Immunology Quiz Questions And Answers

T cells, a type of white blood cell involved in immune responses, are produced in the bone marrow and then migrate to the thymus gland to complete their differentiation. The bone marrow is responsible for the initial production of T cell precursors, while the thymus provides the necessary environment for their maturation and development into functional T cells.

Plasma cells (activated B cells) produce large amounts of antibodies (Igs) and differentiate upon stimulation from CD4+ cells. CD4+ cells play a crucial role in activating B cells and promoting antibody production. CD8+ cells are primarily involved in cytotoxic immune responses and do not produce antibodies. Hence, the correct answer is plasma cells (activated B cells).

CD8+ is a transmembrane glycoprotein that acts as a co-receptor for the T cell receptor (TCR) on cytotoxic T cells. It plays a crucial role in the activation of T cells and the immune response. CD8+ binds to major histocompatibility complex class I (MHC-I) molecules on antigen-presenting cells, which allows the TCR to recognize and respond to specific antigens. This interaction enhances the binding affinity between the T cell and the target cell, leading to the activation of cytotoxic T cells and the destruction of infected or abnormal cells.

CD4 is a glycoprotein that is expressed on the surface of T helper cells, regulatory T cells, monocytes, macrophages, and dendritic cells. It plays a crucial role in the immune response by binding to major histocompatibility complex class II (MHC-II) molecules on antigen-presenting cells. This interaction helps in the activation of T cells and the initiation of an immune response. CD4 is also the primary receptor for the human immunodeficiency virus (HIV), allowing the virus to enter and infect CD4+ T cells. Therefore, CD4 is an important marker for identifying and studying these immune cell populations.

Macrophages are a type of innate immune system cell that are responsible for phagocytosis and bacteriocidal mechanisms, meaning they engulf and destroy pathogens. They also play a role in antigen presentation, which is the process of displaying antigens to activate the adaptive immune response. This allows the immune system to recognize and respond to specific pathogens.

The effector phase of an adaptive immune response is characterized by the eventual elimination of the antigen. During this phase, the immune system responds to the presence of the antigen by producing specific antibodies and activating immune cells to directly attack and eliminate the antigen. This phase is crucial in effectively clearing the infection or eliminating the foreign substance from the body.

The activation phase of an adaptive immune response refers to the stage where immune cells, such as T and B cells, are activated upon encountering an antigen. During this phase, these cells undergo proliferation, meaning they multiply in number, to generate a larger population of cells with matching receptors. This increased cell population allows for a more effective immune response against the antigen. The cognitive phase refers to the initial recognition and processing of the antigen, while the effector phase involves the elimination of the antigen. "None of these" is not the correct answer as it does not match any of the stages described.

Humoral immunity is mediated by antibodies produced by B lymphocytes and is involved in the elimination of extracellular pathogens. Cell-mediated immunity is mediated by T lymphocytes and is involved in the elimination of intracellular pathogens.

The cognitive phase of an adaptive immune response refers to the initial recognition of antigens by immune cells. During this phase, immune cells such as B cells and T cells encounter antigens and begin to process and present them to other immune cells. This recognition is crucial for the immune system to initiate a targeted response against the specific antigen.

Natural killer cells are a type of innate immune system cell that is responsible for the lysis (destruction) of some virally infected cells. They recognize and kill cells that are infected with viruses, helping to prevent the spread of the infection. This is an important function of the innate immune system in defending the body against viral infections.

Speed is not a major feature of the adaptive immune system. The adaptive immune system is known for its specificity, diversity, memory, and ability to improve over time. However, speed is not considered a primary characteristic of the adaptive immune system. While the adaptive immune response can be efficient and effective, it is generally slower compared to the innate immune response, which provides immediate, non-specific defense against pathogens.

In a resting lymphocyte, B cells and T cells cannot be distinguished from each other via a simple blood smear. Both B cells and T cells look similar in appearance and cannot be differentiated based on their morphology alone. Additional tests, such as flow cytometry or immunohistochemistry, are required to accurately distinguish between B cells and T cells.

Neutrophils are a type of innate immune system cell that are responsible for phagocytosis and bacteriocidal mechanisms. They engulf and destroy pathogens through phagocytosis, which involves engulfing the pathogens and breaking them down. Neutrophils also release bacteriocidal substances to kill the pathogens. This function helps to eliminate and control infections in the body.

Dendritic cells are critical in the uptake and presentation of antigens to T cells. They are specialized APCs that capture and process antigens, and then present them to T cells to initiate an immune response. Dendritic cells have a unique ability to efficiently capture antigens from their surroundings and present them to T cells, making them a crucial link between innate and adaptive immunity. Macrophages and B cells also have antigen-presenting capabilities, but dendritic cells are particularly specialized for this function.

To reach a protective level of antibody, it is typically recommended to administer three doses of the Hepatitis B vaccine. Each dose contains 5µg of HBsAg in 0.5mL intramuscular. Therefore, a total of three doses are required to ensure sufficient protection against Hepatitis B.

Eosinophils are a type of innate immune system cell that are primarily responsible for killing parasites. They do this by releasing toxic granules that target and kill parasites. Eosinophils are not involved in phagocytosis and bacteriocidal mechanisms like other immune cells such as neutrophils and macrophages. They also do not play a role in lysing virally infected cells. Instead, eosinophils are specifically specialized in combating parasitic infections. Additionally, eosinophils can also release histamine and other mediators, which can contribute to allergic reactions and inflammation.

B cells are a type of antigen-presenting cell (APC) that have immunoglobulin receptors on their surface. When a B cell encounters an antigen that matches its specific receptor, the antigen is internalized, degraded, and presented to T cells. This process allows for the activation of T cells and the initiation of an immune response. Macrophages and dendritic cells also function as APCs, but they do not have immunoglobulin receptors on their surface. Therefore, the correct answer is B cell.

APCs, such as macrophages and dendritic cells, are found in lymphoid tissues and the skin. They play a crucial role in capturing and presenting antigens to T cells, which is essential for the immune response. The skin is the largest organ in the body and acts as a physical barrier against pathogens. It contains a large number of APCs that constantly survey the environment for potential antigens. When they encounter antigens, they capture and process them, presenting them to T cells to initiate an immune response. Therefore, the skin is an important site for antigen presentation and immune surveillance.

Macrophages are specialized antigen-presenting cells that have the ability to phagocytose (engulf) and degrade particulate antigens. They can then present the degraded antigens on their cell surface using major histocompatibility complex (MHC) molecules to activate T cells. Macrophages are found in various tissues and play a crucial role in the immune response by recognizing and eliminating foreign particles or pathogens. Dendritic cells and B cells also have antigen-presenting capabilities, but they are not specifically specialized for degradation and presentation of particulate antigens like macrophages.

The effector phase of an adaptive immune response involves the secretion of antibodies from large plasma cells that have extensive endoplasmic reticulum. During this phase, the immune system is actively fighting against the pathogen or antigen, and the antibodies produced by the plasma cells help to neutralize or eliminate the foreign invader. This is different from the cognitive and activation phases, which involve the recognition and initiation of the immune response, respectively. Therefore, the correct answer is the effector phase.

Tissue mast cells play a key role in the inflammatory response by releasing histamine and other mediators, which are involved in inflammation and allergic reactions. This function helps initiate the immune response to various pathogens and allergens.