• HLA-DPA1 belongs to the HLA class II alpha chain paralogues. HLA-DPB1 belongs to the HLA class II beta chain paralogues. This class II molecule is a heterodimer consisting of an alpha (DPA) and a beta (DPB) chain, both anchored in the membrane. It plays a central role in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen presenting cells (APC: B lymphocytes, dendritic cells, macrophages). The alpha chain is approximately 33-35 kDa and its gene contains 5 exons. The beta chain is approximately 26-28 kDa and its gene contains 6 exons.
• The exons 1~6 of mouse I-Ab1 gene that encodes the full-length protein of I-Ab1 was replaced by a chimeric CDS sequence encoding the α chain of HLA-DP and a chimeric CDS sequence encoding the β chain of HLA-DP in B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice. The promoter sequence was derived from I-Ea gene. The following sequences were the chimeric CDS of humanized β chain including the β1 domain of human HLA-DPB1*03:01 and the β2, transmembrane, cytoplasmic domains of mouse I-Ab1 gene. The last sequences were the chimeric CDS of humanized α chain including the α1 domain of human HLA-DPA*02:02 and the α2, transmembrane, cytoplasmic domains of  mouse I-Aa gene. The mouse I-A protein was not detectable in the B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice because the mouse I-Ab1 gene was disrupted.
• Human HLA-DP was exclusively detectable in heterozygous B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice, but not in wild-type C57BL/6 mice.
• B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice provide a powerful preclinical model for in vivo evaluation of vaccines.
• Application: For example, this product is used for pharmacodynamics and safety evaluation of vaccines for cancers.

Gene targeting strategy for B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice. The exons 1~6 of mouse I-Ab1 gene that encodes the full-length protein of I-Ab1 was replaced by a chimeric CDS sequence encoding the α chain of HLA-DP and a chimeric CDS sequence encoding the β chain of HLA-DP in B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice. The promoter sequence was derived from I-Ea gene. The following sequences were the chimeric CDS of humanized β chain including the β1 domain of human HLA-DPB1*03:01 and the β2, transmembrane, cytoplasmic domains of mouse I-Ab1 gene. The last sequences were the chimeric CDS of humanized α chain including the α1 domain of human HLA-DPA*02:02 and the α2, transmembrane, cytoplasmic domains of  mouse I-Aa gene. The mouse I-A protein was not detectable in the B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice because the mouse I-Ab1 gene was disrupted.

Strain specific HLA-DP expression analysis in wild type C57BL/6 mice and heterozygous humanized B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice by flow cytometry. Blood cells were collected from wild type C57BL/6 mice (+/+) and heterozygous humanized B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice (H/+), respectively, and analyzed by flow cytometry with species-specific anti-human HLA-DP antibody (BD, 566825). Human HLA-DP was exclusively detectable in B cells(A), DC cells(B), macrophages(C) and monocytes(D) of heterozygous B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice, but not in wild-type C57BL/6 mice. 

Detection of peptide-induced immune responses in B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice by IFN-γ ELISpot assay. Female C57BL/6 mice (n=1) and B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice (n=2)  at the age of 11 weeks were inoculated the peptide at the inside muscle of both legs. One week after the last immunization, mice were sacrificed. The splenocytes were isolated and used as antigen presenting cell. Briefly, spleen cells were loaded with the antigen peptide for 2hrs and washed for co-culture assay. And then the peptide loaded spleen cells were co-cultured with engineered Mock-T or TCR-T cells for overnight for measuring the IFN-γ secretion by ELISA method, respectively. The results demonstrate that the negative control Mock-T cells can’t induce immune responses while the positive group TCR-T cells induce obvious responses in B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice. 

Note: This experiment was performed by the client using B-hHLA-DPA1*2.2/hHLA-DPB1*3.1 mice. All the other materials were provided by the client.