C4A and systemic lupus erythematosus: Sirolimus/rapamycin decreased the number of Th17 cells and Th17/Treg ratio (35), increased the number of CD4 Treg, decreased IL-4 and IL-17 levels, and increased C3 and C4 complement levels (34) along with reduction of disease activity (Systemic Lupus Erythematosus Disease Activity Index [SLEDAI]) and use of prednisone (34, 35).