THE EFFECT OF RECOMBINANT TGF-ALPHA, HUMAN-MILK, AND HUMAN-MILK MACROPHAGE MEDIA ON GUT EPITHELIAL PROLIFERATION IS DECREASED IN THE PRESENCE OF A NEUTRALIZING TGF-ALPHA ANTIBODY

Objective: An in vitro model was devised to compare the relative effec ts of recombinant transforming growth factor-alpha (TGF alpha), aqueou s human milk, and human milk macrophage (HMM) medium on human fetal sm all intestinal cell (FHs-74) proliferation. Methods: Recombinant TGF a lpha at increasing concentrations (range 0.01-1,000 ng/ml media), the aqueous fraction of human milk (AHM), or HMM medium was added to FHs-7 4 cells in the presence or absence of a neutralizing TGF alpha antibod y (1 mu g/ml medium). At 24 h, cell proliferation was measured and exp ressed as percent control. The experimental variables were (1) activat ors of cell growth (TGF alpha, AHM, and HMM medium); (2) increasing co ncentrations of TGF alpha, and (3) neutralizing antibody to TGF alpha. The dependent variable for all experiments was cell proliferation. Re sults: Significant effects for growth stimulators and TGF alpha concen tration as measured by cell proliferation were found. Specifically, th ere was a dose-dependent effect of TGF alpha on cell proliferation to the 5-ng/ml concentration, with a plateau reached in cell proliferatio n at higher concentrations. The stimulatory effect of TGF alpha was de creased in the presence of TGF alpha antibody(mean +/- SD 22 +/- 7.1% decline, p < 0.001). In the presence of TGF alpha antibody, there was a 25 +/- 3.1% decline in HM-stimulated growth (p < 0.004), and a 27.6 +/- 3.2% decline in HMM medium-stimulated growth (p < 0.001). Conclusi ons: Neutralization of recombinant TGF alpha and that present in human milk and HMM medium by TGF alpha antibody led to a consistent decreas e in in vitro human fetal small intestine epithelial proliferation wit hout affecting cell viability. These results support the hypothesis th at TGF alpha, whether derived from human recombinant sources, human mi lk or HMM medium has a measurable; trophic effect on in vitro human gu t epithelial cells.