Association of HLA-DR with susceptibility to and clinical expression of rheumatoid arthritis: re-evaluation by means of genomic tissue typing.

The clinical expression of rheumatoid arthritis (RA) varies considerably among individual patients. Genetic variations in human leucocyte antigen (HLA) may influence clinical expression. We re-examined the association of HLA-DR with susceptibility to and clinical expression of RA using genomic tissue typing, since most studies were based on (less reliable) serological techniques. Seventy-eight patients with recent-onset RA, all participating in a clinical trial on therapeutic strategies, were HLA-DR typed by means of low-resolution genomic typing. Cumulative disease activity within the first 3 yr of disease was measured. Of the RA patients, 54% expressed DR4 (DR4+) vs 26% of healthy controls. Rheumatoid factor (RF)-positive patients had a higher cumulative disease activity than RF-negative patients. Patients who were either DR1+ or DR4+ had a higher cumulative disease activity than those who expressed neither DR1 nor DR4. This association was less obvious after correction for RF status. The association of DR52+ (DR3, 5, 6) and a lower cumulative disease activity could also not be demonstrated after correction for RF status. Among RF-negative patients, DR51+ (or DR2+) was associated with a higher cumulative disease activity. Other HLA-DR types (including DR1 and DR4 separately) were not associated with the severity of RA. DR4 was associated with susceptibility to RA in our patients; HLA-DR low-resolution genomic tissue typing did not yield additional information to RF status for the clinical identification of individual patients with a poor prognosis.