Enzyme-linked immunosorbent assay for human MRP-8/MRP-14 proteins and their quantitation in plasma of hematological patients

We developed a quantitative enzyme immunoassay for human MRP-8/MRP-14, neutrophil cytosolic proteins with calcium-binding and bacteriastatic properties. MRP-8/MRP-14 concentrations were measured in the plasma of 23 healthy volunteers and in 75 patients with hematological disorders. These proteins were detected in plasma of healthy blood donors with mean ± standard deviation 167 ± 114 ng/ml. MRP-8/MRP-14 plasma levels ranged from 435 to 13280 ng/ml in patients with chronic myeloid leukemia (CML), from 50 to 7570 ng/ml in chronic lymphoid leukemia (CLL), from 450 to 2790 ng/ml in polycythemia vera (PV), and were significantly higher than in healthy blood donors ( P < 0.01 for CML and P < 0.05 for others). In CML patients MRP-8/MRP-14 levels strongly correlated with total blood WBC count ( r = 0.82) and with neutrophilic granulocyte (NG) count ( r = 0.80). Correlation of these values in PV amounted to r = 0.70 and r = 0.46, respectively. In CLL patients MRP-8/MRP-14 levels strongly correlated with total WBC count ( r = 0.92), but not with the NG count. We suggest that MRP-8/MRP-14 quantitation may serve as a marker of neutrophil pool turnover in some hematological disorders.