Cytological alterations in dermal dendrocytesin vitro: evidence for transformation to a non-dendritic phenotype

Abstract

Dermal dendrocytes (DDs) are bone marrow-derived cells which are abundant in normal human and murine dermis, where they are closely associated with mast cells in the perivascular space. The biological role of DDs remains enigmatic. DDs express coagulation factor XIIIa and the recently described von Willebrand factor receptor, GPIb alpha, potentially indicating a function in tissue repair and haemostasis, although participation in antigen presentation is also speculated. In healing wounds and 'fibrohistiocytic' tumours, such as dermatofibromas, DDs are often associated with non-dendritic histiocytes, some of which also express factor XIIIa (FXIIIa). We have utilized human skin organ culture to examine the effects of various biological mediators on cytological characteristics of DDs. It was found that by 24 h in organ culture, immunoreactive DDs begin to lose their dendritic shape, assuming more rounded contours. This phenomenon was accentuated by mast cell degranulation; was independent of the nature of mast cell secretagogue; and could not be reproduced by recombinant tumour necrosis factor-alpha, a cytokine known to increase FXIIIa expression in DDs. Like their dendritic precursors, non-dendritic cells expressed variable FXIIIa, CD34 and CD68 and did not express CD1a or CD45. By ultrastructure, non-dendritic cells that develop in vitro resembled non-degenerating monocytes containing occasional primary lysosomes and lipid inclusions, and like DDs, expressed fibronexus-like plaques on the cell membrane. Transition of DDs from dendritic to non-dendritic cells as a consequence of specific microenvironmental influences may provide insight into the frequent concurrence of these two cytological types in fibrohistiocytic tissue reactions and neoplasia.

Toxic epidermal necrolysis

“…Factor XIIIa 1 dendritic cells are increased in a variety of skin disorders, such as psoriasis and atopic dermatitis, and they may also be involved with tissue repair. 107,108 The authors suggest that TEN is not a disease involving T cells alone. Macrophages play a significant role, and TNF-a is a major cytokine.…”

Factor XIIIa+ Dermal Dendrocyte Parasitism in American Tegumentary Leishmaniasis Skin Lesions

“…[24][25][26][27] Parasitism of these cells was observed in other infectious diseases. 20,21 There is only 1 report in the literature that describes the coexistence of a dermatofibroma with Leishmania parasitic colonization in human immunodeficiency virus-coinfected and visceral leishmaniasis coinfected patient.…”

Ação da pentoxifilina nos dendrócitos dérmicos FXIIIa de placas de psoríase

“…Monteiro e cols., 17 utilizando GPIb-alfa como marcador, demonstraram que os DDs se transformam de polidendríticos em arredondados, com morfologia histiocitóide quando explantes de pele são mantidos em cultura. Esse fenômeno é facilitado pela degranulação dos mastócitos, o que pode ser relevante para a coexistência de DDs e células com fenótipo histiocíti-co em algumas doenças.…”