Abstract: Objective To investigate the changes of serum interleukin-21 （IL-21） and chemokine levels in patients with autoimmune hepatitis（AIH） and their implications. Methods 21 patients with AIH were recruited in our hospital between march 2015 and march 2017,and out of them, 5 were diagnosed as severe,and 16 were diagnosed as mild to moderate disease. Serum IL-21 as well as chemokine C-C- ligand 20 （CCL20）,chemokine ligand 9 （CXCL9）,chemokine C-C- receptor 6 （CCR6）,chemokine C-X-C- receptor 3 （CXCR3） were detected by enzyme-linked immunosorbent assay. The efficacy of serum IL-21 level in predicting illness exacerbation and intrahepatic activity index in patients with AIH were analyzed by the area under the recipient’s operating characteristic curve（AUC）. Results Serum albumin,alanine aminotransferase,aspartate aminotransferase,international normalized ratio,bilirubin,CCL20,CCR6 and IL-21 levels in five patients with severe AIH were（2.6±0.2） g/dL,（716.8±363.2） U/L,（632.6±334.9） U/L,（1.4±0.7）,（96.1±4.2） μmol/L,（263.2±123.8） pg/mL, （162.4±70.3） pg/mL and（400.2±102.3）pg/mL,significantly different compared to（3.7±0.4）g/dL,（384.5±143.7） U/L,（327.1±98.6） U/L,（1.2±0.3）, （25.8±4.3） μmol/L,（147.5±63.7） pg/mL,（63.8±25.3）pg/mL and （256.3±122.6） pg/mL,respectively in sixteen patients with mild/moderate AIH （all P<0.05）, while peripheral blood platelet count was （110.4±2.8）×10⁹/L,much lower than （170.4±5.3）×10⁹/L in the latter （P<0.05）; univariate analysis showed that the above parameters in seven patients with hepatic G3 to G4 were significantly different compared to those in fourteen patients with hepatic G1 to G2（P<0.05）,while no significant differences were found as respect to peripheral white blood cell counts,serum CXCL9,CXCR3 and IgG levels between the two groups （P>0.05）;the sensitivity （Se） was 80.0%,and the specificity （Sp） was 100.0% when serum IL-21 level greater than 380 pg/mL was set as the cut-off-value for prediction of clinical illness exacerbation, with the AUC of 0.900（95%CI：0.690 to 0.987）;the Se was 100.0%,and the Sp was 70.0% when serum IL-21 level greater than 405.7 pg/mL was set as the cut-off-value for prediction of intrahepatic histological activity index of grade 3,with the AUC of 0.857（95%CI：0.605 to 0.976）;multivariate analysis showed that serum IL-21≥405.7 ng/mL was the independent factor for predicting severe intrahepatic inflammation（OR:5.673,95%CI:2.952 to 9.118,P=0.000）. Conclusion The detection of serum IL-21 level might helpful in determining disease severity in patients with AIH, which needs further investigation.

Key words: Autoimmune hepatitis, Interleukin-21, Chemokines, Histological activity index, Implication