Serum of Interferon Lambda-1 level as a protein biomarker for the diagnosis of COVID-19 severity
Authors: Abbas Shakir Abdulridha , Ali Hanaa Addai , Ali Rawaa Adday , Mashkur Muthanna Saleh , Hasan Mohammed Saeed Salman , Awad Ayat Saeed , Rufaie Mohauman Mohammed Al 
Published: November 2024

Abstract
SARS-CoV-2, which mostly affects the respiratory system, is the agent that causes COVID-19. The virus enters human cells through the ACE2 receptor, which is expressed on the surface of many different types of cells in the body. Once inside the cell, the virus begins to replicate and spread throughout the body. Interferon Lambda-1, also known as IFN-λ1, is a type of cytokine that is secreted by the immune system of the body in response to viral infections.
Objective to evaluate if serum levels of Interferon Lambda-1 are associated with how severe the COVID-19 infection is, so as to determine if this cytokine may be considered as a disease marker.
This study was undertaken as a case control, using a study population of one hundred and twenty COVID-19 patients (79 males, 41 females). The COVID-19 patients were divided into three groups based on the severity of the illness: critical disease (n=30), severe disease (n=30), and mild/moderate disease (n=60), with (n=60) healthy volunteers as the control group (35 males, 25 females). Between January 2022 and May 2022, the patients were collected from Al-Amal hospitals and the AL-Shefaa center in AL- Najaf City, Iraq. Basic patient clinical and demographic data was obtained, along with blood samples. Enzyme-linked immunosorbent tests (ELISA) were used to measure the blood’s concentration of interferon lambda-1. Total cholesterol, triglycerides and high density lipoprotein content were measured by colorimetric methods. Ichroma was tested for serum ferritin and D-dimer, while CBC was obtained via Swelab to ascertain if interferon Lambda-1 levels are related to the severity of the disease.
Interferon Lambda-1 levels in the patient group were determined to be higher, particularly in cases with mild to moderate (64.19±18.77) pg/mL (P=0.0001), severe (236.51±63.65) pg/mL (P=0.0001), and critical (465.61±62.16) pg/mL (P=0.0001) cases, as compared to healthy controls (41.72±12.92) pg/mL groups, respectively. Our results showed a significant negative correlation between SPO2%, Lymphocyte, HDL, TC and Hb (p.value=0.001) levels in the group of COVID-19 patients. TG, VLDL-C, neutrophils, WBCs, platelets, the N/L ratio, D-dimer, CRP and ferritin all have a significant positive correlation (p.value=0.001) with Interferon Lambda-1 in the COVID-19 patients group. A cutoff value of 50.50 (ng/mL) with a sensitivity of 82.5% and a specificity of 80.9% (AUC: 0.910, 95% CI 0.870-0.950; p<0.0001) for Interferon Lambda-1 predicted severe COVID-19.
In comparison to the mild/moderate patient group and healthy controls, we found that severe and critical COVID-19 patients had considerably greater serum Interferon Lambda-1 concentrations. This could be a useful sign of the disease’s severity. In order to prevent the onset of pulmonary inflammation, high blood Interferon Lambda-1 concentrations in the early stages of COVID-19 should be continuously monitored. Our work also revealed that Interferon Lambda-1 was highly associated with COVID-19 severity. We believe that Interferon Lambda-1 may be a valuable biomarker in determining the severity of the disease in COVID-19 patients.