IL-15 is produced in the thymus and its receptors are expressed by SP8 CD44^hi thymocytes.

Thymocytes from T. cruzi-infected (Tulahuen) WT mice were obtained 14 days after infection. The expression of (A) IL-2/IL-15 β chain (CD122) in SP8 CD44hi and CD44lo thymocytes was evaluated by Flow cytometry. Histograms are representative from 3 independent experiments with 3–5 mice each. Results are shown as mean ± SEM. The statistical test applied was Student’s unpaired t test. SP8 CD44hi versus SP8 CD44lo cells, ***p.001. (B) IL-15 and IL-15Rα chain RNA expression was evaluated by RT PCR in total thymus from control or T. cruzi-infected mice. Figure shows one representative control mouse and 2 T. cruzi-infected mice (1) and (2). (C) IL-15Rα chain and (D) IL-15 RNA expression was evaluated by real time PCR in total thymus from control cDNA or IL-12+IL-18 cDNA-treated mice. Results are shown as mean ± SEM. The statistical test applied was Student’s unpaired t test. Control versus IL-12+IL-18 treatment, *p.05. (E) IL-15 expression was evaluated by RPA in total thymus from control cDNA or IL-12+IL-18 cDNA-treated mice after in vitro stimulation (or not) with rIL-12 (10μg/ml) + rIL-18 (50 μg/ml). (F) IL-15 RNA expression was evaluated by RT PCR in the sorted DN or SP4 thymocytes or by (G) Real-time PCR in the sorted CD11b+/CD11c+ or SP4 cell subset obtained from thymi of T. cruzi-infected mice. Results are shown as mean ± SEM. The statistical test applied was a Student’s unpaired t test, ***p.001.