Presence of epidermal growth factor in human tears.

Epidermal growth factor (EGF) is a polypeptide that stimulates the growth of various tissues, including the cornea. The presence of EGF in tears from normal volunteers and in aqueous humor from cataract patients was investigated via human EGF (hEGF)-specific radioimmunoassay. Immunoreactive hEGF was found to be present at similar concentrations in both reflex (ranging from 0.7 to 8.1 ng/ml) and non-reflex tears (ranging from 1.9 to 9.7 ng/ml), but was undetectable in aqueous humor. Immunoreactive EGF in human tears was indistinguishable immunologically, biologically and biochemically from urine EGF and standard hEGF.