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Peptide Pools for Immune Monitoring? PBMC from HemaCare Help Argue the Case

Jun 29, 2016 1:00:53 PM / by Maria

HemaCare's PBMC were used as evidence that peptide pools, rather than one or a few predicted peptides, may be key for an accurate assessment of antigen-specific CD8+ T cell immunity. Image credit: http://commons.wikimedia.org.How often do predicted peptides actually get recognized by CD8+ cells? The surprising answer was provided in part by HemaCare's PBMC.

We all have our type -- HLA type, that is. Each human has up to six different HLA Class 1 molecules, from out of more than 100  MHC/HLA Class I alleles in existence to "choose" from. These allelic HLA variants are unique in their peptide-binding specificity, meaning that antigen recognition by CD8+ T cells depends on the alleles that you have. "Peptide recognition by CD8 cells is therefore highly variable among individuals of an outbred population, as variable as the HLA system itself." [1]

The research community has accumulated considerable knowledge about the peptide-binding requirements of individual HLA alleles. The CEF (Cytomegalo-, Epstein-barr, Influenza virus) peptide pool, comprising 32 peptides, is frequently employed as a positive control for experiments involving CD8+ cells, including those studying anti-cancer immunity.

But how well do these predictions stand up to the test? One group of researchers used peripheral blood mononuclear cells (PBMC) from 42 donors recruited by HemaCare.  These donors were high-resolution HLA-typed for three alleles, and they were all cytomegalovirus, Epstein-B virus, and influenza virus positive. The researchers used an ELISPOT assay in which interferon-gamma release, a sign that peptide recognition occurred, was measured.

It turns out that the predictions have some room for improvement. Fifty-one percent of the time, the predicted peptide failed to induce a detectable recall response. Other times, it was subdominant or cryptic among several targeted determinants. The authors argue that it would be better to use peptide pools for immune monitoring, rather than hoping that one or a few peptides are truly dominant.

HemaCare is proud to have supplied the PBMC, which were isolated from healthy donors under an Internal Review Board-approved protocol. Please do not hesitate to call us at (877) 397-3087 for any questions related to our products, or to discuss with us your research needs.

Reference

  1. Moldovan, I et al. How frequently are predicted peptides actually recognized by CD8 cells? Cancer Immunology, Immunotherapy (2016) doi: 10.1007/s00262-016-1840-7

Topics: antigens, T Cells, Basic Research

Maria

Written by Maria

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