In addition, relative to control animals, mice in the highest dose group displayed a number of significant hallmark signs of TCDD toxicity: by day 26 post infection, thymus weights (normalized to body weights) were reduced by 57%, the number of lesion draining lymph node cells was reduced by 95%, the percentage of CD4+ cells in lesion-draining lymph nodes was reduced by 44%, and the percentage of those CD4+ cells expressing CD25 was increased nearly two-fold (Table 1). This evidence concerns the gene CD4 and infection.