Abstract: Objective To analyze the changes of serum leptin (Leptin) and chemokine ligand 26 (CCL26) in children with recurrent wheezing, and to explore their correlation with asthma predictive index (API). 
Methods A total of 178 children with recurrent wheezing were selected as the observation group, and they were divided into API positive group (n=92) and API negative group (n=86) according to API, and they all received standardized management. Another 89 healthy children undergoing physical examination during the same period were selected as the control group. Serum Leptin and CCL26 levels were detected in the API positive group and API negative group at the acute stage, remission stage, and in control group at the time of enrollment. The correlation between serum Leptin， CCL26 levels and API and the influencing factors of API positivity in children with recurrent wheezing were analyzed. The children with recurrent wheezing were followed up for 1 year after discharge, and the serum levels of Leptin and CCL26 in the children with recurrent wheezing were compared during the follow-up period. 
Results Serum Leptin and CCL26 levels in the observation group were higher than those in the control group at acute stage and remission stage (P＜0.05). Serum Leptin and CCL26 levels of API positive group were higher than those of API negative group at acute stage and remission stage (P＜0.05). Serum Leptin and CCL26 levels in API positive and API negative groups were higher at acute stage than at remission stage (P＜0.05). The levels of serum Leptin (r=0.480/0.401, P＜0.001) and CCL26 (r=0.481/0.512, P＜0.001) at acute stage and remission stage were positively correlated with API. After the binary logistic regression model was adjusted for premature infants, allergic dermatitis, tobacco exposure history, and maternal active or passive smoking during pregnancy, atopy, high expression of serum Leptin and CCL26 at acute stage still increased the risk of API positivity (P＜0.05). Logistic regression model was established: logit(P)=-7.005+1.020×atopic+1.098×serum Leptin level in acute phase+1.058×serum CCL26 level at acute stage. The Hosmer-Lemeshow goodness of fit test showed that χ2=4.249, DF=6, P=0.452, with goodness of fit. All 178 children with recurrent wheezing were followed up for 1 year, 18 children had wheezing again (10.11%), and 160 children did not have wheezing (89.89%). The positive rate of API in children with wheezing was higher than that in children without wheezing, and the levels of serum Leptin and CCL26 at acute stage and remission stage were higher than those without wheezing (P＜0.05). 
Conclusion Serum Leptin and CCL26 significantly increase in children with recurrent wheezing. They are closely related to API and are independent risk factors for API positivity.

Key words: asthma, Leptin, chemokine ligand 26