Peripheral lymphocyte subset alteration in patients with COVID-19 having differential clinical manifestations.

Background & objectives: The COVID-19 disease profile in Indian patients has been found to be different from the Western world. Changes in lymphocyte compartment have been correlated with disease course, illness severity and clinical outcome. This study was aimed to assess the peripheral lymphocyte phenotype and subset distribution in patients with COVID-19 disease from India with differential clinical manifestations. Methods: Percentages of peripheral lymphocyte subsets were measured by flow cytometry in hospitalized asymptomatic (n=53), mild symptomatic (n=36), moderate and severe (n=30) patients with SARS-CoV-2 infection, recovered individuals (n=40) and uninfected controls (n=56) from Pune, Maharashtra, India. Results: Percentages of CD4+Th cells were significantly high in asymptomatic, mild symptomatic, moderate and severe patients and recovered individuals compared to controls. Percentages of Th memory (CD3+CD4+CD45RO+), Tc memory (CD3+CD8+CD45RO+) and B memory (CD19+CD27+) cells were significantly higher in the recovered group compared to both asymptomatic, mild symptomatic patient and uninfected control groups. NK cell (CD56+CD3-) percentages were comparable among moderate +severe patient and uninfected control groups. Interpretation & conclusions: The observed lower CD4+Th cells in moderate+severe group requiring oxygen support compared to asymptomatic+mild symptomatic group not requiring oxygen support could be indicative of poor prognosis. Higher Th memory, Tc memory and B memory cells in the recovered group compared to mild symptomatic patient groups might be markers of recovery from mild infection; however, it remains to be established if the persistence of any of these cells could be considered as a correlate of protection.

Pro-inflammatory CXCL-10, TNF-α, IL-1ß, and IL-6: biomarkers of SARS-CoV-2 infection.

Currently, the world is witnessing the pandemic of COVID-19, a disease caused by the novel coronavirus SARS-CoV-2. Reported differences in clinical manifestations and outcomes in SARS-CoV-2 infection could be attributed to factors such as virus replication, infiltration of inflammatory cells, and altered cytokine production. Virus-induced aberrant and excessive cytokine production has been linked to the morbidity and mortality of several viral infections. Using a Luminex platform, we investigated plasma cytokine and chemokine levels of 27 analytes from hospitalized asymptomatic (n = 39) and mildly symptomatic (n = 35) SARS-CoV-2-infected patients (in the early phase of infection), recovered individuals (45-60 days postinfection) (n = 40), and uninfected controls (n = 36) from the city of Pune located in the state of Maharashtra in India. Levels of the pro-inflammatory cytokines IL-1ß, IL-6, and TNF-α and the chemokine CXCL-10 were significantly higher, while those of the antiviral cytokines IFN-γ and IL-12 p70 were significantly lower in both asymptomatic and mildly symptomatic patients than in controls. Comparison among the patient categories revealed no difference in the levels of the cytokines/chemokines except for CXCL-10 being significantly higher and IL-17, IL-4, and VEGF being significantly lower in the mildly symptomatic patients. Interestingly, levels of all key analytes were significantly lower in recovered individuals than in those in both patient categories. Nevertheless, the level of CXCL10 was significantly higher in the recovered patients than in the controls, indicating that the immune system of SARS-CoV-2 patients may take a longer time to normalize. Our data suggest that IL-6, IL-1ß, TNF-α, CXCL-10, and reduced antiviral cytokines could be used as biomarkers of SARS-CoV-2 infection.