Analysis of the MHC class II encoded components of the HLA class I antigen processing pathway in ankylosing spondylitis

OBJECTIVES

The evaluation of the role of polymorphism within the class II encoded antigen processing genes, LMP2 and TAP, in susceptibility to ankylosing spondylitis (AS).

METHODS

Eighty five patients with ankylosing spondylitis, 35 B27 positive healthy controls, and 55 unrelated healthy controls were studied. TAP1 and TAP2 alleles were assigned by ARMS PCR, and LMP2 alleles were assigned by restriction enzyme digestion of a PCR product.

RESULTS

The TAP1C allele was increased in the AS group (6%) compared with random controls (1%), p = 0.03 and TAP2E was increased in AS (3.5%) compared with random controls (0%), p = 0.05. However, the frequencies of these alleles were also increased in B27 matched controls. There were no differences in LMP2 allele or genotype frequencies between AS and either of the control groups. Partitioning of patients according to presence or absence of uveitis did not reveal any significant associations.

CONCLUSIONS

Increases of the minor TAP alleles, 1C and 2E, in AS reflect linkage disequilibrium between these alleles and HLA-B27. Polymorphism of the class I antigen processing pathway does not contribute significantly to AS susceptibility nor to the development of anterior uveitis associated with AS.

[Acute anterior uveitis: para-infectious hypothesis in predisposed individuals]

The etiology and the physiopathology of acute anterior uveitis (AAU) is not well understood yet. However, two major predisposing factors have been identified: a bacterial infection especially with gram negative organisms (functioning as a trigger) and a genetic background, in particular the expression of HLA B-27 tissue antigen. We report the case of a young woman returning from travel to the Far East with her partner. Both presented simultaneously a gastrointestinal infection with fever and diarrhea. Despite extensive investigations, the infectious agent was never identified because of early empirical antibiotic therapy. A few days later, the patient developed AAU of a moderate grade in both eyes. HLA B-27 testing was positive for her, but not for her partner. Experimental research, based on a animal model such as endotoxin-induced uveitis (EIU), gives us some insight into the possible pathogenic mechanisms of AAU. Footpad injection of endotoxin (lipopolysaccharide component of the wall of gram negative), produce an acute anterior uveitis in rats. Extensive histologic analysis of other organs shows that the anterior segment of the eye is the only structure involved. Intensity of inflammation varies in different rat strains, stressing the importance of the genetic background. The similarity of the animal model to AAU will contribute to orient clinical research towards identifying more thoroughly the possible infectious agent at the origin of AAU and possibly to develop a prophylactic therapy.

Ophthalmological significance of HLA associated uveitis

The association between HLA-A29 and birdshot chorioretinopathy is the strongest association between HLA and disease ever described. The determination of HLA-A29 is therefore of diagnostic significance. The association between HLA-B27 and acute anterior uveitis (AAU) is much weaker. However, it is evident that B27+ AAU is clinically different from B27-AAU. Half of the B27+AAU patients have or will have ankylosing spondylitis or Reiter's syndrome. The determination of HLA-B27 is therefore of clinical significance and should be determined in each case of AAU. The B27+ patients should be referred to a rheumatologist. The determination of HLA-Bw51 is of limited but significant diagnostic value for the diagnosis of Behçet's disease in countries around the Mediterranean Sea or Japan. In Northern Europe HLA-Bw51 determination will not give much practical information. The structure and function of HLA class I molecules is now known. It is probable that HLA-A29 and HLA-B27 molecules are directly involved in the pathogenesis of respectively birdshot chorioretinopathy and AAU.

Differential enhancement of HLA-B27 by interferon

To further examine the role of the HLA-B27 antigen in the pathogenesis of disorders such as anterior uveitis and ankylosing spondylitis, we have measured the level of enhancement of this antigen on peripheral blood lymphocytes and compared it with that of the class I HLA antigens HLA-A2 and HLA-B7 following interferon treatment. We found that the level of enhancement of HLA-B7 was greater than that of HLA-A2 or -B7 following treatment by alpha or gamma interferon (p less than 0.002). Similarly, the level of enhancement of HLA-B7 was greater than that of HLA-A2 (p less than 0.002) (Mann Whitney U-test). A differential enhancement of HLA-B27 by lymphokines may be important in the pathogenesis of HLA-B27-related disorders.

Endotoxin-induced uveitis in the rat: a hypothesis for preferential involvement of the anterior uvea

Endotoxin-induced Uveitis (EIU) was produced in Lewis rats by footpad injection of Salmonella endotoxin. Protein and cells were measured both in the aqueous humor and in the cerebrospinal fluid (CSF) in order to examine if the inflammation was strictly limited to the anterior uvea. EIU was also induced in Fischer and Brown Norway rats and the inflammation was compared among the three strains. Although the function and structure of the choroid plexus is very similar to the ciliary body, no signs of inflammation were seen in the choroid plexus and the CSF. Among the 3 tested strains of rats, EIU was maximal in Lewis rats, less severe in Fischer rats and least pronounced in Brown Norway rats. It is thought that because of its specific microvascular structure, the ciliary body is specially prone to endotoxin induced inflammation. The amount of inflammation however depends on the genetic background of the animal.

Acute anterior uveitis and HLA-B27

All studies among acute anterior uveitis patients (AAU) agree on the importance of and high association with HLA-B27. However, the majority of the HLA-B27+ population will never develop AAU. The partial association of AAU and HLA-B27 is probably not based on a preferential association with a particular B27 subtype, since the HLA-B27 subtypes are equally distributed among normal controls and AAU patients. Therefore, other factors increase the susceptibility to HLA-B27 associated diseases. Family investigations among the relatives of AAU and AS patients suggest the existence of other pathogenic genetic factors in addition to HLA-B27. Due to extensive research, associations with other genes on chromosome 6 could almost be excluded and associations with genes on other chromosomes were not yet found. The only reproducible association between AAU and any genes or gene products is, at the moment, still the association with HLA-B27. However, its role, which most probably is functional, is far from clear.

Characterization of the class I HLA 9.2-kb PVU II restriction fragment length polymorphism. Linkage to HLA-A and lack of disease association

The strongest reported association between a class I HLA allele and disease is that of HLA-B27 with ankylosing spondylitis (AS). However, it has not been shown whether B27 is the gene that predisposes to the development of AS or if it is merely linked with the disease-susceptibility locus. Furthermore, if B27 itself is the disease-susceptibility gene, there may be epistatic loci that also contribute to the development of AS or modify its clinical manifestation. A class I HLA 9.2-kb Pvu II restriction fragment was recently identified, which, when present in a B27-positive individual, further increased the relative risk for developing AS (from 119 to 297). This study was therefore designed to confirm the association between AS and this restriction fragment length polymorphism (RFLP) and to map the location of this fragment in the genome. The data presented here suggest that the class I HLA 9.2-kb Pvu II RFLP represents a Pvu II polymorphism at the 5' end of the HLA-A locus that is tightly linked with both HLA-A3 and A9 alleles. However, there is no association between this RFLP and AS in a population of patients living in Baltimore.

[Anterior uveitis in ankylosing spondylitis. A retrospective study]

In ankylosing spondylarthritis (AS), there is sometimes an anterior uveitis (AUV) or a previous history of AUV. The authors have reviewed the medical files of 338 hospitalised AS and 30 AS seen in consultation. They found an AUV in 28 hospitalised AS, or 8.3 p. cent of all cases (7.7 p. cent in men and 14.8 p. cent in women). In 3 cases (0.9 p. cent), the AUV was the first manifestation of the disease, preceding joint involvement. AUV was never found in patients seen in consultation. The findings of this investigation agree, but only partially, with those from the literature which, usually, acknowledge a greater frequency of AUV. Comparison with other previous investigations conducted in Italy enables to confirm that among Italian AS, AUV is less frequent than in other European and out of Europe series. It is possible that in a certain number of cases the AUV is not diagnosed clinically. However, it seems that the reduced incidence of the AUV discovered by a few Italian authors is not fortuitous (genetic factors?).

The association between ankylosing spondylitis, acute anterior uveitis and HLA-B27: the results of a Swiss family study

Patients with HLA-B27 positive ankylosing spondylitis (AS) in a Swiss family study developed non-granulomatous acute anterior uveitis (AAU) 11 times more often than their healthy relatives sharing the same HLA-B27 positive haplotype (4.4% versus 0.4%; p less than 0.01) during a period of 6 months.

Alpha 1-antitrypsin phenotypes in acute anterior uveitis

The alpha 1-antitrypsin phenotype PiMZ has been reported to have a higher than normal incidence in patients with acute anterior uveitis, indicating an important role in the immunogenetics of this condition. We have determined the incidence of this phenotype in 72 patients with acute anterior uveitis. It was found to occur in four patients (5.6% of the total), with the highest incidence (3/34 or 8.8%, p less than 0.001) in patients negative for HLA B27 and without sacroiliac joint disease. The incidence in HLA B27 positive patients was normal. No correlation was found with the severity, bilaterality, or recurrence of uveitis. Although this increased incidence is statistically significant in comparison with the normal population incidence of 2.6%, its direct clinical significance is questionable; the most likely explanation for it includes possible linkage with other immunoregulatory genes. We also found a lower than expected incidence of the phenotype PiMS, and discuss the relevance of this finding.

A familial study of the inheritance of HLA-B27-positive acute anterior uveitis

To determine whether factors besides HLA-B27 play a pathogenic role in acute anterior uveitis, we examined 152 first-degree relatives of 42 randomly selected HLA-B27-positive acute anterior uveitis patients. Nine relatives, all from different families, had acute anterior uveitis: eight were HLA-B27 positive and one was HLA-B27 negative. The prevalence of acute anterior uveitis in HLA-B27-positive first-degree relatives of HLA-B27-positive acute anterior uveitis patients was 13% (eight of 63). This is significantly more (P less than .0001) than the frequency of 1% in the normal HLA-B27-positive Dutch population. Ankylosing spondylitis was found in four of 38 (11%) HLA-B27-positive family members over the age of 45 years. This is also significantly more than the prevalence of 1% in a normal HLA-B27-positive Dutch population. Of these four relatives with ankylosing spondylitis, three also had acute anterior uveitis. It was remarkable that two of these four relatives had a proband who had no ankylosing spondylitis.

Association of complement allotype C4B2 with anterior uveitis

We have studied allotypes of the fourth component of complement (C4) in 44 patients with inflammatory eye disease in order to define genetic susceptibility factors further. Twenty-six patients had uveitis (18 had anterior uveitis) and 18 patients had retinal vasculitis. There was an increased incidence of the C4B2 allotype in patients with anterior uveitis (pc less than 0.002), especially in HLA B27 positive males. In contrast, there was no increased incidence of specific allotypes in patients with posterior uveitis or retinal vasculitis. This genetic association may form part of a disease susceptibility supratype in patients with anterior uveitis.

Clinical and immunopathological studies of pars planitis in a family

We examined a family in which two brothers with identical HLA typing have pars planitis with snowbanking. Immunopathological studies of one of their eyes showed that in the area of snowbanking over the pars plana there was mild to moderate inflammatory cell infiltration, consisting of mostly Pan T (Leu 4+) lymphocytes. The ratio of T helper/inducer to T suppressor/cytotoxic cells was approximately 10:1. Few macrophages (OKM1+) were identified. Very few B cells and no NK cells were observed. Some retinal vessels had a perivascular infiltration consisting of mostly T lymphocytes. Most of the inflammatory cells bore class II antigens (HLA-DR+), while T cells bore few IL-2 receptors (anti-TAC+). The snowbank consisted mainly of glial elements (GFAP+) and basement membrane components (type IV collagen and laminin) with the predominant cell the Müller cell (Mü+). A site of inflammation at the iris-ciliary body junction also stained for B cells (Leu 14+). These findings suggest that the snowbank could be formed by the glial elements of the peripheral retina. The chronic inflammation in pars planitis appears to consist of helper T cells, both in the pars plana, and the retinal vasculature.

[HLA-B27 associated spondyloarthritis in childhood]

Ankylosing spondylitis, indefinite juvenile spondyloarthritis (JSA), reactive arthritides, psoriasis arthritis, arthritis of inflammatory bowel disease, and probably other rare diseases, such as the Behçet-syndrome, are sharing several distinctive features which discriminate them as a group from other arthritides, particularly from the rheumatoid arthritis in children (JRA) and adults. These distinctive features are: familial aggregation; association with HLA-B27; enthesopathy, sacroiliitis; predominance of Lower-Limb-arthritis; onset mostly after the age of 10 years, and typical manifestations of the skin and mucous membranes. Based on these characteristics and the probability of a later involvement of the spine, this group of diseases has been designated "HLA-B27-associated spondyloarthritides". Two thirds of all cases do not fit in any of the well-known spondyloarthritides. In this subgroup, designated as JSA, the disease begins usually with oligoarthritis and/or enthesopathy, and based on further clinical criteria it can early be distinguished from the JRA. The diagnosis of the other spondyloarthritides can be established primarily or later on follow-up, based on further characteristic symptoms and findings. In the differential diagnosis of arthritis in children, one third do have a spondyloarthritis and about one half do have JRA. This differentiation is of an important therapeutic and prognostic value, e.g. the slow-acting drugs are effective in JRA but not in spondyloarthritis, and in patients with axial manifestations, the early education and training for correct posture is important to prevent the development of kyphosis.

Alpha 1-antitrypsin in acute anterior uveitis and rheumatic diseases

To test the pathogenetic role of the phenotype MZ of alpha 1-antitrypsin/alpha 1-protease inhibitor (PI) in acute anterior uveitis (AAU) and in different rheumatic diseases we examined 360 unrelated patients including 93 with AAU alone, 24 patients with AAU and ankylosing spondylitis (AS), 21 patients with AAU and Reiter's disease (RD), 26 patients with AAU, AS, and RD 54 patients with AS alone, 16 patients with RD alone, 115 patients with rheumatoid arthritis (RA) alone, and 11 patients with psoriatic arthritis (PA) alone. Of the 164 AAU patients, 80 had a single attack, and 84 had repeated episodes. There were neither significant differences between different groups of the patients and 120 healthy controls nor between patients with AAU alone and patients with AAU and AS or RD in the frequencies of the PI phenotypes tested. The results indicate that the PI MZ type is not closely associated with AAU, AS, RD, RA and PA and that it does not play any role in determining whether AAU shows a pattern of a single attack or repeated episodes, and whether AAU occurs alone or together with AS or RD.

HLA-DP antigens in patients with pauciarticular juvenile rheumatoid arthritis

The distribution of the recently described HLA-DP antigens was examined in a population of patients with pauciarticular juvenile rheumatoid arthritis and iridocyclitis, in an attempt to further characterize the immunogenetically determined susceptibility to this disease. There was a significantly increased frequency of the HLA-DPw2 antigen in the patients compared with the controls (67% versus 34%; odds ratio 3.9, P = 0.003 by Fisher's exact test). Population studies and family studies showed that this association with HLA-DPw2 was not secondary to linkage disequilibrium with the previously defined HLA-D region markers of disease (HLA-DR5 and HLA-DRw8) in these patients. These data raise the possibility that susceptibility to this form of juvenile rheumatoid arthritis may be regulated by more than one HLA-linked gene.

Immunoglobulin allotypes in patients with ankylosing spondylitis, Reiter's syndrome and acute anterior uveitis

The immune response appears to be partially regulated by genes linked to the IgGH chain gene complex. Immunoglobulin allotypic markers Gm groups are distributed in Caucasians largely in 5 relatively well defined phenotypes. We examined the prevalence of these phenotypes in 119 patients with ankylosing spondylitis, Reiter's syndrome or acute anterior uveitis. No significant deviation from the control frequencies was noted.

Genetic aspects of the spondyloarthropathies

Family studies and investigation of the HLA associations have in recent years added to our understanding of the spondyloarthropathies. In regard to ankylosing spondylitis it is likely that B27 itself is the major susceptibility gene but that additional genes may play a secondary role. Heterogeneity of the B27 antigen has been demonstrated but has not yet been shown to be relevant to disease susceptibility. Haplotypes including Cw6 are related to susceptibility to psoriasis and psoriatic arthritis and although the risk for the arthropathy is increased in B27-positive individuals, there is some uncertainty regarding the association with other B locus antigens and further work is needed. There is also uncertainty as to whether B27-associated disorders occur randomly within families, or whether particular disorders cluster in certain families and further evidence in this field would be of considerable interest. Genetic studies, as here outlined, have not as yet had a major impact in clinical medicine but it is anticipated that a deeper understanding of the mechanisms of HLA-linked susceptibility genes and in particular of how they interact with environmental agents, will improve our ability to treat and possibly prevent the relevant diseases.

Pi phenotypes in patients with ankylosing spondylitis, acute anterior uveitis, psoriasis and chronic prostatitis

Pi phenotypes were determined in patients hospitalized with ankylosing spondylitis, acute anterior uveitis, psoriasis or chronic prostatitis. The allele frequencies were calculated. No deviation in allele frequencies from Norwegian controls could be demonstrated.

Ankylosing spondylitis is part of a multifactorial syndrome: hereditary multifocal relapsing inflammation (HEMRI)

Complex associations between the different subgroups of seronegative arthritis, acute anterior uveitis, psoriasis and inflammatory bowel disease were found in a series of patients and relatives. Different HLA-B antigens were associated with different clinical signs. The results indicated the existence of a multigenic syndrome whose main clinical manifestations are relapsing innflammations at various sites. The genetic factors appeared to be 1) HLA-B27 associated disease susceptibility, 2) predisposition to psoriatic arthropathy, 3) predisposition to early onset familial psoriasis and, 4) a probable predisposition to inflammatory bowel disease and its associated arthropathy. The results indicated that the different genetic factors may interact and influence each other's penetrance and expression.

Inherited predisposition to iridocyclitis with juvenile rheumatoid arthritis: selectivity among HLA-DR5 haplotypes

HLA-DR5 is associated with a chronic iridocyclitis and juvenile rheumatoid arthritis with onset in early childhood. Previously published data provided indirect evidence for selective linkage between two HLA-B alleles and HLA-DR5. To test this observation further, 38 families, the probands of which have chronic iridocyclitis and juvenile rheumatoid arthritis, were HLA typed so that haplotypes associated with disease could be established. HLA-DR5 was linked to HLA-Bw44 or to HLA-Bw35 and to HLA-Cw4 in the majority of haplotypes obtained in the probands. Both HLA-Bw44, -DR5 and HLA-Bw35, -Cw4, -DR5 occurred more commonly in the proband haplotypes than in the control haplotypes. The frequency of the haplotype HLA-Bw44, -DR5 was 0.133 compared with 0.007 (X2 = 27.04, P less than 10(-6] and for HLA-Bw35, -Cw4, -DR5, it was 0.093 compared with 0.11 (X2 = 13.83, P = 0.0002). The relative risks were 20.77 and 9.23, respectively, versus 3.52 for HLA-DR5 alone. HLA-Bw44 occurred much more commonly in proband HLA-DR5 haplotypes (0.455) compared with control HLA-DR5 haplotypes (0.067) (X2 = 8.26, P less than 0.01). Not all HLA-DR5-bearing haplotypes predisposed equally to chronic iridocyclitis and early-onset pauciarticular juvenile rheumatoid arthritis.

Genetic markers for acute anterior uveitis

One hundred and sixty-nine patients, 82 with acute anterior uveitis (AAU) only, 48 with AAU and ankylosing spondylitis (AS), and 39 with AS only were studied. The HLA antigen A2 was present in 44/82 AAU only, 31/48 AAU + AS, and 23/39 AS only. Where haplotype analysis was possible by virtue of family studies, A2 B27 was present in 7/16 AAU only, 9/15 AAU and AS and 14/29 AS only. These figures do not differ significantly from the expected values of control populations. Alpha-1-antitrypsin (alpha-1-AT) phenotypes were obtained on 30/82 AAU only, 29/48 AAU + AS, and 27/39 AS only patients. The MZ phenotype appeared in 8/86 patients tested; 4/30 with AAU only and 4/29 AAU + AS patients. This is higher than the expected value for control populations. Therefore, MZ alpha-1-AT phenotype but not HLA-A2 appears increased in patients with AAU.

HLA antigens in acute anterior uveitis and spondyloarthropathies in Asian Indians and their comparison with American whites and blacks

HLA antigen frequencies in 53 unrelated Asian Indian patients with acute anterior uveitis, with or without associated spondyloarthropathies, were compared with our published data on American Whites and Blacks. The most frequent HLA phenotype among uveitis patients with associated ankylosing spondylitis was A9(W24), B27 in Asian Indians as compared to A2, B27 in the American Whites and Blacks.

The cross-tolerance hypothesis, HLA-B27 and ankylosing spondylitis

The association of HLA-B27 with ankylosing spondylitis (AS) can be explained by a cross-tolerance hypothesis, which suggests that Gram-negative bacteria, such as Klebsiella, possess antigens which resemble HLA-B27. Experimental studies with human tissue-typing sera and rabbit anti-Klebsiella sera would appear to be compatible with this hypothesis. Clinical studies indicate that faecal Klebsiella can be isolated more readily from AS patients during active phases of the disease, when this is defined either clinically, with or without uveitis, or biochemically by elevation in ESR and C-reactive protein levels. The cross-tolerance hypothesis proposes that ankylosing spondylitis is a reactive arthritis following infection by Gram-negative bacteria and tissue damage is produced by antibacterial antibody binding to cross-reacting self-antigens.

Seronegative arthropathy and associated diseases--a multigenic syndrome?

Patients hospitalized for psoriasis, acute anterior uveitis, ankylosing spondylitis or with chronic prostatis were examined. From previous reports and our own results we formulated hypotheses of the genetic mechanisms involved. We then examined all available adult relatives of 75 patients with ankylosing spondylitis. Our previously established genetic hypotheses were tested by segregation analyses in these families. All our results point to the existence of a syndrome of distinct but interacting genetic factors. The main factor is the HLA-B27 associated disease predisposition. Manifestation of this predisposition seems to be influenced by sex and by presence of factors coding for psoriasis and/or psoriatic arthropathy. Our results concerning psoriasis and psoriatic arthropathy supported the previous suggestions that these diseases exhibit genetic heterogeneity. It is known that disease signs may be triggered by infection in genetically predisposed persons. The syndrome therefore has a multifactorial aetiology. Seronegative arthropathy is a term that includes all arthritic components of the syndrome. There is a need for a term that encompasses all clinical signs of the genetic factors involved. We propose 'Hereditary multifocal relapsing inflammation' (HEMRI) as a descriptive term for this syndrome. The disease entities included may be regarded as subtypes of the syndrome.

HLA antigens in uveitis

HLA antigens are associated with a number of inflammatory eye diseases, most notably HLA B2 with anterior uveitis (AU). This association varies between different populations and ethnic groups. The aim of this study was to investigate the relationship between uveitis and HLA A, B and DR locus antigens in an Australian population. Seventy-two consecutive patients with uveitis were studied (37 males and 35 females) over a 6 month period. Thirty-two percent of the AU patients were HLA B27+, as were 42% of males (19% females) with their first attack of AU compared with 60% of males (23% females) with recurrent AU. The only significant difference in etiology between males and females was the greatly increased incidence of rheumatic diseases in males, in whom 77% (10/13) had radiological evidence of sacroiliitis. Additional findings included a lack of association between the HLA B7 cross reactive group and DR locus antigens in AU as well as the lack of any HLA associations in the 13 patients with posterior uveitis (PU).

Radiographic changes, HLA B27 and back pain in patients with psoriasis or acute anterior uveitis

Twenty-five female and 23 male consecutive patients hospitalized because of severe psoriasis, and 34 consecutive patients hospitalized because of acute anterior uveitis (AAU) were examined. Twelve of the patients with AAU (35%) and 11 of the patients with psoriasis (23%) had definite sacro-iliitis, which was unilateral in 6 (55%) of the former and in 2 (17%) of the latter. No definite radiographic differences in sacro-iliitis between HLA B27-positive and -negative patients could be detected. The radiographic changes of the dorso-lumbar junction (Th9-L2) related to the diseases, were seen only in HLA B27 positive patients with sacro-iliitis. Scattered lateral syndesmophytes were the commonest paravertebral ossifications in patients with psoriasis, whereas more diffuse and more numerous lateral mixed osteophytes appeared most frequently in AAU patients. Parasyndesmophytes were seen both in patients with psoriasis and in those with AAU. Asymptomatic sacro-iliitis was frequently found in unilateral, psoriatic sacro-iliitis (4 out of 6 patients) but was not restricted to this group. No radiographic indications of aortic valve insufficiency or apical lung fibrosis were found.

Association of ophthalmoplegic migraine with familial acute anterior uveitis

In a family with 3 cases of acute anterior uveitis (AAU) the proband had 13 episodes of recurrent AAU associated 4 times with severe, throbbing ipsilateral headache. During one such episode he had an oculomotor palsy, hyperaesthesia of the cornea, and lack of spontaneous pulsations of the central retinal vein in the eye with AAU. An oculomotor palsy occurred twice intermittently between the AAU episodes. Carotid and vertebral angiographies confirmed the diagnosis of ophthalmoplegic migraine. Prostaglandins liberated by trauma, AAU, or other inflammation may be involved as mediators in ophthalmoplegic migraine attacks. All 3 patients with AAU had sacroiliitis and seronegative polyarthritis. One of their siblings had polyarthritis and one incomplete Reiter's disease. All of them were HLA-B27 positive whereas one healthy sibling was HLA-B27 negative. These findings support the hypothesis that HLA-B27 itself or a pleiotropic HLA-B27 linked gene predisposes the carrier to AAU, sacroiliitis, ankylosing spondylitis, and Reiter's disease.

HLA antigens, psoriasis and acute anterior uveitis in Bechterew's syndrome (ankylosing spondylitis)

One hundred and twenty-two consecutively hospitalized patients with ankylosing spondylitis (AS) were reexamined. Ninety-two per cent were HLA B27 positive. Of the HLA B27 negative patients, 60% were found to have psoriasis, as opposed to 11% of the HLA B27 positive patients. Acute anterior uveitis (AAU) was found only in HLA B27 positive patients, and more frequently in males than in females. The genetic and clinical heterogeneity of AS, together with the overlapping clinical criteria for AS and psoriatic spondylitis, may make the term "Bechterew's syndrome" preferable. Based on these findings and previous reports, we conclude that (i) AAU is a manifestation of Bechterew's syndrome in HLA B27 positive patients, (ii) HLA B27 negative patients without any obvious accompanying manifestations may suffer from psoriatic spondylitis, and (iii) genetic predisposition to psoriasis in persons who are HLA B13, B17 and B37 negative, may interact with the genetic predisposition to Bechterew's syndrome in HLA B27 positive persons and produce Bechterew's syndrome with psoriasis or psoriasis-like skin eruptions.

Iridocyclitis in black Americans: association with HLA B8 suggests an autoimmune aetiology

Histocompatibility (HLA) testing was performed on a total of 171 black Americans, 129 controls, and 42 patients with iridocyclitis. None of the patients had a history of rheumatological disease. The phenotype frequency of HLA B8 was greatly increased among patients than the control group (exact p = 0.0010). Most striking was the almost identical phenotypic frequency of B27 found in patients and in the control group (exact p = 0.07087). No HLA DR antigen in the patient group was found to be significantly raised when compared with controls. The HLA B8 associated diseases was seen more in females, was bilateral and nongranulomatous, had no systemic disease associated with it, and left patients with visual handicap. The HLA B8 antigen has been associated with various entities of presumed autoimmune origin, and these data suggest that iridocyclitis, at least in blacks, may be of similar aetiology.

Association of HLA-A2 with uveitis in HLA-B27 positive patients with ankylosing spondylitis

We studied 175 consecutive patients with ankylosing spondylitis (AS) to define the genetic characteristics of those patients who had associated acute anterior uveitis (AAU). The first 131 patients were tested for HLA antigens of the A and B loci, and the remaining 44 patients were typed only for HLA-B27. AAU was significantly more common in B27 positive patients, occurring in 40 of 144 B27 positive (27.7%) and in only 3 of 31 B27 negative patients (9.7%) (p less than 0.05). Among the B27 positive AS patients, AAU occurred in 24 of 68 patients (35%) who also possessed HLA-A2 and in only 5 of 35 patients (14%) who lacked A2 (p less than 0.025). An independent association of AAU with A2 could not be shown. In the absence of evidence of linkage disequilibrium between A2 and B27 in the general population, the data suggest that the presence of A2 in B27 positive AS patients enhances the risk of AAU above that associated with B27 alone, and that other MHC-linked genetic factors, in addition to B27, are associated with susceptibility to AAU in AS patients.

Histocompatibility antigens (HLA) and uveitis

The studies of histocompatibility (HLA) antigens have contributed to the understanding of the pathogenesis of uveitis. Acute anterior uveitis is associated with rheumatic disorders such as ankylosing spondylitis. HLA-B 27 antigen is present in 98% of these cases. There are genetic and environmental factors influencing the activity of the disease. HLA-B 27 was found to be associated with 43% of cases of acute anterior uveitis without systemic disease. In juvenile chronic polyarthritis with acute anterior uveitis HLA-B 27 helps in differentiating between ankylosing spondylitis and Still's disease. Specific HLA antigens were also found in other forms of uveitis such as Reiter's disease (HLA-B 27), Behcet's syndrome (HLA-B 5), VKH syndrome (HLA-Bw 22J) and ocular histoplasmosis (HLA-B 7). Despite these new findings, there are still many obscure factors and further studies are required to elucidate the pathogenesis of uveitis and to achieve its prevention.

[Acute iridocyclitis, ankylosing spondylitis (Bechterew) and congenital tissue antigens (author's transl)]

The tiysue antigen HLA-B27 was present in 92.6% of 95 Swiss patients with classical ankylosing spondylitis. This tissue antigen is present in only 7.7% of healthy Swiss blood donors. 36% of all patients had one or several acute attacks of anterior uveitis. This usually follows the onset of joint symptoms. In 4% of the 95 patients the iritis was the first symptom. The combination of acute uveitis and ankylosing spondylitis with the tissue antigen HLA-B27 indicates that not only the spondylitis, but also the uveitis is in many cases genetically determined.

HLA-B27 frequency in Greek patients with acute anterior uveitis

The histocompatibility antigen HLA-B27 was identified in 12 out of 33 patients with acute non-granulomatous anterior uveitis. This is a frequency of 36.36%, compared with 4.72% in controls. Seven patients had in addition evidence of systemic disease, including ankylosing spondylitis, sacroiliitis, Reiter's disease, Still's disease, and rheumatoid arthritis. Five of these were HLA-B27 positive, which suggests that the uveitis in many of these cases has a similar aetiology to the uveitis in those with rheumatic disease. It appears that the more severe cases of acute anterior uveitis are related more frequently to the presence of HLA-B27.

Psoriasis associated with anterior uveitis

A patient with psoriasis and anterior uveitis is described. In her family the two entities of iridocyclitis and psoriasis occurred separately in two generations and appeared associated in the third generation. Tissue typing of the family revealed HL-A 27 antigen in two members and HL-A 17 in the other two members. The possible relevance of HL-A antigens to the two clinical entities is discussed.

Acute anterior uveitis and HLA-B27 in families

To determine the hereditary pattern of acute anterior uveitis (AAU) 12 families with 2 cases of AAU in each family were given a routine eye examination which included serological determination of HLA antigens. Members of four families underwent x-ray examination of the lumbosacral spine. Of the 23 cases with AAU examined, 19 had the antigen B27. The genes determining B27 and a2 were inherited together in 14 instances and the gene determining Cwl in 10 of these 14. The lymphocytes of the HLA identical siblings of the three families studied by the mixed lymphocyte culture test did not react against each other. Sacroilities was seen in 62.5% of cases with familial AAU and in 58.6% of their relatives. It is concluded that HLA-B27 is linked with genes predisposing the carrier to familial AAU, which is closely related to the rheumatic group of diseases.

Clinical characteristics of familial acute anterior uveitis

Of 24 patients with familial acute anterior uveitis (AAU) 22 cases were non-granulomatous and 2 granulomatous. Of the 23 HLA tested patients 19 had the antigen HLA-B27. The 2 granulomatous and 2 non-granulomatous AAU cases were HLA-B27 negative. The iritis associated with the antigen HLA-B27 was unilateral, acute and recurrent, with cells and flare in the aqueous humor, and it lasted on an average 5 weeks. Keratic precipitates were never mutton fat, if the antigen B27 was present. X-ray examination of 8 patients revealed sacroilittis in 5. It is concluded that certain factors like trauma or infective agents may provoke familial AAU which is in close relationship with the HLA-B27 associated rheumatic group of diseases.