriatic arthritis. On defined criteria arthritis was present in 41.6%. Peripheral arthritis was present in 15.5%, and sacroiliitis in 43%. A strong association of distal interphalangeal arthritis with psoriasis and nail dystrophy was confirmed. Tissue typing showed a strong association of B23, 17, in Caucasoid psoriatics, while the haplotype A1/B8 was increased in mixed Caucasoid--Negroid psoriatics.

Some recent advances in HLA and skin diseases

During the past 15 years, much has been learned about the human major histocompatibility complex. These new findings have been applied to the whole field of medicine, including transplantation immunology, blood transfusions, association with disease, human genetics, and the mechanism of human immune responses. In clinical medicine, the association between the major histocompatibility complex and various diseases has attracted the greatest interest. In this paper, we summarize the basic information on the human histocompatibility complex and its association with dermatologic disorders. Data from the world literature are reviewed and tabulated. Our own investigations on psoriasis, atopic dermatitis, and epidermolysis bullosa are discussed in detail.