• From: Jeffrey Silverman     Date: 12/30/98
  Subject: Proposed role of CD34 as a signaling molecule

  In vivo, primitive fibroblast-like dendritic cells in many tumors and healing wounds, CD34 reactivity disappears as these cells attain a more differentiated actin positive myofibroblastic or collagenous synthetic phenotype (see previous references). This is similar to CD34 downregulation in differentiating hematopoietic progenitor cells. In vitro, cultured CD34+ dendritic cells and umbilical vein endothelium both lose CD34 reactivity after a few passages and this has hampered study of the biology of CD34. In certain murine fibroblast lines, increased CD34 expression correlates with lack of contact inhibition. My observations in pathologic material and the literature suggest to me that CD34 is a signalling molecule involved in maintenance of a phenotypically plastic state in undifferentiated cells. Engagement of determinants on CD34 is also involved in controlling these cells' cytoskeletal organization and thus their adhesion and migration.

  Greaves MF, Brown J, Molgaard HV, Spurr NK, Robertson D, Delia D and Sutherland DR. Molecular features of CD34: a hemopoietic progenitor cell-associated molecule. Leukemia 1992 6:31 PubMed

  Silverman JS and Tamsen A. Fibrohistiocytic differentiation in subcutaneous fatty tumors. Study of spindle cell, pleomorphic, myxoid, and atypical lipoma and dedifferentiated liposarcoma cases composed in part of CD34+ fibroblasts and FXIIIa+ histiocytes. J Cutan Pathol 1997 24:484 PubMed

  Silverman JS and Brustein S. Myxoid dermatofibrohistiocytoma: an indolent post-traumatic tumor composed of CD34+ epithelioid and dendritic cells and factor XIIIa+ dendrophages. J Cutan Pathol 1996 23:551 PubMed

  Silverman and Knapik. Fibroma of tendon sheath and giant cell tumors are rich in Factor XIIIa+ dendrophages. J Histotechnol 19:45-52, 1996.

  Silverman JS and Lomvardias S. An unusual soft tissue tumor with features of angiomatoid malignant fibrous histiocytoma composed of bimodal CD34 and factor XIIIa positive dendritic cell subsets. CD34 and factor XIIIa in angiomatoid MFH. Pathol Res Pract 1996 193:51 PubMed

  Silverman JS and Tamsen A. Mammary fibroadenoma and some phyllodes tumour stroma are composed of CD34+ fibroblasts and factor XIIIa+ dendrophages. Histopathology 1996 29:411 PubMed

  Ueki S, Takagi J and Saito Y. Dual functions of transglutaminase in novel cell adhesion. J. Cell. Sci. 1996 109:2727 PubMed

  Paye, Nusgens,LaPierre. Haemostasis 9:274-283, 1989.

  Berrutti L and Silverman JS. Cardiac myxoma is rich in factor XIIIa positive dendrophages: immunohistochemical study of four cases. Histopathology 1996 28:529 PubMed
  
  

• From: Jeffrey Silverman     Date: 12/06/97
  Subject: Speculation on FXIIIa signalling via CD34 to dendritic fibroblasts

  In many myxoid, fibrovascular, and fibrohistiocytic mesenchymal tumors, CD34+ fibroblasts are often associated with numerous dendritic histiocytes that express coagulation factor XIIIa. FXIIIa is a pleiotropic fibroblast mitogen that also catalyzes crosslinking of matrix proteins and modulates cytoskeletal organization, adhesion, and spreading of cultured fibroblasts. I wonder if FXIIIa and/or matrix proteins conformationally altered by FXIIIa might ligate with the extracellular mucin domain of CD34 resulting in signalling involved in the growth and differentiation of the CD34+ dendritic fibroblast.

  Silverman JS and Tamsen A. Fibrohistiocytic differentiation in subcutaneous fatty tumors. Study of spindle cell, pleomorphic, myxoid, and atypical lipoma and dedifferentiated liposarcoma cases composed in part of CD34+ fibroblasts and FXIIIa+ histiocytes. J Cutan Pathol 1997 24:484 PubMed

  Silverman JS and Brustein S. Myxoid dermatofibrohistiocytoma: an indolent post-traumatic tumor composed of CD34+ epithelioid and dendritic cells and factor XIIIa+ dendrophages. J Cutan Pathol 1996 23:551 PubMed

  Silverman and Knapik. Fibroma of tendon sheath and giant cell tumors are rich in Factor XIIIa+ dendrophages. J Histotechnol 19:45-52, 1996.

  Silverman JS and Lomvardias S. An unusual soft tissue tumor with features of angiomatoid malignant fibrous histiocytoma composed of bimodal CD34 and factor XIIIa positive dendritic cell subsets. CD34 and factor XIIIa in angiomatoid MFH. Pathol Res Pract 1996 193:51 PubMed

  Silverman JS and Tamsen A. Mammary fibroadenoma and some phyllodes tumour stroma are composed of CD34+ fibroblasts and factor XIIIa+ dendrophages. Histopathology 1996 29:411 PubMed

  Ueki S, Takagi J and Saito Y. Dual functions of transglutaminase in novel cell adhesion. J. Cell. Sci. 1996 109:2727 PubMed

  Paye, Nusgens,LaPierre. Haemostasis 9:274-283, 1989.

  Berrutti L and Silverman JS. Cardiac myxoma is rich in factor XIIIa positive dendrophages: immunohistochemical study of four cases. Histopathology 1996 28:529 PubMed
  
  

• From: Jeffrey Silverman     Date: 12/17/97
  Subject: Fibroblast-like dendritic cells express CD34

  Besides the embryonic fibroblasts, in adult dermis, areolar tissue, fat, and somatic and visceral collagenous connective tissue, there is an almost ubiquitous network of interstitial and adventitial fibroblast-like dendritic cells that express CD34.

  Silverman JS, Albukerk J and Tamsen A. Comparison of angiomyofibroblastoma and aggressive angiomyxoma in both sexes: four cases composed of bimodal CD34 and factor XIIIa positive dendritic cell subsets. Pathol Res Pract 1997 193:673 PubMed
  
  

Modified 10/14/99   mpr@mail.nih.gov