Serum Cytokeratin-18 Fragments as Quantitative Marker of Epithelial Apoptosis in Liver and Intestinal Graft-Versus-Host Disease.

Graft-versus-host disease (GvHD) is the main complication of allogeneic stem cell transplantation (SCT). However, diagnosis and differentiation of GvHD from infectious or toxic clinical conditions as well as evaluation of GvHD response to immunosuppressive treatment remains a challenge. Since apoptosis is a common histopathological finding in GvHD, we investigated whether the caspase-cleaved neo-epitope of cytokeratin 18 fragments (CK18F) might be a serum marker for ongoing GvHD-induced target organ inflammation.

Longitudinal monitoring of serum CK18F kinetics by M30 antibody-based ELISA in 49 patients who fulfilled histopathological and/or clinical criteria diagnostic for GvHD following SCT showed that CK18F were highly elevated in hepatic and intestinal GvHD (6.3±3.8 fold and 4.6±0.8 fold, respectively, over baseline). Responses of GvHD to immunosuppressive therapy were paralleled by CK18F decreases. The extent of CK18F increases tended to correlate with serological severity of acute (r=0.96) and chronic (r=0.76) liver GvHD. Differentially relevant clinical conditions, such as non-complicated infection-related diarrhea and toxic hyperbilirubinemia were not associated with significant CK18F rises. In conclusion, CK18F monitoring provides a simple serum marker for quantitative assessment of GvHD-associated apoptotic activity in intestinal and hepatic GvHD and for distinguishing active GvHD from irreversible end organ damage. Prospective studies are warranted to demonstrate the significance of CK18F for diagnosis, differentiation, prognosis, and treatment guidance of GvHD.