Identification of human leukocyte antigen (HLA) class II restriction molecules. (a,b, top panel) Enzyme‐linked immunosorbent spot (ELISPOT) assays were performed using autologous lymphoblastoid cell lines (LCL) pulsed with peptides in the presence of monoclonal antibody (mAb) against HLA‐DR, DQ and DP. (bottom panel) CD4+ T‐cell clone recognition of HEK‐293T cells transfected with each donor HLA‐DR allele and pulsed with peptide was determined by ELISPOT assay. (c–e) ELISPOT assays were performed using autologous LCL pulsed with peptides in the presence of mAb against HLA‐DR, DQ, DP or HLA‐typed allogeneic LCL pulsed with peptides. All results are the mean of two duplicate values. SFC, spot forming units.