CD44v3 and CD44v6 isoforms on T cells are able to discriminate different disease activity degrees and phenotypes in systemic lupus erythematosus patients

Background Adhesion molecule CD44 contributes to T cell migration into target organs. A higher expression of CD44v3 and v6 isoforms has been identified on T cells from systemic lupus erythematosus (SLE) patients. The aim of this study was to investigate the expression of CD44v3/v6 on T cells of SLE patients in order to evaluate their correlation with clinical features. Methods Sixteen healthy subjects (HSs) and 33 SLE female patients were enrolled. Fifteen patients were in remission (Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) = 0) and 18 patients had an active disease (SLEDAI-2K >= 4). Experiments were conducted by flow cytometry. Results Expression of CD44v3 on CD4(+) and CD8(+) T cells was higher in active patients compared to HSs (p = 0.0097 and p = 0.0096). CD44v3 on CD8(+) T cells was also higher in active patients compared to patients in remission (p = 0.038). CD44v6 was higher on CD4(+) and CD8(+) T cells from active patients compared to HSs (p = 0.003 and p = 0.0036) and to patients in remission (p = 0.01 and p = 0.02). In active patients the ratio CD44v3/v6 was unbalanced towards isoform v6 on both T cell populations. In a receiver operating characteristic curve analysis, CD44v6 on CD4(+) T cells was the most sensitive and specific one (specificity of 81.8%, sensitivity of 75%). Expression of CD44v6 on CD4(+) and CD8(+) T cells correlated with the SLEDAI-2K (p = 0.03, r = 0.38 and p = 0.02, r = 0.39). CD44v6 and CD44v3 on CD8(+) T cells associated with nephritis and arthritis (p = 0.047 and p = 0.023). Conclusions CD44v3/v6 can be used as biomarkers of disease activity and phenotypes; isoform v6 on CD4(+) T cells can be useful as a diagnostic biomarker.