COVID-19 convalescent plasma (CCP) is considered as an important element of therapy for patients in the initial stages of the disease.The main therapeutic effect of CCP is associated with the presence of specific antiviral antibodies. Additionally, the immunomodulatory effect of CCP is considered as therapeutic where cytokines represented one of the main factors. The aim of the study was to evaluate the importance of cytokines and cytokine ratio of transfused CCP for the outcome of the disease in patients who received it during inpatient treatment of COVID-19. Materials and methods. The study included data from 111 patients with COVID-19 who received CCP. The cytokine content in the CCP was measured by enzyme immunoassay Results. It was found that elevated levels of interleukin-6 (IL-6) and interferon-gamma (IFNγ), but not IL-1β, IL-8, IL-10, IL-15, IP-10/CXCL10, MCP-1/CCL2 were detected in CCP transfused mainly to patients who had an unfavorable (fatal) outcome of the disease. Values of cytokine ratios of IFNγ/IL-10, IFNγ/IP-10, IFNγ/MCP-1, IL-6/IL-8, IL-6/IL-10, IL-6/IP-10, IL-6/IL-15 were also significantly increased in these CCP series as compared to CCP samples transfused to patients of the recovered group. Low levels of IL-6 and IFNγ, reduced level of cytokine ratios of IL-6/IP-10, IL-6/IL-15, IFNγ/MCP-1, IFNγ/IP-10, IFNγ/IL-15 were characteristic of CCP, which was transfused to patients, subsequently recovered. The level of IL-6 in the CCP samples transfused to the patients of the recovered group had a strong direct correlation (r = 0.9) with the cytokine ratios of IL-6/IL-10 and IL-6/IP-10, while in the group of the deceased patients there was no strong association (r = 0.6). IFNγ levels in the CCP showed a strong direct correlation with the values of all analyzed cytokine ratios (IFNγ/IL-10 (r = 0.9), IFNγ/IP-10 (r = 0.9), IFNγ/MCP-1 (r = 0.9)). The level of INF-γ in the CCP transfused to patients of the recovered group had a positive correlation with the cytokine ratios of IFNγ/IL-10 (r = 0.78), IFNγ/IP-10 (r = 0.9), IFNγ/MCP-1 (r = 0.75). The level of INFγ in the CCP transfused to patients of the deceased group had higher values of positive correlation with ratios of IFNγ/IL-10 (r = 0.96), IFNγ/IP-10 (r = 0.92), IFNγ/MCP-1 (r = 0.92). Conclusion. The level of cytokines IL-6 and IFNγ, the cytokine ratios based on them in the CCP may affect the outcome of COVID-19 in patients treated with CCP.
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