IL1A - Production and Cellular Sources

Production and Cellular Sources

IL-1α is constitutively produced by epithelial cells. It is found in substantial amounts in normal human epidermis and is distributed in a 1:1 ratio between living epidermal cells and stratum corneum. The constitutive production of large amounts of IL-1α precursor by healthy epidermal keratinocytes interfere with the important role of IL-1α in immune responses, assuming skin as a barrier, which prevents the entry of pathogenic microorganisms into the body.

The essential role of IL-1α in maintenance of skin barrier function, especially with increasing age, is an additional explanation of IL-1α constitutive production in epidermis.

With the exception of skin keratinocytes, some epithelial cells and certain cells in central nervous system, the mRNA coding for IL-1α (and, thus, IL-1α itself) is not observed in health in most of cell types, tissues, and blood, in spite of wide physiological, metabolic, haematopoietic, and immunological IL-1α activities.

A wide variety of other cells only upon stimulation can be induced to transcribe the IL-1α genes and produce the precursor form of IL-1α, Among them are fibroblasts, macrophages, granulocytes, eosinophils, mast cells and basophils, endothelial cells, platelets, monocytes and myeloid cell lines, blood T-lymphocytes and B-lymphocytes, astrocytes, kidney mesangial cells, Langerhans cells, dermal dendritic cells, natural killer cells, large granular lymphocytes, microglia, blood neutrophils, lymph node cells, maternal placental cells and several other cell types.

These data allow to assume IL-1α as an epidermal cytokine.