T-cell response to the S1 domain of SARS-CoV-2 Spike protein in female nonagenarian residents of nursing homes from population with a low centenarian ratio

Aim:
For several decades, understanding ageing and the phenomena of longevity has challenged biologists. Among the possible causes, an impairment of the immune system plays a major role in the ageing process. This study is aimed to measure the immunological cellular response to an mRNA-based SARS-CoV-2 vaccine by applying commercial whole-blood-based IFN-γ release assay (IGRA) and correlating it to the humoral response in female nonagenarians and other elder residents of nursing homes.

Material and methods:
From May to September 2022 a total of 109 female subjects living as residents in three nursing homes for elder people were tested for IgG antibodies to the SARS-CoV-2 S1-protein in serum and for ex vivo release of IFN- γ by specific CD4+ and CD8+ T lymphocytes stimulated by components of the S1 domain of SARS-CoV-2 Spike protein.

Results:
Median levels (IQR) of SARS-CoV-2 IgG and IFN- γ were 3496.3 (1681.9-5363.8) AU/mL and 2100.0 (1144.4-3925) mIU/mL, respectively. There were no differences in the concentration of anti-SARS-CoV-2 antibodies and IGRA between 12 nonagenarians and 97 participants from younger age groups. We found a moderate statistically positive correlation between concentrations of SARS-CoV-2-IgG and INF-γ in IGRA.

Conclusions:
Carrying out costly and requiring additional organisational outlays cellular immunity tests did not enable the identification of nonagenarians or other older residents of nursing homes requiring additional anti-COVID-19 preventive measures.