A chimeric MHC class II complex was created by fusing the human peptide antigen binding domains of class II alpha and beta chains (HLA-DRA and HLA-DRB5*01:01) to the remaining domains of murine class II alpha or beta chains (H2-Ea-ps and H2-Eb1 genes that make up mouse I-Ed). The chimeric gene constructs were manipulated by replacing exon 2 of IEd-alpha or IEd-beta genomic DNA with gene fragments containing exon 2 of HLA-DRA or HLA-DRB5*01:01, respectively. The native murine promoters were left intact. Two lines were created, a high expressing line (hi) and a low expressing line (lo). (J:189816)