Endotoxin Contamination in Isolation of Lamina Propria Mononuclear Cells.

Because the beginning of extraction of lamina propria mononuclear cells is to obtain mucosal tissues that are exposed to luminal bacteria, the contaminated endotoxin in this step and/or the enzymes for mucosal digestion may activate mucosal macrophages and other cells. To address this issue, endotoxin levels in isolation solutions were evaluated during the extraction of lamina propria mononuclear cells from 8 control, 7 Crohn's disease and 8 ulcerative colitis specimens. Endotoxin levels were measured using Toxicolor system based on the limulus tests. Endotoxin levels were consistently below 500 pg/ml, and more importantly, these in enzyme digestion solutions were comparable among control, Crohn's disease, and ulcerative colitis. Therefore, comparative experiments using lamina propria mononuclear cells from these mucosae can be appropriately carried out, at least as far as in a comparable amount of contaminated endotoxin. However, careful consideration is required for the comparative and functional study using peripheral blood and lamina propria mononuclear cells.