Mannose-binding lectin and rheumatoid arthritis in southern Chinese

Objective. Insufficiency of mannose-binding lectin (MBL) is associated with recurrent infections. Rheumatoid arthritis (RA) may represent an aberrant immune response to infections. This study examined the phenotypic expressio n and variant alleles of the MBL gene and its etiologic role in Chinese wit h RA. Methods. We studied 211 RA patients and 196 healthy subjects. Serum MBL con centrations and codon-54 mutation of the MBL gene and its promoter polymorp hisms were analyzed. Clinical characteristics and disease activity were als o examined. Results. Patients with RA had significantly lower serum MBL levels and high er frequency of codon-54 mutation of the MBL gene compared with controls. A dditionally, there was a significant difference in the distribution of prom oter polymorphisms, H/L, between RA patients and controls, although the fre quencies of Y/X and those of nonstructural polymorphisms, P/Q, did not diff er between the 2 groups. Furthermore, patients with RA had a lower incidenc e of the highest-producing haplotype HY and a higher incidence of the lowes t-producing haplotype LX compared with controls. Serum MBL levels did not c orrelate with drug treatment or with disease activity. However, patients wi th erosive and serious extraarticular disease had significantly lower serum MBL levels than those without these disease manifestations at the time of study. Also, significantly more patients with erosive disease had a codon-5 4 mutation of the MBL gene compared with those with nonerosive disease. Conclusion. The codon-54 mutation and low-producing promoter polymorphisms of the MBL gene are associated with RA. A low serum level of MBL predispose s to the development of RA and is a risk factor for severe disease in south ern Chinese.