Expanding the utility of peptide:MHCII tetramer-based analysis of antigen-specific human CD4+ T cells

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Presentation Time: 03:15 PM - 04:30 PM
Poster Board Number: B924
Abstract ID: 5551

Presenting Author:
Shawn A Mahmud , Assistant Professor, Department of Pediatrics, Division of Pediatric Rheumatology at Univ. of Minnesota Med. Sch.

Abstract:

One challenge in peptide:MHCII tetramer-based research on human CD4+ T cells is that the MHCII molecule in the tetramer must match one expressed by each human subject.  HLA-DPA1*0103/HLA-DPB1*0401, also known as DP4, has a high allelic frequency of nearly 80% in the US population.  We therefore hypothesized that peptide:DP4 tetramers would permit analysis of antigen-specific CD4+ T cells without the need for laborious HLA typing.  

We synthesized two DP4 tetramers in which the peptide was covalently bound to the MHCII binding groove: one containing a peptide from RSV G-protein and the other from SARS-CoV-2 spike protein.  We stained peripheral blood mononuclear cells from healthy adult subjects and analyzed cells by flow cytometry.

RSV- or SARS-CoV-2-specific CD4+ T cells were detectable in over 80% of donors after infection or vaccination and were primarily either Th1 or Tfh cells.  We also show that DP4 tetramers loaded with the class II invariant chain peptide, CLIP, can be exchanged with new peptides of interest, rapidly generating novel DP4 tetramers.

These data show that DP4-restricted antigen-specific CD4+ T cells can be identified in most humans without knowledge of HLA haplotype.  The high allelic frequency of DP4 and novel exchangeable DP4 tetramers have potential to increase the utility of tetramer-based analysis of antigen-specific CD4+ T cells in humans.