Antirheumatic drugs, the ESR, and the hypohistidinemia of rheumatoid arthritis.

The longterm administration of prednisone and gold to patients with rheumatoid arthritis (RA), in doses that decreased the sedimentation rate (p less than 0.05), did not alter the serum histidine concentration (p greater than 0.5). In patients with RA receiving various combinations of aspirin, prednisone, and gold, the regression lines relating the serum histidine concentrations to the sedimentation rates had similar slopes but different elevations compared to patients receiving no anti-inflammatory drugs. In the patients receiving anti-inflammatory drugs, the regression lines were displaced so that in patients with similar serum histidine concentrations, the stronger the antirheumatic therapy, the less abnormal the sedimentation rate. These observations are consistent with the hypothesis that hypohistidinemia contributes to the pathogenesis of RA.