Treatment with IL-7 results in increases in naive T cells but declines in TREC levels.

(A) Increases in the absolute number of phenotypically naive CD4⁺ and CD8⁺ lymphocytes with IL-7 treatment at 500 μg/kg/d. Open shapes represent CD8⁺ naive defined as CD45RA^hi/CD27⁺/CD11a^dull/mod, and solid shapes represent CD4⁺ naive defined as CD45RA^hi/CD27. Data from individual animals are represented by a consistent shape. (B) Transient change in CD11a expression on CD8⁺/CD45RA⁺ peripheral blood lymphocytes. (C) Rapid and persistent decline in TRECs per 100 000 CD4⁺ and CD8⁺ lymphocytes in the peripheral blood following IL-7 treatment. Open shapes represent CD8⁺, and solid shapes represent CD4⁺. (D) Decline in absolute number of TREC⁺ T cells per microliter with IL-7 therapy.