CD4 and systemic lupus erythematosus: Hematologic examination revealed significant lymphocytopenia, which is often observed in patients with SLE; this was particularly prominent in HOIL-1LΔRING1/ΔRING1 mice, though neutrophil counts and the T/B and CD4+/CD8+ T lymphocyte ratios were the same (Figure 3C and Supplemental Figure 3, A–C).