The Application Of The Test Of T-SPOT.TB Combining With Cytokine INF-γ、IL-10in Diagnosis Of Tuberculosis

Objective:To evaluate the value of T-SPOT.TB combining with test of plasma cytokines of INF-gamma, IL-10and so on differentiating active tuberculosis(TB) and non-active TB and understand the change of cytokines of Th1/Th2in TB.Methods:75suspected tuberculosis infection inpatients or outpatients and24healthy medical workers since October2012to February2013from The Third Xiangya Hospital were enrolled in this prospective cohort study.All subjects underwent peripheral blood T-SPOT.TB test,collected plasma samples cryopreserved and their intact clinical data. The diagnostic evaluation was made in all objects at study endpoint (May2013).All objects who met the inclusion criteria were divided into three groups named active TB group marked as group A, non-active TB group marked as group B and healthy controls marked as group C respectively.The concentration of plasma INF-γ, IL-2, IL-4, IL-10were tested in three groups and each kind of cytokine was compared between two groups. The comparison of the number of spots was made between group A and group B about subjects whose T-SPOT.TB results were positive.All were considered statistically significant if P was less than0.05.If a cytokine concentration or a number of spots had significant difference between group A and group B, A receiver operating characteristic (ROC) curve analysis was used to assess the size of its diagnostic value.When the Youden index reached the maximum,the cytokine concentration or the number of spots was considered as the optimal cutoff point for the identification of the both groups. We calculated its diagnostic sensitivity, specificity,positive likelihood ratio and negative likelihood ratio in the end.Results:According to the diagnosis and inclusion criteria,72cases were included in the study ultimately which were32cases of group A,20cases of group B (16cases had a previous tuberculosis history and4cases was of latent tuberculosis infection) and20cases of group C.The concentration of plasma INF-y, IL-2, IL-4, IL-10in group A was 115.94±14.01,452.95±209.90,260.70±95.73,152.86±37.11respectively, in group B was89.79±4.25,499.78±197.15,260.46±134.33,86.68±15.71respectively, in group C was90.79±3.88,510.10±103.03,204.98±108.81,64.51±9.66respectively.IFN-γ and IL-10had statistically significant difference between group A and group B (P<0.05);However IL-2and IL-4had no significantly difference between the two groups (P>0.05).Group B compared with group C, INF-y and IL-2had no statistically significant difference between the two groups (P>0.05);To the contrary IL-4and IL-10had statistically significant difference (P<0.05).The median of A-pores(mixed with ESAT-6) spots of group A VS group B with a positive result about T-SPOT.TB was23VS19,B-pores(mixed with CFP-10) was74.5VS25,sum of A-pores and B-pores was115.5VS49respectively.With regard to A-pores spots and sum of A-pores and B-pores spots there was no statistically significant difference between group A and group B(P>0.05). To the contrary, B-pores spots had statistically significant difference (P<0.05).By drawing ROC curve about B-pores spots, plasma INF-y and IL-10concentration of group A and group B, we obtained area under the curve (AUC) was0.69,0.95,0.98respectively.When we took the number of B-pores spots74.5,INF-y concentration94.38pg/ml and IL-10concentration109.82pg/ml as cutoff point identifying active TB and non-active tuberculosis,the sensitivity, specificity, positive likelihood ratio and negativelikelihood ratio was50.0%,93.8%,93.8%;89.5%,85.0%,90.0%;4.76,6.25,9.38;0.56,0.07,0.07respectively.Conclusion:1.The dynamic imbalance of Thl-type/Th2-type cytokines plays an important role in the development of tuberculosis infection.when Th2-type cytokines are dominant,it will promote the development of TB.2.Peripheral blood T-SPOT.TB combining with the test of plasma INF-y or IL-10concentration can make an accurate diagnosis of tuberculosis which has a high diagnostic value.Patients with suspected TB infection can first have a T-SPOT.TB test.If the result is positive, then make a test about plasma INF-gamma or IL-10concentration which can help us distinguish active tuberculosis and non-active tuberculosis well and IL-10which has a higher positive likelihood ratio can do more contribution to the diagnosis of active TB.3.B-pores spots had statistically significant difference between active tuberculosis and non-active tuberculosis with a positive T-SPOT.TB result.However it is not enough by the number of B-pores spots to distinguish active TB and non-active TB better.12figures,3tables,46references.