HLA-DRB1 and systemic lupus erythematosus: We therefore evaluated antigen-specific T cell responses in 10 patients with SLE (n = 6 HLA-A*02:01, n = 4 HLA-DRB1*15:01) and 6 HC (n = 3 HLA-A*02:01, n = 3 HLA-DRB1*15:01) using peptide MHC (pMHC) spheromers displaying SARS-CoV-2 Spike epitopes (24).