Central role of dendritic cells in the regulation and deregulation of immune responses

Abstract

Dendritic cells (DCs) play a critical role in orchestrating the innate and adaptive components of the immune system so that appropriate, coordinated responses are mounted against infectious agents. Tissue-resident DCs interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Antigens use PRR activation to instruct DCs for the appropriate priming of natural killer (NK) cells, followed by specific T-cell responses. Due to the central role of DCs in regulating the activation and progression of immune responses, minor imbalances in the feedback control of Toll-like receptor (TLR)-activated cells have been associated with autoimmunity in genetically prone individuals. We review here recent findings on the role of DCs in the priming of innate and adaptive immune responses and the possible involvement of DCs in inducing and maintaining autoimmune reactions.

Papel de las células dendríticas tolerogénicas ILT3+/ILT4+ en la respuesta inmunitaria a trasplante de órganos y tejidos

“…En reposo, las pDC pueden clasificarse como prepDC (16), pero una vez se activan, adquieren la capacidad para producir grandes cantidades de interferones de tipo I y pueden presentar algunas propiedades de procesamiento y presentación de antígeno (21,22). Se creía que las células dendríticas derivadas de los precursores mieloides inducían sólo respuestas de tipo Th1, mientras que las de origen linfoide inducían sólo respuestas de tipo Th2, pero se ha demostrado que las pDC de origen linfoide también pueden inducir respuestas de tipo Th1 después de la activación con algunos virus o con CD40 (23,24).…”

Leishmania amazonensis impairs DC function by inhibiting CD40 expression via A2B adenosine receptor activation

“…DCs play a critical role in orchestrating the innate and adaptive components of the immune system [5,6]. Immature DCs capture and process antigens located throughout the body.…”

“…Leishmania amazonensis differs from other species because it is able to cause chronic non-healing lesions in mouse strains genuinely resistant to other Leishmania species, such as Leishmania braziliensis and Leishmania major [1][2][3]. In humans, L. amazonensis causes diffuse cutaneous leishmaniasis, a condition characterised by a lack of antigen-specific T-cell responses against the parasite [4].DCs play a critical role in orchestrating the innate and adaptive components of the immune system [5,6]. Immature DCs capture and process antigens located throughout the body.…”

The dendritic cell life cycle

“…This coregulation may ensure the efficient detection and uptake of the antigen by cDCs in a defined space before migration to the lymphoid organs. 11 Once activated by inflammatory stimuli, DCs acquire the ability to prime first NK cells, then T cells, 12 and finally die by apoptosis (Fig. 1). endogenous), migratory and lymphoid tissue-resident cDCs display a decrease in phagocytic activity, accompanied by an increase in processing capacity and an upregulation of MHC and costimulatory molecules at the cell surface.…”

“…45,49 Indeed, CD14 has shown to be an absolute requirement for a full response to the smooth form of LPS (sLPS). 40 We have recently described a third role for CD14 in cDCs: 19 following LPS stimulation, CD14 activates the Ca 2+ /calcineurin and NFAT pathway in a TLR4-independent manner 12 (Fig. 2).…”