Interferon-gamma-induced protein-10 (IP-10) and natural killer cell count as predictive factors for the severity of COVID-19

Abstract

Background: The immune mechanisms underlying the pathology of COVID-19 are currently under immense scrutiny. Following NK and T cell activation, a surge of proinflammatory cytokines, and chemokines such IP-10, are found to increase. These cytokines stimulate the adaptive immune response and recruit other immune cells to the site of infection. Paradoxically, NK cells are known to be decreased in the peripheral circulation of severely ill COVID patients. It is not clear if this decrease in number is due to cell depletion or due to recruitment to sites of inflammation. The purpose of this study was to determine if there is a correlation between IP-10 levels and peripheral NK cell numbers and if this correlates with diseases severity.

Methods: The study involved 30 patients divided into 2 groups (moderate and severe) depending on disease severity, as well as 15 age- and gender-matched controls. Serum IP-10 levels were assessed by ELISA and determination of NK cell numbers were determined by flow cytometry.

Results: The results demonstrate an inverse relationship between NK cell numbers and IP-10 levels. Moreover, severely ill patients characteristically displayed decreased peripheral NK cell numbers and increased serum IP-10 levels in a manner that correlates with disease severity.

Conclusion: severity is associated with increased production of chemokines such as IP-10 in the serum which The results demonstrate that disease may be involved in the recruitment of NK cells to peripheral tissues such as the lung, which may partially explain the decreased NK cell number associated with severe pathology.