Which came first, MHC class I or MHC class II? For decades, it has been debated which of these two similar classes came first in evolution. Now, Keiichiro Hashimoto and his group at Fujita Health University, Japan, in collaboration with European research groups, have provided an answer to this question in a new article in PNAS. They discovered an ancient category of MHC molecules, MHC-W, that represents a missing link for explaining how class I molecules evolved from a class II-like origin. Peter Parham, professor at Stanford and the PNAS guest editor who handled the Okamura et al. paper, declares: “In demonstrating that MHC class II evolved prior to MHC class I, which evolved from MHC class II, this landmark study has resolved an important and outstanding puzzle in immunogenetics.”
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Source: Phys.org