Asunto(s)
Dermatitis por Contacto/etiología , Dermatitis Profesional/etiología , Hipersensibilidad Respiratoria/inducido químicamente , Triazoles/toxicidad , Urea/análogos & derivados , Adulto , Asma/inducido químicamente , Femenino , Humanos , Masculino , Persona de Mediana Edad , Rinitis/inducido químicamente , Urea/toxicidad , Urticaria/inducido químicamente , Adulto JovenRESUMEN
Follicular dendritic cells (FDC) are specialized cells found only within lymphoid follicles. They bind immune complexes and play a role in the presentation of antigen to follicular B cells and in the generation of B cell memory. In the present report the isolation of FDC from human tonsils and adenoids is described. These isolated cells have an unusual spherical arrangement and enclose lymphocytes within extensions of their membranes. Their ultrastructural features are similar to those observed in situ. The reactivity of isolated FDC with a number of monoclonal antibodies was analyzed by immunofluorescence and by immunostaining (at the electron microscopic level) with colloidal gold. In keeping with the results of previous investigations on tissue sections IgM, IgG and IgA (but not IgD) can be detected on the surface of isolated FDC, as can C3b receptors and the FDC-associated antigen detected by monoclonal antibody R4/23. The immunoglobulins associated with FDC are mostly embedded in an electron-dense material. The majority of the lymphoid cells enclosed within the membrane extensions of FDC are of B cell type. These results suggest that isolated FDC may be suitable for further in vitro investigation of their role in the humoral immune response.
Asunto(s)
Tonsila Faríngea/ultraestructura , Antígenos de Superficie/inmunología , Comunicación Celular , Tonsila Palatina/ultraestructura , Tonsila Faríngea/inmunología , Tonsila Faríngea/metabolismo , Anticuerpos Monoclonales/inmunología , Separación Celular , Técnica del Anticuerpo Fluorescente , Histocitoquímica , Humanos , Linfocitos/inmunología , Macrófagos/inmunología , Tonsila Palatina/inmunología , Tonsila Palatina/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismoRESUMEN
Follicular dendritic cells have been isolated from human tonsils and adenoids and characterized at the ultrastructural level. Follicles were dissected and digested with different hydrolytic enzymes. The cells were separated by sedimentation at unit gravity. By this procedure we obtained follicular dendritic cells enveloping lymphocytes with their cytoplasmic extensions in a way analogous to that described for isolated thymic nurse cells. The ultrastructural features of isolated follicular dendritic cells are similar to those observed in situ. Prolonged enzymatic action caused loss of the enveloped lymphocytes.
Asunto(s)
Tonsila Faríngea/citología , Separación Celular/métodos , Técnicas Inmunológicas , Tonsila Palatina/citología , Tonsila Faríngea/metabolismo , Tonsila Faríngea/ultraestructura , Comunicación Celular , Niño , Preescolar , Histocitoquímica , Humanos , Linfocitos/ultraestructura , Tonsila Palatina/metabolismo , Tonsila Palatina/ultraestructuraRESUMEN
Follicular dendritic cells (FDC) isolated from human tonsils and adenoids appear as round clusters where the FDC surround lymphoid cells. Using fluorescein and colloidal gold labelled antibodies we determined their surface antigens, the immunoglobulins they fix and the cells they envelope. Isolated FDC react with specific anti-FDC antibodies but also with an anti-monocyte/macrophage antibody and with anti-HLA-DR antibodies. They retain IgG, IgM, IgA and IgE but not IgD immunoglobulins; this retention occurs, according to our results, via their Fc and C3b receptors. The cells they envelope are mainly B cells, but also occasionally T helper cells. T suppressor cells were only rarely found in contact with FDC. We suggest that FDC create a micro-environment favourable to the proliferation and differentiation of B cells during the humoral response.
