The Clinical Value Of Serum KL-6 Level In ANCA Associated Vasculitis With Interstitial Lung Disease

Objective To investigate the clinical significance of serum KL-6 level in ANCA associated vasculitis(AAV)with interstitial lung disease(ILD).Methods A total of 90 AAV patients from the First Affiliated Hospital of Zhengzhou University from January 2016 to July 2018 were selected.Among them,21 AAV with pulmonary infection,23 AAV without pulmonary infection,20 related ILD without pulmonary infection,26 related ILD with pulmonary infection.Twenty patients with simple pulmonary infection and 20 normal people admitted to our hospital at the same time period were selected as the control group.Clinical manifestations,laboratory data,lung functions and HRCT were performed and recorded Serum levels of KL-6 in the following patients were determined by ELISA: AAV,pulmonary infection without AAV and healthy control.The clinical value of serum KL-6 level in AAV patients in the diagnosis,changes in pulmonary disease and prognosis were statistically analyzed.Results In the AAV group,the mean serum kl-6 concentration was found from high to low in the following order :(775±234)U/ml in AAV related ILD with pulmonary infection;(745±194)U/ml in AAV related ILD without pulmonary infection;(255 ±130)U/ml in AAV without pulmonary infection;(243±142)U/ml in AAV with pulmonary infection.The mean concentration of serum kl-6 in the control group was from high to low :(268±105)U/ml in the healthy control group;the pure lung infection group was(249±100)U/ml.Statistical analysis showed the significance(P<0.05)of the serum KL-6 level in the AAV-ILD patients without pulmonary infection compared to AAV without pulmonary infection,pure pulmonary infection,and control groups.No statistically significant difference was detected between AAV-ILD without pulmonary infection and AAV-ILD with pulmonary infection(P>0.05).Statistical analysis showed the significance(P<0.05)of the serum KL-6 level in the AAV patients without pulmonary infection compared to AAV with pulmonary infection,pure pulmonary infection,and control groups.The serum KL-6 level of AAV patients was positively correlated with abnormal pulmonary functions such as short of breath(r=0.429,P<0.05).In addition,the serum KL-6 level of AAV patients was negatively correlated with total lung capacity(TLC%)(r=-0.737,P<0.05)and carbon monoxide dispersion(DLCO%)(r=-0.692,P<0.05)in pulmonary function examination,but was not correlated with ESR(r=0.010,P=0.928),CRP(r=0.019,P=0.871),increased creatinine(r=0.011,P=0.917),and positivity of ANCA(r=0.017,P=0.876).Pulmonary functions of some AAV-ILD patients,showed that 6 patients with progressive pulmonary fibrosis and increased serum KL-6 concentration.Conclusion 1.Serum KL-6 in AAV patients could be used as a serological marker of AAV related ILD.2.Changes in serum KL-6 level can be used as a marker for interstitial lung disease.3.Persistent high serum level of KL-6 may indicate poor prognosis of pulmonary fibrosis in AAV patients.