Soluble MHC class I chain-related protein A is a specific biomarker for the early detection of graft-versus-host disease.

INTRODUCTION: MHC class I chain-related protein A (MICA) acts as a marker of cellular stress and its expression is a destruction-signal for NKG2D-expressing cytotoxic cells. Soluble MICA (sMICA) concentrations after allogeneic hematopoietic stem cell transplantation (HSCT) were associated with worse outcomes and graft-versus-host disease (GVHD). We hypothesized that (i) sMICA could be a prognostic biomarker for the development of GVHD and (ii) may act as an acute phase reactant. METHODS: In this prospective study we included 48 patients undergoing HSCT and drew blood samples before conditioning (baseline), during engraftment and 100 days after HSCT. The follow-up period was 1 year for each patient. Soluble MICA and established acute phase reactants (C-reactive Protein, von Willebrand Factor) were measured by enzyme-linked immunoassay (ELISA). RESULTS: Of the 44 patients in the final analysis, 30 (68%) developed GVHD (16 acute GVHD, 8 chronic GVHD, 6 acute and chronic GVHD). Soluble MICA concentrations at baseline and during engraftment were significantly higher in patients who developed acute or chronic GVHD (p = 0.017). Receiver operating characteristic (ROC) curve analysis for the baseline values showed an area under the curve of 0.78 (p < 0.001; 95% confidence intervals 0.64-0.91) for diagnosis of acute or chronic GVHD. Soluble MICA concentrations above 93.5 pg/mL had a specificity of 93% for the diagnosis of GVHD, while the sensitivity was only 47%. DISCUSSION: Soluble MICA did not correlate with other acute phase reactants and remained stable during engraftment. Soluble MICA may potentially serve as a biomarker with high specificity for the prediction of GVHD.