Dynamic Changes in Neutrophil Counts and Neutrophil Granular Protein Levels in Convalescent COVID-19 Patients

Author(s): Anuradha Rajamanickam, Nathella Pavan Kumar, Arul Nancy P, Nandhini Selvaraj, Saravanan Munisankar, Rachel Mariam Renji, Vijayalakshmi V, Manoj Murhekar, Jeromie Wesley Vivian Thangaraj, Muthusamy Santhosh Kumar, CP Girish Kumar, Tarun Bhatnagar, Manickam Ponnaiah, R Sabarinathan2, V Saravanakumar, Subash Babu

Neutrophils play an important role in the pathophysiology of COVID-19. However, the dynamics of changes in neutrophil numbers and function in convalescent individuals of SARS-CoV2 infection has not been well explored. Hence, we aimed to determine absolute counts, percentages of neutrophils, Neutrophil-To-Lymphocyte Ratio (NLR) and the plasma levels of neutrophil elastase (NE), myeloperoxidase (MPO) and proteinase-3 (PTN-3) in seven groups of COVID-19 individuals, based on days since RT-PCR confirmation of SARS-CoV-2 infection. Our data demonstrated that both absolute counts and percentages of neutrophils, neutrophil-to-lymphocyte ratio (NLR), as well as the circulating levels of NE, MPO and PTN-3 decreased from Days 15-30 to Days 91-120 and plateaued thereafter. Severe COVID-19 patients exhibited increased levels of neutrophil counts and percentages, NL ratio and NE, MPO and PTN-3. Thus, our study provides an important insight into the kinetics of alterations in neutrophil counts, percentages, the NL ratio and the levels of neutrophil granular proteins in convalescent COVID-19 individuals.

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