CD4 and systemic lupus erythematosus: Indeed, in other autoimmune diseases, and prevalently in SLE, the role of autophagy in T lymphocytes has been extensively studied: atg5−/− CD8+ T lymphocytes displayed increased cell death, and atg5−/− CD4+ and CD8+ T cells demonstrated deficient proliferation after T cell receptor stimulation [15]; atg7-deficient T lymphocytes had increased cell death and also showed expanded mitochondria, expanded ER content, and altered calcium flux [33].