Background Testing the presence of latent or active tuberculosis using IGRA tests is necessary part of the diagnostic screening at risk individuals. QuantiFERON-TB Gold Plus (QFT-Plus) is a test for cell-mediated immune (CMI) responses to peptide antigens that simulate mycobacterial proteins. Peptide antigens in TB1 tube elicit CMI responses from CD4+ T-helper lymphocytes, in TB2 tube from CD8+ T-cytotoxic lymphocytes. Test is based on the ability of effector T lymphocytes to produce the cytokine interferon gamma (IFN-γ).
Objectives To compare and evaluate levels of IFN-γ produced by CD4+ and CD8+ cells in TB1 and TB2 tubes.
Methods It was studied 33 subjects with latent form of tuberculosis (LTBI) and 33 subjects with active TB. QFT-Plus was used to detect in vitro responses to peptide antigens associated with Mycobacterium tuberculosis infection (ELISA, QIAGEN). Results were obtained by calculation of INF-γ levels in Mitogen, TB antigen (TB1, TB2) and Negative control tubes using QFT analysis software.
Results QFT-Plus positive results were observed in both groups of people. Increased levels of IFN-γ produced by CD4+ cells (TB1) has been detected in 21 subjects with LTBI (63,64%) and in all 33 subjects with active TB (100,0%). Increased levels of IFN-γ produced by CD8+ cells (TB2) has been detected in 27 people with LTBI (81,82%) and in all 33 people with active TB (100,0%). Joint increase levels of IFN-γ in the tubes TB1 and TB2 was observed in 16 individuals with LTBI (48,48%) and in all 33 individuals with active TB (100,0%). In the group of patients with a negative QFT-Plus it was not observed increased levels of IFN in tubes TB1 and TB2.
Conclusions Our findings confirm specific CD4+ and CD8+ T cell response to mycobacterial protein antigens in individuals with LTBI and also in active TB subjects, in which INF-γ was frequently found. The immunological response represented by CD4+ and CD8+ T cells was not detected in subjects with QFT-Plus negative.
Disclosure of Interest None declared