Isolation and purification of a small peptide with activity of increasing E-receptor expression from calf thymus.

A small peptide of molecular mass lower than 1,000 daltons was isolated and purified from a crude extract of calf thymus. It has been demonstrated to have the activity of increasing E-rosette formation and E-receptor expression of human and porcine T-lymphocytes with three different in vitro assays. Amino acid composition analysis showed that this peptide consists of glutamic acid, aspartic acid and glycine residues at a molecular ratio of 3:3:2. A hypothesis of a multi-factoral and multi-staged mechanism of regulation of thymocyte differentiation and maturation in the thymus is proposed.