There was no difference when comparing the percentages of IFN-γ-producing PD-1+CD4+ T-cells in SLE patients with LN versus SLE patients without LN (36.1 ± 14.0% vs. 29.6 ± 16.2%; p = 0.20); likewise, no difference was found between SLE patients with LN and HC (36.1 ± 14.0% vs. 41.8 ± 14.3%; p = 0.40). Here, CD4 is linked to systemic lupus erythematosus.