Proteomic Profiling of Human Peripheral Blood Cell Targets of IgG Induced by SARS-CoV-2: Insights into Vaccine Safety.

BACKGROUND/OBJECTIVES: COVID-19 has been associated with a wide range of immune responses, including the production of autoantibodies, particularly in severe cases. This study investigates the IgG autoantibody responses in patients with varying severities of COVID-19 infection and compares these responses with vaccinated individuals. METHODS: We utilized proteomic profiling to analyze autoantibody reactivity against a broad spectrum of proteins expressed in lymphoid and myeloid cell subsets in serum samples from severe and moderate COVID-19 patients, as well as vaccinated individuals who received the inactivated CoronaVac (Sinovac) vaccine. RESULTS: Our findings indicate a marked increase in the diversity and number of IgG autoantibodies targeting intracellular and membrane-associated proteins in severe COVID-19 cases, compared to those with moderate cases of the disease. The autoantibody response in severe cases was found to primarily target proteins involved in immune cell activation, signaling, and differentiation, suggesting potential pathways of immune dysregulation and autoimmunity. In contrast, vaccinated individuals did not exhibit similar autoantibody reactivity, pointing to a more controlled immune response post-vaccination. Notably, no significant autoimmune responses were detected in the vaccinated cohort, suggesting that the inactivated vaccine does not induce autoreactive IgG. These findings align with the established safety profile of COVID-19 vaccines, especially in comparison to the heightened immune dysregulation observed in severe COVID-19 patients. The absence of a significant autoantibody response in vaccinated individuals supports the notion that vaccines, while inducing robust immune activation, do not typically trigger autoimmunity in healthy individuals. CONCLUSIONS: Our study underscores the importance of distinguishing between the immune responses triggered by infection and vaccination and highlights the need for the continued monitoring of autoimmune responses in severe COVID-19 cases. Future research should focus on the long-term persistence and clinical relevance of these autoantibodies, particularly in individuals with pre-existing autoimmune conditions or genetic predispositions.