title: In vitro complement binding in human skin cells with altered differentiation.
abstract: Exposure of cytoskeletal intermediate-sized filaments (ISF) of various cell populations in normal human skin to normal human serum (NHS) results in the deposition of C3 upon these structures; this phenomenon most likely occurs antibody-independently, is initiated by Clq binding to ISF, and is followed by the activation of the classical complement pathway. In the present study we investigated the cytoplasmic C3-binding properties of skin cells undergoing altered differentiation. Incubation of cryostat skin sections of dermal melanocytic nevi with NHS and, subsequently, with fluorescein isothiocyanate-conjugated rabbit antihuman C3 resulted in a bright cytoplasmic staining of the vast majority of nevus cells. Immunoelectron microscopic studies demonstrated that ISF within nevus cells represented the only cytoplasmic C3-binding structures. In contrast, ISF within melanoma cells, basal cell carcinoma cells, and keratinocytes constituting psoriatic lesions lacked C3-binding properties. We propose that changes in structure and subunit protein composition of ISF in certain cells undergoing altered differentiation results in a decrease or loss of their C3-binding capacity.
mesh_terms: D002280:Basal Cell Carcinoma / Q000473:pathology / Q000648:ultrastructure; D002454:Cell Differentiation; D003176:Complement C3 / Q000378:metabolism; D015932:Complement C3c; D003165:Complement System Proteins / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D008544:Melanocytes / Q000166:cytology* / Q000276:immunology; D008545:Melanoma / Q000473:pathology / Q000648:ultrastructure; D008854:Microscopy, Electron; D009506:Nevus / Q000473:pathology / Q000648:ultrastructure; D011951:Receptors, Complement; D012867:Skin / Q000166:cytology*; D012878:Skin Neoplasms / Q000473:pathology / Q000648:ultrastructure
chemical_list: D003176:Complement C3; D011951:Receptors, Complement; D015932:Complement C3c; D003165:Complement System Proteins