Human Anatomy and Physiology : Help with Proteins and Signals of Adaptive Immunity

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #11 : Immune Physiology

The human immune system is organized along two broad arms: innate immunity and adaptive immunity. The differences between these two approaches to immunity are not always black and white, but can be described in general terms with regard to immunological memory. Adaptive immunity displays this type of memory, and mounts a more intense response to pathogens upon second and subsequent exposures.

Within adaptive immunity, the system is further divided into humoral immunity and cell-mediated immunity. We can say that antibodies are the primary mediators of the former, while CD8 T-cell based cytotoxicity is the mediator of the latter.

CD4 T-cells, unlike their CD8 counterparts, are involved in both the humoral and cell-mediated arms of adaptive immunity. These CD4 cells drive isotype switching, a process that changes the types of antibodies produced after initial exposure to a pathogen to increase their molecular affinity. Additionally, CD4 cells promote the activity of macrophages to directly digest invading pathogens.

A scientist is attempting to upregulate the activity of macrophages in a petri dish. The macrophages have already been exposed to bacterial pathogens. The addition of which chemical to the petri dish is most likely to enhance macrophage-mediated killing?

Possible Answers:

Interleukin-5

IFN-alpha

Interleukin-2

IFN-beta

IFN-gamma

Correct answer:

IFN-gamma

Explanation:

IFN-gamma is the main chemokine produced by CD4 T-cells to promote the oxidative killing of phagocytosed organisms in macrophages. Without IFN-gamma, macrophages can still ingest pathogens, though their killing efficiency will be far reduced.

Example Question #1 : Help With Proteins And Signals Of Adaptive Immunity

The human immune system is organized along two broad arms: innate immunity and adaptive immunity. The differences between these two approaches to immunity are not always black and white, but can be described in general terms with regard to immunological memory. Adaptive immunity displays this type of memory, and mounts a more intense response to pathogens upon second and subsequent exposures.

Within adaptive immunity, the system is further divided into humoral immunity and cell-mediated immunity. We can say that antibodies are the primary mediators of the former, while CD8 T-cell based cytotoxicity is the mediator of the latter.

CD4 T-cells, unlike their CD8 counterparts, are involved in both the humoral and cell-mediated arms of adaptive immunity. These CD4 cells drive isotype switching, a process that changes the types of antibodies produced after initial exposure to a pathogen to increase their molecular affinity. Additionally, CD4 cells promote the activity of macrophages to directly digest invading pathogens.

Which of the following surface proteins is most likely to be used as a marker to distinguish T-lymphocytes from B-lymphocytes?

Possible Answers:

CD20

CD21

CD5

CD28

CD19

Correct answer:

CD28

Explanation:

The CD family of surface proteins (short for cluster of differentiation) is best understood as a set of nametags to distinguish one set of cells from another. CD28 is the most commonly used marker for T-cells, as it is unique to this cell type. In contrast, B-cells use a number of other unique markers, including CD20 and CD21, among others.

CD5 is used to distinguish chronic lymphocytic leukemia from other leukemic states.

Example Question #3 : Help With Proteins And Signals Of Adaptive Immunity

The human immune system is organized along two broad arms: innate immunity and adaptive immunity. The differences between these two approaches to immunity are not always black and white, but can be described in general terms with regard to immunological memory. Adaptive immunity displays this type of memory, and mounts a more intense response to pathogens upon second and subsequent exposures.

Within adaptive immunity, the system is further divided into humoral immunity and cell-mediated immunity. We can say that antibodies are the primary mediators of the former, while CD8 T-cell based cytotoxicity is the mediator of the latter.

CD4 T-cells, unlike their CD8 counterparts, are involved in both the humoral and cell-mediated arms of adaptive immunity. These CD4 cells drive isotype switching, a process that changes the types of antibodies produced after initial exposure to a pathogen to increase their molecular affinity. Additionally, CD4 cells promote the activity of macrophages to directly digest invading pathogens.

A team of physicians is preparing a patient for a bone marrow transplant. To prevent graft-versus-host disease, where the transplanted T-cells attack the host into which they have been introduced, the physicians make sure that the donor and host have a matching human leukocyte antigen (HLA) type.

Which HLA gene product interacts with receptors on CD8 T-cells most avidly?

Possible Answers:

Major histocompatibility complex II

B7

CD8

CD5

Major histocompatibility complex I

Correct answer:

Major histocompatibility complex I

Explanation:

The protein MHC I is present on the surface of all nucleated cells, and provides a means for cytotoxic CD8 T-cells to exert cell killing on any nucleated cell that becomes infected with a pathogen.

MHC II is a related protein, that is only present on antigen-presenting cells (APC). These antigen-presenting cells must interact with CD4 T-cells. As a result, we can make the generalization that CD4 T-cells interact with MHC II, restricted in expression to APCs, and CD8 T-cells interact with MHC I with far broader expression.

Example Question #2 : Help With Proteins And Signals Of Adaptive Immunity

The human immune system is organized along two broad arms: innate immunity and adaptive immunity. The differences between these two approaches to immunity are not always black and white, but can be described in general terms with regard to immunological memory. Adaptive immunity displays this type of memory, and mounts a more intense response to pathogens upon second and subsequent exposures.

Within adaptive immunity, the system is further divided into humoral immunity and cell-mediated immunity. We can say that antibodies are the primary mediators of the former, while CD8 T-cell based cytotoxicity is the mediator of the latter.

CD4 T-cells, unlike their CD8 counterparts, are involved in both the humoral and cell-mediated arms of adaptive immunity. These CD4 cells drive isotype switching, a process that changes the types of antibodies produced after initial exposure to a pathogen to increase their molecular affinity. Additionally, CD4 cells promote the activity of macrophages to directly digest invading pathogens.

Patients with clear cell carcinoma of the kidney often undergo therapy that uses an inflammatory cytokine to upregulate T-cell activity. Which of the following cytokines is most likely used as a treatmnt for clear cell carcinoma?

Possible Answers:

IL-3

IL-2

IL-8

Interferon

IL-5

Correct answer:

IL-2

Explanation:

IL-2 is the third signal that activates T-cell activity. T-cells are initially activated by MHC/T-cell receptor binding, and then the second B7 signal further primes activity. After these two signals, the T-cell produces its own IL-2, which acts in an autocrine fashion to further accelerate T-cell proliferation.

Example Question #3 : Help With Proteins And Signals Of Adaptive Immunity

The human immune system is organized along two broad arms: innate immunity and adaptive immunity. The differences between these two approaches to immunity are not always black and white, but can be described in general terms with regard to immunological memory. Adaptive immunity displays this type of memory, and mounts a more intense response to pathogens upon second and subsequent exposures.

Within adaptive immunity, the system is further divided into humoral immunity and cell-mediated immunity. We can say that antibodies are the primary mediators of the former, while CD8 T-cell based cytotoxicity is the mediator of the latter.

CD4 T-cells, unlike their CD8 counterparts, are involved in both the humoral and cell-mediated arms of adaptive immunity. These CD4 cells drive isotype switching, a process that changes the types of antibodies produced after initial exposure to a pathogen to increase their molecular affinity. Additionally, CD4 cells promote the activity of macrophages to directly digest invading pathogens.

A scientist develops a protein that is able to interrupt the normal function of CD8 T-cells, preventing them from actively killing target cells. Except for actively killing targets, T-cells behave, physically bind to target cells, and develop normally after treatment with this protein. Which protein/receptor pair interaction on CD8 T-cells is most likley being interrupted by this protein?

Possible Answers:

IL-2/IL-2 receptor

CD-19/CD-19 receptor

T-cell receptor/major hisotcompatibility complex I

Fas/Fas ligand

CD28/B7

Correct answer:

Fas/Fas ligand

Explanation:

The interaction of Fas and Fas ligand is the most direct option among these choices that drives cell killing. The remainder of the options are either not relevant to T-cells, or are involved in simple binding or development. The interaction of Fas and its ligand actually drives cell death.

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