Dendritic cells (DCs) play a critical role in inducing tolerance by capturing apoptotic cells. Immature DCs can take up proteins, immune complexes, microbes, and dying cells, but they must mature to present these antigens to T cells. DC maturation is triggered by various stimuli, including inflammatory cytokines, CD40 ligand, and microbial components. Maturation changes DCs to become potent antigen-presenting cells, expressing costimulatory molecules, producing IL-12, and migrating to lymph nodes. The uptake of apoptotic cells by immature DCs is crucial for maintaining peripheral tolerance. Huang et al. found that DCs in afferent lymph carry apoptotic bodies from the intestinal epithelium, delivering samples of this tissue to the lymph node. Sauter et al. showed that only necrotic cells cause DC maturation, while apoptotic cells do not. Both studies suggest that DCs can induce tolerance to self-antigens by processing apoptotic cells. DCs are essential for peripheral tolerance, as they can process and present peptides from dying cells to T cells. This is particularly important during infections, where DCs must focus immunity on the pathogen while avoiding immune responses to self-antigens. Peripheral tolerance is induced by marrow-derived cells in draining lymph nodes, which can present self-antigens to T cells and induce anergy or deletion. The capture of tissue cells by DCs is a key mechanism for inducing tolerance. DCs phagocytose apoptotic bodies, which are derived from cells undergoing normal cell turnover. These cells are then transported to lymph nodes, where they can induce tolerance to self-antigens. The processing of apoptotic cells by DCs involves the exogenous pathway, where antigens are presented on MHC class I and II molecules. Apoptotic cells can induce DC maturation, but this process is tightly regulated to prevent immune responses to self-antigens. Immature DCs can phagocytose apoptotic cells without maturing, allowing them to induce tolerance. This process is critical for maintaining immune homeostasis, as DCs must balance the induction of immunity to foreign antigens with the prevention of autoimmune responses. In conclusion, DCs are essential for both immunity and tolerance. They can capture and process apoptotic cells, inducing tolerance to self-antigens while presenting foreign antigens to T cells. This dual role is crucial for maintaining immune homeostasis and preventing autoimmune diseases.Dendritic cells (DCs) play a critical role in inducing tolerance by capturing apoptotic cells. Immature DCs can take up proteins, immune complexes, microbes, and dying cells, but they must mature to present these antigens to T cells. DC maturation is triggered by various stimuli, including inflammatory cytokines, CD40 ligand, and microbial components. Maturation changes DCs to become potent antigen-presenting cells, expressing costimulatory molecules, producing IL-12, and migrating to lymph nodes. The uptake of apoptotic cells by immature DCs is crucial for maintaining peripheral tolerance. Huang et al. found that DCs in afferent lymph carry apoptotic bodies from the intestinal epithelium, delivering samples of this tissue to the lymph node. Sauter et al. showed that only necrotic cells cause DC maturation, while apoptotic cells do not. Both studies suggest that DCs can induce tolerance to self-antigens by processing apoptotic cells. DCs are essential for peripheral tolerance, as they can process and present peptides from dying cells to T cells. This is particularly important during infections, where DCs must focus immunity on the pathogen while avoiding immune responses to self-antigens. Peripheral tolerance is induced by marrow-derived cells in draining lymph nodes, which can present self-antigens to T cells and induce anergy or deletion. The capture of tissue cells by DCs is a key mechanism for inducing tolerance. DCs phagocytose apoptotic bodies, which are derived from cells undergoing normal cell turnover. These cells are then transported to lymph nodes, where they can induce tolerance to self-antigens. The processing of apoptotic cells by DCs involves the exogenous pathway, where antigens are presented on MHC class I and II molecules. Apoptotic cells can induce DC maturation, but this process is tightly regulated to prevent immune responses to self-antigens. Immature DCs can phagocytose apoptotic cells without maturing, allowing them to induce tolerance. This process is critical for maintaining immune homeostasis, as DCs must balance the induction of immunity to foreign antigens with the prevention of autoimmune responses. In conclusion, DCs are essential for both immunity and tolerance. They can capture and process apoptotic cells, inducing tolerance to self-antigens while presenting foreign antigens to T cells. This dual role is crucial for maintaining immune homeostasis and preventing autoimmune diseases.