Myeloid DCs

Definition

Myeloid dendritic cells (myeloid DCs) are a subset of dendritic cells that originate from myeloid progenitor cells. They are professional antigen-presenting cells that play a crucial role in initiating and regulating immune responses by processing and presenting antigens to T cells.

5 Must Know Facts For Your Next Test

1. Myeloid DCs are derived from myeloid progenitor cells, which are distinct from the lymphoid progenitor cells that give rise to lymphoid dendritic cells.
2. Myeloid DCs are efficient at phagocytosing and processing antigens, and they express high levels of major histocompatibility complex (MHC) class I and II molecules for antigen presentation.
3. Myeloid DCs can be further classified into subtypes, such as classical (or conventional) myeloid DCs and inflammatory myeloid DCs, based on their functional and phenotypic characteristics.
4. Myeloid DCs play a critical role in the induction of primary immune responses by activating naive T cells and promoting their differentiation into effector T cells.
5. The cytokines and co-stimulatory molecules expressed by myeloid DCs can influence the type of T cell response, such as promoting Th1, Th2, or regulatory T cell responses.

Review Questions

• Explain the role of myeloid DCs in the context of major histocompatibility complexes and antigen-presenting cells.
  • Myeloid DCs are a type of professional antigen-presenting cell that play a central role in the adaptive immune response. They express high levels of major histocompatibility complex (MHC) class I and II molecules, which allow them to present processed antigens to T cells. This antigen presentation by myeloid DCs is crucial for the activation and differentiation of naive T cells into effector T cells, initiating the adaptive immune response. Myeloid DCs are particularly efficient at capturing, processing, and presenting antigens, making them key players in the MHC-mediated antigen presentation pathway.
• Describe how the cytokines and co-stimulatory molecules expressed by myeloid DCs can influence the type of T cell response.
  • The cytokines and co-stimulatory molecules expressed by myeloid DCs can have a significant impact on the type of T cell response they elicit. For example, myeloid DCs that produce high levels of IL-12 can promote the differentiation of naive T cells into Th1 effector cells, which are important for cell-mediated immunity against intracellular pathogens. Conversely, myeloid DCs that express high levels of IL-4 and co-stimulatory molecules like OX40L can drive the differentiation of naive T cells into Th2 effector cells, which are involved in humoral immunity and allergic responses. Additionally, myeloid DCs that produce anti-inflammatory cytokines like IL-10 can induce the differentiation of regulatory T cells, which play a crucial role in maintaining immune tolerance and suppressing excessive or inappropriate immune responses.
• Analyze the significance of the distinct origins of myeloid DCs and lymphoid DCs in the context of their functional roles in the immune system.
  • The distinct origins of myeloid DCs and lymphoid DCs have important implications for their functional roles in the immune system. Myeloid DCs are derived from myeloid progenitor cells, which give rise to various myeloid cell lineages, including monocytes, macrophages, and granulocytes. This myeloid lineage origin allows myeloid DCs to share certain functional characteristics with these other myeloid cells, such as their efficiency in phagocytosis and antigen processing. In contrast, lymphoid DCs originate from lymphoid progenitor cells, which also give rise to T and B lymphocytes. This lymphoid lineage origin may confer lymphoid DCs with a greater capacity for antigen presentation and T cell activation compared to myeloid DCs. The different developmental origins of these two DC subsets contribute to their distinct roles in initiating and shaping the adaptive immune response, with myeloid DCs playing a more prominent part in the induction of primary immune responses, while lymphoid DCs may be more involved in the regulation and modulation of ongoing immune reactions.

Related terms

Dendritic Cells:

Dendritic cells are a type of antigen-presenting cell that are responsible for capturing, processing, and presenting antigens to T cells, initiating adaptive immune responses.

Myeloid Progenitor Cells: Myeloid progenitor cells are hematopoietic stem cells that differentiate into various myeloid cell lineages, including monocytes, macrophages, granulocytes, and dendritic cells.

Antigen Presentation:

Antigen presentation is the process by which antigen-presenting cells, such as dendritic cells, display fragments of antigens on their surface for recognition by T cells, triggering an adaptive immune response.