Characteristics of peripheral Leukocyte in moderate infection of COVID-19

: Background: Blood leukocytes are an important part of the body’s defense system, and infection status can be predicted by measuring WBC levels . COVID-19 may involve many organ systems in its host. Studies suggest that hematological profiles change during SARS-CoV-2 illness. Patients and methods: This study included 504 mild infected patients with confirmed COVID-19 infection, these study subjects were randomly selected irrespective of the age group and both genders were included, EDTA blood sample was collected for performing total and differential white blood cells (Diagon D-cell 60 hematology analyzer Europe-Diagon Ltd. Hungary). Results: The present study included patients aged from14 years to 75 years mean age was 44.5 ±30.5 who were confirmed to have Covid-19 based on real-time reverse transcription-polymerase chain reaction, female gender was more frequent (n=280, 55.6%) than Male gender (n=224, 44.4%). This study reveals normal total WBCs count in 320 patients (63.5%), neutrophilia with a sensitivity of 77.8%, and lymphopenia with a sensitivity of 73%. Conclusion: Neutrophilia has a sensitivity of 77.8% and lymphopenia has a sensitivity of 73% for diagnosis or prognosis of mild infection of COVID-19 patients (Outpatients and patients under home observation). lymphopenia, biomarker.

dysfunctions together lead to viral sepsis with immunologic impairment (5) . As components of blood routine tests available for almost all hospitalized patients, PBICs usually serve as practical markers in infectious diseases. Indeed, leukocytosis, leukopenia, and lymphopenia have been reported to be commonly seen in COVID-19 patients (6) .
Blood leukocytes are an important part of the body's defense system, and infection status can be predicted by measuring WBC levels (7) . COVID-19 may involve many organ systems in its host. Studies suggest that hematological profiles change during SARS-CoV-2 illness. Neutrophils are involved in early anti-viral defense. However, during severe pneumonia, neutrophils become cytotoxic through degranulation and lysis (8) . Studies have suggested that neutrophil recruitment may exacerbate COVID-19 immunopathology (9) .
Lymphocytes play a crucial role in maintaining immune homeostasis during virus infection, especially SARS-CoV-2 (10) , among hematological parameters, lymphopenia is associated with disease severity; patients who have died from COVID-19 have had significantly lower lymphocyte counts than survivors.
Repletion of lymphocytes may be an important factor for recovery (11) (Henry, 2020

Study population Patients
This study included 504 hospitalized patients with confirmed COVID-19 infection, these study subjects were randomly selected irrespective of the age group and both genders were included.
It was performed following the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All the studied population was informed about the purpose of sample collection. Patients were free to refuse to include in this study.

Data collection
In this cross-sectional study, we obtained data regarding 504 hospitalized patients with confirmed COVID-19 via real-time reverse transcriptionpolymerase chain reaction (PCR), they came to Alyameny laboratory in Alexandria, Egypt for biomarkers and complete blood count investigations, and reviewed the medical records and compiled data between August 12 and December 30, 2020.

Collection and processing of blood samples:
EDTA blood sample was collected for performing complete blood count and platelet count (Diagon D-cell 60 hematology analyzer Europe-Diagon Ltd. Hungary) on 504 Positive COVID-19 patients for individuals matching in age and gender.
This study showed normal leukocyte count at 63.5%, leukopenia at 7.9%, leukocytosis at 28.6%, while neutrophilia has a sensitivity of 77.8% and lymphopenia has a sensitivity of 73% in mild COVID-19 infection which was less than CRP has a sensitivity 90.2% (16) , while other biomarkers have different sensitivity in mild COVID-19 infection as ferritin which has a sensitivity of 71.4% (17) , LDH has a sensitivity 67.7% (18) , and D-dimer has a sensitivity 36.4% (19) .
Neutrophils are immune cells that are well known to be present in various lung diseases, including viral respiratory disease (20) . As a hallmark of the pathophysiology, it is widely accepted that neutrophils can exit the circulation into the airways, either through the postcapillary venule in the systemic circulation or through the capillary in the pulmonary circulation (21,22) , this study showed high neutrophils count or neutrophilia has a sensitivity of 77.8% as a biomarker for COVID-19 diagnosis or prognosis in mild infected COVID-19 patients (Outpatients and patients under home observation).
Neutrophils are involved in early anti-viral defense.
A study involving 90 hospitalized COVID-19 patients reported an association between lymphopenia and disease severity (27) , this study showed lymphopenia has a sensitivity of 73%, and it was a significant biomarker for COVID-19 diagnosis or prognosis in mild COVID-19 patients (Outpatients and patients under home observation).

Conflict of interest
There are no conflicts of interest.

Financial support and sponsorship
This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors.