CD4 and systemic lupus erythematosus: At sacrifice, the frequency of CD44+ cells was reduced in both CD4+ and CD8+ T lymphocyte populations in the spleen and LN of mice treated with SOCS1-KIR, while the frequency of CD44+ cells in CD4− CD8− double negative T cells (often associated with SLE and ALPS progression) was reduced only in lymph nodes (Fig. 3C).