Clinical Application of Matrix Metalloproteinase-8 and Matrix Metalloproteinase-9 Expression in Patients with CML.

Neutrophils are the first cells to arrive at the site of infection where they play a critical role in host defense against invading microbes. To perform this process, neutrophils produce and secrete a lot of molecules to destroy the infectious agent. Among proteolytic enzymes identified in the neutrophils, matrix metalloproteinases (MMPs) have attracted considerable attention for their proposed role in the destruction of extracellular matrix under physiological and pathological conditions. The first MMP identified in neutrophils is MMP-8 or neutrophil collagenase that is stored in the specific granules and is capable of cleaving type I collagen. MMP-9, neutrophil gelatinase, are stored in the gelatinase granules and is capable of cleaving type VI collagen. Chronic myeloid leukemia (CML) is a malignant clonal disorder that originates from a transformed stem cell and involves myeloid lineage. The affected cells have both proliferative and functional impairment. Leukemoid reaction (LR) often encountered in association with severe infections or malignancy, shows extreme elevations of the leukocyte count with left shift including myeocytes, promyelocytes and blasts that would be confused with CML. The laboratory differential diagnosis of CML and LR are based on the leukocyte alkaline phosphatase (LAP) score, philadelphia chromosome analysis and bone marrow analysis. Our previous study revealed that the level of marrow MMP-9 may be a useful surrogate marker for monitoring disease status in AML and propose it as a potential prognostic factor. In this study, CML patients at diagnosis, various patients with leukemoid reaction and several normal individuals were assessed, to evaluate the potentiality of MMP-9 or/and MMP-8 to be differential diagnostic markers between CML and LR. We determined the MMP-8 and MMP-9 concentrations in peripheral blood by ELISA method, and the MMP-8 and MMP-9 contents in neutrophils by immunocytochemical staining and flow cytometry. We found that the plasma MMP-8 levels were less than 10ng/ml in all normal individuals studied, those were 10 – 100ng/ml in CML patients and those were more than 100ng/ml in LR patients. The same trend was shown in MMP-9 levels, which were less than 50ng/ml, 50 – 450ng/ml and more than 450ng/ml, respectively. Immunocytochemical staining revealed MMP-8 and MMP-9 contents in cytoplasm of neutrophils were abundant in patients with LR, compared with those in patients with CML and normal individuals; further flow cytometric analysis also showed the same trend. These results suggest that the MMP-8 and MMP-9 concentrations and individual neutrophil MMP-8 and MMP-9 contents might contribute to discriminate between CML and LR, and to be useful surrogate markers for differential diagnosis.