The first study used a dose of 0.5 million IU/day for SLE patients with infection (5-day course), revealing that low-dose IL-2 treatment upregulated the number of total T cells, B cells, CD4+ T cells, CD8+ T cells, Th1, Th17, and Treg cells, which were similar to those in healthy controls (155). Here, CD4 is linked to systemic lupus erythematosus.