51Cr-EDTA: a marker of early intestinal rejection in the rat

Intestinal permeability was studied after accessory intestinal transplantation in Lewis rats. Five groups were evaluated: Group 1--isografts (N = 6); Group 2--Lewis X Brown Norway F1 (LBN-F1) allografts (N = 6); Group 3--isografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 4--LBN-F1 allografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 5--LBN-F1 allografts treated with CsA 4 mg/kg/day X 28 days (N = 6). Chromium-labeled ethylenedimianetetraacetate (51Cr-EDTA) was given through the proximal stoma of the graft. Renal clearance of 51Cr-EDTA and mucosal biopsies were followed post-transplant. The biopsies of the intestinal graft showed no rejection in Groups 1, 3, and 5; fulminant rejection in Group 2; and mild atypical rejection in Group 4. 51Cr-EDTA clearance was elevated in all groups during the first 7 days post-transplant. Thereafter, 51Cr-EDTA excretion fell to lower levels in the animals with histologically normal grafts (Groups 1, 3, and 5). 51Cr-EDTA excretion in Group 4 was increased with the first histological evidence of rejection on Day 14 and remained elevated until sacrifice (P less than 0.02 compared to Groups 3 and 5). A transient permeability defect occurs after intestinal grafting. Once the graft has recovered from this injury, 51Cr-EDTA is a sensitive marker for intestinal rejection.