Radioimmunoassay for thymopoietin.

A radioimmunoassay for thymopoietin was developed that detects thymopoietin concentrations greater than 5 ng/ml. A critical point in development of the radioimmunossay was preparation of 125I-labeled thymopoietin by the Bolton-Hunter method, since direct iodination of tyrosyl residues impaired the immunoreactivity of thymopoietin.