Summary of percentages of regulatory T cells in healthy donor and HL patient PBMCs and HLILs. A comparison of the percentage of healthy donor PBMCs (n = 4) and HL patient PBMCs (n = 9) and HLILs (n = 6) that stained positive for either CD4 and IL-10 (Tr1 phenotype), CD4 and CD25, or CD4 and CTLA-4. The percentage of cells with each phenotype is shown on the vertical axis, and the source of cells is shown on the horizontal axis. Where PBMC and HLIL samples were obtained from the same patient, these linked samples are indicated by the solid lines. Cells were stained within 24 hours of purification and were unstimulated prior to staining.