gp120 protects from GVHD. (A) 10⁷ PBMC were injected with or without 5 μg gp120 into newborn NOD-Scid mice. Untreated mice served as controls. Each point represents the cumulative mean weight data of one group (5 mice per group; one of 5 experiments is shown). Survival of mice at day 52: untreated: 5/5; PBMC: 0/5; and PBMC + gp120: 5/5. (B) GTP serum levels of mice belonging to different groups 3 weeks after PBMC transfer. (C) Histologic pulmonary tissue analysis 4 weeks after PBMC transfer. (D) Representative flow cytometric analysis of bronchoalveolar lavage from mice belonging to different groups 3 weeks after PBMC transfer. (E) Colitis score and endoscopic pictures of mice belonging to different groups of mice 3 weeks after PBMC transfer. (F) Regulatory T cells and gp120 inhibiting expansion of human T effector cells in lymphoid tissues. Frequencies of human CD45⁺ leukocytes and the CD4:CD8 T-cell ratios in the CD45⁺ population 28 days after PBMC transfer are shown. Columns and error bars indicate average expression plus or minus SD of 3 different mice. One representative result of 3 is shown.