Final crossmatch testing is routinely used to assess the risk of antibody-mediated graft injury/rejection post-transplant. Analogously, we postulated that quantitative measurements of anti-donor effector/memory T cells pre-transplant would independently assess post-transplant risk. To address this hypothesis, we determined the frequencies of pre-transplant, donor-specific interferon-γ (IFN-γ) enzyme-linked immunosorbent spots (ELISPOTs) and correlated the results with post-transplant outcomes in 37 African American recipients of deceased donor kidney transplants treated with tacrolimus- and sirolimus-based immunosuppression.
A positive ELISPOT test (>25 spots/300 000 cells) was detected in 14 (38%) of 37 patients. The incidence of biopsy-proven acute rejection was 50% (7/14) in ELISPOT-positive versus 17% (4/23) in ELISPOT-negative patients (p = 0.036). Calculated glomerular filtration rate (MDRD) at 12 months was 37 ± 16 mL/min in ELISPOT-positive versus 55 ± 20 mL/min in ELISPOT-negative patients (p = 0.01). ELISPOT status remained a correlate of allograft function at 12 months by linear regression analysis (p = 0.001), independent of rejection and other contributing variables. Pre-transplant donor-directed IFN-γ ELISPOT assessment of anti-donor cellular immunity may function as a ‘cellular crossmatch’ and independently correlates with renal allograft function in African Americans receiving tacrolimus- and sirolimus-based immunosuppression.