A strong negative correlation was found between the frequencies of NKG2D+CD4+ T cells and CD4+ T cells (R2 = 0.2832, P < 0.0001) in the PBMCs of SLE patients, but no correlation was found for the frequency of CD8+ T cells or CD19+ B cells (Fig. 2A). The gene discussed is KLRK1; the disease is systemic lupus erythematosus.