OBJECTIVETo detect the expression of B7-H1 gene in bone marrow mononuclear cells (BMMNCs) from leukemia patients and explore its clinical implications.

METHODSThe B7-H1 mRNA expression levels of BMMNCs from 74 newly diagnosed leukemia patients and 10 normal volunteers were detected by real-time quantitative PCR. At the same time, BMMNCs from 12 patients in complete remission (CR) after chemotherapy and 5 in relapse were followed up. The correlation between the clinical features of 74 de novo leukemia patients and the expression level of B7-H1 gene was analyzed.

RESULTSThe mRNA expression level of B7-H1 gene in BMMNCs from de novo leukemia patients (RQ = 0.125) was lower than that from normal control (RQ=1). When patients achieved CR the gene expression level (RQ = 69.07) was significantly higher than that before CR (P = 0.001). After relapsed, its level (RQ=4) was still higher than that before CR (P > 0.05). No clinical parameters such as gender, age, peripheral white blood count, blast cells ratio in BM, CD34 positive cells were significantly correlated with the expression level of B7-H1 except the response to therapy. The initial expression level of B7-H1 gene in non CR patients after therapy was significantly higher than that in CR patients (RQ = 26. 91, P = 0.005).

CONCLUSIONThe mRNA expression level of B7-H1 gene in newly diagnosed leukemia patients is lower than that in normal controls, and is higher in CR patients than in newly diagnosed patients. There is a correlation between the gene expression level and responsiveness to therapy.