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5swq
From Proteopedia
Crystal Structure of HLA-A*0201 in complex with NA231, an influenza epitope
Structural highlights
Disease[B2MG_HUMAN] Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:241600]. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation.[1] Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] Function[1A02_HUMAN] Involved in the presentation of foreign antigens to the immune system. [B2MG_HUMAN] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Publication Abstract from PubMedalphabetaT cell receptor (TCR) genetic diversity is outnumbered by the quantity of pathogenic epitopes to be recognized. To provide efficient protective anti-viral immunity, a single TCR ideally needs to cross-react with a multitude of pathogenic epitopes. However, the frequency, extent, and mechanisms of TCR cross-reactivity remain unclear; with conflicting results on anti-viral T cell cross-reactivity observed in humans. Namely, both the presence and lack of T cell cross-reactivity has been reported with HLA-A*02:01-restricted epitopes from the Epstein-Barr and influenza viruses (BMLF-1 and M158, respectively) or with the hepatitis C and influenza viruses (NS31073 and NA231, respectively). Given the high sequence similarity of these paired viral epitopes (56% and 88%, respectively), the ubiquitous nature of the three viruses, and the high frequency of the HLA-A*02:01 allele, we selected these epitopes to establish the extent of T cell cross-reactivity. We combined ex vivo and in vitro functional assays, single-cell alphabetaTCR repertoire sequencing, and structural analysis of these four epitopes in complex with HLA-A*02:01 to determine if they could lead to heterologous T cell cross-reactivity. Our data show that sequence similarity does not translate to structural mimicry of the paired epitopes in complexes with HLA-A*02:01, resulting in induction of distinct alphabetaTCR repertoires. The differences in epitope architecture might be an obstacle for TCR recognition, explaining the lack of T cell cross-reactivity observed. In conclusion, sequence similarity does not necessarily result in structural mimicry, and despite the need for cross-reactivity, antigen-specific TCR repertoires can remain highly specific. Lack of heterologous cross-reactivity towards HLA-A*02:01 restricted viral epitopes is underpinned by distinct alphabetaT cell receptor signatures.,Grant EJ, Josephs TM, Valkenburg SA, Wooldridge L, Hellard M, Rossjohn J, Bharadwaj M, Kedzierska K, Gras S J Biol Chem. 2016 Sep 19. pii: jbc.M116.753988. PMID:27645996[15] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Human | Gras, S | Josephs, T M | Rossjohn, J | Cross-reactivity | Heterologous immunity | Hla-a*02:01 | Immune system | T cell | Tcr
