The proliferation of belatacept‐resistant T cells requires early IFNα pathway activation

Belatacept was developed to replace calcineurin inhibitors in kidney transplantation. Its use is associated with better kidney transplant function, a lower incidence of anti-donor antibodies and higher graft survival. However, it is also associated with a higher risk of cellular rejection. We studied the activation and proliferation mechanisms of belatacept-resistant T lymphocytes (TLs), to identify new pathways for control. We performed a transcriptomic analysis on CD4(+)CD57(+)PD1(-) memory TLs, which are responsible for a higher incidence of graft rejection, after allogeneic stimulation with activated dendritic cells (aDCs) in the presence or absence of belatacept. After six hours of contact with aDCs, the (CD4(+)CD57(+)PD1(-)) (CD4(+)CD57(+)PD1(+)) and (CD4(+)CD57(-)) lymphocytes had different transcriptional profiles with or without belatacept. In the CD4(+)CD57(+)PD1(-)population, the IFN alpha-dependent activation pathway was positively overrepresented, and IRF7 transcript levels were high. IRF7 was associated with IFN alpha/beta and IL-6 regulation. The inhibition of both these cytokines in a context of belatacept treatment inhibited the proliferation of CD4(+)CD57(+)PD1(-) T cells. Our results show that IRF7 is rapidly upregulated in belatacept-resistant CD4(+)CD57(+)PD1(-) TLs. The inhibition of type I IFN or IL-6 in association with belatacept treatment reduces the proliferation of belatacept-resistant TLs, paving the way for new treatments for use in organ transplantation.