L3 (overview lecture) Flashcards
How do the timing and speed of response differ between the innate and adaptive immune systems?
Innate: Fast, immediate response.
Adaptive: Slower to develop (5–6+ days).
How do the innate and adaptive immune systems detect pathogens?
Innate: Uses germline-encoded, limited, unchanging receptors.
Adaptive: Uses randomly generated antigen receptors with huge diversity and specificity to individual molecules.
What is the specificity of the immune response in the innate versus adaptive systems?
Innate: Nonspecific, recognizes broad patterns of pathogens.
Adaptive: Highly specific to individual molecules (antigens).
What are the key cell types involved in the innate and adaptive immune systems?
Innate: Phagocytic cells (macrophages, neutrophils, dendritic cells).
Adaptive: Lymphocytes (B and T cells).
How do the innate and adaptive immune systems respond to repeat infections?
Innate: Response is the same each time.
Adaptive: Response is faster and more effective with each subsequent exposure (memory).
What are the major components of the innate and adaptive immune systems
Innate: Barriers (e.g., skin), phagocytes, pattern recognition molecules.
Adaptive: T and B lymphocytes, antigen-specific receptors, antibodies.
What are the key takeaways about the phases of the immune response?
Many phases to the immune response.
Takes time to develop.
How long does the innate immune response last, and how fast is it?
The innate immune response is fast and only lasts for days.
What is the role of pattern recognition receptors (PRRs) in the immune system?
PRRs provide an initial discrimination between self and non-self by recognizing broad categories of molecules commonly found in pathogens (PAMPs).
What are pathogen-associated molecular patterns (PAMPs)?
PAMPs are common foreign structures that characterize whole groups of pathogens. They are present in many microorganisms but not in the host body’s own cells.
Which receptors are involved in recognizing PAMPs?
Toll-like receptors (TLRs) are a type of PRR involved in recognizing PAMPs.
How do macrophages recognize different pathogens?
Macrophages express several receptors, including PRRs, that allow them to recognize different pathogens.
What happens when PRRs on innate immune cells, like macrophages, are activated?
Activation of PRRs can directly induce effector functions in these cells, such as phagocytosis.
How do innate immune cells amplify the immune response?
By producing inflammatory mediators, including cytokines and chemokines.
What are the roles of cytokines and chemokines in the immune response?
Cytokines: Signal other immune cells to enhance the immune response.
Chemokines: Attract immune cells to the site of infection or injury.
What triggers an inflammatory response during infection?
Cells produce mediators like chemokines and cytokines.
What are the mediators of inflammation, and what do they do?
Chemokines: Attract immune cells to the site of infection.
Cytokines: Signal and regulate the immune response.
What are the four hallmarks of inflammation?
Redness, heat, swelling, and pain.
How do dendritic cells link the innate and adaptive immune systems?
Dendritic cells travel from the site of infection to local secondary lymphoid tissue, where they interact with and activate T cells.
Where do dendritic cells activate T cells?
In secondary lymphoid tissue.
Where does T and B cell activation occur?
In the peripheral lymphoid tissue, specifically the lymph nodes.
How are T cells activated?
T cells are activated by antigen-presenting cells (APCs) through three crucial signals.
What are the three signals required for T cell activation?
1) Interaction of specific molecules (e.g., receptors).
2) Cytokine signaling.
3) Additional co-stimulatory signals (details can be added later as needed).
What is an epitope, and how is it related to an antigen?
An epitope is a specific part of an antigen, which can be a piece of peptide buried within a protein.
How is an antigen or epitope presented to T cells?
The antigen/epitope is presented using a Major Histocompatibility Complex (MHC), which interacts with the T cell receptor (TCR).
Where does the activation of antigen-specific adaptive immune cells occur?
In secondary lymphoid tissues, such as lymph nodes.
Which cells are activated during adaptive immunity?
T cells and B cells.
How is antigen specificity determined in T and B cells?
1) T cells: By their T cell receptor (TCR).
2) B cells: By their B cell receptor (BCR), which is also known as an antibody or immunoglobulin.
What are antibodies (Abs), and how are they produced?
Antibodies are secreted immunoglobulin (Ig) molecules made by B lymphocytes and their progeny plasma cells.
What is the primary function of antibodies?
Antibodies bind to antigens (Ag).
Where are antibodies found in the body?
Antibodies circulate in the serum, the fluid component of blood.
Can two antibodies recognize different epitopes on the same antigen?
Yes, two antibodies can recognize different epitopes on the same antigen.
Where do B cells and T cells arise and mature?
1) B cells: Arise and mature in the bone marrow.
2) T cells: Arise from bone marrow progenitors but mature in the thymus.
How do B cell receptors (BCRs) and T cell receptors (TCRs) differ in their form?
1) BCR: Can be membrane-bound or secreted as antibodies (Abs).
2) TCR: Exists only as a membrane-bound receptor.
How do BCRs and TCRs recognize antigens?
1) BCR: Recognizes antigens in their natural form.
2) TCR: Recognizes small pieces of antigens bound to MHC molecules on the surface of Antigen-Presenting Cells (APCs).
What is the origin of the diversity of lymphocyte specificity?
A single progenitor cell gives rise to a large number of lymphocytes, each with a different specificity for a distinct antigen.
What is the specificity of BCRs and TCRs in individual B and T cells?
Each B and T cell has an individual specificity for a single antigen and expresses many identical copies of one receptor specific to that antigen.
How is the diversity of antigen specificities among lymphocytes achieved?
Through the rearrangement and editing of genomic DNA that encodes antigen receptors in B and T cells.
What is the theoretical potential of BCR and TCR specificity?
The immune system has a huge diversity of lymphocytes, providing the potential to respond to any antigen.
What happens if a lymphocyte reacts to a self-antigen during development?
It is eliminated through clonal deletion, which removes potentially self-reactive immature lymphocytes.
What happens during clonal selection in B or T cells?
When a B or T cell interacts with its specific antigen, it is selected and activated.
What is the result of activation in clonal selection?
The activated lymphocyte proliferates, producing a large number of clones, each reactive against the original antigen
What is the process of clonal selection in terms of lymphocyte activation?
Mature naive lymphocytes encounter a foreign antigen, leading to the proliferation and differentiation of activated lymphocytes into a clone of effector cells.
What happens after T and B cells are activated in lymphoid organs?
They become effector cells capable of fighting infections.
What is humoral immunity, and how does it combat pathogens?
Humoral immunity combats pathogens via antibodies.
What is cell-mediated immunity, and which cells are involved?
Cell-mediated immunity involves primarily T lymphocytes.
How do humoral and cell-mediated immunity work together?
Both humoral and cell-mediated activities contribute to the immune response to fight infections.
How do T cells contribute to adaptive immunity?
T cells contribute to adaptive immunity in many ways, including activating other immune cells and killing infected cells.
How do different T cell subsets function in cell-mediated immunity?
1) Some T cells help activate B cells.
2) Some T cells help activate macrophages.
3) Some T cells kill infected cells directly.
How does humoral immunity contribute to adaptive immunity?
Humoral immunity contributes by producing specific antibodies that can clear and neutralize antigens.
What are the types and functions of antibodies in humoral immunity?
There are different types of antibodies.
Antibodies can act in various ways, including clearing and neutralizing antigens.
What is the role of regulation and memory in immune responses?
Regulation involves downregulation of lymphocytes, and immunological memory helps the immune system respond faster to subsequent infections.
What is the difference between active and passive immunization?
(1)
Active Immunization: Induces an adaptive immune response.
- Natural: Natural infection.
- Induced: Vaccination.
(2)
Passive Immunization: Involves transfer of immunity through cells or molecules.
- Natural: Transfer of antibodies from mother to fetus.
- Induced: Monoclonal antibody therapy.
