Question 1

TCRs recognize epitopes only after the immunogens have been partially degraded.

Accepted Answer

TCRs recognize epitopes presented on MHC molecules only after the antigenic protein has been partially processed and degraded by antigen presenting cells. This allows for the presentation of peptide fragments on the MHC molecule, which can then be recognized by the TCR.

Question 2

Class I MHC proteins are found ONLY on the surface of B lymphocytes, macrophages, and dendritic cells.

Accepted Answer

Class I MHC proteins are found on the surface of all nucleated cells in the body, not just B lymphocytes, macrophages, and dendritic cells.

Question 3

Symptoms of delayed-type hypersensitivity may appear several hours to days after secondary exposure to the eliciting antigen.

Accepted Answer

Delayed-type hypersensitivity reactions involve the activation of T cells, which takes time to develop and may not manifest until several hours to days after exposure to the antigen.

Question 4

HLAs are responsible for immune-mediated organ transplant rejection.

Accepted Answer

HLAs (Human Leukocyte Antigens) are important markers on the surface of cells that help the immune system distinguish between self and non-self. They are involved in immune-mediated organ transplant rejection, as the recipient's immune system recognizes the transplanted organ as non-self if the HLAs are not compatible. This recognition can trigger an immune response that leads to organ rejection.

Question 5

Tolerance is the acquired ability to make an adaptive immune response directed to self-antigens.

Accepted Answer

Tolerance is the acquired ability to NOT make an immune response against self-antigens, preventing the immune system from attacking the body's own cells and tissues.

Question 6

An individual can receive injections of an antiserum or purified antibodies derived from an immune individual.

Accepted Answer

Antiserum or purified antibodies can be given as a passive immunization to an individual to provide immediate protection against a specific pathogen.

Question 7

Men are 20 times more likely to develop systemic lupus erythematosus (SLE) than women.

Accepted Answer

This statement is false, as systemic lupus erythematosus (SLE) is actually more common in women than in men. Women are 9 times more likely to develop SLE than men.

Question 8

A high-affinity antibody binds nonspecifically and loosely to an antigen.

Accepted Answer

A high-affinity antibody has a specific and strong binding to its target antigen, not a nonspecific and loose binding.

Question 9

Haptens CANNOT bind to or induce an immune response but CAN bind to antibodies.

Accepted Answer

Haptens are small molecules that cannot induce an immune response on their own but can bind to antibodies once they are attached to larger molecules, such as proteins. This can lead to an immune response against the hapten-protein complex, known as a hapten-carrier complex.

Question 10

In the adaptive immune response, effective immunity cannot be detected for several days after the first contact with the pathogen.

Accepted Answer

This is because the adaptive immune response takes time to develop and requires the activation, proliferation, and differentiation of specific immune cells. This process can take several days to occur, during which time the pathogen may continue to replicate and cause harm to the host. Once the adaptive immune response is established, however, it can provide long-lasting protection against the pathogen through the production of memory cells.

Question 11

The inducing antigens that react with an antibody are called heterologous antigens.

Accepted Answer

Heterologous antigens refer to antigens that are different from the host's own antigens (also known as self-antigens) and can elicit an immune response. They may or may not react with antibodies depending on various factors, including the specificity and sensitivity of the antibody and the presence of other interfering substances. Therefore, the term "inducing antigens" is not a precise or widely used term in immunology.

Question 12

Antihistamines are used to treat some allergic symptoms because they neutralize the histamine mediators that cause rapid dilation of blood vessels and contraction of smooth muscles that initiate the symptoms of systemic anaphylaxis.

Accepted Answer

Antihistamines work by blocking the histamine receptors and preventing the histamine mediators from inducing the symptoms of systemic anaphylaxis.

Question 13

TH2 cells interact directly with the pathogens.

Accepted Answer

TH2 cells are helper T cells that secrete cytokines to activate and stimulate the functions of other cells involved in the immune response, such as B cells and macrophages. They do not interact directly with pathogens.

Question 14

Individuals with severe combined immunodeficiency syndrome (SCID) have a genetic defect that prevents proper formation and expression of immunoglobins and T cells and therefore do not have adaptive immunity.

Accepted Answer

Severe combined immunodeficiency syndrome (SCID) impairs the development and function of both B and T cells, resulting in a lack of adaptive immunity. This is caused by genetic defects affecting the genes involved in lymphocyte development and function, including genes encoding immunoglobulin molecules and the components of the T-cell receptor.

Question 15

All antigens are immunogens.

Accepted Answer

While all immunogens are antigens, not all antigens are immunogens. Antigens are any substance that triggers an immune response, but only certain antigens have the ability to stimulate the production of antibodies and activate the immune system, making them immunogens.

Question 16

IgE is found in extremely small amounts in serum.

Accepted Answer

IgE is present in very small amounts in the blood serum, usually less than 0.05% of total immunoglobulins.

Question 17

T cell receptors on a particular T cell can recognize more than two antigens.

Accepted Answer

T cell receptors (TCRs) on a particular T cell are specific to a single antigenic peptide presented by the major histocompatibility complex (MHC) molecules, not multiple antigens.

Question 18

CD4 and CD8 proteins are used for in vitro tests as T cell markers to differentiate TH cells from TC cells.

Accepted Answer

CD4 and CD8 are commonly used cell surface markers to distinguish between helper T cells (TH) and cytotoxic T cells (TC) in vitro tests. CD4 is predominantly expressed on TH cells while CD8 is predominantly expressed on TC cells.

Question 19

The use of antivenom to treat snakebite is an example of artificial passive immunity.

Accepted Answer

Antivenom is created by collecting antibodies from animals such as horses that have been vaccinated with snake venom. These antibodies are then purified and administered to the human bitten by the venomous snake in order to neutralize the venom toxins. This provides temporary immunity until the body can produce its own antibodies. Therefore, the use of antivenom is an example of artificial passive immunity.

Question 20

Self-reactive T cells are eliminated during the development of tolerance in the immune system.

Accepted Answer

During the process of central tolerance in the thymus gland, self-reactive T cells that recognize self-antigens with high affinity are deleted or inactivated to prevent them from attacking the body's own tissues. This ensures that only T cells that are able to recognize and respond to foreign antigens are able to participate in the immune response.

Quiz 27: Adaptive Immunity: Highly Specific Host Defenses