Impaired negative selection and antibody-induced thymocyte death in γδ^– × hδTg mice. Dot plots (A) of CD4 and CD8 expression in thymocytes and splenocytes from WT and γδ^– × hδTg HY TCR male mice, or (B) of thymocytes removed from WT (left) and γδ^– × hδTg (right) mice 48 hours after intraperitoneal injection with either vehicle alone (PBS) or 200 μg anti-TCRβ antibody. Percentages of gated cells and total thymocyte numbers are shown within and above plots, respectively. MFI denotes mean fluorescence intensity of CD8 staining in the gated region. (C) In vitro anti-TCR antibody–induced death of WT (•) and γδ^– × hδTg (○) thymocytes cultured for 48 hours in plastic wells precoated with the indicated amount of anti-TCRβ antibody. Cell death was assessed by propidium iodide staining and flow cytometry.