Interleukin-2 receptor expression in peripheral blood lymphocytes from systemic lupus erythematosus patients: relationship to clinical activity.

Deficient interleukin-2 (IL-2) production and other T-cell dysfunctions have been demonstrated in active systemic lupus erythematosus (SLE). The generation of IL-2 receptors is known to be important to the growth and differentiation of T and B lymphocytes. This study investigated IL-2 receptor expression in peripheral blood lymphocytes (PBL) from patients with active and inactive SLE. PBL from 27 SLE patients, diagnosed by revised ARA criteria, were assayed for IL-2 receptor expression, IL-2 and immunoglobulin (Ig) production. PBL from SLE patients with active disease spontaneously expressed increased numbers of IL-2 receptors compared to those with inactive disease (P less than 0.01) and normal donors (P less than 0.01). There was no significant increase in IL-2 receptors expression in PBL from active SLE patients in response to mitogenic stimulation with PHA compared to inactive SLE patients and normal donors. There was negligible IL-2 production in response to mitogenic stimulation and increased spontaneous IgG production by PBL from active SLE patients compared to normal donors (P less than 0.001). Purified B cells isolated from active SLE patients showed significant spontaneous IL-2 receptor expression when compared to spontaneous IL-2 receptor expression by normal B cells (P = 0.005). Therefore, in addition to derangements in Ig and IL-2 production, the level of spontaneous expression of IL-2 receptors may represent a cellular indicator of disease activity, and hence, may be a useful parameter in monitoring disease activity in SLE patients. The significance of the increased IL-2 receptor expression on B cells of active SLE patients is unknown, but may represent a marker of polyclonal activation of these cells.