Provided are compositions, including isolated, synthetic or recombinant peptides for: expanding regulatory T cells (Treg) populations for treating or ameliorating a vascular inflammation, and Kawasaki disease (KD) or a pediatric acute vasculitis of the coronary arteries, including vascular coronary abnormalities, and acute or chronic vascular inflammatory abnormalities, and methods for making and using them. Provided are immunotherapies for promoting expansion of natural, Treg to establish, or re-establish, vascular homeostasis or, for ameliorating: a disease or condition associated with an autoimmune disease or condition an immune-mediated vascular disorder a disease or condition treated with intravenous immunoglobulin (IVIG) therapy a vascular coronary abnormality an acute or a chronic vasculitis an autoimmune inflammatory vasculitis a T cell mediated pediatric vasculitis Kawasaki disease (KD) or a pediatric acute vasculitis of the coronary arteries atherosclerosis preventing miscarriage in autoimmune women rheumatoid arthritis or Juvenile Idiopathic Arthritis a neoplastic hematological disorder, or a leukemia.
