9. tolerancia inmunológica
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Semelhante a 9. tolerancia inmunológica
Semelhante a 9. tolerancia inmunológica (20)
Mais de Medicina Eclectica, U. Xochicalco, SE Universitario
Mais de Medicina Eclectica, U. Xochicalco, SE Universitario (18)
9. tolerancia inmunológica
- 10. Tolerancia • Estado en el cual un individuo es INCAPAZ de desarrollar una RESPUESTA INMUNE ante un antígeno (Ag) específico. • Autotolerancia es la falta de respuesta a los Ag propios armonía entre células y tejidos.
- 12. • Falta de Regulación Inmunológica: o Hipersensibilidad (alergias). o Autoinmunidad.
- 15. Tolerancia • Central. o LsT (timo) y LsB (MO) autoreactivos apoptosis (maduración). o LsT-B con receptores de ↑ afinidad por autoAg Del.
- 16. • Periférica. o Anergia. o Supresión por LsT reguladores (CD4+, IL-10/TGF- β). o Deleción clonal por activación/inducción de apoptosis (Fas + FasLLsT activados). o Secuestro Ag (sitios inm privilegiados) ojo, testículos y cerebro.
- 19. Enfermedades Autoinmunes • Mecanismos para protegernos de nuestros “protectores”. • Desarrollo de autoinmunidad: o Herencia de genes susceptibles influencia en mantenimiento de autotolerancia. o Gatillantes ambientales (infecciones) promueven la activación de Ls autoreactivos.
- 20. • Clin Exp Immunol. 2009 January; 155(1): 1–15.
- 21. Fiebre reumática: • Streptococcus pyogenes (Estreptococo beta-hemolítico del grupo A). • Proteína M superficie (principal factor de virulencia). • Protege de fagocitosis. • Homología estructural con la miosina cardiaca y otras moléculas Carditis reumática aguda.
- 22. • Clin Exp Immunol. 2009 January; 155(1): 1–15.
- 24. Mol que fijan Ag específicos • Inmunoglobulinas (Igs). • Receptores LsT (TCR). • Complejo mayor de histocompatibilidad (MHC I, II y III).
Notas do Editor
- **cutaneous lymphocyte-associated antigen (CLA) is a T cell skin homing receptor that defines T lymphocytes associated with the cutaneous immune response
- Local inflammation and the phagocytosis of invading bacteria can also be triggered as a result of the activation of a group of plasma proteins known collectively as complement. Activation of the complement system by bacterial surfaces leads to a cascade of proteolytic reactions that coats microbes, but not the body's own cells, with complement fragments.
- LsTreguladores (LsTautoreactivos no destruidos en la tolerancia central… o inducidos en la periferia.)LsT CD4+ expresan CD25+ (cadenaα del receptor de IL-2) foxp3 (fact transcripcion) requeridopara el desarrollo y funcion.Fas (CD95)expresado en muchascel (Lstmb), miembro de la familia de receptores-TNF. Esactivadopor el FasL (Fas ligand) expresadoprincipalmente en LsTactivados.IL2 factor de crecimiento de LsT!!! Ayuda en desarrollo de LsTreg!!! Promueve apoptosis mediadapor Fas (expo prolongada)!!!
- Each lymphoid progenitor gives rise to a large number of lymphocytes, each bearing a distinct antigen receptor. Lymphocytes with receptors that bind ubiquitous self antigens are eliminated before they become fully mature, ensuring tolerance to such self antigens. When a foreign antigen interacts with the receptor on a mature naive lymphocyte, that cell is activated and starts to divide. It gives rise to a clone of identical progeny, all of whose receptors bind the same antigen. Antigen specificity is thus maintained as the progeny proliferate and differentiate into effector cells. Once antigen has been eliminated by these effector cells, the immune response ceases, although some lymphocytes are retained to mediate immunological memory.
- “Who’s watching the watchmen?”
- (a) Molecular mimicry occurs when pathogen-derived epitopes are cross-reactive with self-derived epitopes. Pathogen-derived epitopes are taken up by antigen-presenting cells (APCs) and presented to cytolytic T cells (Tc) via major histocompatibility complex (MHC) class I or to helper T cells (Th) via MHC class II. T cells activated by pathogenic epitopes that are cross-reactive with self-epitopes can then damage self-tissue via lysis (Tc) or release of cytokines (Th). Cytokines released by activated Th cells can activate macrophages (M) or provide help to B cells. Pathogen-derived surface antigens are recognized by a B cell's B cell receptor (BCR), which triggers the secretion of antibodies. These antibodies can cause damage by binding to cross-reactive epitopes on the surface of tissues and disrupting tissue function, or the Fc portion of the antibody can bind simultaneously to the Fc receptor (FcR) on M; this will trigger the M to produce tissue-damaging cytokines. Damaged tissue will release more cross-reactive antigens, which will be taken up by APCs, propagating further damage. (b) In epitope spreading, the immune response to a persisting pathogen, or direct lysis of self-tissue by the persisting pathogen, causes damage to self-tissue. Antigens released from damaged tissue are taken up by APCs, and this initiates an immune response directed towards self-antigens.
- La proteína M. Mientras que la región carboxilo-terminal se encuentra anclada a la membrana, la región amino terminal se extiende hacia la superficie, en forma de un dímero alfa helicoidal, dando la apariencia de “fibrillas”. La proteína M esta formada por 4 unidades de repetición (A-D), donde la variación de la unidad A (localizada en la región amino-terminal) es la más importante debido a que en ella se encuentra la especificidad de serotipo; protege a la bacteria de la fagocitosis al unirse al factor H (proteína reguladora del complemento) y fibrinógeno, y favorece la degradación del factor del complemento C3b.La proteína M comparte homología estructural con la miosina cardiaca y otras moléculas alfa helicoidal super enrolladas tal como la tropomiosina, keratina y laminina, por lo que se ha sugerido que esta homología es la responsable de los hallazgos patológicos en la carditis reumática aguda.
- (c) In bystander activation, the various parts of the immune system respond to the invading pathogens. The inflammatory environment triggered by this response damages self-tissue in an antigen non-specific manner, and in addition triggers non-specific activation of immune cells. (d) In contrast to dominant antigenic determinants, subdominant cryptic antigens are normally invisible to the immune system. The inflammatory environment that arises after infection can induce increased protease production and differential processing of released self-epitopes by APCs.
- Polimorfismo de MHC:HLA-A: 50 alelosdistintosHLA-B: 100 alelos.HLA-C: 35 alelos.