In Nasal Mucosal Secretions, Distinct IFN and IgA Responses Are Found in Severe and Mild SARS-CoV-2 Infection

Abstract

Likely as in other viral respiratory diseases, SARS-CoV-2 elicit a local immune response, which includes production and releasing of both cytokines and secretory immunoglobulin (SIgA). Therefore, in this study, we investigated the levels of specific-SIgA for SARS-CoV-2 and cytokines in the airways mucosa 37 patients who were suspected of COVID-19. According to the RT-PCR results, the patients were separated into three groups: negative for COVID-19 and other viruses (NEGS, n = 5); negative for COVID-19 but positive for the presence of other viruses (OTHERS, n = 5); and the positive for COVID-19 (COVID-19, n = 27). Higher specific-SIgA for SARS-CoV-2, IFN-β, and IFN-γ were found in the COVID-19 group than in the other groups. Increased IL-12p70 levels were observed in OTHERS group as compared to COVID-19 group. When the COVID-19 group was sub stratified according to the illness severity, significant differences and correlations were found for the same parameters described above comparing severe COVID-19 to the mild COVID-19 group and other non-COVID-19 groups. For the first time, significant differences are shown in the airway's mucosa immune responses in different groups of patients with or without respiratory SARS-CoV-2 infection.

Longitudinal Analysis of Inflammatory Response to SARS-CoV-2 in the Upper Respiratory Tract Reveals an Association with Viral Load, Independent of Symptoms

“…We observed that only some patients had S1-specific IgA in the nasal cavity while almost none had IgG, the magnitude of the response was lower than the one measured in serum. These heterogeneity of the S1-specific IgA levels at the mucosa has been recently reported by others [ 48 – 50 ]. IgA is important for early neutralization of SARS-CoV-2 in blood and saliva [ 41 ].…”

Long term positivity of SARS-CoV-2 total immunoglobulins in convalescent plasma and blood donors

“…IgG in combination with IgM and IgA would have greater neutralization capacity than IgG alone, a broader repertoire of antibodies correlates with a stronger SARS-CoV-2 neutralization [22]. Initial IgA plasmablast's response declines quickly, whereas IgA-producing plasma cells persist for years in mucosae [23]. It might explain that individuals mounting a strong IgA response would seem to loose antibodies, but it will be interesting to check out whether salivary IgA remains positive or not so far IgA antibodies are the major component of the neutralizing antibodies developed in response to SARS-CoV-2 infection [24] Lower lymphocyte counts and higher neutrophils and as well higher seric IgA would help predict future negativization of antibodies.…”

Mucosal antibody response to SARS-CoV-2 in paediatric and adult patients: a longitudinal study

“…A major limitation in mucosal immunity research is the inaccuracy of the results due to mucosal sample collection methods, such as, the nasal swabs or irrigation methods, which are subjected to low sample yield and inconsistency of the dilution effect. 20, 21 In our study, conjunctival fluid (CF) samples were collected with a technique similar to the Schirmer’s test 22, 23 while the nasal epithelial lining fluid (NELF) samples were collected by nasal strips. 24, 25 These methods are standardised and exhibit extended sample stability even when stored at room temperature, 26 which ensure sample validity.…”