Among the CD4+ T subsets, the frequency of NKG2D+CD4+ T cells was found to be negatively correlated with the frequency of Treg cells (R2 = 0.4975, P < 0.0001), but not with the frequency of Th1, Th2 or Th17 cells (Fig. 2A), suggesting that the aberrant expansion of NKG2D+CD4+ T cells correlates with a decrease in Treg cells and with CD4+ T cell frequencies in SLE patients. Here, CD4 is linked to systemic lupus erythematosus.