Neutrophilia, lymphopenia and myeloid dysfunction: a living review of the quantitative changes to innate and adaptive immune cells which define COVID-19 pathology

Abstract

Destabilisation of balanced immune cell numbers and frequencies is a common feature of viral infections. This occurs due to, and further enhances, viral immune evasion and survival. Since the discovery of the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), which manifests in coronavirus disease 2019 (COVID-19), a great number of studies have described the association between this virus and pathologically increased or decreased immune cell counts. In this review, we consider the absolute and relative changes to innate and adaptive immune cell numbers, in COVID-19. In severe disease particularly, neutrophils are increased, which can lead to inflammation and tissue damage. Dysregulation of other granulocytes, basophils, and eosinophils represent an unusual COVID-19 phenomenon. Contrastingly, the impact on the different types of monocytes leans more strongly to an altered phenotype, e.g. HLA-DR expression, rather than numerical changes. However, it is the adaptive immune response which bears the most profound impact of SARS-CoV-2 infection. T cell lymphopenia correlates with increased risk of ICU admission and death; therefore, this parameter is particularly important for clinical decision making. Mild and severe disease differ in the rate of immune cell counts returning to normal levels post disease. Tracking the recovery trajectories of various immune cell counts may also have implications for long-term COVID-19 monitoring. This review represents a snapshot of our current knowledge, showing that much has been achieved in a short period of time. Alterations in counts of distinct immune cells represent an accessible metric to inform patient care decision or predict disease outcomes.

Molnupiravir as an Early Treatment for COVID-19: A Real Life Study

“…In the course of COVID-19, eosinophilopenia is also common. These are cells with antiviral effects [ 36 , 37 , 38 , 39 ]. Eosinophils contain and produce particles with antiviral activity and participate in adaptive immunity, presenting as antigen-presenting cells, as demonstrated against some respiratory viruses in vitro and in vivo, including respiratory syncytial virus and influenza [ 40 , 41 ].…”

Activation of Herpes Viral Infection as a Manifestation of Post-Covid Syndrome

“…Другие исследования [13] подтверждают эти данные; более того, повышение уровня смертности имело место при критическом снижении СD8+ лимфоцитов (на 20% и более) и СD4+ лимфоцитов менее 200 клеток/мл. На нарушение функций адаптивного иммунитета (гранулоцитов, базофилов и эозинофилов) указывают авторы обзора [21].…”

Dapsone Lowers Neutrophil to Lymphocyte Ratio and Mortality in COVID-19 Patients Admitted to the ICU

“…A significant tissue destructive element of COVID-19 lung dysfunction is wrought by neutrophils [ 22 , 23 , 24 , 25 ]. It was on this basis that dapsone was proposed in 2020 to be part of standard care in ARDS, including that during severe COVID-19 [ 3 , 4 , 5 , 26 ].…”

“…Neutrophils, although essential for defense against infections, also participate in tissue destruction when their activity becomes overly exuberant, as occurs in human pathological inflammatory states for which dapsone is used such as bullous pemphigoid, Behcet’s disease, dermatitis herpetiformis, etc. [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”