ICOS and systemic lupus erythematosus: Interestingly, comparing the advantage of prednisone treatment of SLE patients and prednisone+IL-2 treatment of SLE patients, it was found that 36.36% patients had a reduced proportion of Treg cells upon prednisone treatment, and prednisone treatment downregulated the Foxp3 expression in CD4+ T cells and the expression of CD39, ICOS, Bcl-2, and STAT5 in CD4+Foxp3+Treg cells (149).