Effect of IL-6 and CRP titer with antibody level on severity of COVID-19 infection

Abstract

OBJECTIVE:

SARS Coronavirus 2 (SARS-CoV-2) infection is combined with a high death rate and morbidity in different regions across the world. Interleukin-6 (IL-6) is a pleiotropic cytokine secreted in response to tissue injury, primarily produced by macrophages. C-reactive protein (CRP) is considered a part of innate immunity and is elevated in response to infection and cancer.

METHODS:

This study includes one hundred patients infected with the viral pathogen known as SARS-CoV-2 and fifty healthy individuals attending Al-Salam Hospital in Baghdad. Approximately 5 ml of samples were collected from each virus-infected patient and healthy control, then separated by centrifuge and stored in a refrigerator until testing. The study timeline was from October 1st, 2020, to January 15th, 2021. The SARS-CoV-2 (IgM, IgG) antibody was measured using the immunofluorescent technique with the Afias instrument. The IL-6 was measured using the ELISA technique with a human Elisa reader. The CRP titer was measured using the immunofluorescent technique with the Afias instrument. The level of SARS-CoV-2 (IgM, IgG) antibody was 0.01 $\pm$ 0.004, 0.02 $\pm$ 0.004, respectively, in healthy controls, while in COVID-19 patients, the level of SARS-CoV-2 IgM antibody was 2.45 $\pm$ 1.87, and the level of IgG antibody was 5.16 $\pm$ 2.63 in COVID-19 patients. The IL-6 level was 0.88 $\pm$ 0.28, 5.82 $\pm$ 3.28 in healthy controls and COVID-19 patients, respectively. The CRP titer in healthy controls was 1.25 $\pm$ 0.36, while in COVID-19 patients, it was 13.8 $\pm$ 4.85. The aim of the research is to focus on the association between IL-6 level and CRP titer, with a concentration on COVID-19 patients, and to determine if IL-6 possesses the potential to serve as a biomarker for prognosticating the extent of COVID-19 infection.