EXPRESSION OF SLAMF1 AND PDL1 IN NEUTROPHILS FROM PATIENTS WITH ACTIVE TUBERCULOSIS CORRELATES WITH THE SEVERITY OF THE DISEASE

CANDELA MARTIN; ANA BAZAN; MARIA PAULA MORELLI; CAMILA MARTINENA; LUCIA DONNOLI; ROCIO ZUAZO; AGUSTIN VITTI; AMIANO, NICOLÁS O; NANCY L. TATEOSIÁN; FEDERICO BLANCO; FABIANA BIGI; , ROSA M. MUSELLA,; A LORENA CIALLELA,; ADRIANA RODRIGUEZ MIERES,; RODRIGO D. FAILDE; GRACIELA CASADO; DOMINGO J. PALMERO; , GARCÍA V.E

Congreso; ALACI 2024; 2024

ABSTRACT: Background: Neutrophils are the first line of defense against pathogens, combating them by using several antimicrobial mechanisms such as phagocytosis, reactive oxygen species and neutrophil extracellular traps, being the predominantly infected cells in the human lungs during active Mycobacterium tuberculosis (Mtb) infection. We previously demonstrated that SLAMF1 activation in Mtb-Ag stimulated neutrophils significantly augmented intracellular ROS levels. Here we further analyzed surface molecules´ expression and the microbicidal capacity of neutrophils from tuberculosis (TB) patients presenting distinct immunological status and disease severity. Objective: To elucidate if the differential expression of the surface molecules SLAMF1 and PD-L1 correlates with microbicidal ability of neutrophils in TB patients with different disease severity. Methods: TB patients were classified as high or low responders (HR or LR) in accordance with their T cell activity against a Mtb lysate (Mtb-Ag). Neutrophils were purified from heparinized blood by Ficoll-Hypaque centrifugation, dextran sedimentation, and hypotonic lysis. Cells (2×106 /mL) were estimulated with Mtb-Ag for 2h and stained with anti-SLAMF1 and anti-PD-L1 fluorophore-conjugated antibodies. For Colony Forming Unit (CFU) assay neutrophils (2.5x106/mL) were infected with Mtb H37Rv (MOI:5) for 2h, incubated for 24h, washed and lysed. CFUs were counted on Middlebrook 7H11 agar plates. Results: We found that, in comparison with LR TB patients, HR TB patients showed a significantly higher percentage of SLAMF1+ and PD-L1+ neutrophils after Mtb-Ag stimulation (Mann-Whitney test p