Expression And Clinical Significance Of PD-1/PD-L1 In Children With Acute Lymphoblastic Leukemia

[Objective]It was found that PD-1/PD-L1 pathway was one of the most important immune checkpoint pathways in tumor immune micro-environment in past few years' research.Programmed death receptor 1(PD-1)can be induced to express on the surface of T-lymphocytes,B-lymphocytes and NKT cells.PD-L1 is one of the ligands of PD-1.When PD-L1 is combined with PD-1,it can activate the inhibition signal and accelerate the apoptosis of effector T-lymphocytes.It was found that,if the expression of PD-L1 increased in solid tumor cells,it can inhibit the function of T cells through PD-1/PD-L1 signaling pathway,and evaded the immune surveillance function of T cells,then mediated the immune escape mechanism of tumor.However,the study of PD1/PD-L1 expression in childhood acute lymphoblastic leukemia is rare in domestic and abroad researches.The purpose of this study is to explore the mechanism of PD-1/PD-L1 signaling pathway in the treatment of childhood acute lymphoblastic leukemia by studying the difference of PD-1/PD-L1 expression before and after the treatment.And to explore the feasibility of PD-1 and PD-L1 as potential therapeutic targets for the treatment of acute lymphoblastic leukemia.So as to provide new ideas for the diagnosis and treatments of acute lymphoblastic leukemia.[Method]Bone marrow samples of newly diagnosed children with acute lymphoblastic leukemia(1-14 years old)from September 2018 to July 2019 in the First Affiliated Hospital of Zhengzhou University were collected as ALL group,containing the bone marrow before chemotherapy,the bone marrow on the 33rd day of induction treatment,and the bone marrow after early intensive treatment.The bone marrow samples of children with non hematologic malignancies of the same age were collected as the CONTROL group.The expression of PD-1 and PD-L1 were detected by flow cytometry.At the same time,the data of clinical cases were collected,containing genders,ages,clinical manifestations,laboratory examination results,bone marrow cytology(M),cellular immunology(I),cytogenetics(C)and Molecular Biology(M).In order to explore the relationship between the expression of PD-1/PD-L1 and the development of ALL.[Results]1.47 children were researched in this study.The median age of the patients was 5(3,7)years old,including 28 males(59.57%)and 19 females(40.43%).The main clinical manifestations were as below,26 cases(55.32%)in fever,9 cases(19.15%)bleeding in skin and mucosa,8 cases(17.02%)in anemia,6 cases(12.77%)in limb pain,and 2 cases(4.26%)in nausea.There were 23(48.94%)patients with lymphadenopathy and 24(51.06%)patients with hepatosplenomegaly.Cerebrospinal fluid examination showed 1(2.13%)cases of central nervous system leukemia,and there is no testicular leukemia..2.PD-1 and PD-L1 were expressed in all patients in this ALL group,but there was no correlation between the expression of PD-1 and PD-L1 in each treatment stage(P>0.05).3.The results showed that the expression of PD-1 was 21.78%(13.89%,23.96%)in the CONTROL group and 24.74%(15.88%,36.10%)in the newly diagnosed ALL group.There was no significant difference between the two groups(Z=-1.049,P=0.166>0.05).The expression of PD-L1 was 0.38(0.29,0.58)%in the CONTROL group and 0.63%(0.19%,1.21%)in the newly diagnosed ALL group.The difference was significant statistically(Z=-2.041,P=0.040<0.05),and the expression of PD-L1 in the bone marrow mononuclear cells of the newly diagnosed ALL group was higher than that in the CONTROL group.4.In this study,we found that there was no correlation between the expression of PD-1 protein and th e age,gender,the number of peripheral blood leukocytes,hemoglobin,platelet,neutrophil and immunophenotype of children with ALL.But there was correlation between the expression of PD-L1 and the immunophenotyping of leukemia(P<0.05),and the expression of PD-L1 in T-ALL group was higher than that in B-ALL group.5.Through the modeling analysis of generalized estimation equation,we can find the expression of PD-1 as below.Compared with the expression of PD-1 before treatment and after early intensive treatment,B=2.265>0 and P=0.064>0.05;and compared with the expression of PD-1 after the induction treatment and after early intensive treatment,B=-0.765<0 and P=0.543>0.05.So the research was found as the expression of PD-1 can not be affected significantly in each treatment stage.Meanwhile,compared with the expression of PD-1 in low risk group and high risk group,B=-2.62<0 and P=0.727>0.05;and compared with the expression of PD-1 in medium-risk group and high risk group,B=5.207>0 and P=0.495>0.05.The research was found as different risk grades of low-risk group,medium-risk group and high-risk group could not affect the expression of PD-1 significantly.6.Through the modeling analysis of generalized estimation equation,we can find the expression of PD-L1 as below.Compared with the expression of PD-L1 before treatment and after early intensive treatment,B=1.293>0 and P=0.028<0.05;and compared with the expression of PD-1 after the induction treatment and after early intensive treatment,B=0.036>0 and P=0.015<0.05.The results showed that different treatment stages could affect the expression of PD-L1 significantly.It can be concluded that the expression of PD-L1 decreased gradually during all the above treatments.Meanwhile,compared with the expression of PD-1 in low risk group and high risk group,B=-3.912<0 and P=0.011<0.05;and compared with the expression of PD-1 in medium-risk group and high risk group,B=-3.595<0 and P=0.02<0.05.The results showed that different risk grades could affect the expression of PD-L1 significantly.The results showed that PD-L1 expression was the highest in high risk group,the second in medium risk group and the lowest in low risk group.[Conclusions]1.PD-1 and PD-L1 were expressed in all bone marrow mononuclear cells of children in this ALL group,but there was no correlation between them.2.The expression of PD-1 may not be related to the pathogenesis and prognosis of ALL in children.3.The high expression of PD-L1 might be related to the pathogenesis of childhood acute lymphoblastic leukemia,and might indicate a poor prognosis.