Prolonged cold ischemia storage (CIS) of donor organs is a major risk factor for acute and chronic graft injury. The goal of this study was to test how increased CIS time influences humoral alloimmunity using a mouse model of renal transplantation.

B6 (H-2^b) mice received BALB/c (H-2^d) renal allografts subjected to 0.5 h or 6 h CIS in University of Wisconsin solution (0.5 h CIS and 6 h CIS groups). Second recipient kidney was removed at the time of transplantation. Compared to 0.5h CIS, recipients from 6 h CIS group had increased titers of donor-MHC class II but not class I reactive IgG DSA, elevated frequencies of both class I and class II-reactive antibody secreting cells and higher frequencies of donor-reactive IFNγ-secreting T cells on d.14 posttransplant. Renal allografts from this group had significantly higher proportion of glomeruli infiltrated with macrophages compared to 0.5 h CIS controls. B cell depletion with anti-mouse CD20 mAb inhibited DSA generation and reduced intragraft C4d deposition and macrophage glomerular infiltration on d.14. In addition, B cell depletion resulted in decreased priming of donor-reactive IFNγ-secreting T cells and reduced T cell infiltration into the graft.

Regardless of CIS duration, serum creatinine levels were <0.6 mg/dl in all recipients at d. 60 posttransplant (<0.4 mg/dl in non-transplanted mice). By d. 60, the grafts from 0.5 h CIS group had moderate segmental sclerosis in a limited number of glomeruli. In contrast, 6 h CIS grafts had extensive glomerular injury including thickened capillary loops, segmental or global sclerosis and thrombotic microangiopathy with red cell congestion, intracapillary fibrin thrombi, mesangiolysis and elevated intragraft levels of acute kidney injury markers NGAL and osteopontin. In addition, 6 h CIS recipients had increased serum levels of anti-class II but not anti-class I IgG DSA and increased numbers of class I and class II-reactive ASCs compared to 0.5 CIS group. The frequencies of IFNγ-producing donor-reactive T cells were low and comparable in both groups.

Our findings suggest that the augmented humoral rather than cellular immune responses account for the transplant glomerulopathy after prolonged CIS. Posttransplant inflammation not only facilitates DSA development but also spreads the specificity of DSA responses from class I to class II and may thus influence renal allograft pathology.

CITATION INFORMATION: Gorbacheva V., Fan R., Baldwin W., Valujskikh A. Prolonged Cold Ischemia Storage of Renal Allografts Shifts DSA Specificity and Enchances Glomerular Injury Am J Transplant. 2017;17 (suppl 3).

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