Serum Levels of IL-21 and IL-27 do not Reflect differential Avidity  of Anti-SARS-CoV-2 IgG Antibodies in Symptomatic and Asymptomatic COVID-19 Patients

Mozhdeh  Ebrahimpour; Mehrdad  Hajilooi; Ghasem  Solgi; Mohsen  Rastegari-Pouyani

doi:10.18502/ijaai.v24i3.18687

Mozhdeh Ebrahimpour Department of Immunology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
Mehrdad Hajilooi Department of Immunology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
Ghasem Solgi Department of Immunology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
Mohsen Rastegari-Pouyani Department of Immunology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran

DOI: https://doi.org/10.18502/ijaai.v24i3.18687

Keywords: Antibody avidity; Interleukin-21; Interleukin-27; Severe acute respiratory syndrome coronavirus 2

Abstract

The quantity and quality of anti-Spike (anti-S) antibodies, rapidly elicited by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are necessary for understanding the immune response induced by infection. Antibody avidity is a good indicator of the quality of antibody response. Interleukin (IL)-21 and IL-27 are two cytokines that play vital roles in the affinity maturation process. Therefore, we decided to investigate whether there are any relationships between the avidities of antibodies against spike and nucleocapsid (N) antigens of SARS-CoV-2 and serum levels of these cytokines in symptomatic and asymptomatic coronavirus disease 2019 (COVID-19) patients.

Forty symptomatic COVID-19 patients and 40 asymptomatic carriers were enrolled. Anti-S and anti-N IgG avidity indices (AIs) were determined using a modified enzyme-linked immunosorbent assay (ELISA). Serum levels of IL-21 and IL-27 were quantified by specific ELISA kits.

AI values of both anti-S and anti-N IgG were lower in the symptomatic group compared to asymptomatic cases, while only that of anti-N IgG was statistically significant. For IL-21 and IL-27 serum levels, no significant difference between the two groups was shown. Also, we could not find any correlations between cytokine levels and antibody AI values. However, an inverse correlation between anti-S AI value and IL-27 serum level was found in asymptomatic patients.

Our study suggests that serum levels of IL-21 and IL-27 cannot predict differences in anti-S and anti-N IgG avidity between symptomatic and asymptomatic COVID-19 patients.