Size heterogeneity of epidermal growth factor in human body fluids

We measured the concentration of immunoreactive (IR) hEGF in various body fluids by radioimmunoassay (RIA) and evaluated its size heterogeneity by size exclusion high performance liquid chromatography combined with RIA or with time-resolved immunoflurometric assay (TR-IFMA). Mean concentration was 80 ng/ml in urine, 65 ng/ml in milk, 50 ng/ml in seminal plasma, 25 ng/ml in armpit sweat, 1 ng/ml in breast sweat, 0.3 ng/ml in third-trimester amniotic fluid, 3 ng/ml in saliva, 1.5 ng/ml in tears and 0.3 ng/ml in gastric juice.

All the fluids except armpit sweat and gastric juice contained two to five molecular sizes of IR-hEGF. As well as the 6200-dalton (6.2kDa) hEGF we found at least four other different molecular sizes with approximate weights of 300, 150, 70 and 20kDa. The authentic 6.2kDa form made up >90% of the total IR-hEGF in all except the amniotic fluid where its proportion was 71%, and the seminal plasma where the proportion could not be determined.