CD4 and systemic lupus erythematosus: In CD4+ T cell subsets, the percentages of CD4+Tn MMP-Low (P < 0.001), CD4+Tem MMP-Low (P = 0.002), and CD4+ Tcm MMP-Low (P < 0.001) were significantly lower in patients with SLE than in HCs (Figure 2A).