ULTRASTRUCTURAL IMMUNOGOLD LOCALIZATION OF SUBCELLULAR SITES OF TNF-ALPHA IN COLONIC CROHNS-DISEASE

Tumor necrosis factor-alpha, a proinflammatory cytokine, might have an important role(s) in initiating, modifying, and/or sustaining chronic inflammatory processes such as those that characterize Crohn's diseas e, an inflammatory bowel disease of unknown etiology. We used an immun ogold ultrastructural morphometric approach to localize tumor necrosis factor-alpha in colonic Crohn's disease biopsies. Tumor necrosis fact or-alpha was present in seven cell types (fibroblasts, eosinophils, ma st cells, macrophages, colonic epithelial absorptive cells, Paneth cel ls, neutrophils). Tumor necrosis factor-alpha-containing subcellular o rganelles included lipid bodies (fibroblasts, eosinophils, macrophages , mast cells, colonic epithelial cells, neutrophils), secretory granul es (eosinophils, Paneth cells), phagolysosomes (macrophages, colonic e pithelial cells), and Golgi structures and vesicle membranes (neutroph ils). A gradient of extracellular tumor necrosis factor-alpha immunore activity surrounded eosinophils, mast cells, and macrophages. P values of gold counts/mu m(2) were significant for all cells, organelles, an d extracellular spaces measured, and all positive structures significa ntly exceeded the background labeling density/mu 2 Specificity control s (normal rabbit serum, tumor necrosis factor-alpha-absorbed primary a ntibody) either failed to label these sites or gave markedly reduced s pecific tumor necrosis factor-alpha labeling, respectively. These find ings represent the first ultrastructural localization of the subcellul ar sites of TNF-alpha in vivo in seven cell lineages in human colonic tissues.