Clinical Immunology And Serology Quiz

The correct answer is epitope. An epitope is the specific part of an antigen that binds to an antibody or a receptor on a T cell. It is also known as an antigenic determinant. The paratope, on the other hand, is the specific part of an antibody or a T cell receptor that binds to the epitope. Valence refers to the number of antigen-binding sites on an antibody molecule. Therefore, the correct answer is epitope, as it specifically refers to the binding site of an antigen.

Skin, lactic acid secretions, stomach acidity, and the motion of cilia are all natural defense mechanisms of the body. These mechanisms provide a non-specific, innate form of immunity that helps protect the body from pathogens and foreign substances. This type of immunity is known as natural immunity. It is present from birth and does not require prior exposure to specific pathogens.

Graft versus host disease (GVHD) occurs when the transplanted immune cells (graft) attack the recipient's tissues (host). This immune response is most commonly associated with bone marrow transplants. In a bone marrow transplant, the recipient receives new bone marrow, which contains immune cells that can recognize the recipient's tissues as foreign and mount an attack. This can lead to inflammation and damage to various organs and tissues in the recipient's body. GVHD is less commonly associated with other types of transplants such as corneal, bone matrix, or lung transplants.

IgM is the first antibody produced during an immune response and is considered a primary response antibody. It is a pentamer structure and contains a J chain, which helps stabilize its structure. IgM is also known to fix complement, which is an important part of the immune response. However, IgM cannot cross the placenta, unlike other antibodies such as IgG.

Opsonization refers to the process in which antibodies and/or complement components coat a particulate antigen, such as a bacterium or a virus, making it more easily recognized and engulfed by phagocytic cells. This coating enhances the phagocytosis of the antigen by immune cells, such as macrophages and neutrophils. Opsonization plays a crucial role in the immune response against pathogens, as it facilitates the efficient removal of these pathogens from the body.

IgG is the most abundant circulating antibody in human plasma. It is the main antibody involved in secondary immune responses and provides long-term immunity against pathogens. IgG can cross the placenta, providing passive immunity to the fetus, and it also plays a role in opsonization, neutralization, and activation of complement. IgM is the first antibody produced during an initial immune response, but it is not as abundant as IgG in the circulation. IgD, IgE, and IgA have more specialized roles in the immune system and are not as abundant as IgG in the plasma.

MHC molecules are associated with all of the above options. MHC molecules play a crucial role in the immune system by presenting antigens to T cells. This presentation helps in determining whether a graft will be rejected, as MHC molecules help identify foreign tissues. MHC molecules are also involved in autoimmune diseases, as they can present self-antigens, leading to an immune response against the body's own tissues. Additionally, MHC molecules are responsible for determining which agents an individual responds to, as they present antigens to T cells, initiating an immune response. Therefore, all of the given options are correct.

If cells of an individual are not agglutinated by serum from anyone else, this indicates that the individual does not have any antigens on their red blood cells. This is characteristic of Type O blood, which is known as the universal donor because it can be safely transfused to individuals with any other blood type.

The L chains of an antibody molecule can be either kappa or lambda. In this case, the correct answer is kappa, which is one of the possible L chains of an antibody molecule.

Serum inactivation serves multiple purposes. It destroys the native complement, removes heat-labile anti-complementary substances, and stabilizes the serologic properties of the serum. Therefore, the correct answer is "all of the above."

The thymus is a primary lymphoid organ because it is responsible for the development and maturation of T cells, a type of white blood cell involved in the immune response. The thymus is where T cells undergo selection and differentiation, acquiring the ability to recognize and respond to specific antigens. This process is crucial for the proper functioning of the immune system. Lymph nodes, spleen, and mucosal associated lymphoid tissue are secondary lymphoid organs, where immune responses are initiated and carried out.

Cold agglutinins are a type of antibodies that can cause red blood cells to clump together at lower temperatures, typically below body temperature. These antibodies are predominantly IgM, which is the primary antibody produced during the initial immune response to an infection. IgM antibodies are large and pentameric, allowing them to efficiently bind to multiple antigens and initiate the agglutination process. IgG, IgA, IgD, and IgE are not typically involved in cold agglutination.

The inflammatory process is characterized by increased blood supply to the area, migration of white blood cells, and the appearance of acute phase reactants. However, decreased capillary permeability is not a characteristic of the inflammatory process.

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If cells are not centrifuged long enough in an agglutination reaction, the false-negative result might occur. This means that the test would incorrectly indicate that the reaction did not occur or that the substance being tested for is not present, even though it actually is.

A negative test for VDRL but positive for FTA-ABS suggests early syphilis. The VDRL test is a screening test for syphilis, and a negative result indicates the absence of antibodies against the bacteria that causes syphilis. However, the FTA-ABS test is a confirmatory test that detects specific antibodies produced in response to syphilis infection. A positive result on the FTA-ABS test indicates the presence of these antibodies, confirming the diagnosis of syphilis. Therefore, a negative VDRL and positive FTA-ABS is consistent with early syphilis.

During convalescence from an infection, the body's immune system develops natural active immunity. This means that the immune system produces its own antibodies to fight off the infection. This type of immunity is long-lasting and provides protection against future infections by the same pathogen.

An allograft is a type of graft where the tissue or organ is transferred from one individual to another of the same species, but with different genetic makeup. In this case, the graft is from a mother to her child, indicating that they are genetically different. Therefore, the correct answer is allograft.

Antigen-stimulated T cells play a crucial role in the immune response by releasing cytokines. Cytokines are small proteins that act as chemical messengers, allowing T cells to communicate with other immune cells. They regulate various immune responses, including inflammation, cell proliferation, and differentiation. Therefore, the presence of cytokines can be attributed to antigen-stimulated T cells. The other options, such as humoral response, plasma cells, and antibodies, are more closely associated with B cells and the production of antibodies.

A positive direct Coombs test can occur under any of the given circumstances: hemolytic disease of the newborn, autoimmune hemolytic anemia, or antibodies to drugs that bind to red cells. This test is used to detect antibodies or complement proteins that are bound to the surface of red blood cells, which can lead to their destruction. Therefore, if any of these conditions are present, the test would be positive.

Metchnikoff first described phagocytosis.

Ehrlich developed the Side Chain Theory of antibody formation.

HLA typing refers to the process of determining the specific human leukocyte antigen (HLA) alleles present in an individual. HLA class II typing is particularly useful for detecting certain autoimmune diseases, including type 1 diabetes mellitus. This is because certain HLA class II alleles, such as HLA-DR3 and HLA-DR4, are strongly associated with an increased risk of developing type 1 diabetes. Therefore, by typing the HLA class II alleles, it is possible to identify individuals who may be at a higher risk for developing diabetes mellitus.

CD4 antigens are found on the T cell subset known as "inducers". CD4 is a glycoprotein that is expressed on the surface of helper T cells, which play a crucial role in activating and coordinating immune responses. CD4 helper T cells recognize and bind to antigens presented by antigen-presenting cells, initiating the immune response. CD3, CD8, and CD11 are antigens found on other T cell subsets, but not specifically on inducers.

The correct answer is "Humoral immunity primarily involves B lymphocytes." This statement is correct because humoral immunity refers to the immune response mediated by antibodies, which are produced by B lymphocytes. B lymphocytes are responsible for recognizing antigens and producing specific antibodies to neutralize them. This type of immunity is particularly important in defending against extracellular pathogens and toxins.

RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests are both used to detect antibodies in the blood that are associated with syphilis. However, these tests are not specific for syphilis and can also be positive in other conditions such as autoimmune diseases, certain infections, and pregnancy. Therefore, the statement "These are non-specific for syphilis" is true.

IgM and IgD are both types of immunoglobulins (antibodies) that are found on mature B cells. These antibodies play a crucial role in the immune response by recognizing and binding to specific antigens. The presence of IgM and IgD on B cells allows them to respond to a wide range of pathogens and initiate an immune response. The other options listed (IgG and IGD, alpha and beta chains, CD3 and CD4) are not typically found on mature B cells.

Not washing red cells thoroughly would cause a false-negative result in DAT because the test relies on the detection of antibodies or complement proteins attached to the surface of red blood cells. If the red cells are not properly washed, any antibodies or complement proteins present may not be adequately removed, leading to a false-negative result where the presence of these substances is not detected.

IgD plays a role in enhancing the proliferation of B cells. It is a type of antibody that is found on the surface of B cells and helps to activate and stimulate the growth of B cells. This is important for the immune response, as B cells are responsible for producing antibodies to fight off infections. Therefore, the main function of IgD is to support the proliferation and activation of B cells.

The Classical Pathway of complement activation is specific because immune complexes activate the pathway. This means that when antibodies bind to antigens to form immune complexes, it triggers the activation of the Classical Pathway. Other substances such as cobra venom factor, aggregated IgA's, and bacterial LPS can also activate the pathway, but the specific trigger mentioned in the answer is immune complexes.

A phagolysosome is the structure formed by the fusion of engulfed materials and enzymatic granules within a phagocytic cell. This structure combines the functions of a phagosome, which is responsible for engulfing and containing the materials, and a lysosome, which contains enzymes to break down the engulfed materials. Therefore, the correct answer is phagolysosome.

The Schick's test is used to diagnose diphtheria. This test involves injecting a small amount of diphtheria toxin into the skin and observing for a local reaction. If there is no reaction, it indicates that the person is susceptible to diphtheria and may require vaccination.

The "H" antigens are a crucial component in the classification and identification of certain bacteria, particularly in the genus Salmonella. These antigens are protein structures that constitute the flagella, which are whip-like appendages protruding from the cell body of bacteria. The flagella play a pivotal role in bacterial motility, allowing the bacteria to navigate through their environment.

Vi agglutination refers to the clumping of bacteria when exposed to specific antibodies. In this case, Vi agglutination is correlated to patients harboring Salmonella typhi. This means that if a patient shows positive Vi agglutination, it indicates that they are infected with Salmonella typhi bacteria. The other options, Escherichia coli, Proteus spp., and Brucella spp., are not specifically associated with Vi agglutination.

A good immunogen should have internal complexity, a large molecular weight, and the presence of numerous epitopes. However, it should not be found on host cells as this would indicate that the immune system recognizes it as self and would not mount an immune response against it.

ELISA is the most commonly used method to detect antibodies in a patient’s serum. It involves the binding of antibodies to specific antigens and uses enzyme-labeled detection systems to produce a measurable signal. ELISA is widely used for its sensitivity, specificity, and ability to test multiple samples quickly. While PCR and Western Blot are useful in molecular and protein detection, ELISA remains the primary tool for antibody testing.

Agglutination of dyed bacterial cells represents direct agglutination. This type of reaction occurs when antibodies directly bind to antigens on the surface of bacterial cells, causing them to clump together or agglutinate. In this case, the bacterial cells are dyed, making it easier to visualize the agglutination reaction.

In an Ouchterlony immunodiffusion reaction, crossed lines indicate that the two antigens are unrelated. This means that there is no reaction or interaction between the antigens, suggesting that they do not share any common epitopes or similarities. Therefore, the crossed lines indicate that there is no antigen-antibody binding occurring between antigens 1 and 2, indicating that they are unrelated.

IgG is not the best complement fixing immunoglobulin. Complement fixation is a process in which antibodies bind to antigens and activate the complement system, leading to the destruction of the target. While IgG can fix complement, IgM is considered the most efficient complement fixing immunoglobulin.

Carcinoembryonic antigen (CEA) is a protein that is often elevated in individuals with colon cancer. It is commonly used as a tumor marker for this type of cancer. Therefore, the correct answer is colon cancer.

A positive titer of 1/160 for OX19 Proteus antigen is considered significant in Rocky Mountain Spotted Fever. This indicates that the patient has a high level of antibodies against the OX19 Proteus antigen, which is commonly used in serological tests for Rocky Mountain Spotted Fever. This suggests that the patient has been exposed to the bacteria that causes the disease and has mounted an immune response. Therefore, this positive titer is indicative of a significant infection with Rocky Mountain Spotted Fever.

Serologic diagnosis for cryptococcus can be made by testing CSF. CSF stands for cerebrospinal fluid, which is the fluid that surrounds the brain and spinal cord. Cryptococcus is a type of fungus that can cause infections, particularly in individuals with weakened immune systems. Testing the CSF for cryptococcus can help diagnose an infection and guide appropriate treatment. Other specimens such as urine and serum may also be tested, but CSF is the most specific and reliable specimen for serologic diagnosis of cryptococcus.

Bence Jones proteins are monoclonal immunoglobulin light chains, specifically either kappa or lambda chains. They are produced by abnormal plasma cells and are often found in the urine of patients with multiple myeloma. Therefore, the correct answer is L chains.

The correct answer is "Concentration is directly proportional to the square of the diameter." This means that as the concentration of the substance being measured increases, the diameter of the endpoint also increases, and the relationship between concentration and diameter is a direct proportion. This characteristic is specific to the endpoint method of RID.

IgG is sometimes referred to as an incomplete antibody because it may be too small to produce lattice formation. Lattice formation refers to the clumping of antigens and antibodies together, which is important for certain immune responses such as agglutination. IgG, being a smaller antibody, may not have enough size or structure to effectively form lattices and clump antigens. This can affect its ability to carry out certain immune functions.

A 4% solution of RBC means that there is 4 grams of RBC in 100 mL of solution. To find the dilution, we need to compare this concentration to the concentration of the packed red blood cells. Since the answer is 1:25, it means that 1 part of packed red blood cells is diluted with 25 parts of solution. This dilution ratio allows for the desired 4% concentration of RBC in the final solution.

IgE is an antibody primarily involved in responses to allergens and is known for its role in the immune system's allergic responses and in immunity against parasites. IgE binds to allergens and triggers histamine release from mast cells and basophils, thereby contributing to inflammation and other allergic symptoms. Key characteristics of IgE include its ability to attach to tissue mast cells and its presence in the serum of allergic individuals. It also fails to fix complement, which is a system used for enhancing the ability of antibodies and phagocytic cells to clear microbes and damaged cells. However, IgE is sensitive to heat and is not heat stable, which is the correct response to the question as it does not maintain its function when exposed to high temperatures.

The recognition unit consists of C1q, C1r, and C1s, and the subunits require calcium for binding together. C1q activates C4. However, it is not a part of the Properdin Pathway.

Ficolle medium is a density gradient solution commonly used for the separation of lymphocytes. It is a mixture of colloidal silica particles and a polysaccharide called ficoll. When a sample containing lymphocytes is layered on top of the Ficolle medium and centrifuged, the lymphocytes will migrate to a specific region in the density gradient based on their density. This allows for the isolation and purification of lymphocytes from other cell types in the sample.