Treatment with IL-7 induces profound peripheral T-cell cycling.

(A) Transient and marked increase in the percentage of Ki67⁺/CD4⁺ and Ki67⁺/CD8β T cells with IL-7 treatment. The numbers in the upper quadrant are the percentage of CD4⁺ and CD8β⁺ cells that stain with Ki67. (B) Increased BrdU uptake by CD4⁺ and CD8β⁺ T cells during 18 hour ex vivo culture initiated following in vivo exposure to IL-7. (C) Reversible decrease in p27^kip1 and p16^Ink4a proteins in peripheral blood mononuclear cells following IL-7 treatment. The ratio of p27^kip1 and p16^Ink4a to tubulin densitometry readings are shown below each lane.