Interferon-gamma enhances expression of secretory component, the epithelial receptor for polymeric immunoglobulins.

Recombinant interferon-gamma (IFN-gamma) increased in a dose-dependent manner the intracellular pool, the membrane expression, and the shedding of secretory component (SC) in human colonic adenocarcinoma cell line (HT-29). A similar dose-response relationship was observed when we examined the binding of polymeric IgA to HT-29 cells treated with IFN-gamma, thus reflecting expression of functional SC. Because IFN-gamma is produced by T cells during immune responses, activated T cells may be able to promote the external transport of dimeric IgA and pentameric IgM and thereby enhance the efferent limb of the secretory immune system. This is, therefore, the first observation indicating how the secretory transport capacity may be adjusted to increased local immunoglobulin production.