| Objective To investigate the clinical significance of myeloperoxidase expression in the classification and diagnosis of acute leukemia by using capillary electrophoresis to continuously detect the level of MPO in the single cell of acute leukemia.Methods (1) Patient samples: Bone marrow or blood cells were obtained from 51 patients with acute leukemia and 30 controls. Amongs these 51 patients, there were 36 new cases of acute non-lymphocytic leukemia(ANLL), which including 4 cases of ANLL-M1, 7 of M2, 9 of M3, 6 of M4, 8 of M5, 2 of M6. The others were 15 cases of acute lymphocytic leukemia (ALL) .The blast percentage of all new cases weren't less than 60%. The control cases were persons in condition. (2) Experimental methods: First of all, we used digitionin (Dig) in PBS to dissolve cholesterol on the cell membrane and form microholes on it. So that low molecules could pass through the membrane while macromolecules such as some enzymes were still within the cell. Then buffer solution, H2Q and H2O2 were added into the capillary ,and the living cells with miroholes on membrane were continuously pressured to undergo the catalysis of MPO .At the same time,electrochemistrial methods were employed to detect the products BQ and obtained the corresponding curves of the level of MPO. Finally, MPO were quantified by using the capillary electrophoresis (CE) to detect the activity of the MPO in the extract of all the cells in each sample.Results The level of MPO were between 10-10 and 10-9 in the 30 controls; 8 of the 15 ALL were 0, 4 were between 10-11 and 10-12, which were considered to be polluted by granulocytes; 3 had high expression of MPO, which were approved to be AHL by analysing of immunology and RT-PCR. In the cases of ANLL,the level of MPO were between 10-10 and 10-7.The M3 cases showed the highest expression of MPO, followed by the cases of M2 and M4, then were cases of M1. Cases of M5showed the lowest level of MPO expression. The difference between M3, Mi and M5 was significant in statistics (P<0.05); the difference between M2 and M4 was insignificant (P>0.05) , but it was significant with the others. Because of the cases were not enough, we didn't carry out statistic analysis to M2a and M2b,M4a and M4b,M5a and Msb. But compared the values of MPO expression,we found that they accorded with the trend of M2b>M2a> M4a>M4b and M5b>M5a .Among the 15 ALL cases, the POX staining were all negative,one case's MPO(detected by flow cytometry) is positive,three cases were finally diagnosed AHL by using capillary electrophoresis to continuously detect MPO expression of single cell. It's clear that using capillary electrophoresis to continuously detect MPO expression of single cell is more sensitive than POX staining and MPO detection by flow cytometry.Conclusions The study shows that capillary electrophoresis is a sensitive method in detecting the expression of MPO, which is more sensitive than that detected by cytochemical study and flow cytometry. It will help us to find AHL cases in ALL cases diagnosed according to FAB.The MPO expression is of great difference among the different subtypes of ANLL, but they accord with the rule of M3>M2>M4>M6>Mi>M5, among which M2b>M2a> M4a>M4b and M5b>M5a .So that the detection of MPO by capillary electrophoresis technique is an useful method for classification of acute leukemia.
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