Quiz On Immunology Organized By Microbiology Deptt., Y. C. College Lakhandur, Dist- Bhandara.

All of the given statements are correct explanations for how the skin prevents pathogen entry. The dead cells of the skin's outer layer act as a barrier to prevent pathogens from entering the body. The skin also secretes oil through sebaceous glands, which creates an acidic environment on the skin's surface that is unfavorable for pathogen growth. Additionally, sweat produced by sudoriferous glands also contributes to the skin's acidity, further inhibiting pathogen entry.

B cells mature in the bone marrow and gut associated lymphoid tissue (GALT), while T cells mature in the thymus.

Type I hypersensitivity is an immediate allergic reaction mediated by IgE antibodies. It is characterized by the release of histamine and other inflammatory mediators from mast cells and basophils. Penicillin allergy, dust sickness, and pollen allergy all fall under Type I hypersensitivity as they involve an immune response triggered by specific allergens. However, serum sickness is not a Type I hypersensitivity reaction. It is a Type III hypersensitivity reaction caused by the formation of immune complexes and subsequent inflammation.

Type II hypersensitivity is called antibody-mediated cytotoxic hypersensitivity. In this type of hypersensitivity, antibodies bind to antigens on the surface of cells, leading to their destruction by various mechanisms such as complement activation or antibody-dependent cell-mediated cytotoxicity. This type of hypersensitivity is associated with autoimmune diseases, transfusion reactions, and some drug reactions.

The first line of defense includes the skin, mucus, and lysozyme secretion. The skin acts as a physical barrier, preventing pathogens from entering the body. Mucus traps and removes foreign particles and pathogens from the respiratory and digestive tracts. Lysozyme is an enzyme found in various secretions, such as tears and saliva, that can break down bacterial cell walls. All of these mechanisms work together to protect the body from potential infections and pathogens.

Arthus' reaction is a characteristic reaction for the identification of Type III hypersensitivity. This type of hypersensitivity involves the formation of immune complexes that deposit in tissues, leading to inflammation and tissue damage. Arthus' reaction specifically refers to a localized immune complex-mediated reaction in the skin, which occurs when a person is re-exposed to an antigen that they have previously been sensitized to. This reaction typically results in a localized inflammatory response, with symptoms such as redness, swelling, and pain at the site of exposure.

B and T cells are produced by stem cells that are formed in the bone marrow. The bone marrow is a soft, spongy tissue found in the center of bones. It is responsible for the production of various types of blood cells, including B and T cells. B cells are responsible for producing antibodies that help in fighting off infections, while T cells play a role in cell-mediated immunity and directly attack infected or cancerous cells. Therefore, the bone marrow is the correct answer as it is the primary site of B and T cell production.

Asthma is an example of Type I hypersensitivity because it involves an immediate allergic response triggered by an allergen. In Type I hypersensitivity, the immune system overreacts to harmless substances such as pollen, dust mites, or pet dander, causing the release of histamine and other chemicals that lead to inflammation and constriction of the airways. This results in symptoms like wheezing, shortness of breath, and coughing. Type II hypersensitivity involves antibody-mediated destruction of cells, Type III hypersensitivity involves immune complex deposition, and Type VI hypersensitivity is not a recognized type of hypersensitivity.

Innate immunity refers to the nonspecific host defenses that are present in the body before exposure to any specific antigen. These defenses include physical barriers like the skin, as well as cellular and molecular components such as phagocytes and antimicrobial proteins. Unlike acquired immunity, which develops after exposure to an antigen, innate immunity is always present and provides a general level of protection against a wide range of pathogens. Therefore, the correct answer is innate immunity.

Haptens are small molecules that are unable to stimulate an immune response on their own. However, when they bind to a larger molecule, such as a protein, they can become immunogenic and trigger an immune response. This is because haptens are too small to be recognized by immune cells directly, but when attached to a larger molecule, they can be presented to immune cells, leading to the activation of an immune response. Therefore, haptens require conjugation to larger molecules to elicit an immune response.

Innate immunity is referred to as "all of these" because it encompasses various aspects. It is called "familial" because certain immune responses can be inherited within families. It is referred to as "genetic" because it is influenced by an individual's genetic makeup. Additionally, it is known as "inborn" because it is present at birth and provides immediate defense against pathogens. Therefore, all of these terms accurately describe innate immunity.

T cytolytic cells, also known as cytotoxic T cells or killer T cells, are immune cells that are most effective at destroying intracellular pathogens. These cells recognize infected cells by binding to antigens presented on their surface and release cytotoxic substances, such as perforin and granzymes, to induce cell death. This allows them to directly kill infected cells and eliminate the intracellular pathogens. T helper cells, B cells, antibodies, and complement play important roles in the immune response, but they are not as effective at directly destroying intracellular pathogens as T cytolytic cells.

Infection with a disease-causing organism followed by recovery is the most likely process to acquire immunity. When a person is infected with a pathogen, their immune system responds by producing specific antibodies to fight off the infection. Once the person recovers, their immune system retains memory of the pathogen, allowing for a faster and stronger response if they are exposed to the same pathogen in the future. This process is known as natural immunity and is a natural defense mechanism of the body. Vaccination also works on a similar principle by introducing a weakened or inactivated form of the pathogen to stimulate an immune response and provide immunity without causing the disease. Drinking colostrum, which is the first milk produced by a mother after giving birth, can provide some passive immunity to newborns but is not a process of acquiring long-term immunity.

Attenuated refers to a living microbe that has been weakened or altered in a way that it still retains its ability to stimulate an immune response but has reduced virulence, meaning it causes less severe or no disease symptoms. This weakened microbe is used in vaccines to induce an immune response without causing illness. Therefore, the correct answer is "Attenuated".

Plasma cells are B cells that have been activated and differentiated to produce and release large amounts of antibodies. They are responsible for the humoral immune response and play a crucial role in defending the body against pathogens. Memory cells, on the other hand, are long-lived B cells that are capable of quickly producing antibodies upon re-exposure to a specific antigen. Basophils, killer cells, and neutrophils are different types of immune cells with distinct functions in the immune system, but they are not directly involved in the production and release of antibodies.

Type IV hypersensitivity is also called cell mediated hypersensitivity because it involves the activation of T cells and the release of cytokines, rather than the involvement of antibodies like in other types of hypersensitivity reactions. In this type of hypersensitivity, T cells recognize antigens presented by antigen-presenting cells and release cytokines, causing inflammation and tissue damage. This type of hypersensitivity is commonly associated with delayed-type hypersensitivity reactions, such as contact dermatitis and tuberculin skin tests.

Naturally acquired active immunity provides the longest lasting immunity to an infectious agent. This type of immunity occurs when a person's immune system responds to a natural infection, such as getting sick with a disease, and develops antibodies to fight off the infection. These antibodies remain in the body even after the infection is cleared, providing long-term protection against future infections from the same agent. This is in contrast to passive immunity, where antibodies are obtained from an external source and provide temporary protection.

Cell mediated immunity is carried out by T cells while humoral immunity is mainly carried out by B cells. T cells are responsible for directly attacking infected cells and activating other immune cells, while B cells produce antibodies that can neutralize pathogens and mark them for destruction by other immune cells. This division of labor allows the immune system to effectively combat different types of pathogens and provide comprehensive protection against infections.

B cells are a type of white blood cell that plays a crucial role in the immune response. They are primarily activated by antigens, which are foreign substances that trigger an immune response. When antigens enter the body, B cells recognize and bind to them using their specific antigen receptors. This binding activates the B cells, leading to their proliferation and differentiation into antibody-producing plasma cells. Therefore, antigens are the primary activators of B cells in the immune response.

Innate immunity is the body's first line of defense against pathogens and involves various mechanisms to protect against infections. Anatomic barriers, such as the skin and mucous membranes, act as physical barriers to prevent the entry of pathogens. Phagocytic cells, such as macrophages and neutrophils, engulf and destroy invading pathogens. Inflammatory mechanisms, including the release of chemical mediators and recruitment of immune cells, help to eliminate pathogens and promote tissue repair. Antibody production, on the other hand, is a characteristic of adaptive immunity, which is a more specific and targeted response involving the production of antibodies by B cells in response to a specific pathogen.

The specificity of an antibody is due to the variable portion of the heavy and light chain. This is because the variable region contains antigen-binding sites that can recognize and bind to specific antigens. The heavy chains and Fc portion of the molecule do not directly contribute to the specificity of the antibody. The valence of an antibody refers to the number of antigen-binding sites it possesses, but it does not determine the specificity. Therefore, the variable portion of the heavy and light chain is responsible for the specificity of an antibody.

Monoclonal antibodies are designed to recognize and bind to specific molecules called antigens. Antigens are foreign substances that can trigger an immune response in the body. Monoclonal antibodies are produced from a single clone of cells and are highly specific in their recognition of antigens. They can be used for various purposes, such as diagnosing diseases, treating cancer, and studying immune responses. By recognizing a single antigen, monoclonal antibodies can target and neutralize specific pathogens or abnormal cells in the body.

Killer cells, also known as cytotoxic T cells, play a role in Type II hypersensitivity reactions. In Type II hypersensitivity, the immune system mistakenly targets normal cells or tissues, leading to their destruction. IgM antibodies are involved in this process by binding to antigens on the surface of the target cells, marking them for destruction by killer cells. This immune response can result in various autoimmune diseases and tissue damage. Therefore, the correct answer is Type II hypersensitivity.

In agglutination reactions, the antigen is a whole cell or a soluble molecule. This means that the antigen can be either a complete cell or a molecule that is able to dissolve in a liquid. Agglutination reactions involve the clumping together of antigens and antibodies, and this clumping can occur with whole cells or soluble molecules. In precipitation reactions, on the other hand, the antigen is a soluble molecule. This means that the antigen is a molecule that can dissolve in a liquid, but it is not a complete cell. Precipitation reactions involve the formation of a solid precipitate when antigens and antibodies react together.

Tolerance refers to the ability of the immune system to distinguish between self and nonself antigens. This means that the immune system can recognize and tolerate self antigens, which are the body's own molecules, while mounting a response against nonself antigens, such as pathogens or foreign substances. This is crucial for preventing autoimmune diseases, where the immune system mistakenly attacks the body's own cells and tissues. Tolerance is an important aspect of the immune system's ability to maintain homeostasis and prevent unnecessary immune responses.

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Type I hypersensitivity is an allergic reaction that is mediated by mast cells and IgE antibodies. Mast cells are primarily responsible for releasing histamine and other inflammatory mediators when they come into contact with an allergen. IgE antibodies, produced by B cells, bind to mast cells and sensitize them to specific allergens. When the allergen is encountered again, it binds to the IgE antibodies on the mast cells, triggering the release of histamine and causing the allergic response.

When a plasma cell and a tumor cell fuse together, they create a hybridoma. A hybridoma is a type of cell that is produced by fusing a specific antibody-producing plasma cell with a tumor cell. This fusion results in a cell that has the ability to continuously produce large amounts of a specific antibody, known as a monoclonal antibody. Hybridomas are commonly used in laboratory research and in the production of therapeutic antibodies for various medical purposes.

Serum sickness is an example of Type III hypersensitivity. Type III hypersensitivity is characterized by the formation of immune complexes that deposit in various tissues, leading to inflammation and tissue damage. In the case of serum sickness, it occurs when a person is exposed to a foreign protein, such as an antibiotic or antiserum, which triggers an immune response. Immune complexes are formed and deposited in tissues, causing symptoms such as fever, rash, joint pain, and organ damage. This immune response is mediated by the activation of complement and the recruitment of inflammatory cells.

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