Jl. Nelson et al., RHEUMATOID-FACTOR, HLA-DR4, AND ALLELIC VARIANTS OF DRB1 IN WOMEN WITH RECENT-ONSET RHEUMATOID-ARTHRITIS, Arthritis and rheumatism, 37(5), 1994, pp. 673-680
Objective. To examine the relationship of rheumatoid factor (RF) to HL
A-DR4 and alleles of DRB1 in women with recent-onset rheumatoid arthri
tis (RA). Methods. Incident cases of RA were identified as part of a p
rospective, population-based case-control study. HLA typing was comple
ted for 246 cases meeting criteria for definite or classic RA. Results
. One hundred thirty-six patients (55%) were positive for DR4, and 130
(53%) were RF positive. DR4 was found to be strongly associated with
seropositivity (odds ratio 4.1, P < 0.0001). Patients with a shorter i
nterval from RA onset to RF testing had a higher frequency of seroposi
tivity than those with a longer interval (less than or equal to 18 mon
ths 60%, >18 months 33%). Further analysis of patients who had RF test
ing within 18 months of RA onset showed that the frequency of seroposi
tivity was significantly greater among DR4-positive patients who had t
he shared sequence stretch of DR beta 1 associated with RA susceptibil
ity (76% RF positive) than among DR1-positive patients who had this se
quence (45% RF positive) (odds ratio 3.8, P = 0.01). Moreover, the fre
quency of seropositivity among DR1-positive patients with the sequence
did not differ from that among all patients without the shared sequen
ce (47%) (odds ratio 0.9, P = 0.8). Conclusion. HLA-DR4 is strongly as
sociated with seropositivity in women with recent-onset RA. The amino
acid sequence of DR beta 1 that is associated with susceptibility to R
A and is shared between DR4 and DR1 appears not to be the primary dete
rminant of seropositivity in these women.