Tumor necrosis factor-alpha up-regulates expression of secretory component, the epithelial receptor for polymeric Ig.

Secretory component (SC) is the receptor that facilitates transcytosis of polymeric IgA and polymeric IgM through secretory epithelial cells and into exocrine fluids. The present study showed that rTNF-alpha enhanced the cellular pool, membrane expression, and secretion of functionally SC in a human colonic carcinoma cell line (HT-29m2) which is known to express and process SC like normal glandular cells. TNF-alpha also up-regulated membrane expression of the constitutive HLA class I molecules, whereas the cells remained HLA class II-negative.