Systemic Mastocytosis: A Concise Clinical and Laboratory Review (Review Article) (Report)

Systemic Mastocytosis: A Concise Clinical and Laboratory Review (Review Article) (Report)

The discovery of mast cells (MCs) in 1878 is credited to Paul Ehrlich, who first described cells that stained with metachromatic dyes such as toluidine blue, which he termed MCs. Since then, extensive work has been done on the physiology, pathology, and genetics of normal MCs and their pathologic counterparts in mast cell disease (MCD). It is now known that MCs are myeloid lineage cells that arise from bone marrow (BM) precursors, more specifically from [CD34.sup.+] and [Kit.sup.+] hematopoietic progenitors and not from monocytes or basophils as previously thought. (1-5) The cytokine stem cell factor (also known as Kit ligand) plays a key role in inducing differentiation of MCs from their progenitors, in concert with other cytokines including interleukin 3. (6-8) Normal MCs are round or oval cells, with a round, centrally located, nonlobated nucleus, and have abundant, uniformly distributed cytoplasmic granules. Immunophenotypic characterization of normal MCs typically reveals the presence of 2 characteristic surface markers, the CD117 antigen (c-Kit; the receptor for stem cell factor) and the high affinity receptor for immunoglobulin (Ig) E (Fc RI), neither of which, however, are MC specific. (9,10) The typical profile of MCs in normal BM has been described as [CD117.sup.++]/[CD34.sup.-]/[CD38.sup.-]/[CD138.sup.-]/ [CD45.sup.+]/Fc[epsilon][RI.sup.+]. Mast cells play an integral role in type I hypersensitivity reactions implicated in bronchial asthma, urticaria, anaphylaxis, and other allergic conditions. Here, engagement of Fc[epsilon]RI receptors promotes MC degranulation and release of histamine and other mediators including proteases, heparin, prostaglandins, leukotrienes, cytokines, and chemokines that mediate many of the clinical features of MCD (reviewed by Castells (11)). MAST CELL DISORDERS

Systemic Mastocytosis: A Concise Clinical and Laboratory Review (Review Article) (Report)

Systemic Mastocytosis: A Concise Clinical and Laboratory Review (Review Article) (Report) | | 4.5