Epidermal growth factor regulation of DNA synthesis in human colonic lamina propria lymphocytes

Epidermal growth factor (EGF) is a potent growth factor for many tissues including the gastrointestinal tract. EGF is present in the gut lumen and is absorbed through the mucosa in the developing animals. In addition, EGF has been found to alter the immune system. In this study, we investigated the in vitro effect of EGF on normal colonic lamina propria lymphocyte DNA synthesis and ornithine decarboxylase activity. Human colonic lamina propria lymphocytes were isolated by collagenase-EDTA digestion. The effect of EGF on Con A-stimulated lymphocyte thymidine incorporation was tested. We observed that EGF suppressed DNA synthesis and ornithine decarboxylase (ODC) activity in lamina propria lymphocytes. EGF did not alter the time course of thymidine incorporation into LPL stimulated by the combination of phorbol 12,13-dibutyrate (PDB) and ionomycin. Our data suggest that (1) EGF suppresses DNA synthesis in human colonic lamina propria lymphocytes as well as ODC activity and (2) this inhibition may be mediated through protein kinase C or calcium flux. We postulate that EGF may have a role in modulating the human gut immune system.