Increasing evidence suggests that there is a close interrelationship between the immune system and the hypothalamic-pituitary-adrenal axis. One way these systems are linked is through specific receptor proteins for glucocorticoid hormones in lymphocytes. We sought to determine whether the levels of these receptors differ in patients with rheumatoid arthritis (RA), compared with levels in healthy subjects.
We determined the density and affinity of lymphocyte glucocorticoid receptors, as well as basal cortisol levels, in 90 patients with active RA and in 200 healthy controls, using a whole cell binding assay.
The number of glucocorticoid receptors in RA patients was significantly lower than in controls (mean +/- SD 2,144 +/- 500 per cell versus 5,619 +/- 1,373 per cell; P less than 0.001), whereas there were no differences in binding affinity or cortisol levels. Glucocorticoid receptor density did not correlate with inflammatory disease activity.
Since glucocorticoids are potent immunosuppressive agents, the decrease in their receptors suggests an impairment of the immune-hypothalamic-pituitary-adrenal axis in patients with RA.