SARS-CoV-2 specific plasma cells acquire the phenotype of long-lived plasma cells in the human bone marrow

Establishment of long-lived plasma cells (PC) in the bone marrow (BM) is important for the development of long-term specific humoral immunity. While SARS-CoV-2-specific, resting, affinity-matured, IgG-secreting plasma cells were described in human bone marrow approx. 6-7 months after infection or vaccination, the long-term durability of these PC remains unclear. We here show that approximately 20% of SARS-CoV-2-specific human BM plasma cells, including RBD-specific PC accommodate the phenotype of long-lived plasma cells, characterized by the lack of CD19 and/or CD45. This result provides evidence in support of the emergence of persistent SARS-CoV-2 specific plasma cells in humans sustaining the durable production of specific serum IgG protecting against severe courses of COVID-19.