Interleukin 2 augementation of the defective natural killer cell activity in patients with primary Sjogren's syndrome

Natural Killer (NK) cell activity against K562 target cells was measured in 21 female patients with primary Sjogren's syndrome (primary SS) and in 20 female normal controls matched for age. The in vitro effect of α-interferon (IF) and interleukin 2 (IL-2) on NK cell activity was examined and the percentage of large granular lymphocytes (LGL) in blood was measured. Median baseline NK cell activity in primary SS was 15.4% versus 24.4% in the controls (P<0.05). Median IF-enhanced NK cell activity in the SS group was 35.5% versus 49.6% in the controls (P<0.02). IL-2-enhanced NK cell activity was 35.5% versus 37.6% in the controls (n.s.). The proportion of LGL did not differ in the two groups. Median LGL/lymphocytes was 4.0% in the primary SS patients versus 4.5% in the controls (n.s.). We conclude that the defective NK cell activity in patients with primary SS is functional, as the number of LGL is normal. Further the NK cell activity of SS was restored by IL-2.