Immunological and Hematological Characterisation of Mycobacterium Tuberculosis (M. Tb) Infected Patients

Differentiating TB phenotypes remains a diagnostic challenge due to the absence of a universally accepted standard test. Although the interferon gamma release assay (IGRA) is recommended for Latent TB Infection (LTBI), its application varies across clinical settings. This study utilized IGRA to immunologically categorize subclinical individuals and compare hematological parameters, including the complete blood count (CBC) and differential leukocyte count (DLC) among subclinical, clinical, and cured individuals to assess their diagnostic utility.

IGRA was performed to differentiate TB phenotypes. Demographic data, CBC, and DLC values were recorded. The Mann-Whitney U test was used for intergroup comparisons. Receiver Operating Characteristic (ROC) curve analysis assessed the diagnostic performance of significant markers.

IGRA stratified subclinical individuals into LTBI (13.2%) and healthy controls (HC; 86.8%). RBC and TLC were elevated, while platelet counts were reduced in active TB (ATB) compared with HC and LTBI (p <0.0001). Neutrophils and ESR were significantly elevated in ATB and TB-cured (TB-CU) groups. Monocyte counts were lower in ATB than in other phenotypes. ROC analysis showed good predictive value for neutrophils (AUC 0.845), ESR (AUC 0.844), and monocytes (AUC up to 0.814). NLR exhibited strong discriminatory power (AUC>0.83, adjusted OR=1.59).

The results highlight the potential of hematological markers, particularly NLR and ESR, in distinguishing TB phenotypes. While promising, the findings are limited by smaller sample sizes in the LTBI and TB-CU groups and the absence of IGRA in TB-CU individuals.

CBC and DLC parameters vary across TB phenotypes. NLR, neutrophils, ESR, and monocytes show potential as supportive diagnostic tools. Further longitudinal studies are warranted.