Class 18 Adaptive Immunity

<p>Each class can have the same binding sites but different constant regions. (A)</p> Signup and view all the answers

<p>It has the least specificity among the antibody classes. (C)</p> Signup and view all the answers

<p>To recognize a wide range of antigens with varying affinities (A)</p> Signup and view all the answers

<p>Confirmation from a specific T Helper lymphocyte (A)</p> Signup and view all the answers

<p>Plasma cells (C)</p> Signup and view all the answers

<p>Selected cells multiply and some form antibody-secreting plasma cells (D)</p> Signup and view all the answers

<p>Affinity maturation and class switching (D)</p> Signup and view all the answers

<p>Triggering classical pathway of complement system (A)</p> Signup and view all the answers

<p>IgG (C)</p> Signup and view all the answers

<p>To neutralize toxins and viruses (A)</p> Signup and view all the answers

<p>IgE (B)</p> Signup and view all the answers

<p>80% to 85% (D)</p> Signup and view all the answers

<p>21 days (A)</p> Signup and view all the answers

<p>It is involved in the development and maturation of antibody responses. (C)</p> Signup and view all the answers

<p>To neutralize toxins and viruses (D)</p> Signup and view all the answers

<p>IgD (A)</p> Signup and view all the answers

<p>By releasing histamines and other mediators (B)</p> Signup and view all the answers

<p>To enhance the ability of B-cell receptors to bind antigen (D)</p> Signup and view all the answers

<p>IgG (C)</p> Signup and view all the answers

<p>They undergo apoptosis (D)</p> Signup and view all the answers

<p>It involves memory cells (D)</p> Signup and view all the answers

<p>Class switching and affinity maturation (B)</p> Signup and view all the answers

<p>To block toxins and viruses from binding to cells (A)</p> Signup and view all the answers

<p>They produce antibodies that are already fine-tuned (B)</p> Signup and view all the answers

<p>To enhance phagocytosis of pathogens (D)</p> Signup and view all the answers

<p>IgA (A)</p> Signup and view all the answers

<p>They undergo apoptosis (D)</p> Signup and view all the answers

<p>To present antigens to naive T cells (A)</p> Signup and view all the answers

<p>It eliminates immature T and B cells that recognize 'self' (D)</p> Signup and view all the answers

<p>By inducing apoptosis in infected cells (A)</p> Signup and view all the answers

<p>Reduce immune responses to prevent overreaction (A)</p> Signup and view all the answers

<p>The T cell becomes inactive (C)</p> Signup and view all the answers

<p>Helper T cells (C)</p> Signup and view all the answers

<p>It prevents activation of mature T and B cells (D)</p> Signup and view all the answers

<p>A substance that induces an immune response (A)</p> Signup and view all the answers

<p>They require TH cell help for B cell activation. (C)</p> Signup and view all the answers

<p>Bone marrow and thymus (C)</p> Signup and view all the answers

<p>Lipids (C)</p> Signup and view all the answers

<p>They transport lymph and help in antigen exposure. (B)</p> Signup and view all the answers

<p>By eliminating self-reactive lymphocytes. (C)</p> Signup and view all the answers

<p>They induce apoptosis in antibody-bound self cells. (C)</p> Signup and view all the answers

<p>To house mature lymphocytes and facilitate antigen interaction. (B)</p> Signup and view all the answers

<p>Inflammatory response. (C)</p> Signup and view all the answers

<p>They can be proteins but are usually carbohydrates with repeating subunits. (B)</p> Signup and view all the answers

<p>Flu-like symptoms such as fever and headache. (B)</p> Signup and view all the answers

Antibodies are Y-shaped proteins made of two identical heavy chains and two identical light chains. They can be split into Fab (antigen-binding) and Fc (constant) fragments.

Antibodies are grouped into classes (like IgM, IgG, IgA, IgD, and IgE) each with unique constant regions, functions, and properties.

IgM is a pentameric antibody, meaning it's composed of five basic antibody units, offering ten antigen-binding sites.

Antibodies bind to specific antigens (targets), marking them for destruction by other immune cells.

IgM is the primary antibody produced during the first encounter with an antigen, often less specific but potent.

IgG is the most abundant immunoglobulin, providing long-term protection (21 days). It neutralizes toxins, prevents pathogen attachment, and activates the complement system. It crosses the placenta for fetal immunity.

IgG is crucial for fighting bloodstream infections due to its large size, which prevents it from easily leaving the bloodstream to enter tissues.

IgG efficiently activates the complement system, playing a vital role in immune response.

IgA exists mostly as a dimer (secretory IgA) and plays a crucial role in mucosal immunity, protecting the digestive, respiratory, and genitourinary tracts.

IgA works by neutralizing toxins, viruses, and preventing microbes from attaching to host cells.

IgA is produced by plasma cells in mucosa-associated lymphoid tissue (MALT).

IgD is a less than 1% of serum immunoglobulin and is involved in the progression of antibody responses. Its exact role in serum is unclear.

IgE is primarily involved in allergic reactions and parasitic infections. It is bound to mast cells and basophils for immune response triggering.

Antibody diversity begins with the flexibility of a hematopoietic stem cell having different segments for variable, diversity, and joining regions that can rearrange through DNA deletion and splicing during transcription.

The process involves combining segments of DNA and different ways to cut and paste.

B cells are activated when they encounter their specific antigen. This binding initiates a series of steps, including proliferation (copying) of the B cell, but also a check to ensure it's not reacting against the body's own tissues.

Before fully activating and attacking, B cells must receive confirmation from a T helper cell. This ensures the immune response targets foreign threats and not the body's own cells (self-tolerance).

Activated B cells multiply rapidly, creating many copies (clones). Some of these clones become plasma cells, which release antibodies. Others develop into memory cells, ready for a quicker immune response in the future.

The primary response is the initial immune reaction to a new antigen. It involves activation, expansion of B cells, and production of IgM antibodies. It also leads to the formation of germinal centers, where B cells further optimize their response.

Germinal centers are specialized regions within lymphoid organs where activated B cells undergo fine-tuning. This includes affinity maturation (improving antibody binding) and class switching (changing antibody type).

A process where B cells improve their ability to bind antigens. During this process, B cells that bind an antigen for a longer period are more likely to divide and produce more antibodies, leading to antibodies with higher affinity.

A process where B cells change the type of antibody they produce. Initially, B cells produce IgM, but they can switch to producing other classes like IgG or IgA, depending on the location and type of infection.

The decrease in antibody production after the initial immune response. This happens as the antigen is cleared and B cells die off, but some become memory B cells.

A more rapid and effective immune response to a previously encountered antigen. This is due to the presence of memory B cells, which quickly produce antibodies and eliminate the pathogen before it causes harm.

The process of resolving the secondary immune response involves even more effective antibody production and a larger pool of memory B cells, preparing for future encounters with the same antigen.

A method of antibody action where antibodies bind to viruses or toxins, preventing them from attaching to host cells.

A method of antibody action where antibodies coat pathogens, making them more attractive to phagocytes and enhancing their destruction.

A method of antibody action where antibodies activate a cascade of proteins in the complement system, leading to the lysis (destruction) of pathogens.

A method of antibody action where antibodies bind to bacterial flagella or pili, preventing them from moving or attaching to host cells.

A method of antibody action where two arms of an antibody bind to separate antigens, aggregating pathogens and making them easier to target.

A molecule that specifically interacts with an antibody, B-cell receptor, or T-cell receptor. It triggers an immune response.

The ability of an antigen to stimulate an immune response, causing the body to mount a defense.

Proteins usually trigger a strong immune response. Lipids and nucleic acids often don't. Small molecules typically aren't immunogenic unless they bind to larger carrier molecules.

An antigen that requires the help of a T helper (TH) cell to activate B cells for antibody production.

An antigen that can directly activate B cells without the need for a T helper (TH) cell.

A network of tissues and organs that transports lymphocytes, filters lymph, and connects with the immune system.

Fluid that bathes tissues and contains antigens, circulating through lymphatic vessels.

Organs where lymphocytes develop and mature, such as the bone marrow and the thymus.

Organs where mature lymphocytes encounter antigens and initiate immune responses, like lymph nodes, spleen, and tonsils.

Cells of the innate immune system that can kill infected or cancerous cells without prior sensitization.

The process where immature lymphocytes (T and B cells) that recognize self-antigens are eliminated in the thymus (for T cells) and bone marrow (for B cells) during their development. This prevents the immune system from attacking the body's own tissues.

A mechanism that suppresses mature T and B lymphocytes that escaped central tolerance from reacting against self-antigens or harmless molecules. It ensures immune responses are specific and targeted to foreign threats.

Dendritic cells (DCs) act as antigen-presenting cells. They collect antigens (from pathogens, etc.), travel to T cell areas, and present them to naive T cells. They also produce co-stimulatory molecules for T cell activation if the antigen is dangerous.

T cells become activated when their TCR (T cell receptor) recognizes an antigen presented by a dendritic cell. This requires co-stimulatory signals from the DC, indicating the antigen is dangerous.

These T cells directly kill infected cells. They survey cell surfaces for their specific antigen. If found, they induce apoptosis (programmed cell death) in the infected cell. They also generate memory cells for faster responses in the future.

Helper T cells do not directly kill cells. They produce cytokines (signaling molecules) that activate macrophages, B cells, and other T cells. They also contribute to memory cell development for future responses.

These T cells prevent overreaction of the immune system. They reduce immune responses, acting like 'brakes' to control inflammation and autoimmunity.

There are many T cell subclassifications, like CD8 and CD4. For this section, we'll focus on Helper T cells and Cytotoxic T cells. Others will be covered later when needed.