Synergistic effect of CXCR5(+)CD8(+)T(Absupp) cell therapy and mTOR inhibition (but not calcineurin inhibition) in suppressing alloantibody following kidney transplant in mice

Abstract CXCR5+CD8+TAb-supp cells inhibit alloantibody (alloAb) production, AMR, and prolong graft survival in mouse models. To determine if this cell therapy is compatible with standard immunosuppression (IS) strategies, we investigate the interaction of CD8+ TAb-supp adoptive cell therapy (ACT) and IS [mTOR inhibitors (mTORi) or CNi] in a mouse model of kidney transplant (KTx). CXCR5+CD8+ T cell ACT to CCR5 KO recipients on day 1 after KTx (D1) significantly suppresses D14 alloAb titer (1259±114) versus untreated controls (5951±630; p=0.0001). Administration of mTORi significantly inhibits alloAb titer (495±77; p<0.0001), while CNi does not (6473±434; p=ns). ACT combined with mTORi significantly reduces alloAb titer compared to ACT alone (387±63 vs 1259±114; p=0.0007). Conversely, CNi treatment partially negates the beneficial effects of ACT on alloAb titer (2385±114; p=0.03). Similarly, ACT reduced the quantity of D14 splenic germinal center (GC; GL-7+Fas+B220+) B cells compared to untreated KO recipients (4037±515 vs 5815±655 cells/mm3; p=0.03). Addition of mTORi to ACT preserves ACT-mediated suppression of GC B cells (4498±940 cells/mm3) while CNi negates ACT-mediated GC B cell suppression (6130±834 cells/mm3; p=0.04). Analysis of persisting GFP+CXCR5+CD8+ T cells D14 after ACT shows that concurrent mTORi treatment is associated with comparable quantity (1671±139 cells/mm3; p=ns), while CNi is associated with reduced quantity (900±83 cells/mm3; p=0.01)of transferred GFP+CXCR5+CD8+ T cells detected in the spleen compared to ACT alone (1601±116 cells/mm3). ACT with CXCR5+CD8+TAb-supp cells is optimal when combined with mTORi, not CNi, to significantly inhibit alloAb production and reduce quantity of splenic GC B cells. Supported by NIH R01 AI083456 (to GLB), T32 AI106704-07 and F32 AI161844 (to JLH), CA016058, UL1TR002733, the OSU Division of Transplant Surgery, and the OSU College of Medicine.