Updated project metadata. The immune response to SARS-CoV-2 varies among patients. We used proteomic analysis to study CD19+ lymphocytes, which are important for the immune response. By comparing the proteomes of CD19+ cells from healthy individuals and COVID-19 patients, we discovered proteins and signaling pathways involved in the immune response during COVID-19. This knowledge improves our understanding of immune dysregulation in COVID-19 and can help develop targeted therapies. Our research also explores the role of CD19+ lymphocytes in COVID-19 and identifies potential biomarkers. Overall, our findings contribute to understanding COVID-19 immunology and inform future research efforts.