Expansion and disappearance of postthymic T cells during the course of GVHD. A cell suspension containing 6 × 10⁷B6.SJL T cells was injected into unirradiated B6AF1 recipients. Shown is a time course evaluation of the numbers of host- and donor-derived B cells (A) and T cells (B) found in the spleen of GVHD⁺recipients. CD44 phenotype of host (C) and donor (D) T cells found in the spleen of GVHD⁺ recipients. Three-color staining was performed using PE-labeled anti-CD19, anti-Thy1.2, or anti-CD44; Cy-chrome–labeled anti-CD4 or anti-CD8; and FITC-labeled anti-Ly5.1 or anti-Ly5.2. Results are presented as the mean ± SD in (A) and (B); for the sake of clarity, only the mean is shown in (C) and (D). There were three to four mice per group.