Keratinocyte and lymphocyte apoptosis: relation to disease outcome in systemic lupus erythematosus patients with and without cutaneous manifestations

Our aim was to assess the relationship of keratinocyte and lymphocyte apoptosis and macrophage function to disease outcome in systemic lupus erythematosus patients with and without cutaneous manifestations. 50 systemic lupus erythematosus patients [25 with cutaneous manifestations (group I), 25 without cutaneous manifestations (group II)] and 20 normal controls (group III) were studied. Assessments of disease activity, peripheral lymphocyte apoptosis, macrophage function and apoptotic cells in skin and renal biopsies were carried out. The mean systemic lupus erythematosus disease activity index score was significantly higher in group I than II (18.6 +/- 6, 8.8 +/- 2.7 respectively, p < 0.001). The mean percentage of peripheral apoptotic lymphocytes was significantly higher in group I than groups II, III (55.3 +/- 21.4, 25.6 +/- 8.7 & 19.4 +/- 3.2 respectively, P < 0.001), so was serum neopterin level (27.5 +/- 7.3, 14.9 +/- 2.7, 9.4 +/- 1.1 respectively, p < 0.001), and the mean number of protein53 positive apoptotic keratinocytes in skin (20.6 +/- 5.4, 1.6 +/- 0.5, 1.7 +/- 0.4 respectively, p < 0.001). A higher percentage of class IV, V glomerulonephritis was found in group I (47%, 26%, respectively) compared to group II (11% both) (p < 0.001). The mean number of protein53 positive apoptotic skin keratinocytes showed a significant positive correlation to disease activity, percentage of peripheral apoptotic lymphocytes and serum neopterin (P < 0.001). In conclusion, an accumulation of apoptotic keratinocytes and lymphocytes in systemic lupus erythematosus with cutaneous manifestations is associated with a worse disease outcome.