Moreover, urinary mRNA levels of the CXCR3 ligand CXCL10 and CXCR3+ CD4+ T cells in the urine were suggested as non-invasive tools for monitoring the activity in lupus nephritis and might therefore provide a new biomarker for acute nephritis flares in systemic lupus erythematosus patients (Enghard et al. 2009). Here, CD4 is linked to systemic lupus erythematosus.