Figure 3: Memory T cells are present in newborn, infant and adult skin. Frozen human foreskin samples from a neonate (3 days) an infant (6 months) and male breast skin (19 years) were labeled with an anti-CD45RO mAb, visualized with an AlexaFluor-546 goat anti-mouse IgG and counterstained with an anti- CD3-FITC mAb. CD3+CD45RO+ cells were extremely rare in newborn epidermis (not shown here), but their numbers increased with age. CD3+CD45RO+ cells are indicated with arrows (dermis) and arrowheads (epidermis). Shown is one representative experiment out of 10. Scale bars: 20 μm. E = Epidermis, D = Dermis.