Overview Thymulin (also known as FTS — facteur thymique sérique, or serum thymic factor) is a nonapeptide (9 amino acids; pyroglutamate-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn) produced by thymic epithelial cells (TECs) in the thymus gland. First isolated by Bach and colleagues in France in the 1970s…