Rheumatoid factor expression and complement activation in children congenitally infected with human immunodeficiency virus

Rheumatic disease manifestations and autoimmune phenomena are common in adults infected with human immunodeficiency virus (HIV). On the other hand, rheumatic disease manifestations are rare in children congenitally infected with HIV. We studied the relationship between autoimmune phenomena and rheumatic diseases by examining HIV-infected children for the presence of rheumatoid factors (RFs), immune complexes, and complement activation fragments. RFs (principally IgA) were detected in 12 of the 24 HIV-infected patients (50%) and in none of the uninfected (HIV-exposed, seroreverted) controls (n = 22). Mean levels of complement activation fragments C3a and Bb were elevated in the HIV-infected children compared with the controls. A correlation was seen between the presence of IgA RF and alternative complement pathway activation as measured by plasma levels of Bb. None of the children had clinical or laboratory evidence of rheumatic disease.

IgM rheumatoid factor and the inhibition of covalent binding of C4b to IgG in immune complexes

Work by other investigators has shown that IgM-rheumatoid factors (IgM-RF's) can impede complement-mediated inhibition of immune precipitation. We examined the binding of complement component C4b to radiolabelled IgG in model immune complexes and demonstrate that IgM-RF's are capable of reducing the covalent binding of C4b to 125I-IgG in the complexes. Reduced binding to IgG, however, may not be accompanied by binding of C4b to IgM-RF's within the complex, as we also demonstrate that IgM-RF's are relatively poor at C4b capture compared with normal IgM.

Complement activation and immune complexes in juvenile rheumatoid arthritis

We investigated the potential role of the complement system in juvenile rheumatoid arthritis (JRA) by examining plasma for levels of complement activation fragments C4d and Bb. We correlated findings with both disease activity and laboratory abnormalities, including immune complex (IC) levels. While there was a strong correlation between active disease and both C4d and Bb plasma levels in JRA, no strong correlations could be made between IC levels and complement activation products; weak associations were seen between complement activation fragments and erythrocyte sedimentation rate. Our data suggest that plasma complement activation is a concomitant of active disease in JRA; however, its role in the pathophysiology of JRA remains uncertain.

Detection of IgM rheumatoid factors by enzyme-linked immunosorbent assay in children with juvenile rheumatoid arthritis: correlation with articular disease and laboratory abnormalities

This study was undertaken to determine the clinical relevance of IgM rheumatoid factors (RFs) detected by enzyme-linked immunosorbent assay (ELISA) in children with juvenile rheumatoid arthritis (JRA) by examining their association with severity of acute articular disease. ELISAs for IgM-RF were performed on serum specimens from 65 children with JRA. Activity of articular disease was estimated by an arbitrary scoring system. Significant differences were seen in articular disease activity between the group of children with polyarticular disease who were IgM-RF-positive by ELISA compared with those who were IgM-RF-negative (P = .0003). When a small group of individual children with polyarticular disease were followed longitudinally, similar correlations were found between severity of acute disease and the presence of IgM-RFs detected by ELISA. In children with pauciarticular JRA, expression of IgM-RFs appeared to be a transient phenomenon with no correlation with either articular disease or laboratory abnormalities.

Increase in CD5+ B Cells in Juvenile Rheumatoid Arthritis

OBJECTIVE

To investigate the association between CD5+ B cell expression and IgM rheumatoid factor (IgM-RF) in juvenile rheumatoid arthritis (JRA).

METHODS

CD5+ B cell levels analyzed by flow cytometry and IgM-RF expression determined by enzyme-linked immunosorbent assay were compared in children with JRA, children with other collagen vascular diseases, and healthy controls.

RESULTS

Children with polyarticular JRA had expanded populations of CD5+ B cells, and expansion of CD5+ B cells and IgM-RF both correlated with disease activity.

CONCLUSION

The results indicate that an expanded CD5+ B cell population leads to IgM-RF production in patients with polyarticular JRA, as well as patients with RA.