IL-7 concentration in supernatants from skin explant cultures. Normal and CTCL skin explants were cultured under various conditions. The concentration of IL-7 in the supernatant was analyzed by ELISA. IL-7 levels were significantly higher in CTCL samples than in healthy controls. Treatment with the Th2 cytokines IL-4 and/or IL-13 did not significantly increase IL-7 production.