Immunoglobulin allotypes in families with pauciarticular-onset juvenile chronic arthritis

Immunoglobulin allotypes (GM and KM) and their interactions with HLA antigens in autoimmune diseases: a review

GM and KM immunoglobulin (Ig) allotypes and their interactions with HLA antigens have been analyzed in various autoimmune diseases: multiple sclerosis, rheumatoid arthritis, insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, coeliac disease, Crohn's disease, Graves' disease, atrophic thyroiditis, Hashimoto's thyroiditis, myasthenia gravis, chronic active hepatitis, alopecia areata, uveitis, vitiligo, Turner's syndrome, glomerular nephritis, Berger's disease and idiopathic dilated cardiomyopathy. This review reports published results about associations or linkages, as well as the origins of the populations, the numbers of patients and controls tested. The possible role of Ig polymorphisms in the physiopathology of autoimmune diseases is discussed. Ig allotypes and statistical methods used to analyse the HLA and Ig data are also described.

Gm phenotype linkage to subsets of juvenile chronic arthritis (JCA) with influence on IgG subclass response

The serum hyper IgG of 76 JCA patients of different clinical subsets, 8 systemic, 37 polyarticular and 31 oligoarticular, were investigated by IgG subclass quantitation and Gm allotype determination. The well known increased serum IgG in JCA was confirmed as increased IgG1, IgG2 and IgG3 in the whole group. Investigating the clinical subsets IgG1 was significantly increased in all subsets while IgG2 and IgG3 increased only in the polyarticular form. In search of a genetic linkage for the clinical JCA subsets and the different IgG subclass patterns found, the alternative Gm allotypes G1m(a), G1m(f) for IgG1, G2m(n), G2m(") for IgG2 and G3m(g) , G3m(b) for IgG3 gene loci were investigated. The Gm (a,",g) haplotype was significantly increased in the whole JCA group and in the polyarticular subset. In the systemic subset the Gm (a,",g/a",g) phenotype was significantly increased, but the Gm (a,'h,g/f,n,b) phenotype was increased in the oligoarticular subset. The number of JCA patients with G1m(f,f)-,G3m(b,b)-phenotypes were significantly decreased. In such phenotypes, remission was more common. The susceptibility of JCA, its different clinical subsets and outcome of the disease is determined by Gm allotypes, affecting characteristic IgG subclass patterns.

Distribution of Gm allotypes in juvenile chronic arthritis

The immunoglobulin allotypes G1m(a), G1m(x), G2m(n), G3m(b) and Km(1) were determined in 76 Swedish patients with juvenile chronic arthritis (JCA). Eight of the patients had the systemic form of the disease. 37 belonged to the polyarticular and 31 to the oligoarticular subset. The frequency of the G1ma(x), G3m-b haplotype was significantly increased in the polyarticular subset but not in the oligoarticular subset, compared with the normal population (p less than 0.01). The polyarticular subset also differed from the oligoarticular subset with increased frequency (p less than 0.01) and higher levels (p less than 0.01) of IgM rheumatoid factor and a lower rate of remission (p less than 0.05). The few JCA patients in the systemic subset showed similar features as the polyarticular patients. The frequencies of G2m(n) and Km(1) did not deviate from the expected in any of the JCA subsets.

Complement C3b receptors on erythrocytes in patients with juvenile rheumatoid arthritis

Forty patients with juvenile rheumatoid arthritis (JRA) were examined for C3b receptor (CR1) levels on erythrocytes (by an enzyme-linked immunosorbent assay), levels of circulating immune complexes (IC) (by a polyethylene glycol precipitation-complement consumption method), C3d split products (by intermediate gel rocket immunoelectrophoresis), and HLA-A, B, and C (by microdroplet lymphocytotoxicity test). Lower CR1 levels were found predominantly among patients with JRA (mean 57%) compared with 40 age-matched controls (mean 68%) (P = 0.008). The CR1 levels differed when the JRA patients were grouped by mode of disease onset and by clinical state at the time of testing (levels in patients with pauciarticular disease were higher than those in patients with polyarticular disease, and levels in patients with polyarticular disease were higher than those in patients with systemic disease) or by sex (girls had higher levels than boys; P = 0.01). The levels of circulating IC and C3d were elevated in 25% and 40% of JRA patients, respectively, and were mutually correlated (P less than 0.05, tau = 0.20). A negative correlation was found between levels of C3d and the numbers of CR1 (P less than 0.01, tau = -0.28), but concentrations of circulating IC did not correlate with CR1 values. CR1 levels were the same in 6 HLA-B27 positive and 25 HLA-B27 negative patients. These findings do not represent conclusive evidence that the number of CR1 on erythrocytes serves as a predictor of disease severity or as an indicator of disease activity in patients with JRA.

Occurrence of the immunoglobulin haplotypes Gm1,17;23;21 and Gm1,2,17;23;21 in a sample of Australian Caucasians

Phenotypes positive for G2m(23) but negative for G1m(3) and G3m(5,10,11,13,14) are generally very infrequent in Caucasian populations. We recently Gm typed 372 Australian blood donors, predominantly of European descent, and found two Gm(1;23) and five Gm(1,2;23) individuals among them. This finding suggests that the haplotypes Gm1,17;23;21 and Gm1,2,17;23;21 may occur, in some European populations, with a frequency considerably higher than has been generally assumed.