Homologous radioimmunoassay for epidermal growth factor in human saliva.

Epidermal growth factor (EGF) is a small polypeptide with potent mitogenic activity. Its synthesis by mouse submaxillary gland is stimulated by certain hormones. To assess its physiological significance in man, we have developed a homologous radioimmunoassay for human epidermal growth factor (hEGF) in saliva. A satisfactory standard curve was readily obtained using either buffer or peptide-free saliva. The mean IC50 was 436 +/- 200 pM (mean +/- SD) and sensitivity approximately 35 pM. The mean normal salivary hEGF in 63 males was 314.6 +/- 21.7 pM (+/- SEM) and 354 +/- 27.8 pM in 48 females. The difference between the means of the sexes was not significant. Assays of aliquots stored under different conditions showed hEGF in saliva to be stable and the method reproducible. Salivary hEGF secretion did not suggest diurnal rhythmicity and was unrelated to meals.