Kinetics of infiltration of liver (A) or spleen (B) in the GVL system by donor cells (□), CD4⁺ T cells (▪), CD8⁺ T cells (▵), and SER-4⁺ macrophages (▴). Immunohistochemically stained frozen tissue sections were analyzed under the microscope. The data indicate the means and standard deviations from two experiments with 2 to 3 animals per time point.