Recognition of Distinct Cross-Reactive Virus-Specific CD8+ T Cells Reveals a Unique TCR Signature in a Clinical Setting

Abstract

Human CMV still remains problematic in immunocompromised patients, particularly after solid organ transplantation. CMV primary disease and reactivation greatly increase the risks associated with incidences of chronic allograft rejection and decreased survival in transplant recipients. But whether this is due to direct viral effects, indirect viral effects including cross-reactive antiviral T cell immunopathology, or a combination of both remains undetermined. In this article, we report the novel TCR signature of cross-reactive HLA-A*02:01 (A2) CMV (NLVPMVATV [NLV])–specific CD8+ T cells recognizing a specific array of HLA-B27 alleles using technical advancements that combine both IFN-γ secretion and multiplex nested RT-PCR for determining paired CDR3α/β sequences from a single cell. This study represents the first evidence, to our knowledge, of the same A2-restricted cross-reactive NLV-specific TCR-α/β signature (TRAV3TRAJ31_TRBV12-4TRBJ1-1) in two genetically distinct individuals. Longitudinal posttransplant monitoring of a lung transplant recipient (A2, CMV seropositive) who received a HLA-B27 bilateral lung allograft showed a dynamic expansion of the cross-reactive NLV-specific TCR repertoire before CMV reactivation. After resolution of the active viral infection, the frequency of cross-reactive NLV-specific CD8+ T cells reduced to previremia levels, thereby demonstrating immune modulation of the T cell repertoire due to antigenic pressure. The dynamic changes in TCR repertoire, at a time when CMV reactivation was subclinical, illustrates that prospective monitoring in susceptible patients can reveal nuances in immune profiles that may be clinically relevant.

Abundant cytomegalovirus (CMV) reactive clonotypes in the CD8+ T cell receptor alpha repertoire following allogeneic transplantation

“…These four clonotypes accounted for 16Á5% of all detectable TCR-a NGS reads. Public motifs for TCR-a and TCR-b [23][24][25] were found in this patient (Table 4). Table 1).…”

“…One additional clonotype was found with a read frequency >1% only in the sample from day 525 (Supporting information, Table S2). Previously described common motifs within the CDR3 amino acid sequence of CMV-specific T cells [23][24][25] were identified in four of the nine clonotypes with >1% read frequencies (NNNDM, GNQF and YGQNF, Fig. 2a).…”

“…2b). The CDR3 sequence of TCR-a-IE-2 contained a known common motif for CMV-specific T cells (GNQF [23][24][25][26]). …”

“…One of the most frequent clonotypes contained a public CMV motif (NNNDM [23][24][25]). The clonotypes identified in the CMV pp65 -specific CD8 1 T cells represented 22Á5% of all detectable reads in the total CD8 1 T cells.…”

“…The clonotypes identified in the CMV pp65 -specific CD8 1 T cells represented 22Á5% of all detectable reads in the total CD8 1 T cells. Assessing the rest of the CD8 1 compartment for public CMV motifs [23][24][25][26] revealed three additional highly represented clonotypes that contained the CMV motifs GNQF and NTGNQF within their CDR3 sequence. Paired TCR-ab sequencing of single CMV pp65 -specific T cells identified four different clonotypes in 33 analysed cells.…”