Microbiology Exam 5 Immunology Part II

T cells are a type of lymphocyte that mature in the thymus, which is a primary lymphoid organ. B cells, on the other hand, mature in the bone marrow. Therefore, the correct answer is T cells.

The five classes of antibodies are IgM, IgG, IgA, IgD, and IgE. These classes of antibodies differ in their structure and function. IgM is the first antibody produced during an immune response and is responsible for the initial defense against pathogens. IgG is the most abundant antibody in the blood and is involved in long-term immunity. IgA is found in secretions such as saliva and breast milk, providing protection at mucosal surfaces. IgD is involved in the activation of B cells. IgE is involved in allergic reactions and defense against parasites.

Helper T cells are a major functional population of T lymphocytes that play a crucial role in orchestrating the immune response. They have the ability to activate cell-mediated immune responses and macrophages (Th1-type) as well as humoral (B cells) response (Th2-type). Helper T cells can stimulate other T cells and possess the CD4 marker. They recognize antigens displayed by MHC class II molecules. Therefore, the correct answer is Helper T cells as they are responsible for coordinating and regulating the immune response.

The lymphoid system includes lymphatic vessels, primary lymphoid organs, and secondary lymphoid organs. Lymphatic vessels are responsible for transporting lymph fluid throughout the body. Primary lymphoid organs, such as the thymus and bone marrow, are where lymphocytes are produced and mature. Secondary lymphoid organs, such as lymph nodes and spleen, are where lymphocytes gather to encounter and respond to antigens. Therefore, all of the options listed are correct and are part of the lymphoid system.

Negative selection refers to the process in the thymus where T cells that recognize "self" antigens are eliminated or inactivated. This is important for preventing autoimmunity, as T cells that react strongly to self-antigens can potentially attack the body's own cells and tissues. During negative selection, T cells that bind strongly to self-antigens presented by thymic epithelial cells undergo apoptosis or become functionally inactive. This process helps to ensure that only T cells with appropriate specificity for foreign antigens are allowed to mature and leave the thymus to participate in immune responses.

The correct answer is "Immobilization and prevention of adhere". Antibodies can bind to antigens on the surface of pathogens or cells, preventing them from adhering to host cells and causing infection. This immobilization prevents the pathogen from entering host cells and spreading throughout the body, thus protecting against infection.

Memory lymphocytes are long-lived descendants of activated lymphocytes and are responsible for the speed and effectiveness of the secondary immune response. They remember the antigen from previous exposures and quickly mount a response upon subsequent exposure. These cells have undergone clonal selection, where those lymphocytes with high affinity for the antigen were selected and allowed to proliferate, leading to the formation of memory lymphocytes.

T-dependent antigens are compounds that require the assistance of T helper cells to evoke an immune response. These antigens are usually protein antigens that are presented to B lymphocytes by T helper cells, which then activate the B lymphocytes to produce antibodies. In contrast, T-independent antigens can directly stimulate B lymphocytes without the need for T helper cells. Therefore, the correct answer is T-dependent antigens.

The statement is true. In the anatomy of the lymphoid system, primary lymphoid organs are where immature lymphocytes develop into mature lymphocytes. Once mature, these cells leave the primary lymphoid organs and migrate to secondary lymphoid organs. In secondary lymphoid organs, such as lymph nodes and spleen, the mature lymphocytes wait to encounter antigens, which are substances that can trigger an immune response. Therefore, the statement accurately describes the process of lymphocyte maturation and migration within the lymphoid system.

The correct answer is MHC class I. MHC class I molecules are involved in presenting endogenous antigens, which are antigens that originate from within the cell. These antigens are typically derived from intracellular pathogens or abnormal proteins produced by the cell itself. MHC class I molecules present these antigens to cytotoxic T lymphocytes (CD8+ T cells), which can recognize and destroy infected or abnormal cells. Therefore, MHC class I molecules play a crucial role in the immune response against intracellular pathogens and cancer cells.

The strategy of adaptive immune response, specifically cellular immunity, focuses on eliminating intracellular pathogens. This response may take a week or more to develop and is referred to as a sequence response. It is effective in targeting and clearing intracellular pathogens, which are pathogens that reside within the cells of the body. This strategy is crucial in defending against viruses and certain bacteria that can invade and replicate within host cells.

The statement is true because the adaptive immune response involves two predominant subsets of T cells: cytotoxic (CD8*) T cells and helper (CD4*) T cells. These subsets play different roles in the immune response. Cytotoxic T cells are responsible for directly killing infected cells, while helper T cells aid in the activation of other immune cells and coordinate the immune response. Therefore, the statement accurately describes the strategy of adaptive immune response.

The lymphatic system is a network of vessels that carries lymph, a fluid containing white blood cells, throughout the body. Lymphatic vessels transport lymph to lymph nodes, which are small bean-shaped organs that filter the lymph and help fight infections. Therefore, the statement "Lymph travels through vessels to lymph nodes" is true.

The correct answer is "Formation of memory cells." This is because the passage states that B cells that have undergone class switching produce IgG antibody, which is the antibody of memory. It also mentions that IgG antibody can circulate in the body for years, providing long-term protection against specific antigens. Additionally, it states that memory lymphocytes are responsible for the speed and effectiveness of the secondary response. Therefore, the formation of memory cells is the most relevant explanation for the given information.

Humoral immunity is a type of immune response that involves the production of antibodies by B lymphocytes. These antibodies circulate in the blood and other bodily fluids, targeting and neutralizing pathogens such as bacteria and viruses. B lymphocytes, also known as B cells, are responsible for recognizing specific antigens and producing antibodies against them. Therefore, it is correct to say that humoral immunity is mediated by B lymphocytes.

B cells are a type of white blood cell that plays a crucial role in the immune response. When B cells encounter an antigen (a foreign substance), they can differentiate into plasma cells, which produce antibodies to fight off the antigen. Additionally, some B cells can differentiate into memory cells. Memory B cells are long-lived and can "remember" the antigen, allowing for a faster and stronger immune response upon re-exposure to the same antigen. Therefore, it is true that some B cells produce memory cells.

Antibody-dependent cellular cytotoxicity (ADCC) is a mechanism of immune response in which antibodies bind to specific antigens on the surface of target cells, marking them for destruction by immune cells such as natural killer (NK) cells. This process involves the binding of the Fc region of the antibody to Fc receptors on the NK cells, triggering the release of cytotoxic granules and inducing cell death in the target cells. ADCC plays a crucial role in eliminating infected cells and tumor cells, providing a protective outcome through the binding of multiple antibodies to a cell.

Combinatorial Associations refers to the process by which different combinations of light and heavy chains are formed during antibody production. This allows for a vast diversity of antibodies to be generated from a limited number of genes. In this context, the explanation suggests that the diversity of antibodies is achieved through the specific groupings of light and heavy chains, rather than having separate genes for each antibody.

The given information states that some B cells switch programming and differentiate into plasma cells that secrete other classes of antibodies, commonly IgG. This process is known as class switching. Class switching allows B cells to change the type of antibody they produce, which enables the immune system to respond effectively to different types of pathogens. Therefore, the correct answer is class switching.

The term "secondary response" refers to the immune response that occurs upon subsequent exposure to a pathogen. This response is enhanced compared to the initial response, as the immune system has already encountered and remembered the pathogen. It may take a week or more to develop because the immune system needs time to recognize the pathogen and mount a specific response. The secondary response is responsible for eliminating both extracellular and intracellular pathogens, providing a more robust defense against the pathogen.

The given answer is correct because cellular immunity, which is a strategy of adaptive immune response, is primarily mediated by T lymphocytes (T cells). B lymphocytes (B cells) are responsible for humoral immunity, which involves the production of antibodies. T cells, on the other hand, directly attack infected cells and regulate immune responses. Therefore, T lymphocytes play a crucial role in cellular immunity.

Cellular immunity refers to the immune response mediated by T cells. The thymus is a primary lymphoid organ where T cells mature and develop their specific functions. It is in the thymus that T cells undergo a process of education and selection, acquiring the ability to recognize foreign antigens and differentiate into effector cells. On the other hand, the bone marrow is responsible for the production of all blood cells, including immune cells such as B cells and natural killer cells, but not T cells. Therefore, the correct answer is that cellular immunity matures in the thymus.

IgE antibodies are barely detectable in circulation and are bound by FcRs (Fc receptors) of mast cells and basophils. They have a monomeric structure.

Positive selection is the process in the thymus where T cells that recognize self MHC molecules are selected to survive and mature. This ensures that T cells are able to recognize and respond to antigens presented by the body's own cells. In contrast, negative selection eliminates T cells that recognize self antigens too strongly, preventing the development of autoimmune responses. The given answer, "Positive Selection," is correct because it accurately describes the process of selecting T cells that recognize MHC molecules.

The spleen is a secondary lymphoid organ that plays a crucial role in the immune system. It acts as a filter for the blood, trapping and concentrating foreign substances such as bacteria and viruses. The spleen contains specialized cells called macrophages, which engulf and destroy these foreign particles. Additionally, the spleen also functions in the production of antibodies and the removal of old or damaged red blood cells from circulation. Therefore, the spleen is an important organ in the lymphoid system for trapping and concentrating foreign substances carried in the blood.

Humoral immunity is a type of immune response that involves the production of antibodies by B cells. These B cells mature in the bone marrow, where they undergo a process called V(D)J recombination to generate a diverse repertoire of B cell receptors. This process allows B cells to recognize a wide range of antigens, leading to the production of specific antibodies that can neutralize pathogens or mark them for destruction by other immune cells. Therefore, it is correct to say that humoral immunity is developed in the bone marrow.

Plasma cells are a type of white blood cell that plays a crucial role in the immune response. They are responsible for producing antibodies, which are proteins that help to identify and neutralize harmful pathogens such as bacteria and viruses. Antibodies are essential for the body's defense against infections and diseases. They bind to specific antigens, which are molecules found on the surface of pathogens, and mark them for destruction by other immune cells. Therefore, the correct answer is antibodies.

The correct answer is "Sites where lymphocytes gather to encounter antigens." This answer accurately describes the function of secondary lymphoid organs, which are the sites where lymphocytes gather to encounter antigens and initiate an immune response. These organs include lymph nodes, spleen, tonsils, and Peyer's patches in the intestines. In these organs, lymphocytes interact with antigens presented by antigen-presenting cells, leading to the activation and proliferation of specific immune responses.

Cytotoxic T cells are the correct answer because they are the T lymphocytes that proliferate and differentiate to destroy infected or cancerous "self" cells. They have the CD8 marker and recognize MHC class I. Helper T cells, on the other hand, orchestrate the immune response but do not directly destroy infected or cancerous cells.

Agglutination and precipitation are the protective outcomes of antibody-antigen binding. When antibodies bind to antigens on the surface of bacteria cells, they can cause the clumping of these cells, known as agglutination. This clumping makes it easier for immune cells to recognize and eliminate the bacteria. Additionally, the binding of antibodies to antigens can lead to the formation of immune complexes, which can precipitate out of solution. This precipitation helps to remove the antigens from the body, preventing their harmful effects.

B cells are a type of lymphocyte that plays a crucial role in the immune response. They are responsible for producing antibodies, which are proteins that specifically recognize and bind to foreign substances (antigens) in the body. B cells mature in the bone marrow, where they undergo a process called V(D)J recombination to generate a diverse repertoire of antigen receptors. Once mature, B cells migrate to secondary lymphoid organs, such as the spleen and lymph nodes, where they can encounter antigens and initiate an immune response. Therefore, the given answer correctly states that B cells mature in the primary lymphoid organ, which is the bone marrow.

When an antibody binds to an antigen, it can trigger the classical pathway of complement activation. The complement system is a part of the immune system that helps to clear pathogens and damaged cells from the body. Activation of the complement system leads to the recruitment and activation of immune cells, destruction of pathogens through the formation of membrane attack complexes, and the promotion of inflammation. Therefore, complement activation is a protective outcome of antibody antigen binding.

The correct answer is A-2, D-1, C-4, B-3. This is because mucosa-associated lymphoid tissue (MALT) is associated with the bronchus (A-2), skin-associated lymphoid tissue (SALT) is associated with the gut (D-1), gut-associated lymphoid tissue (GALT) is associated with the skin (C-4), and bronchus-associated lymphoid tissue (BALT) is associated with the mucosa (B-3).

Antibodies are indeed produced when an antigen binds to the B cell receptor (BCR). The BCR recognizes and binds to specific antigens, which triggers a series of events leading to the activation of B cells. Once activated, B cells differentiate into plasma cells, which are responsible for producing and secreting antibodies. These antibodies then circulate in the body, binding to antigens and helping to eliminate them. Therefore, the statement that antibodies are produced when antigen binds BCR is true.

The correct answer is "Lymph nodes". Lymph nodes are secondary lymphoid organs that are strategically located throughout the body. They play a crucial role in the immune system by trapping and filtering antigens that enter through the lymphatic vessels. Lymph nodes contain specialized immune cells called lymphocytes, which help in the recognition and elimination of foreign substances. Therefore, lymph nodes are highly efficient in the immune response and are an essential part of the lymphoid system.

The lymphoid system functions to concentrate antigens from all parts of the body into a few lymphoid organs. It also circulates lymphocytes through lymphoid organs so that antigens can interact with antigen-specific cells. Additionally, it carries products of the immune response, such as antibodies and effector cells, to the bloodstream and tissues. Therefore, the correct answer is "All of the Above."

IgA is the correct answer because it is the most abundant antibody produced, accounting for 10-13% of antibodies in circulation. It is mainly secreted from sigA, which is important in mucosal immunity in the gastrointestinal, genitourinary, and respiratory tracts. IgA is found in various secretions such as breast milk, mucous, tears, and saliva. Structurally, it exists as a monomer in serum and a dimer in secretions, with the monomers connected by a J chain. It is transported across epithelia by the poly Ig receptor, and the secretory component protects it from proteolytic enzymes.

IgG is the correct answer because it is the dominant antibody in circulation, accounting for 80-85% of antibodies present. It has a monomeric structure and is the only antibody that can cross the placenta, providing protection to the baby during and after birth. IgG is also found in colostrum, the first breast milk produced after birth, and can be absorbed by the intestinal tract of babies. Additionally, IgG is responsible for inducing "classical" complement activation with the highest avidity.

Opsonization is the process in which antibodies coat bacteria or other pathogens, making them more recognizable and easily engulfed by phagocytic cells such as macrophages and neutrophils. This enhances the process of phagocytosis, leading to the clearance of the pathogen from the body. Complement activation and antibody-dependent cellular cytotoxicity are also immune responses mediated by antibodies, but they do not directly involve the coating of bacteria to enhance phagocytosis like opsonization does.

The given statement is true. B cells carry multiple B cell receptors (BCRs) on their membrane, which are derivatives of the antibody (Ab) that the B cell is programmed to produce. These BCRs play a crucial role in recognizing and binding to specific antigens, initiating an immune response. The diversity of BCRs allows B cells to recognize a wide range of antigens, providing a diverse and adaptive immune response.

The correct answer is that the bone marrow and thymus are primary lymphoid organs where stem cells mature into B and T cells and acquire BCRs or TCRs. These organs are crucial for the development and maturation of lymphocytes, which are essential for the immune response. The bone marrow is responsible for the production of B cells, while the thymus is responsible for the production of T cells. Both of these organs play a vital role in the formation of a functional immune system.

T or FB cells, which refer to T cells or B cells, can be triggered to proliferate into plasma cells. This means that when these cells are activated by antigens, they can undergo a process called clonal expansion, leading to the production of a large number of plasma cells. These plasma cells are responsible for producing and secreting antibodies, which are essential for immune responses against pathogens. Therefore, the statement is true.

Activated lymphocytes are a type of lymphocytes that have encountered an antigen and have been stimulated to respond. They have undergone clonal selection, a process in which lymphocytes with receptors specific to the antigen are selected for proliferation and activation. Activated lymphocytes are capable of proliferating, meaning they can multiply and increase in number, and they have bound antigen, indicating that they have recognized and attached to the antigen that triggered their activation. This distinguishes them from other types of lymphocytes such as naive, effector, immature, and memory lymphocytes, which may not have encountered an antigen or undergone activation.

During a primary immune response, B cells undergo changes that enhance the immune response. Affinity maturation is the process by which B cells with higher affinity for the antigen are selected and proliferated, leading to the production of antibodies with higher affinity. Class switching is the process by which B cells change the class of antibodies they produce, allowing for different effector functions. Formation of memory cells occurs during the primary response, leading to a faster and stronger immune response upon re-exposure to the antigen. Therefore, all of the given options (affinity maturation, class switching, and formation of memory cells) are characteristics of the primary response.

The correct answer is Lymph nodes, spleen, tonsils, adenoids, appendix. These are all secondary lymphoid organs where lymphocytes gather to encounter antigens. Lymph nodes filter lymph fluid and contain immune cells. The spleen filters blood and removes old or damaged red blood cells. Tonsils and adenoids are located in the throat and help to trap and remove bacteria and viruses. The appendix is a small pouch connected to the large intestine and may play a role in immune function.

The correct answer is T- independent antigens. T- independent antigens are able to activate B cells without the help of helper T cells. They can directly bind to B cell receptors and stimulate B cell activation. These antigens include certain polysaccharides and lipopolysaccharides (LPS). It is also mentioned that the immune systems of young children, around 2 years old, respond poorly to T- independent antigens.

The correct answer is "May take a week or more to develop". This is because the primary response of the adaptive immune system to a particular antigen may take some time to develop, usually around a week or more. This primary response is the initial recognition and activation of immune cells against the antigen. On the other hand, the secondary response, which occurs upon re-exposure to the same antigen, is faster and more efficient due to the presence of memory cells. Therefore, the primary response may take longer to develop compared to the secondary response.

The correct answer is "Eliminates extracellular pathogens." This is because humoral immunity, which is a part of the adaptive immune response, is primarily responsible for fighting extracellular pathogens. It involves the production and release of antibodies that can neutralize or eliminate pathogens present outside of cells. This response may take some time to develop, but it is highly effective in targeting and eliminating extracellular pathogens.

IgM is the first antibody to respond to an infection and constitutes 5-13% of antibodies in circulation. It has a pentameric structure and is primarily involved in controlling bloodstream infections. IgM is found on the surface of B lymphocytes as a monomer. It is the most efficient antibody at eliciting the classical complement cascade and is effective in agglutination and precipitation reactions. IgM is the only class of antibody that can be produced in response to T-independent antigens. Additionally, IgM is the only antibody that can be formed by the fetus if infected in utero, with production beginning after birth.

Naive lymphocytes are characterized by having antigen receptors but not having encountered any antigen. This means that they have not been activated or differentiated into effector or memory lymphocytes. Naive lymphocytes are the initial pool of lymphocytes that are ready to respond to antigens when they are encountered. They are considered "naive" because they have not yet been exposed to any specific antigen and have not undergone any clonal selection or expansion.