Engraftment of donor T cells in spleens of recipient mice. Analysis of recipient spleens for the presence of donor-derived T cells was performed 2 weeks after transfusion. Splenocytes were analyzed using two-color flow cytometry with antibodies for CD3⁺ cells on the vertical axis and recipient specific MHC class I H-2^b on the horizontal axis. Donor T cells appear in the upper left-hand quadrant. Spleens of two mice in each group were analyzed and the figure shown is representative of both mice in their respective group. As expected, mice in the control group had no allogeneic donor T cells present in their spleens 2 weeks after transfusion. Mice in the GVHD group had 37% donor-derived T cells. Mice in the PCT and Gamma groups had no evidence of donor-derived T cells in their spleens, similar to the control group.