HISTOCOMPATIBILITY TYPING IN THE RHEUMATIC DISEASES

Animal models of inflammatory spinal and sacroiliac joint diseases

Many cartilage matrix proteins or domains such as collagen types II, IX, and XI, GP39, AG1, VG1, and LP are potential antigens that might induce polyarthritis in susceptible animals (Table 1). Ordinarily, spondylitis is not a feature of polyarthritis induced with collagen types II, IX, and XI, GP39, cartilage matrix protein (matrilin-1) and cartilage LP. It seems that only the proteoglycans aggrecan and versican are capable of inducing sacroiliitis and spondylitis. Both molecules are structural proteins in intervertebral discs. Moreover, the arthritogenic or spondylitogenic epitopes of both molecules have been localized to the homologous N-terminal G1 globular domains. This region of versican and aggrecan is highly conserved, with 52% identity of amino acids. The homology is seen exclusively in the G1 domain and is concentrated between residues 115 and 332 (AG1 numbering) near the natural cleavage DIPEN site of aggrecan [84, 85]. Extra-articular pathology is often seen in rheumatic diseases, especially in AS. Other tissues, such as the sclera of the eye [86] and the media of the arteries [86, 87], also contain type II collagen, AG1, VG1, and LP, and versican is present in the central and peripheral nervous systems. Thus, there is the potential for an immune response against cartilage G1 and LP to be directed against related structures in extra-articular tissues. The presence of versican in the tendon and trochlea of the human superior oblique muscle might account for the occurrence of transient attacks of acquired Brown syndrome in patients with juvenile and adult forms of chronic RA [88]. Thus, it will be interesting to determine whether or not extra-articular expression of these cartilage proteins is closely related to extra-articular pathogenic expression in rheumatic diseases. Uveitis develops in VG1-immunized BALB/c mice, which is not seen in AG1-, and LP-treated animals. There is evidence that aggrecan and LP are also localized at these sites in the eye, but only immunity to versican can induce uveitis. In sacroiliitis and enthesitis of AS patients, the inflammation is associated with chondrometaplasia. In versican-induced sacroiliitis, replacement of cartilage by bone is seen with relatively little inflammation, somewhat resembling the situation in AS (Fig. 2). Versican can also stimulate chondrocyte proliferation [43]. Three conserved domains of human cartilage matrix molecules, namely VG1, AG1, and LP, show considerable homology [77, 79, 80, 89], and each is capable of inducing a unique inflammatory arthritis in BALB/c mice, with VG1 inducing only spondylitis [65], LP inducing peripheral arthritis with no spondylitis [90], and AG1 inducing axial and peripheral arthritis [66, 91]. It remains a mystery why such similar molecules cause different pathology in different target tissues. The exact immunopathogenic mechanisms deserve further study.

Neurologic manifestations of systemic vasculitis

The clinical features, diagnosis, and treatment of polyarteritis nodosa, Kawasaki disease, hypersensitivity angiitides (including drug-related vasculitis, serum sickness, Henoch-Schönlein purpura, hypocomplementemic vasculitis and cryoglobulinemia), Wegner's granulomatosis, temporal arteritis and Takayasu's arteritis are reviewed from a neurological perspective.

HLA markers in a community-based rheumatoid arthritis series

We wanted to investigate whether rheumatoid arthritis (RA) patients, defined by the American College of Rheumatology (ACR) 1987 criteria and selected from one community by the help of the official Finnish data registers, share the common HLA susceptibility genes. The HLA frequencies of 88 RA patients representing 85% of the prevalent cases of RA in the community were compared with those of 188 healthy controls. Fifty-four per cent of the index cases with RA had DR4 compared with 30% of the healthy controls (P <0.001). The 'RA susceptibility sequence' was found in 75% of the DRB1 genes in the index cases, but it did not correlate with the severity of the disease. The frequency of DR3 was not increased in RA patients but it was associated with features of severe disease, that is, with a high erythrocyte sedimentation rate (P<0.05), extra-articular disease (P<0.01) and prostheses in large joints (P<0.05). According to our results community-based RA patients satisfying the new ACR criteria show the common DR4 association. DR3 was the only HLA allele which showed some disease-modifying effect correlating with the severity of RA.

HLA-DRB1 alleles in Greek rheumatoid arthritis patients and their association with clinical characteristics

The association of certain HLA-DRB1 alleles in Green rheumatoid arthritis (RA) patients with several features of the disease, the gender of the patient and the age at onset was investigated. This case control study includes 86 Greek RA patients and 130 healthy controls unrelated to the patients. HLA typing was performed by polymerase chain reaction (PCR) and hybridization with sequence-specific oligonucleotide (SSO) probes. HLA-DR4 was significantly increased in RA patients. The alleles *0101, *0401, *0405 and *1001 were associated with a higher risk of RA. The *0408 allele was absent from our patients. Sixty-five per cent of RA patients carried the 'sharp epitope' (SE) compared with 31.5% of controls. The risk for RA in individuals carrying a single allele positive for SE was 2.85 times higher, and for those carrying two alleles positive for SE 8.57 times higher, than in SE-negative individuals. The risk was higher in those carrying the *0401 allele, followed by *0405 and *0101, while the genotype *0401/*0404 was absent. Alleles positive for SE comprise a predisposing factor for RA at an early age, particularly in men, and are associated with positive rheumatoid factor, nodules and erosions.

Rheumatologic view of the rheumatoid foot

Rheumatoid arthritis is a common systemic disease that affects between 0.3% and 1.5% of the general population worldwide. In 1988, it was estimated by the National Arthritis Foundation that there were 4 to 6 million cases of rheumatoid arthritis in the United States. There is general agreement that the feet are a major source of pain and disability at some point in the course of the illness. The frequency of involvement of the feet among 1000 patients with rheumatoid arthritis studied by Vainio was 91% in females and 85% in males. The clinical features and pathogenesis of the rheumatoid foot and an approach to initial nonsurgical treatment will be discussed.

Rheumatoid arthritis as a bone marrow disorder

Both the concept of rheumatoid arthritis (RA) as an autoimmune process restricted to joints and the major role of T cells in its pathogenesis have been challenged in the literature. Fibroblastlike and macrophagelike synoviocytes play an important role in RA pannus, and these cells originate in or have their counterpart in bone marrow (BM). Yet the B cell autoimmunity characteristic of RA occurs early, and synovial tissue, like BM, favors the B cell response. Because BM is abnormal in RA, and because germinal centers are unique to RA synovium, RA could be regarded as a disorder of the microenvironments able to sustain B cell response. In fact, RA could even begin in BM, with its onset facilitated by stem cell abnormalities. Moreover, most viruses suspected of playing a role in RA share a BM tropism. This may explain why RA frequently overlaps with other autoimmune disorders and benign lymphoproliferations, such as large granular T lymphocytosis. Because remissions from RA have been reported after BM transplantation, careful studies of the rheumatological outcome of RA patients undergoing such therapeutic procedures are needed. Although RA is a complex process, it can be considered initially as a stem cell disorder requiring treatment similar to that administered to transplant patients. Animal models have provided convincing evidence for these assumptions.

A comparative study of HLA genes in HLA-B27 positive ankylosing spondylitis and HLA-B27 positive peripheral reactive arthritis

OBJECTIVE

To determine whether HLA-B27 positive patients with ankylosing spondylitis (AS) and reactive arthritis (ReA) share additional HLA factors that confer disease susceptibility.

METHODS

HLA class I antigens were typed serologically, and class II antigens molecularly, in samples taken from 33 patients with AS, 30 patients with ReA, and 55 healthy HLA-B27 positive controls.

RESULTS

There was no major difference between the HLA alleles in AS and ReA patients, but deviations were observed when compared with healthy controls, especially between the antigens that were probably encoded by genes in the non-B27 chromosome.

CONCLUSION

These results suggest that both HLA class I and class II genes may influence the pathogenesis of HLA-B27 positive ReA, whereas class I antigens seem to be the major additional genetic factors in HLA-B27 positive AS.

Autoantibodies in black South Africans with systemic lupus erythematosus: spectrum and clinical associations

The clinical features and autoantibody profile of 111 black South Africans (103 females and 8 males) with systemic lupus erythematosus were retrospectively analysed. The mean age of the patients was 35.1 years and mean duration of disease 3.5 years. The commonest clinical and laboratory features noted were arthritis (62.2%), hypocomplementaemia (61.2%), haematological abnormalities (60.5%) and malar rash (55%). The serological abnormalities included antinuclear antibodies (98.2%), anti-dsDNA (66.2%), anti-Sm (44.2%), anti-RNP (65.5%), anti-Ro (60.5%), anti-La (28.4%) and rheumatoid factor (10.1%). Positive clinicoserological associations observed included: combination of anti-dsDNA antibodies and low C4 levels with renal disease; anti-dsDNA antibodies with cutaneous vasculitis; anti-Sm antibodies with psychosis; anti-RNP antibodies with Raynaud's phenomenon; anti-Ro antibodies with renal disease, psychosis and malar rash. Anti-La antibodies showed a weak negative association with serositis and Raynaud's phenomenon. Most of these clinical correlates are consistent with past studies. The high frequency of anti-Sm and anti-RNP antibodies is similar to the observations in African-Americans and Afro-Caribbeans.

Autoantibodies in black South Africans with systemic lupus erythematosus: spectrum and clinical associations

The clinical features and autoantibody profile of 111 black South Africans (103 females and 8 males) with systemic lupus erythematosus was retrospectively analysed. The mean age of the patients was 35.1 years and mean duration of disease 3.5 years. The commonest clinical and laboratory features noted were arthritis (62.2%), hypocomplementaemia (61.2%), haematological abnormalities (60.5%) and malar rash (55%). The serological abnormalities included antinuclear antibodies (98.2%), anti-dsDNA (66.2%), anti-Sm (44.2%), anti-RNP (65.5%), anti-Ro (60.5%), anti-La (28.4%) and rheumatoid factor (10.1%). Positive clinicoserological associations observed included: combination of anti-dsDNA antibodies and low C4 levels with renal disease; anti-dsDNA antibodies with cutaneous vasculitis; anti-Sm antibodies with psychosis; anti-RNP antibodies with Raynaud's phenomenon; anti-Ro antibodies with renal disease, psychosis and malar rash. Anti-La antibodies showed a weak negative association with serositis and Raynaud's phenomenon. Most of these clinical correlates are consistent with past studies. The high frequency of anti-Sm and anti-RNP antibodies is similar to the observations in African-Americans and Afro-Caribbeans.