Schwann cells and recruited macrophages produce TNFα, IL-1α, and IL-1β protein. Nerve-derived fibroblasts produce low levels of TNFα but not IL-1α or IL-1β protein. Single-cell type cultures of resident Schwann cells and fibroblasts and recruited macrophages were obtained from intact, rapid-WD, and freeze-damaged PNS of C57/BL mice. The non-neuronal cells were studied for the presence of TNFα, IL-1α, and IL-1β protein by immunofluorescence microscopy. High levels of immunoreactivity for all cytokines were detected in the cytoplasm of Schwann cells and macrophages. In fibroblasts, levels of immunoreactivity to TNFα were slightly above control levels, whereas levels of immunoreactivity to IL-1α and IL-1β were the same as for control. Immunoreactivity of cytokines was localized to the cytoplasm and not cell surfaces because immunoreactivity was detected in cells permeabilized by Triton X-100 but not in non-permeabilized cells (data not shown). Magnification: 400×.