A corneal cytokine triggers the in vivo synthesis of serum amyloid A by hepatocytes.

Recently a cytokine released by primary corneal epithelial cell cultures as well as by a rabbit corneal cell line (SIRC), corneal epithelial cell-derived thymocyte-activating factor (CETAF) has been described. The biological and biochemical properties of CETAF are similar to those of epidermal cell-derived factor (ETAF) and macrophage-derived interleukin 1 (IL 1). Like IL 1 or ETAF, SIRC supernatant, as well as partially purified CETAF (both molecular weight pools) significantly enhanced serum amyloid A production by hepatocytes, when injected intraperitoneally into C3H/HeJ mice. Therefore, corneal epithelial cells, by a nonspecific helper factor, CETAF, may exert immunoregulatory functions during chronic corneal inflammation.