The set of immunological tests for detection of active tuberculosis in children with latent infection

<b>Introduction:</b> Immunological identification of active TB among children with latent TB when no X-ray signs of TB are detected is necessary. <b>Aims:</b> To develop a combination of tests using recombinant antigen ESAT-6-CFP-10 (E6C10): antigen-specific interferon-gamma (IFN-γ) induction, specific antibodies and nonspecific inflammation protein amyloid A detection. <b>Methods:</b> 2 groups of patients were studied. 1^st group included 75 children (7-14 y/o) hospitalized for TB of intrathoracic lymph nodes with “+” skin test for E6C10. 2^nd group - 76 children with latent TB with “+” skin test; they got a specific anti-TB therapy as prevention. Patients from both groups had in vitro tests for IFN-γ induction of whole blood samples with E6C10, kit “Tubinferon”. E6C10-antibodies were determined by ELISA in 1:40 diluted sera, which were taken as “+” if their OD at least twice exceeded the control. Amyloid A level was estimated in all samples. <b>Results:</b> “+” results of E6C10-induced IFN-γ in the 1^st group comprised 82.6% and in the 2^nd group - 79%. The number of people with “+” anti-TB antibodies in the 1^st group was 86.7%, whereas in the 2^nd - 32.8%. Among patients from both 1^st or 2^nd group, those were selected who had a combination of “+” reactions to E6C10: IFN-γ, anti-TB antibodies and high serum amyloid A (minimum 4 mg/ml). In the 1^st group, we identified 18 patients like that, while in the 2^nd – 7. After additional examination, 4 of 7 of those patients were diagnosed with active TB and referred to inpatient treatment. <b>Conclusions:</b> Thus, the set of the 3 in vitro tests, may possibly identify pediatric patients who need in-depth examination and longer specific therapy.