Anti-TBX21 Monoclonal antibody, clone 5C20 [PE/Cy7®]

Boosting T cell immune response posttransplant with checkpoint inhibitors increases graft-versus-lymphoma (GVL) effects at the cost of increasing acute graft-versus-host disease (aGVHD). A combined targeted therapy is needed to decrease checkpoint inhibitors-induced aGVHD without impairing GVL. We studied whether this competition could be avoided by giving concurrent anti-PD-1 antibody and ruxolitinib in allotransplant mouse models in which recipients were challenged with A20 or EL4 lymphoma cells. Given alone the PD-1 antibody increased GVL but did not improve survival of recipients challenged with A20 cells because of increased deaths from aGVHD. Adding ruxolitinib decreased levels of effector T cells and related cytokines. Tbx21(-)T cells had higher PD-1 levels compared with Tbx21(+)T cells. Ruxolitinib increased PD-1 levels on donor T cells by suppressing Tbx21 expression. Ruxolitinib increased apoptosis of T cells which was reversed by the PD-1 antibody. PD-1 antibody preserved expression of granzyme B and cytotoxicity of T cells which were decreased by ruxolitinib. The net result of combined therapy was increased GVL, no increase in aGVHD and increased survival. The combined therapy improved survival of recipients challenged by A20 cells which expressed high level of PD-L1, but not EL4 cells which do not express PD-L1.

The onset of protective immunity against pathogenic SIV challenge in SIV Delta nef-vaccinated macaques is delayed for 15-20 weeks, a process that is related to qualitative changes in CD8(+) T cell responses induced by SIV Delta nef. As a novel approach to characterize cell differentiation following vaccination, we used multi-target qPCR to measure transcription factor expression in naive and memory subsets of CD8+(+) T cells, and in SIV-specific CD8(+) T cells obtained from SIV Delta nef-vaccinated or wild type SIVmac239-infected macaques. Unsupervised clustering of expression profiles organized naive and memory CD8(+) T cells into groups concordant with cell surface phenotype. Transcription factor expression patterns in SIV-specific CD8(+) T cells in SIV Delta nef-vaccinated animals were distinct from those observed in purified CD8(+) T cell subsets obtained from naive animals, and were intermediate to expression profiles of purified central memory and effector memory T cells. Expression of transcription factors elicited by SIV Delta nef vaccination also varied over time: cells obtained at later time points, temporally associated with greater protection, appeared more central-memory like than cells obtained at earlier time points, which appeared more effector memory-like. Expression of transcription factors associated with effector differentiation, such as ID2 and RUNX3, were decreased over time, while expression of transcription factors associated with quiescence or memory differentiation, such as TCF7, BCOR and EOMES, increased. CD8(+) T cells specific for a more conserved epitope expressed higher levels of TBX21 and BATF, and appeared more effector-like than cells specific for an escaped epitope, consistent with continued activation by replicating vaccine virus. These data suggest transcription factor expression profiling is a novel method that can provide additional data complementary to the analysis of memory cell differentiation based on classical phenotypic markers. Additionally, these data support the hypothesis that ongoing stimulation by SIV Delta nef promotes a distinct protective balance of CD8(+) T cell differentiation and activation states.