Transforming growth factor in lacrimal gland tissue

After the demonstration of the epidermal growth factor (EGF) in lacrimal gland tissue the author investigated lacrimal gland tissue for TGF-alpha. This growth factor has structural similarities to EGF, binds to the same receptor and has also wound healing promoting effects. Stained with specific antibodies 30 specimens of bovine lacrimal glands were investigated immunohistochemically for the presence of TGF-alpha. In all sections TGF-alpha was detected in the acini. Here it was located in the lacrimocytes in a pattern that resembles the localization of the secretory granules. This gives strong evidence that also TGF-alpha is, like suggested for EGF, produced and secreted by the lacrimal gland. This implies the possibility that also TGF-a is present in tear fluid, an initial result that is strongly supported by recent studies. It is concluded that the current models on the effect of EGF on the ocular surface should also consider the simultaneous presence of TGF-a. The possibility that both growth factors are simultaneously present in tear fluid and bind to the same receptor has direct clinical relevance.