Figure S1: Mixed pig/human chimerism when cytotoxicity of human NK cells to pig cells was determined. (A) Determination of sensitivity of pig cell detection by flow cytometry. Pig PBMCs were titrated by twofold dilution in mixtures with a fixed number of mouse splenocytes and human PBMCs. The cell mixtures were then stained with antimouse CD45, anti-pan-pig and antihuman CD45 antibodies and analyzed by flow cytometry. Representative flow cytometry data with actual and corresponding detected percentages are shown on the left. Correlation of the actual and detected percentages is shown on the right. The assay detected 0.003% pig cells. (B) When pig/human mixed chimeric mice were euthanized for isolation of splenic human NK cells, pig chimerism in various tissues was routinely determined. Pig/human mixed chimerism in various tissues from one representative chimeric and one nonchimeric mouse in one experiment is shown. (C) Pig cell numbers in tissues of 9 mixed chimeric mice when they were euthanized for cytotoxicity assay. Pig chimerism in tissues of other 4 mixed chimeric mice was shown in Figure 3. BM, bone marrow; PB, peripheral blood; SP, spleen.