EVALUATION OF MONOCYTES AND LOW-DENSITY GRANULOCYTES AS POTENTIAL BIOMARKERS IN PULMONARY TUBERCULOSIS

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb). It is estimated that only 5%–15% of infected individuals develop the active form of the disease. Part of the apparent resistance observed in individuals seems to be related to proper immune system function. Monocytes and granulocytes are responsible for bacillus identification and destruction, release of inflammatory mediators, and antigen presentation. However, there is a need for studies that further elucidate the role of these cellular groups. Thus, this study aimed to evaluate the association between monocytes and granulocytes and the development of active TB. The study was conducted at the Instituto Aggeu Magalhães (Fiocruz Pernambuco) and was approved by the Research Ethics Committee (CAAE: 48498821.2.0000.5190 / Opinion No. 4.951.816). Peripheral blood and sputum samples were collected from 36 individuals from SUS-PE healthcare services, divided into: patients with pulmonary TB (PTB) (n=16), patients with other respiratory diseases (No TB) (n=12), and “healthy” individuals (n=8). Sputum samples were submitted to microbiological culture and the Rapid Molecular Test for Mtb identification. Blood samples were processed for leukocyte isolation. Leukocytes were labeled with monoclonal anti-CD14+ and anti-CD36+ antibodies to identify the studied populations and then submitted to flow cytometry immunophenotyping. Data analysis was performed using FSC × SSC scatter plots. Values of p<0.05 were considered significant. Patients with PTB presented a mean percentage of monocytes of 22.27% relative to total leukocytes. The No TB group and healthy individuals presented percentages of 14.21% and 15.11%, respectively (p=0.016 and p=0.049). A high percentage of low-density granulocytes (10.03%) was observed in TB patients compared to healthy individuals (p=0.044). The results suggest that monocyte counts may be used as a potential biomarker in TB investigation. Low-density granulocytes also emerged as promising diagnostic targets. These findings open avenues for future research that may support new therapeutic strategies related to pulmonary TB.