ROLE OF PERIPHERAL CD8 LYMPHOCYTES AND SOLUBLE IL-2 RECEPTOR IN PREDICTING THE DURATION OF CORTICOSTEROID TREATMENT IN POLYMYALGIA-RHEUMATICA AND GIANT-CELL ARTERITIS

Objectives-To determine if the presence of low percentages of CD8 posi tive cells of high levels of soluble interleukin-2 receptors (sIL-2R) define a subgroup of patients with more severe polymyalgia rheumatica and giant cell arteritis (PMR/GCA). Methods-38 PMR/GCA patients were f ollowed up prospectively. Serum levels of sIL-2R and peripheral blood CD8 lymphocytes were measured before the start of corticosteroid treat ment, after six months of treatment and at the last visit. Phenotypica l analysis of lymphocyte subpopulations was performed with a two colou r technique, and assay of sIL-2R was performed using an enzyme-linked immunosorbent kit. Forty four healthy people matched for age and gende r comprised a healthy control group. Results-The median duration of fo llow up was 28 months (range 7-65). Corticosteroid treatment lasted a median of 23.5 months (7-65). Eleven patients (29%) were in remission at the end of follow up; 45% of the patients had at least one relapse or recurrence. Compared with controls, patients with active disease ha d a significantly lower percentage of CD8 cells and significantly incr eased sIL-2R levels. Erythrocyte sedimentation rate, C reactive protei n, and sIL-2R values were significantly less after six months of stero id treatment compared with before treatment. The percentage of CD8 cel ls remained significantly lower at six months and the end of follow up compared with controls, while sIL-2R levels remained significantly gr eater. Patients in whom the percentage of CD8 cells at six months was lower than one SD of the mean of normal controls (26%) had a significa ntly longer duration of corticosteroid treatment, a greater cumulative dose of prednisone and more relapses or recurrences compared with pat ients in whom the percentage was in the normal range. The duration of treatment and the cumulative dose of prednisone were not influenced by the percentage of CD8 cells before treatment therapy or by the levels of sIL-2R after six months of treatment. Conclusions-A reduced percen tage of CD8 cells after six months of treatment may be a useful outcom e parameter which would identify a group of PMR/GCA patients likely to experience more severe disease, defined as longer duration of cortico steroid treatment, higher cumulative dose of prednisone, and relapse o r recurrence of disease.