Cow's milk protein induced changes in the expression of HLA-DR antigens on colonic epithelial cells.
BACKGROUND
Normal colonic epithelial cells do not express HLA-DR antigens unless they become inflamed. It is possible that colonic epithelial cells may function as antigen-presenting cells once HLA-DR is induced by infection or inflammation.


OBJECTIVE
The aim of this study was to investigate whether cow's milk protein (CMP) is capable of inducing changes in HLA-DR expression on colonic epithelial cells, providing indirect evidence that CMP may activate cell-mediated immune mechanisms within intestinal mucosa.


METHODS
HLA-DR expression was evaluated by flow cytometry on cultured human colonic epithelial cell line (HT-29) before and after treatment with bacterial lipopolysaccharide (LPS) or recombinant gamma interferon (IFN-gamma). Untreated and LPS- or IFN-gamma-treated HT-29 cells were then cultured in the presence of CMP. The changes in epithelial HLA-DR expression induced by CMP on untreated and LPS- or IFN-gamma-treated HT-29 cells were examined.


RESULTS
Untreated HT-29 cells expressed very little HLA-DR molecule. Bacterial LPS or IFN-gamma induced a significant HLA-DR expression on HT-29 cells. When untreated HT-29 cells were cultured in the presence of CMP, there was little induction of HLA-DR expression. Culture of LPS- or IFN-gamma-treated HT-29 cells in the presence of CMP induced a significant increase in HLA-DR expression, which was much greater than on HT-29 cells treated with bacterial LPS or IFN-gamma only.


CONCLUSIONS
Our results suggest that CMP initiates an immune response in the intestinal mucosa and may be responsible for the activation of cell-mediated immunity after enteric infection or inflammation.
Chung
Hai Lee
HL
Department of Pediatrics, School of Medicine, Catholic University of Taegu, Taegu, Korea. hlchung@cataegu.ac.kr
Lee
Jeong Jin
JJ
Kim
Sang Gyung
SG
D002460:Cell Line; D003106:Colon / Q000166:cytology*; D004357:Drug Synergism; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology; D006684:HLA-DR Antigens / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008894:Milk Proteins / Q000494:pharmacology*
D006684:HLA-DR Antigens; D008070:Lipopolysaccharides; D008894:Milk Proteins; D007371:Interferon-gamma