ASSOCIATION OF COMPLEMENT C4 AND HLA-DR ALLELES WITH SYSTEMIC LUPUS-ERYTHEMATOSUS IN KOREANS

Objective. To examine the association of complement C4 and HLA-DR to s ystemic lupus erythematosus (SLE) susceptibility in Korea. Methods. Co mplement C4 protein typing was carried out by immunofixation and immun oblotting methods using EDTA-plasma from 60 patients with SLE and 72 h ealthy controls. Restriction fragment length polymorphism analysis of C4 genes was also carried out using TaqI or HindIII for restriction en zymes. HLA-DR was determined by polymerase chain reaction amplificatio n with sequence specific primers using genomic DNA from 67 patients wi th SLE and 72 healthy controls. Results. The frequency of the C4AQ0 al lele was significantly higher in the patients with SLE than in control s (41.7 vs 25.0%, p < 0.05). The deletion of the C4A gene commonly fou nd in Caucasian patients with SLE was not observed in any patients. Fo r HLA-DR, a significant increase of the haplotype DRB1()1501-DRB5(*)0 101 was observed in the patients (26.9 vs 12.5%, p < 0.05) and DR9 was also significantly increased (23.9 vs 11.1%, p < 0.05). An increase i n each DR2 and DR9 was independent of an increase in C4AQ0. The freque ncies of DR2 and DR9 were significantly decreased in patients with ren al involvement and alopecia, respectively. Conclusion. Our data sugges ted that the presence of C4AQ0 allele, DRB1()1501-DRB5(*)0101 haploty pe and DR9 contributed to susceptibility to SLE in Koreans and that Ko rean SLE is based on a different genetic background from Caucasian pat ients.