10: The Immunological Structure of the Skin Flashcards
What is the primary role of the skin as a border organ?
The skin serves as a border organ, separating the host’s structural constituents from the environment while allowing communication between the inside and outside world. This dual role is commonly referred to as ‘skin barrier function’.
What are the major tasks of the skin in maintaining tissue homeostasis?
The major tasks of the skin include securing and maintaining tissue homeostasis and preserving host integrity. In response to major danger signals, it allows for the rapid generation and mobilization of effective host defense reactions to neutralize pathogens.
What components make up the skin immune system?
The skin immune system consists of various cells and molecules, including:
- Macrophages: Phagocytosis and cytokine production
- Dendritic cells: Antigen presentation and activation of T cells
- T cells: Adaptive immune response
- B cells: Antibody production
- Mast cells: Release of histamine and other mediators
- Neutrophils: First responders to infection
- Eosinophils: Defense against parasites and allergic reactions.
What are the two components of the skin immune system?
The skin immune system has two components: an innate component, which provides immediate defense against pathogens, and an adaptive component, which involves a more specific and long-lasting immune response.
What is the dual role of the skin as a ‘Grenzorgan’ and how does it contribute to immune responses?
The skin acts as a ‘Grenzorgan’ by separating the host’s structural constituents from the environment while allowing communication between the inside and outside. This dual role is known as ‘skin barrier function’, which secures tissue homeostasis and preserves host integrity. In response to pathogenic microorganisms, it enables rapid host defense reactions to neutralize threats.
What are the key components of the skin immune system and their roles?
The skin immune system consists of both innate and adaptive components. Key cellular constituents include:
- Macrophages: Phagocytosis and antigen presentation
- Dendritic cells (DC): Antigen capture and presentation to T cells
- T cells: Adaptive immune response
- Mast cells: Release of mediators in allergic responses
- Neutrophils: First responders to infection
- Eosinophils: Defense against parasites and modulation of allergic responses.
What are pattern recognition receptors (PRRs) and their role in innate immunity?
Pattern recognition receptors (PRRs) are a large family of surface-bound and/or cytoplasmic receptors that enable leukocytes and non-leukocytes involved in innate immunity to rapidly sense danger signals such as microbes, their constituents, hapten, and UV radiation.
How do innate immunocytes respond to pathogens?
Innate immunocytes either expand in situ or are recruited from circulation to elaborate mediators that neutralize and/or eliminate pathogens.
What is the difference in onset between innate and adaptive immunity?
Innate immunity has a rapid onset, while adaptive immunity takes 10-14 days to develop.
What is the capacity of innate immunity in terms of danger discrimination?
Innate immunity has the capacity to discriminate between danger and non-danger signals only.
What is the role of neutrophils in the innate immune system?
Neutrophils act as the first responders after most forms of injury in the innate immune system.
A patient with a bacterial skin infection shows rapid recruitment of immune cells to the site of injury. Which innate immune cells are the first responders?
Neutrophils act as the first responders after most forms of injury.
A patient with a history of UV radiation exposure shows activation of pattern recognition receptors (PRRs). What is the role of PRRs in this context?
PRRs, such as Toll-like receptors (TLRs), rapidly sense danger signals like UV radiation and initiate immune responses.
A patient with a skin infection shows a lack of memory response upon repeated antigen exposure. Which component of the immune system is likely involved?
The innate immune system, which lacks memory, is likely involved in this scenario.
What is the role of pattern recognition receptors (PRRs) in innate immunity?
Pattern recognition receptors (PRRs) are essential for both leukocytes and non-leukocytes in innate immunity, enabling them to rapidly sense danger signals such as microbes, haptens, and UV radiation.
How do innate immunocytes respond to the presence of pathogens?
Innate immunocytes either expand in situ or are recruited from circulation to elaborate mediators that neutralize and/or eliminate pathogens.
What are the key differences between innate and adaptive immunity in terms of response time and memory?
Innate immunity has a rapid onset, while adaptive immunity takes 10-14 days to develop. Innate immunity lacks memory, whereas adaptive immunity reacts in an enhanced fashion to repeated antigen challenges.
What is the function of neutrophils in the innate immune system?
Neutrophils act as the first responders after most forms of injury, playing a crucial role in the initial immune response.
What is the primary function of eosinophils in the immune response?
Eosinophils are much less efficient phagocytes than polymorphonuclear neutrophils. They release preformed cationic proteins that are toxic to several parasites, providing efficient protection against them.
What role do basophils play in allergic tissue inflammation?
Basophils contain histamine-filled granules and are a rich source of cytokines such as interleukin (IL)-4 and IL-13. They resemble mast cells and play an important role in allergic tissue inflammation.
What are the key functions of mast cells in the immune system?
Mast cells exhibit membrane-bound and cytoplasmic granules containing preformed mediators (e.g., histamine, serotonin) and molecules upon activation (e.g., TNF, IL-3,4,13). They release mediators through the interaction of complement cleavage products with their receptors and Fc-mediated binding of IgE, leading to type 1 hypersensitivity reactions.
How do macrophages contribute to the elimination of invading microbes?
Macrophages are heavily involved in the elimination of invading microbes through phagocytosis and the subsequent killing of pathogens by reactive oxygen species. They also clean up the stage and promote tissue regeneration and repair.
What is the role of dendritic cells in antiviral defense?
Dendritic cells play a major role in antiviral defense by producing type 1 interferons upon activation of TLR7 and TLR9. Imiquimod provides a strong activation signal, enhancing both interferon production and expression of lytic molecules, which is significant in treating conditions like genital warts and basal cell carcinomas.
What are innate lymphocytes and their primary function?
Innate lymphocytes are a family of non-T non-B lymphoid cells that include cytotoxic natural killer (NK) cells and helper ILCs. NK cells are responsible for the recognition and killing of virally infected and neoplastic cells, as well as the secretion of IFN-γ, a main immunoregulatory cytokine.