Lymphopenia an important immunological abnormality in patients with COVID‐19: Possible mechanisms

Abstract

The lymphopenia as a major immunological abnormality occurs in the majority of severe COVID‐19 patients, which is strongly associated with mortality rate. A low proportion of lymphocytes may express the main receptor for SARS‐CoV‐2, called angiotensin‐converting enzyme 2 (ACE2). Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) can also use ACE2‐independent pathways to enter lymphocytes. Both SARS‐CoV‐2‐ and immune‐mediated mechanisms may contribute to the occurrence of lymphopenia through influencing the lymphocyte production, survival or tissue re‐distribution. The metabolic and biochemical changes can also affect the production and survival of lymphocytes in COVID‐19 patients. Lymphopenia can cause general immunosuppression and promote cytokine storm, both of them play an important role in the viral persistence, viral replication, multi‐organ failure and eventually death. Here, a comprehensive view concerning the possible mechanisms that may lead to the lymphocyte reduction in COVID‐19 patients is provided, while highlighting the potential intervention approaches to prevent lymphopenia.

Contribution of STAT3 to the pathogenesis of COVID-19

“…Lymphopenia may happen in about 1.0%–80.0% of mild/moderate COVID-19 patients and in about 33.0%–96.0% of severe COVID-19 patients [ 53 ]. The blood counts of T cells (including total CD3 + cells, CD4 + T- and CD8 + T cells), B lymphocytes and NK cells are diminished in COVID-19 patients, particularly in severe cases [ 53 ].…”

“…Lymphopenia may happen in about 1.0%–80.0% of mild/moderate COVID-19 patients and in about 33.0%–96.0% of severe COVID-19 patients [ 53 ]. The blood counts of T cells (including total CD3 + cells, CD4 + T- and CD8 + T cells), B lymphocytes and NK cells are diminished in COVID-19 patients, particularly in severe cases [ 53 ]. SARS-CoV-2- and immunologic-related mechanisms may lead to the appearance of lymphopenia by affecting the lymphopoiesis, lymphocyte viability, and tissue re-distribution of lymphocytes [ 53 ].…”

“…The blood counts of T cells (including total CD3 + cells, CD4 + T- and CD8 + T cells), B lymphocytes and NK cells are diminished in COVID-19 patients, particularly in severe cases [ 53 ]. SARS-CoV-2- and immunologic-related mechanisms may lead to the appearance of lymphopenia by affecting the lymphopoiesis, lymphocyte viability, and tissue re-distribution of lymphocytes [ 53 ]. Lymphopenia can cause general immune-dysfunction and reinforce cytokine storm, both of them perform a major role in viral spreading and multi-organ dysfunction [ 53 ].…”

Landscapes and dynamic diversifications of B-cell receptor repertoires in COVID-19 patients

“…The copyright holder for this this version posted December 29, 2020. ; https://doi.org/10.1101/2020.12.28.424622 doi: bioRxiv preprint COVID-19 patients [15,16,17,18] . However, we found that the percentage of B lymphocytes showed an opposite trend to T cells, among these patients, the percentage of B cells in patient P3, P4 and P5 reached the highest value until 14 th , 6 th and 17 th day after the onset of the disease, respectively (Supplementary Table 1).…”

Clinical Features for Severely and Critically Ill Patients with COVID-19 in Shandong: A Retrospective Cohort Study

“…19 Based on earlier finds regarding SARS and MERS, Some scholars also speculated that SARS-COV-2 can induce apoptosis of lymphocytes. 20 It was worth mentioning that p53, as a key pro-apoptosis gene, was highly expressed in PBMCs collected from COVID-19 patients. 21 In addition, due to the expression of ACE2 on the membrane of hematopoietic stem cells (HSCs), it is considered that SARS-COV-2 can directly infect the pool of HSCs and cause pyroptosis in these cells.…”