Analysis of cell-mediated immunity in people with long Covid.

Montes, N.; Domenech, E.; Guerrero, S.; Olivampaacuten-Blampaacutezquez, B.; Magallon-Botalla, R.

Introduction: The objective of this study is to analyse the specific immune response against SARS-CoV-2 in those affected by Long Covid (LC), attributable to T cells (cell-mediated immunity) and to carry out a parallel analysis of the humoral response and lymphocyte typing. Methodology: Descriptive cross-sectional study of 74 patients with LC for at least 4 months since diagnosis. The collected data were: information on the COVID-19 episode and the persistent symptoms, medical history and a specific cell-mediated immunity to SARS-CoV-2 through flow cytometry, assessing the release of interferon-gamma (IFN-{gamma}) by T4 lymphocytes, T8 lymphocytes and NK cells. Descriptive and comparative analyses were carried out. Results: Patients with LC had negative serology for Covid-19 in 89% of cases but 96% showed specific cellular immunity to SARS-CoV-2 an average of 9.5 months after infection: 89% of this response corresponded to T8 lymphocytes, 58% to NK cells, and 51% to T4 lymphocyte (20% negligibly positive). Most of them had altered immune cell typing and we found that T4 lymphocyte counts were low in 34% of cases and NK cell high in 64%. Macrophage populations were detected in the peripheral blood of 7% of them. Patients displayed a higher percentage of illnesses related to ''abnormal'' immune responses, either preceding SARS-CoV-2 infection (43%) or following it in 23% of cases. Conclusion: The immune system appears to have an important involvement in the development of LC and viral persistence could be the cause or consequence of it. Further analysis with a control group should be performed.