FIGURE 4.
Donor colon, frozen sections, patient 2, day 27. (a) Donor-specific antibody Bw6 stains epithelial and endothelial cells but not the cellular infiltrate. (b) Recipient specific antibody HLA 25/32 give a mirror image to (a); the infiltrating cells in the lamina propria are of recipient phenotype (c) HLA-DR staining reveals intense expression on epithelial as well as infiltrating cells. Surprisingly, some glands (arrow) are unstained. (d) Many of the infiltrating lymphoid cells bear CD25 (IL-2) receptors × 220.