Question 1

Which of the following best describes an antigen?

Accepted Answer

A substance that can be recognized and bound by immune receptors, potentially triggering an immune response.

Question 2

Which of the following factors does NOT increase the immunogenicity of a molecule?

Accepted Answer

Being a small, simple peptide with only one epitope.

Question 3

Which statement correctly distinguishes between B-cell and T-cell antigen recognition?

Accepted Answer

B-cell receptors can recognize free-soluble or surface-bound epitopes, while T-cell receptors require antigen presentation by MHC molecules.

Question 4

A patient is exposed to a small molecule that binds to immune receptors but does NOT induce an immune response unless attached to a carrier protein. This molecule is best described as a:

Accepted Answer

Hapten

Question 5

Which of the following is TRUE regarding the function of MHC class I molecules?

Accepted Answer

They present peptides to CD8+ cytotoxic T-cells and are found on all nucleated cells.

Question 6

Which of the following best describes the role of pattern recognition receptors (PRRs) in the innate immune system?

Accepted Answer

They recognize pathogen-associated molecular patterns (PAMPs) and trigger inflammation.

Question 7

A laboratory experiment involves injecting a mouse with a hapten conjugated to a carrier protein. Which immune response is most likely to occur?

Accepted Answer

An immune response will occur against both the hapten and the carrier protein.

Question 8

Which of the following is a key difference between MHC class I and MHC class II molecules?

Accepted Answer

MHC class I molecules present peptides to CD8+ T-cells, while MHC class II molecules present peptides to CD4+ T-cells.

Question 9

Which of the following best explains why a person’s adaptive immune system can recognize a vast array of different antigens?

Accepted Answer

Somatic gene rearrangement and mutation generate a unique set of receptors in each lymphocyte.

Question 10

Which of the following is a function of killer inhibition receptors (KIRs) on natural killer (NK) cells?

Accepted Answer

They detect the presence of MHC class I molecules on host cells, preventing NK cell activation.

Question 11

A mutation causes a patient’s phagocytes to lose the ability to enzymatically cleave proteins. Which aspect of immunogenicity is most directly affected?

Accepted Answer

Chemical properties required for antigen processing

Question 12

Which of the following best describes the interaction between a T-cell receptor (TCR) and an antigen?

Accepted Answer

TCR binds to antigenic peptides presented by MHC molecules on the surface of antigen-presenting cells.

Question 13

Which of the following is TRUE regarding the response of the innate immune system to repeated exposure to the same antigen?

Accepted Answer

The response is the same regardless of the number of exposures.

Question 14

Which of the following best describes the role of complement receptors on phagocytic cells?

Accepted Answer

They recognize and bind complement-coated microbes, facilitating phagocytosis.

Question 15

Which of the following is a characteristic of tolerogens?

Accepted Answer

They induce immune unresponsiveness, leading to tolerance.

Question 16

Which of the following best explains why MHC molecules are described as 'codominantly expressed'?

Accepted Answer

Both maternal and paternal alleles are expressed simultaneously on the cell surface.

Question 17

A patient’s dendritic cells are unable to express MHC class II molecules. Which immune function would be most directly impaired?

Accepted Answer

Activation of CD4+ T-helper cells

Question 18

Which of the following best describes the relationship between epitopes and antigens?

Accepted Answer

An epitope is a region of an antigen recognized by immune receptors.

Question 19

Which of the following is TRUE regarding the peptide-binding groove of MHC class II molecules?

Accepted Answer

It is formed by the α1 and β1 domains and accommodates peptides of 18-20 amino acids.

Antigens and Major Histocompatibility Complex: Principles of Immune Recognition

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