Induction of autoimmune disease in BALB/c mice by administration of anti–CTLA-4 Ab with or without anti-CD25 Ab. Samples were stained with hematoxylin and eosin (original magnification: ×25). Immunologic self-tolerance maintained by CD25(+)CD4(+) regulatory T cells constitutively expressing cytotoxic T lymphocyte-associated antigen 4: Takahashi T, Tagami T, Yamazaki S, Uede T, Shimizu J, Sakaguchi N, Mak TW, Sakaguchi S - The Journal of experimental medicine (2000). Not altered. CC.