The Expression Of Lineage Specific Cytoplasmic Antigens In Patients With Acute Leukemia And Its Significance

Background and ObjectiveCell morphology and cytochemistry can improve the classification accuracy of acute leukemia up to89%in the diagnosis of acute leukemia. Because of the high accuracy and sensitivity, immunophenotyping plays an important role in the diagnosis of leukemia. The immunophenotype of acute leukemia is method to classify acute leukemia, based on the specific antigens expressed on acute leukemia blasts, which bind to specific antibodies conjugated with fluorescent detected by flow cytometer. This technique is used in the diagnosis and classification of acute leukemia cases with atypical morphology which cannot be diagnosed by bone marrow morphology and cytochemistry. In the diagnosis of acute lymphoblast leukemia, immunophenotype can be used to differentiate ALL from AML as well as to differentiate B-All from T-ALL, which is a compliment to the morphological diagnosis of ALL. However, it is found that AML leukemic cells express not only myeloid-associated antigen, but also the lymphocyte-associated antigen and vice versa. It is difficult to distinguish cross-lineage expression from mixed-lineage acute leukemia (MAL). Therefore it is necessary to choose more specific markers to confirm the diagnosis of acute leukemia, which plays an important role in the patient’s treatment and prognosis. On the base of the immunophenotype of cellular surface antigens, we performed a cytoplasmic antigen staining in order to investigate the expression of lineage specific cytoplasmic antigens in patients with acute leukemia and its significance.MethodsOne hundred and thirty-eight cases of acute leukemia were treated in the Department of Hematology of the First Affiliated Hospital of Zhengzhou University form September2010to May2011, including86male cases and52female cases. These patients range from14years old to76years old, with the median age at37.5years old.All patients were diagnosed by CBC, liver function, renal function, bone marrow cell morphology and histochemistry, immunophenotype and cytogenetics.The membrane antigens were detected in138patients with acute leukemia using three-color fluorescent by flow cytometry. Cytoplasmic antigens were detected in cases which difficulty to diagnose with morphological classification and cases with cross-lineage expression. Cytoplasmic antigens cMPO was selected for myeloid, Cytoplasmic antigens cCD79a was selected for acute B-lymphoblastic leukemia, and Cytoplasmic antigens cCD3was selected for acute T-lymphoblastic leukemia.Results1. DignosisAccording to the FAB classification,76out of138cases were diagnosed as AML and49/138cases were diagnosed as ALL, and other13/138cases were not explicitly classified. By immunophenotype, the49/138cases of ALL were subdivided into B-ALL (40cases) and T-ALL (9cases). In the cases morphologically not defined subtypes,2/13cases were diagnosed as AML-MO,5/13cases as B-ALL,2/13cases as T-ALL and4/13cases as mixed-lineage acute leukemia.2. The expression of cross-lineage antigensThere were41.3%of acute leukemia express Cross-lineage antigen. The cross-lineage antigen expression rates were50%in AML,26.7%in B-ALL and18.1%in T-ALL. Cross-lineage antigen expression in AML is mainly CD7(53.8%) and CD19(30.8%). CD33was expressed in83.3%of B-ALL, significantly higher than that of CD13and CD2(P<0.05).3. The specificity and sensitivityThe sensitivity of the antibody used in the diagnosis of AML were listed from high to low as CD33, CD33, cMPO, CD117, and the specificity from high to low as CD117, cMPO, CD13, CD33. The sensitivity of cytoplasmic antigens cMPO was lower than that of CD33and CD13, but the specific was higher than that CD33and CD13.There was no significant difference in the specificity between cMPO and CD117(P=0.312), but the sensitive of cMPO was higher than CD117(P=0.027). The sensitivity of the antibody used in the diagnosis of B-ALL were listed from high to low as CD19, cCD79a, CD10, CD20. There was no significant difference with specificity between cCD79a and CD10(P=0.312), CD20(P=0.287), but it was significantly higher than that of CD19(P=0.018). The sensitivity of antibodies used in the diagnosis of T-ALL were listed from high to low as cCD3, CD7, CD2, the specific from high to low as cCD3, CD2and CD7.The sensitive of cCD3was higher than CD7(P=0.042) and CD2(P=0.047), The specificity of cCD3had no difference with CD2(P=0.426), but it was significantly higher than that of CD7(P=0.022).4. The expression of Cytoplasmic antigen cMPO, cCD79a and cCD3The positive rates of cMPO were88.6%in AML,9.5%in B-ALL and0in T-ALL. The expression of cMPO in AML was significantly higher than that in ALL (P<0.05). There was no statistically significance in the expression of cMPO between B-ALL and T-ALL (P>0.05). The positive rates of cCD79a were92.7%in B-ALL,9.0%in T-ALL and0in AML. There was no statistically significance in the expression of cCD79a between T-ALL and AML (P>0.05). The positive rate of cCD3in T-ALL was100%. There were no cCD3expression in AML and B-ALL.Conclusion1. Cytoplasmic antigen cMPO, cCD79a, cCD3are specific markers of AML, B-ALL, and T-ALL. Their lineage specificity is higher than the cell surface antigen2. The detection of Cytoplasmic antigen cMPO, cCD79a, cCD3plays an importment role in the accurate diagnosis and classification of acute leukemia, especially in the cases with atypical morphology and cross-lineage antigen expression, such as mixed-lineage acute leukemia.