The Study Of Serum YKL-40 And Humoral Immunity In Children With Recurrent Pneumonia

Background and objectivePneumonia is a common respiratory disease in children,With the continuous improvement of medical technology,its mortality rate is obviously decreased,but its incidence rate is increasing year by year,and some children can be diagnosed with pneumonia more than one time,that is,recurrent pneumonia.The mechanism of recurrent pneumonia is complex,in addition to the common underlying diseases,there are still some children with unknown etiology.In view of the high incidence of pneumonia,the current study of recurrent pneumonia is rare.YKL-40,also known as Chitinase-3-like protein 1,human chondrolyte glycoprotein39,is a member of the human chitinase family,can be expressed and secreted by phagocytic cells(mainly neutrophils and macrophages),play an important role in anti-infection,defense and tissue repair.Recent studies have shown that serum levels of YKL-40 in children with pneumonia is elevated and is associated with severity and prognosis.In addition,the dysfunction of humoral immunity is a recognized cause of recurrent pneumonia,and many immunized preparations have been reported to significantly reduce the number of recurrent pneumonia.So,this study selected children with recurrent pneumonia as the object to observe the changes of serum YKL-40 and humoral immunity,and evaluate whether serum YKL-40 can be used as a laboratory reference index for diagnosing recurrent pneumonia.At the same time,we observe the correlation of serum YKL-40 and humoral immunity index serum IgG,IgA,IgM,IgE,C3,C4 in children with recurrent pneumonia,and explore the possible mechanism of recurrent pneumonia.Methods1.Blood samples were collected from 30 children with recurrent pneumonia(recurrent pneumonia group),30 children with acute pneumonia(acute pneumonia group)and 30 healthy children(healthy control group).2.Serum YKL-40 concentrations were measured by ELISA.3.Gender,age,body weight,Serum IgG,IgA,IgM,IgE,C3,C4 were collected.4.The correlation analysis between serum YKL-40 and the above laboratory indexes was performed.5.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic value of serum YKL-40 for recurrent pneumonia.Results1.There were no significant differences in gender,age and body weight among the three groups(?~2=1.33,P=0.25;H=3.19,P=0.20;H=3.27,P=0.07).2.The concentration of serum YKL-40 in the recurrent pneumonia group was higher than that of the acute pneumonia group and the healthy control group(Z=-5.53,P=0.00;Z=-6.65,P=0.00).The concentration of serum YKL-40 in the acute pneumonia group was higher than that of the healthy control group(Z=-5.64,P=0.00).3.Serum IgG,IgA and C4 of the recurrent pneumonia group were lower than that of the acute pneumonia group(Z=-2.81,P=0.005;Z=-2.02,P=0.043;Z=-2.61,P=0.009).There was no significant difference in the serum IgM,IgE,C3 between the acute pneumonia group and the recurrent pneumonia group(Z=-0.15,P=0.88;Z=-0.19,P=0.85;Z=-0.16,P=0.87);Serum IgG,IgA and C4 of the recurrent pneumonia group were lower than that of the healthy control group(Z=-5.22,P=0.00;Z=-2.10,P=0.04;Z=-2.91,P=0.00).Serum IgE of the recurrent pneumonia group were higher than that of the healthy control group(Z=-2.48,P=0.01).There was no significant difference in the serum IgM and C3 between the healthy control group and the recurrent pneumonia group(Z=-1.13,P=0.26;Z=-0.16,P=0.87).4.Serum YKL-40 was negatively correlated with serum IgG(r=-0.557,P=0.001),serum YKL-40 was negatively correlated with serum C4(r=-0.481,P=0.007).There was no correlation between serum YKL-40 and serum IgA,IgM,IgE,C3(r=-0.000,P=0.998;r=0.124,P=0.514;r=-0.153,P=0.421;r=-0.046,P=0.810).5.The area under the ROC curve of serum YKL-40 for diagnosing recurrent pneumonia was 0.958(95%CI:0.921~0.994).Conclusions1.YKL-40 may be involved in the occurrence of recurrent pneumonia.2.Humoral immunity was disorder in children with recurrent pneumonia.