The majority of patients known to be infected with SARS-CoV-2 appear to exhibit a typical immune response. In a normal immune response, various types of immune cells and cytokines cause a mild inflammatory state. The first cytokines released are interleukin-1 (Beta) and tumor necrosis factor-alpha. Cells of the innate immune system-neutrophils, monocytes, macrophages, and natural killer (NK) cells are also associated with the immune response. These cells directly attack the invading virus and release additional cytokines (e.g., Interleukin-6 (IL-6)). IL-6 is essential for invoking T cells, B cells, and T helper (Th) cells.7
In a study conducted by the Mayo Clinic8, most suspected female long COVID patients had a sharp rise in IL-6. These patients had high IL-6 levels up to three months after being infected with SARS-CoV-2. IL-6 has been associated with fatigue and sleep problems, and it also causes inflammation.
Anti-inflammatory cytokines help to turn off the pro-inflammatory response and return the immune system to a nonactivated but vigilant state. The deadliest manifestation of an abnormal immunological response is Cytokine Storm Syndrome, which can result in significant tissue damage in various body organ systems. A Cytokine Storm is now associated with the severe increase of cytokines in COVID-19 caused by SARS-CoV-2. Although the concept of a cytokine storm and the biological consequences of cytokine overproduction is not yet completely understood, one important molecular factor associated with overproduction is the kinetics of cytokine and chemokine gene expression.
97. Turgeon ML: Immunology and Serology in Laboratory Medicine, ed.7, St.Louis, 2022, pp. 20-23.8. Ganesh R, Grach S, Bierle D: Post-COVID symptoms: Women differ distinctly from men. Mayo Clinic, December 2, 2021. https://newsnetwork.mayoclinic.org/discussion/post-covid-symptoms-women-differ-distinctly-from-men/. 9. Turgeon ML: Immunology and Serology in Laboratory Medicine, ed. 7, St. Louis, 2022. pp. 35-39, 71-72.
