S100A9

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S100A9

A gene on chromosome 1q21 that encodes a member of the S100 family of proteins, which contain 2 EF-hand calcium-binding motifs and as a group regulate cell cycle progression and differentiation and other cellular processes. S100A9 has antimicrobial activity against bacteria and fungi and provides resistance to invasion by pathogenic bacteria, and it upregulates transcription of genes under the control of NF-kappa-B; it is linked to the endotoxic shock response to bacterial lipopolysaccharide. S100A9 promotes tubulin polymerisation and macrophage and granulocyte migration and infiltration into wound sites; it is a pro-inflammatory mediator and upregulates IL8 release and cell surface expression of ICAM1. Extracellular S100A9 (calprotectin) binds to target cells and promotes apoptosis.
 
Molecular pathology
Altered expression of S100A9 is linked to cystic fibrosis.
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References in periodicals archive ?
Squamous differentiation in primary urothelial carcinoma of the urinary tract as seen by MAC387 immunohistochemistry.
McCaughan, "Increases in intrahepatic CD68 positive cells, MAC387 positive cells, and proinflammatory cytokines (particularly interleukin 18) in chronic hepatitis C infection," Gut, vol.
Meanwhile, histiocyte-like mononuclear cells and Reed-Sternberg-like multinuclear cells expressing CD68 and Mac387 were also observed.
Reed- Sternberg-like and histiocyte-like cells displayed CD68 (Figure 1D) and Mac387 expression; however, no reaction was determined with CD15 (LeuM1) and CD30 (Ki-1).
Lysozyme, OKM1, S-100, Mac387, and HAM-56 are among those with histiomonocytic lineage positivity, BMA 120, von Willebrand factor, and UEA-1 lectin with endothelial lineage positivity.
Immunohistochemical staining revealed positivity for histiocytic markers MAC387 and CD68 in most of the larger cells (figure 2, D).
(8) Immunohistochemically, the histiocytes and plasmacytoid monocytes are positive for CD4, CD43, CD68, Ki-M1P, and MAC387. (9) B-cell lymphocyte markers are typically negative.
(1) In the current World Health Organization classification, the diagnosis of HS requires the verification of histiocytic lineage and exclusion of malignancies of other lymphohematopoietic lineages with extensive immunophenotypic workup including histiocytic markers such as CD68, lysozyme, MAC387, [[alpha].sub.1]-antitrypsin, and [[alpha].sub.1]-antichymotrypsin.