摘要Background Central nervous system leukemia (CNSL) is an important relapse in children with acute lymphoblastic leukemia (ALL).We investigated the possible role of endogenous hydrogen sulfide (H2S) of cerebrospinal fluid (CSF) in predicting CNSL.Methods From August 2008 to December 2010,380 children were enrolled in this study at Shijitan Hospital,China.These children were from 2 to 16 years old,and the median age was 6.5 years.They were divided into a CNSL group (7 cases),a leukemia group (307 cases),a non-leukemia group (26 cases) and a healthy group (40 children).CSF specimens were obtained from conventional lumbar punctured,then centrifuged and supernatants preserved for H2Sdetection.Leukemic cells precipitates from CSF were found in three cases,the hCSE and hCBS mRNA expression was detected by reverse transcription polymerase chain reaction (RT-PCR),and H2S levels in serum were also measured.The receiver operating characteristic (ROC) curve and area under curve (AUC) were used to assess the predictive diagnosis role of CSF H2S in children with ALL and CNSL.Results The serum H2S contents of the CNSL and leukemia groups were (96.98+15.77) μmol/L and (93.35+17.16)μmol/L respectively,much higher than those of healthy,(44.29+2.15) μmol/L,and non-leukemia,(46.32±6.54) μmol/L,groups (P ＜0.01).Compared with the leukemia group,CSF H2S content of the CNSL group was significantly high (P ＜0.01).Meanwhile,in contrast to the non-leukemia group,CSF H2S contents of the CNSL and leukemia groups were both significantly increased (P ＜0.01).In addition,leukemic cells from CSF precipitations could express CBS and CSE mRNA.Furthermore,the ROC analysis showed the UAC was 0.929 (95％ Cl:0.857-1.000),and the optimum cut-off value of CSF H2S was 12.08μmol/L,and the sensitivity and specificity were 83.3％ and 97.2％ respectively.Conclusions CSF H2S contents were significantly increased in children with CNSL.After treatment,H2S contents were decreased subsequently.Therefore,we speculated that H2S levels of CSF would predict CNSL in ALL children.