Serum Soluble Interleukin-2 Receptor Alpha in Systemic Lupus Erythematosus

Introduction. This study aimed at determination of circulating soluble interleukin-2 receptor (IL-2 R) alpha in the sera of patients with systemic lupus erythematosus (SLE) and correlating the level of expression of these receptors with the SLE disease activity. Materials and Methods. The study included 55 patients with SLE and 20 healthy volunteers as controls. The following investigations were done: serum complement component 3, complement 4, erythrocyte sedimentation rate, complete blood count, serum creatinine, creatinine clearance, 24-hour urinary protein, urinalysis, and serum soluble IL-2R alpha level. Kidney biopsy was performed and examined with light microscopy for patients with lupus nephritis by a single pathologist blinded to the clinical activity of the disease. The results were analysed in relation to the clinical activity index of systemic lupus activity measure (SLAM). Results. The study showed that levels of soluble IL-2R alpha were significantly higher in the total group of patients with SLE compared to the controls (P < .001). Furthermore, serum IL-2R alpha levels were significantly higher in patients with lupus nephritis than those without nephritis. There were strong positive correlations between IL-2R alpha levels and the SLAM score, histological activity index, erythrocyte sedimentation rate, and 24-hour urinary protein excretion. Also, significant inverse correlations with complement 3 and packed cell volume was observed (r = 0.738; r = 0.669; r = 0.328; r = 0.705; r = -0.444; r = -0.420, respectively). Conclusions. Serum soluble IL-2R alpha is a reliable marker of disease activity in patients with SLE and could be used as an indicator of early renal involvement with the possibility of using it for follow-up.