Induction of GVHD by purified CD4⁺ T cells from WT and gene-deficient C57BL/6 donors. Lethally irradiated BALB/c host mice were given intravenous injections of 2 × 10⁶ TCD bone marrow cells from WT C57BL/6 donors with or without CD4⁺ T cells from WT, CD62L^-/-, β₇^-/-, or CD62L^-/-/β₇^-/- donors. There were 10 hosts in each group. (A) Survival of irradiated hosts given TCD bone marrow cells alone or with 0.25 × 10⁶, 0.125 × 10⁶, or 0.0625 × 10⁶ WT CD4⁺ T cells. (B) Survival of irradiated hosts given TCD bone marrow cells and 0.125 × 10⁶ CD4⁺ T cells from WT or gene-deficient donors. (C) Mean body weights of host mice given TCD bone marrow and CD4⁺ T cells as in panel A. Brackets show standard errors of the mean. Analysis was stopped for a given group when there were 2 hosts remaining (+). (D) Mean body weights of host mice given cells as in panel B.