Increased levels of sCD23 in rheumatoid arthritis are related to disease status.

The low affinity receptor for IgE (Fc epsilon RII, CD23) is involved in many aspects of T and B cell regulation. In the current study, serum levels of sCD23 were measured in monozygotic (MZ) twins discordant for rheumatoid arthritis (RA) to examine whether an increased level of sCD23 in RA is, at least in part, genetically determined. Paired analysis showed significantly elevated sCD23 levels in affected twins when compared with their unaffected co-twins (p < 0.01). There was no significant difference in sCD23 in the unaffected twins compared with normal controls. Higher levels of sCD23 were found in males compared to females in both affected and unaffected twins. Soluble CD23 showed a significant increase with age in RA affected twins (p = 0.013), but no association with disease duration (p = 0.87). There was no significant variation in sCD23 level with HLA-DR phenotype. We conclude that elevations in serum sCD23 in patients with RA are primarily disease related.