Specific Cytokines Analysis Incorporating Latency-Associated Antigens Differentiates Infection Status: An Exploratory Study.

INTRODUCTION

Current immunologic methods cannot distinguish (Mtb) infection statuses, especially to discriminate active tuberculosis (ATB) from latent tuberculosis infection (LTBI). This study explored the potential of latency-associated antigens (Rv1733cSLP and Rv2028c) and multifactorial cytokine detection to distinguish tuberculosis infection states.

METHODS

ATB patients (20), LTBI healthcare workers (25), fever patients (11), and healthy controls (10) were enrolled. Cytokine levels (IFN-γ, TNF-α, IL-2, IL-6, IP-10, IL-1Ra, CXCL-1, and MCP-1) were measured using Luminex with/without MTB-specific virulence factor and latency-associated antigens stimulation.

RESULTS

Without antigen stimulation, IL-6, IP-10, MCP-1, and IL-1Ra were higher in the ATB group than in the LTBI group (p<0.05), but no significant differences between the ATB group and the fever group. Stimulated with the four antigens, respectively, the cytokines, including IP-10, IP-10, IFN-γ, IFN-γ, IL-6, IL-6, IL-6, IL-2, IL-2 , IL-1Ra, IL-1Ra, IL-1Ra, CXCL-1, CXCL-1, CXCL-1, CXCL-1, MCP-1 and MCP-1, demonstrated accurate discrimination between ATB and LTBI (<0.05). Additive concentrations demonstrated significant secretion differences of IFN-γ, IP-10 and IL-2, primarily by virulence factors in ATB and latency-associated antigens in LTBI. Latency-associated antigens synergized with virulence factors, enhancing TH1-type cytokine diagnostic efficacy for discriminating ATB from LTBI, the AUC for TNF-α increased from 0.696 to 0.820 (=0.038), IFN-γ increased from 0.806 to 0.962 (=0.025), and IL-2 increased from 0.565 to 0.868 (=0.007). Model selected by forward likelihood method indicated combined detection of IFN-γ, IFN-γ, IP-10, and CXCL-1 achieved ATB diagnosis (AUC=0.996) and ATB-LTBI differentiation (AUC=0.992). Combined detection of IFN-γ and IFN-γ achieved tuberculosis infection diagnosis (AUC=0.943).

CONCLUSION

Latency-associated antigens enhance multiple cytokine discriminatory ability, particularly TH1-type cytokines, for differentiating Mtb infection statuses.