New reservoirs of HLA alleles: pools of rare variants enhance immune defense.

摘要: Highly polymorphic exons of the major histocompatibility complex (MHC, or HLA in humans) encode critical amino acids that bind foreign peptides. Recognition peptide-MHC complexes by T cells initiates adaptive immune response. The particular structure these facilitates gene conversion(GC) events, leading to generation new alleles. Estimates for allele creation and loss indicate more than 10000 such alleles are circulating at low frequencies human populations. Empirical sampling has affirmed this expectation. This suggests MHC loci have a system moving valuable often variants into service. Here, we argue carry many mutant prepared assume epidemiologically meaningful roles when called on selection provoked exposure evolving pathogens. Because appear population lowest possible frequency (i.e., single copy), they typically been thought as having little consequence. However, large rare yet potentially may contribute pathogen defense.