Tissue sections of the large intestine and skin of BALB/c hosts given BMTs from C57BL/6 donors show no evidence of GVHD.

Sections are stained with hematoxylin and eosin, and magnified × 400. (A) A representative section of the large intestine from a positive control BALB/c host given lethal TBI (800 cGy) and an intravenous injection of 1.5 × 10⁶ TCD bone marrow and 0.1 × 10⁶ spleen cells 40 days earlier. Asterisk shows interstitial lymphocytic infiltrate, and arrowhead shows extension into crypt. Arrow shows apoptotic crypt cell. (B) A representative section of skin from the host in panel A. Arrow shows epidermal hyperplasia, arrowhead shows dermal infiltrate, and asterisk shows epidermal blister. Panels C and D show large intestine and skin, respectively, from a negative control BALB/c host given BCL_l tumor cells, sublethal irradiation, and an intravenous injection of 50 × 10⁶ TCD BM cells 40 days earlier. Panels E and F show representative sections of the large intestine and skin, respectively, from BALB/c hosts given BCL₁ tumor cells, sublethal irradiation, and 25 × 10⁶ whole BM cells 100 days earlier.