The chimpanzee major histocompatibility complex class II DR subregion contains an unexpectedly high number of beta-chain genes.
The major histocompatibility complex (MHC) class II DR subregion of the chimpanzee was studied by restriction fragment length polymorphism (RFLP) analysis. Genomic DNA obtained from a panel of 94 chimpanzees was digested with the restriction enzyme Taq I and hybridized with an HLA-DR beta probe specific for the 3' untranslated (UT) region. Such a screening revealed the existence of 14 distinct DRB/Taq I gene-associated fragments allowing the definition of 11 haplotypes. Segregation studies proved that the number of chimpanzee class II DRB/Taq I fragments is not constant and varies from three to six depending on the haplotype. Comparison of these data with a human reference panel manifested that some MHC DRB/Taq I fragments are shared by man and chimpanzee. Moreover, the number of HLA-DRB/Taq I gene-associated fragments detected in a panel of homozygous typing cells varies from one to three and corresponds with the number of HLA-DRB genes present for most haplotypes. However, a discrepancy is observed for the HLA-DR4, -DR7, and -DR9 haplotypes since a fourth HLA-DRB pseudogene present within these haplotypes lacks its 3' UT region and thus is not detected with the probe used. These results suggest that chimpanzees have a higher maximum number of DRB genes per haplotype than man. As a consequence, some chimpanzee haplotypes must show a dissimilar organization of the MHC DR subregion compared to their human equivalents. The implications of these findings are discussed in the context of the trans-species theory of MHC polymorphism.
Bontrop
R E
RE
ITRI-TNO, Primate Center, Rijswijk, The Netherlands.
Broos
L A
LA
Pham
K
K
Bakas
R M
RM
Otting
N
N
Jonker
M
M
D000818:Animals; D015139:Blotting, Southern; D004247:DNA / Q000032:analysis; D005787:Gene Frequency; D006239:Haplotypes; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D002679:Pan troglodytes / Q000235:genetics*; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length
D000949:Histocompatibility Antigens Class II; D004247:DNA