[Expression of transporter associated with antigen processing (TAP) in childhood acute leukemia and its clinical...

Transporter associated with antigen processing(TAP) participates in immune surveillance, so it is probably relevant to carcinogenesis. Investigation of expression of TAP and its clinical significance in childhood acute leukemia will be helpful to clarify pathogenesis and to develop immunotherapy strategy.

RT-PCR analysis was used to detect the expression of TAP1 and TAP2 in leukemia cells from bone marrow in 34 inpatients with primary acute lymphoblastic leukemia (ALL), 15 inpatients with relapsed ALL, 20 inpatients with acute medullary leukemia (AML), and 20 surgical inpatients without systematic disorders as control. And then,the absorbance (A) values of expanded bands were measured by digital imaging analyzer and relative A values were worked out based on A value of GAPDH (positive inside control).

The relative A values of TAP1(0.448+/-0.167 and 0.169+/-0.021,respectively) and TAP2(0.196+/-0.180 and 0.112+/-0.020, respectively) in primary ALL group and relapsed ALL group were lower than those in control group (P< 0.01). The A values of LMP2, LMP7, and PA28alpha (991.4+/-532.7, 686.3+/-663.8, and 2022.3+/-1622.3, respectively) in relapsed ALL group were lower than those in control group (P less than 0.01,0.01 and 0.05, respectively). The A value of LMP2 in relapsed group was lower than that in control (P< 0.01). The A values of LMP7 for the cases with no remission and relapse were both lower than that for the cases with constant complete remission in primary ALL group (P< 0.01). The relative A value of TAP2 in AML group was lower than that in control group (P< 0.05). The relative A value of TAP1 in relapsed ALL group was lower than that in primary ALL group (P< 0.05). In primary ALL group, the relative A value of TAP1 (0.215+/-0.159) for cases with relapse (6/34 cases) was lower than that (0.462+/-0.189) for those with constant complete remission (24/34 cases) (P< 0.05).

There exists decreased expression of TAP in both childhood ALL and AML, which probably contributes to the escape of leukemia cells from immune surveillance. Decreased expression of TAP1 subunit is probably related to the relapse of ALL.