To investigate whether the treatments performed with the compounds could induce the nonspecific activation of CD4+ T cells, which might also represent a susceptible target for new infection (57), the resting CD4+ T cells isolated from healthy donors were treated with higher concentrations of FICZ or Kyn for 4 days, and the levels of nonspecific activation of cells were evaluated by detecting surface CD69 expression. This evidence concerns the gene CD4 and infection.