Background: Cytokines participate in regulating the immune response of lymphocytes. Interleukin 2 (IL-2) is the main modulator of T lymphocyte development, homeostasis, and function, whereas interleukin 7 (IL-7) regulates the development and homeostasis of immune cells and plays a crucial role in the maintenance of memory cells. The study aims to assess the blood IL-2 and IL-7 concentration in relation to the obtained cellular and humoral response in adults, six months after vaccination against COVID-19. Methods: We measured the concentration of IL-2 and IL-7 with ELISA, CoV2-IgG with an indirect chemiluminescence test, and the levels of IFN-γ with interferon gamma release assay (IGRA) post SARS-CoV-2 antigen stimulation. The study group (n = 76; F = 66, M = 10) was divided into 41 individuals, who did not report any chronic disorder (ChrD-Neg), and 35, who did (ChrD-Pos). Results: ChrD-Pos group presented higher IL-7 compared to ChrD-Neg (p = 0.023). Negative correlations were observed in the entire study population between IL-2 and age (R = −0.252, p = 0.028), as well as between IL-7 and IFN-γ (R = −0.295, p = 0.010). We found a positive correlation between IL-2 and IL-7 concentrations in the entire study population (R = 0.305, p = 0.007) and the ChrD-Pos group (R = 0.358, p = 0.035), and people with a positive IGRA result (R = 0.359, p = 0.005). Conclusions: The interaction of IL-2 and IL-7 may be important for achieving post-vaccination immunity, especially in adults with chronic diseases. Age is a factor modifying the post-vaccination response (decreased IL-2), whereas IL-7 may be an important factor in achieving a satisfactory post-vaccine response in people with chronic diseases.

Background: Vaccination against COVID-19 activates the cellular and humoral immune response.Aim: The aim of the study was to determine the anti-SARS-CoV-2 IgG (CoV2- -IgG) and T lymphocyte response to specific SARS-CoV-2 stimuli by releasing interferon gamma (IFN-γ) and humoral and cellular compounds, as well as to determine the impact of previous COVID-19, age, and BMI on the tested parameters in healthy volunteers six months after vaccination.Material and methods: We assessed the concentration of anti-SARS-CoV-2 IgG with an indirect chemiluminescence test and the concentration of IFN-γ with the interferon gamma release assay (IGRA).Results: CoV2-IgG was present in all subjects (n = 80), but not all tested volunteers were positive for IGRA (n = 62). The concentrations of both parameters were higher in people who had contracted COVID-19 before the test. The concentration of CoV2-IgG was higher in the IGRA-S1-positive group than in the IGRA-S1- -borderline group. Age (R = –0.237, p = 0.05) and BMI (R = –0.343, p = 0.003) were negatively correlated with the concentration of antibodies in the group with no history of COVID-19. The concentrations of anti-SARS-CoV-2 IgG and IFN-γ were positively correlated (R = 0.384, p = 0.001) among the vaccinated people.Conclusions: A moderate similarity was observed among the entire study group in the humoral and cellular post-vaccination effects. SARS-CoV-2 infection followed by vaccination against COVID-19 may result in a more robust humoral and cellular response than the vaccination itself. On the other hand, the humoral response may be impaired in its ability to mount an effective immune response following vaccination with age. The lymphocyte T response to specific SARS-CoV-2 stimuli seems not to be affected by BMI, while further steps leading to successful IgG production may be impaired with increasing body mass.