immunology intro-Clive Gray Flashcards
Explain the difference between innate and adaptive immunity, and how are they linked in the context of immune responses?
Innate immunity is the initial, rapid, and nonspecific defense mechanism against pathogens. It involves various cells like macrophages and dendritic cells (DCs) recognizing pathogens using Pattern Recognition Receptors (PRRs). On the other hand, adaptive immunity is a slower and more specific response that develops after exposure to specific pathogens. These two types of immunity are linked because the innate immune response helps initiate and shape the adaptive immune response by presenting antigens to adaptive immune cells and releasing signaling molecules.
What are Pattern Recognition Receptors (PRRs) and how do they function in innate immunity?
Pattern Recognition Receptors (PRRs) are receptors expressed on cells of the innate immune system, such as macrophages and dendritic cells. They recognize Pathogen Associated Molecular Patterns (PAMPs) present on pathogens, which are repeating patterns of molecular structures. PRRs act as “pattern recognition” receptors because they can identify these specific patterns on pathogens, triggering an immune response against them.
Describe the concept of memory in the context of the immune system. How does it contribute to immune responses?
Memory in the immune system refers to the ability of the immune system to respond more rapidly and effectively to antigens that have been encountered previously. Memory cells, such as memory T cells and memory B cells, are formed after an initial exposure to a pathogen. If the same pathogen is encountered again, these memory cells can quickly mount a strong immune response, leading to faster and more robust protection against the pathogen.
What is MHC restriction and how does it relate to T-cell specificity?
MHC (Major Histocompatibility Complex) restriction refers to the requirement that T cells can recognize antigens only when they are presented in the context of MHC molecules on the surface of antigen-presenting cells. T cells have specific T cell receptors that can bind to antigens presented by MHC molecules. This interaction between T cell receptors and MHC-antigen complexes ensures T cell specificity, allowing T cells to distinguish between self and non-self antigens.
Explain the concept of tolerance in the immune system. How does the immune system maintain tolerance?
Tolerance in the immune system refers to the mechanisms that prevent the immune system from reacting against self-antigens, which could lead to autoimmune diseases. There are two main types of tolerance: central tolerance, which occurs during lymphocyte development and eliminates self-reactive lymphocytes, and peripheral tolerance, which occurs after lymphocytes leave the primary lymphoid organs and involves mechanisms to control any potentially self-reactive lymphocytes that might escape central tolerance.
How does the immune system maintain a balance between activation and tolerance? Provide an example of immune activation and tolerance.
The immune system maintains a balance between activation and tolerance to ensure effective responses against pathogens while preventing excessive reactions against self. Activation involves immune responses against pathogens, such as inflammation. Tolerance mechanisms ensure that immune cells do not react against self-antigens, preventing autoimmune diseases. An example of immune activation is the immune response against pathogens like bacteria, while an example of tolerance is the prevention of an immune attack against the body’s own tissues, as seen in autoimmune disorders like lupus or rheumatoid arthritis.
