C-ANCA-positive IgG fraction from patients with Wegener's granulomatosis induces lung vasculitis in rats.

The aim of the present study was to analyse in rats the ability of C-ANCA-positive IgG fraction in triggering inflammatory response on pulmonary tissue. Wistar rats (n = 18) were injected via the the internal jugular vein with 20 mg of total C-ANCA-positive IgG fraction isolated from serum of three different Wegener's granulomatosis patients obtained before therapy. Similarly, control rats were treated with IgG fraction from two rheumatoid arthritis patients (n = 7), IgG from six normal human sera (n = 15) or saline (n = 18), respectively. Animals were sacrificed after 24h of injection for histological analysis of the lungs. Vasculitis and inflammatory infiltrate were consistently absent in rats injected with rheumatoid arthritis IgG or saline and in 14/15 of normal IgG treated animals. In contrast, marked vasculitis was observed in all 18 animals injected with C-ANCA-positive IgG fraction. The histological features were characterized by the presence of a perivascular pleomorphic cellular sheath, particularly around small vessels, endothelial adherence and diapedesis of polymorphonuclear leucocytes and presence of granuloma-like lesions. A dose-response relationship was observed between protein concentration of C-ANCA IgG sample and the intensity of the inflammatory response in the animals. In addition, IgG fraction with undetectable C-ANCA, obtained from one patient in remission after treatment, was not able to reproduce the pulmonary tissue alterations induced by its paired IgG that was positive for C-ANCA taken before therapy. The experimental model described herein may be useful to characterize more effectively the pathogenic mechanism of C-ANCA in Wegener's disease.

HLA class II antigens in rheumatic fever. Analysis of the DR locus by restriction fragment-length polymorphism and oligotyping.

We recently described an association of serologically defined HLA class II antigens DR7 and DR53 with RF. This study aimed at determining more precisely the class II gene associated with the disease. We studied patients and age- and race-matched controls. Genomic DNA was digested with four different enzymes and hybridized with HLA cDNA probes for DR beta, DQ beta, DQ alpha, and DP beta genes. RFLP analysis disclosed a fragment of 13,81 kb on Taq I DR beta blots, which correlates with HLA-DR53 and HLA-DR16, according to data from the Tenth International Histocompatibility Workshop. Of 24 patients, 20 (83.3%), were positive for the 13.81-kb/Taq I/DR beta allogenotope, compared with 16 (34%) of 47 healthy individuals (p = 0.000079, Fisher's exact test). Search for specific nucleotide sequences was performed using polymerase chain reaction technique. Oligonucleotides corresponding either to allele-specific DR7 and DR53 sequences, or shared by DRB1 and DRB3, DRB4, or DRB5 sequences were screened. Differences were tested throughout the second exon up to codon 100. Results were as expected by simple comparison with the published sequences of individual alleles. Although a clear association with DRB loci is shown, a susceptibility associated either with an allele or with a unique sequence was not found. A promiscuous presentation of the putative cross-reacting peptide or a heterogeneity of the causative agent might be the origin of these results. Genetic complementarity may be an additional factor defining inherited susceptibility to this disease.

Association of human leukocyte class II antigens with rheumatic fever or rheumatic heart disease in a Brazilian population.

BACKGROUND: The incidence of rheumatic heart disease is great in Brazil. We analyzed the distribution of human leukocyte (HLA) antigens in a Brazilian population sample with rheumatic fever or rheumatic heart disease, with the aim of better understanding the mechanisms involved. METHODS AND RESULTS: HLA class I (A, B, and C) and class II (DR and DQ) antigen distribution was studied in 40 patients with diagnosis of rheumatic fever or rheumatic heart disease and compared with a control group of 617 healthy individuals for class I typing, from which 118 were drawn for class II typing. A strong correlation between rheumatic fever and rheumatic heart disease and HLA-DRw53 (72.9% in the disease group versus 39% in the control group: p = 0.00061, relative risk, 4.2; etiologic fraction, 0.43) was found. We also found an increase in the frequency of HLA-DR7 (57.5% in the disease group versus 26.3% in control group: p = 0.00715; relative risk, 3.8; etiologic fraction, 0.56). HLA class I and HLA-DQ typing did not point to any association with these diseases. CONCLUSIONS: HLA-DR7 and HLA-DRw53 are markers for susceptibility to rheumatic fever and rheumatic heart disease in Brazil. These results could be explained by genetic differences resulting from racial or geographical diversity.

Anticardiolipin antibodies in patients with rheumatoid arthritis.

Anticardiolipin antibodies (ACA) were assayed by ELISA in 73 patients with rheumatoid arthritis. Twelve (16.48%) patients showed levels of ACA three standard deviations above the value of the control group and were considered positive; these patients were compared to the group with ACA within the normal levels regarding the following clinical and laboratorial characteristics: spontaneous abortions, central nervous system involvement, systematization and activity of disease, alterations in platelet counts, presence of antinuclear antibodies and rheumatoid factor. Significant statistical association could be demonstrated between systematization and presence of antinuclear antibodies (ANA) and positiveness to ACA (IgG, IgM or both). These findings might indicate that ACA in patients with RA could have relevance to morbidity of disease or perhaps to its pathogenesis.