The ADCC-defective anti-Fn14 mAb variant 18D1-dead reduces allo-HCT–triggered and TNF-induced cell death of GI cells. (A) 3 µm intestinal tissue sections from mice shown in Figure 2 were analyzed by immunohistochemistry with a cleaved PARP1-specific antibody. Upper panel: graphic evaluation of apoptotic cells per field. Lower panel: representative photomicrographs. (B) Balb/c (H-2^d) were injected with 18D1-dead (200 µg in PBS), murine TNF (10 µg in PBS), a mixture of both, or with saline. After 6 hours, the mice were euthanized and small intestinal tissues were analyzed by immunohistochemistry for the presence of apoptotic cells with anticleaved caspase-3 (upper panel) and anticleaved lamin A-specific antibodies (lower panel). Mean ± SEM. *P ≤ .05; **P ≤ .01.