CD134 expression on CD4 + T cells is associated with nephritis and disease activity in patients with systemic lupus erythematosus

Summary Systemic lupus erythematosus (SLE) is characterized by a deviation of the immune system that involves T cell‐dependent autoantibody production. The aim of this study was to investigate the role of co‐stimulatory markers on T cells in this disease. Twenty‐eight patients with SLE as defined by the American College of Rheumatology (ACR) criteria and 11 healthy controls were included into the study. Eleven patients had biopsy‐proven lupus nephritis while 17 patients had no clinical evidence of lupus nephritis. Clinical disease activity was assessed according to the systemic lupus erythematosus disease index (SLEDAI). CD4 + T cell populations in the peripheral blood were analysed for the expression of co‐stimulatory markers CD45RO, CD70, CD80, CD86, CD137, CD137L, CD134, CD152, CD154 and ICOS. SLE patients showed an increased frequency of peripheral CD4 + T cells expressing high levels of CD80, CD86 and CD134 compared to healthy controls (7·1 ± 1·5% versus 1·7 ± 0·9%; P  < 0·005; 2·3 ± 0·4% versus 1·0 ± 0·2%; P  = 0·008, 20·2 ± 2·0% versus 10·6 ± 1·9%; P  < 0·005, respectively). Significantly higher levels of CD80 on CD4 + T cells were detected in SLE patients with lupus nephritis compared to patients without nephritis (11·9 ± 3·3% versus 4·0 ± 0·7%; P  < 0·005). There was an increased presence of CD134 + CD4 + cells in SLE patients with lupus nephritis (27·5 ± 4·0% versus 15·5 ± 1·3%; P  < 0·005). CD80 and CD134 expression was significantly correlated with SLEDAI ( r  = 0·42, P  = 0·03; r  = 0·56, P  < 0·005). Co‐stimulatory molecules on CD4 + T cells are associated with renal disease and disease activity in patients with systemic lupus erythematosus.