An H-2 haplotype possibly derived by crossing-over between (A alpha A beta) duplex and the E beta locus

Area of Science:

• Immunogenetics
• Molecular immunology
• Mice models

Background:

• The H-2w27 haplotype was identified in a wild mouse population near Ann Arbor, Michigan.
• Class II major histocompatibility complex (MHC) genes play critical roles in immune responses.

Purpose of the Study:

• To characterize the molecular and functional properties of the H-2w27 haplotype.
• To investigate the genetic relationship between the H-2w27 haplotype and other known MHC haplotypes.

Main Methods:

• Serological analysis to detect antigenic determinants.
• Biochemical characterization using tryptic peptide mapping.
• Functional assays involving cytotoxic T cell recognition.

Main Results:

• The A alpha and A beta loci products of H-2w27 are indistinguishable from those of B10.A(5R).
• The E beta locus product of H-2w27 (Ew27 beta chain) differs significantly from the B10.A(5R) Eb beta chain, lacking and possessing distinct antigenic determinants.
• Peptide mapping revealed at least six differences between Eb beta and Ew27 beta chains, with cytotoxic T cells not recognizing Ew27 beta.

Conclusions:

• The significant differences suggest Ew27 beta is not a direct mutation of Eb beta.
• H-2w27 is likely a recombinant haplotype formed by crossing over between the A alpha-A beta duplex and the E beta locus.
• This represents the first identified recombinant haplotype that separates these specific class II loci.