S100 proteins

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 03.09.2021

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S100; S-100; S100 protein family; S100 Protein Family

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Calcium-binding proteins with a molecular mass of 9-13 kDa that influence a variety of different cellular processes. The S100 proteins include at least 25 members that are expressed in a wide variety of cell types:

  • S100B: in astrocytes, adipocytes, melanocytes and chondrocytes.
  • S100A1: in cardiomyocytes, in cells of the salivary glands, in kidney and muscle cells, in hippocampal neurons.
  • S100A6: in connective tissue cells and muscle cells.
  • S100A8 and S100A12: primarily in phagocytes. Serum concentration correlates with the activity of inflammatory diseases.
  • S100A9: screening parameter for prostate carcinoma.
  • S100A15: In the normal epidermis, S100A15 is expressed by basal and differentiated keratinocytes, melanocytes and Langerhans cells of the epidermis. Within the pilosebaceous unit, S100A15 is found in the inner and outer root sheath and in the basal layer of the sebaceous gland. In the dermis, S100A15 is produced by dendritic cells, smooth muscle cells, endothelial cells and fibroblasts to control tissue regeneration.

General information
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Standard value: < 0,1 µg/l.

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S100 antibodies are frequently usedin dermatohistology. Due to the small size of the S100 proteins, formalin fixation is necessary for imaging in tissue. It can be washed out of cryostat sections and insufficiently fixed tissue. The S100 staining can be nucleolar or cytoplasmic. S100 marked: melanocytes and nevus cells, Langerhans cells, Schwann cells, myoepithelia, cartilage cells, etc. It is the most important marker of desmoplastic melanocytic markers.

S100 i.S. (melanoma screening): In malignant melanomas, S100-positivity is often found even if other melanocytic markers are no longer formed due to progressive de-differentiation. Salivary gland tumours and tumours of the eccrine sweat glands often also show an expression of S100.

Notice! For melanoma screening, it is not so much the absolute values as the course of the disease that are important.

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  1. Hantschke M et al (2016) Immunohistological techniques. In: L. Cerroni et al. histopathology of the skin. Springer Publishing House Berlin-Heidelberg p. 33.
  2. Sedagath F et al (2008) S100 protein family and its application in clinical practice. Hippocratia 12: 198-204


Last updated on: 03.09.2021