Enzyme immunoassay measurement of thymosin beta 4 in human serum.

An enzyme immunoassay (EIA) for measurement of human serum thymosin beta 4 is described. Antiserum to synthetic thymosin beta 4, raised in rabbits, is incubated with a standard or serum. The unbound antibody in liquid-phase then binds with solid-phase thymosin beta 4. The EIA is both sensitive and accurate and is capable of detecting as little as 2.5 ng/ml thymosin beta 4 in serum. No cross-reactivity was observed with common serum proteins or other putative thymic hormones. High-performance liquid chromatography of serum samples reveals a single thymosin beta 4 peak that corresponds to the authentic thymosin beta 4 peak in the standard. Human serum levels range from 3 to 82 ng/ml in 142 healthy adult human volunteers. Newborn cord serum levels of thymosin beta 4 are lower than in adults.