Resident epidermal T cells produce IGF-1 upon stimulation in vitro. (A) Flow cytometry of freshly isolated epidermal cells stimulated with PMA and ionomycin, and stained with anti-IGF-1. (B) Statistical analysis of IGF-1 expression in normal epidermal T cells (n = 17). The population was distributed as follows: sex, 12 females and 5 males; age, 44.8 ± 22.2 yr. There is a significant difference in IGF-1 expression before and after stimulation in the αβ⁺ and the Vδ1⁺ subsets according to a one-tailed Student's t test. In all flow cytometry analyses, protein production was determined by subtracting the geometric mean fluorescence intensity (GMFI) of the control secondary antibody from the GMFI of cells treated with specific antibodies. Results represent means of data ± SEM.