Lymphocyte sub-population counts after a single 40 mg administration of piroxicam in 20 patients with rheumatoid arthritis

Abstract

Patients with active rheumatoid arthritis are characterized by a decrease in the number of circulating T-suppressor lymphocytes (identified by OKT₈), resulting in an imbalance between helper (identified by OKT₄) and suppressor cells. Piroxicam is a non-steroidal anti-inflammatory agent which modulates lymphocytic functions, especially by reducing the concentration of the rheumatoid factor in vitro and in vivo. A double-blind placebo-controlled study was performed in 20 patients suffering from active RA to investigate the acute effect of a single administration of piroxicam 40 mg on the number of circulating OKT₃, T₄, T₈ and Ia₁ positive cells. Blood samples were obtained 16 hours before and 0,2,6, 8, 24, 48, and 72 h after administration of piroxicam or placebo. There was a significant decreaseP< 0.05) in T₄/T₈ cell ratio 48 and 72 h after piroxicam, whereas placebo had no effect. There were no significant changes in absolute numbers of total T-lymphocyte (OKT₃ positive cells), T-helper-inducer (OKT₄ positive cells) and T-suppressor cytotoxic lymphocytes (OKT₈ positive cells). The number of IA₁ positive cells (B-cells and activated T-lymphocytes) was significantly higher in the afternoon samples (at 14.00 and 16.00 hours) than in the morning samples (at 08.00 and 10.00 hours) after both placebo and piroxicam administrationP<0.05). These data show that piroxicam decreases the T₄/T₈ cell ratio in active RA, but only 48 h after the first administration. These results contrast with those previously obtained after low doses of prednisolone(5- and 10mg) which induced a decrease inthe T₄/T₈ ratio as early as 6 h after intake, but which was no longer apparent after 24 h. Furthermore, these results demonstrate a diurnal rhythm for the number of IA₁ positive lymphocytes.