Immunology: Antigens and Antibodies Quiz

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What is the primary characteristic that makes a molecule an effective antigen?

High molecular weight

Ability to induce an immune response on its own

Structural complexity

Foreignness to the host (correct)

Which of the following is NOT a property that makes a molecule a more effective antigen?

Larger molecular mass between 5,000 and 100,000 daltons

Parenteral route of administration

Ability to induce an immune response on its own (correct)

Stable molecular structure

What is the main difference between high molecular weight and low molecular weight antigens?

Low molecular weight antigens are proteins or polysaccharides, while high molecular weight antigens are not

Low molecular weight antigens have a molecular mass between 5,000 and 100,000 daltons, while high molecular weight antigens do not

High molecular weight antigens can induce an immune response on their own, while low molecular weight antigens cannot (correct)

High molecular weight antigens are more immunogenic than low molecular weight antigens

What is the main function of an antigenic determinant or epitope?

To bind to antigen-specific membrane receptors on lymphocytes or secreted antibodies Signup and view all the answers

Which of the following is NOT a factor that determines the antigenicity of a molecule?

Ability to induce an inflammatory response Signup and view all the answers

Why are incomplete antigens or haptens unable to induce an immune response on their own?

They are too small to be recognized by the immune system Signup and view all the answers

What is the primary function of MHC class I molecules?

Regulation of immune responses to intracellular parasites Signup and view all the answers

What is the structure of an MHC class I molecule?

α1, α2, α3, and β2 macroglobulin Signup and view all the answers

What is the primary function of MHC class II molecules?

Regulation of immune responses to exogenous antigens Signup and view all the answers

What is the structure of an MHC class II molecule?

2α chains (α1, α2) and 2β (β1, β2) Signup and view all the answers

Which T cell type is activated by MHC class I molecules?

CD8+ T cells Signup and view all the answers

Which T cell type is activated by MHC class II molecules?

CD4+ T cells Signup and view all the answers

What are the two types of antigenic determinants described in the text?

Conformational and sequential determinants Signup and view all the answers

Which type of antigenic determinant is mainly recognized by T cells according to the text?

Sequential determinants Signup and view all the answers

What is the chemical nature of antigens described as being very good immunogens in the text?

Proteins Signup and view all the answers

Which type of antigen has entered the body from the outside, for example by inhalation, ingestion, or injection?

Exogenous antigens Signup and view all the answers

What are the examples of bacterial antigens mentioned in the text?

Somatic antigen (O), Capsular antigen, Flagellar Ag (H) Signup and view all the answers

Which type of antigen is described as being poorly immunogenic?

Nucleic acids Signup and view all the answers

Which of the following is the mechanism by which immature dendritic cells take up large molecular or microbe antigens?

Phagocytosis Signup and view all the answers

Which receptor-mediated process is used by macrophages to take up low levels of particulate or soluble antigens?

Receptor-mediated pinocytosis Signup and view all the answers

Which of the following is the first step in antigen processing?

Degradation of externally- or internally-derived antigen into short peptide sequences Signup and view all the answers

Which MHC molecule is involved in the presentation of exogenous antigens to CD4+ T cells (Th)?

MHC class II Signup and view all the answers

Where does the association of peptides with MHC class II molecules take place?

Lysosome and endosome Signup and view all the answers

Which of the following receptors are involved in the uptake of exogenous antigens?

All of the above Signup and view all the answers

Which of the following best describes the effect of superantigens on T-cells?

Superantigens activate a large fraction of T-cells in a polyclonal manner. Signup and view all the answers

Which of the following statements about superantigens is correct?

Superantigens are produced by some pathogenic viruses and bacteria, likely as a defense mechanism. Signup and view all the answers

What is a key difference between conventional T-dependent antigens and superantigens?

Superantigens activate a larger fraction of T-cells than conventional antigens. Signup and view all the answers

Which of the following bacterial toxins are examples of superantigens?

All of the above. Signup and view all the answers

What is a requirement for T-cell response to microbial antigens?

Microbial antigens must be transported to the lymph nodes to encounter T-cells. Signup and view all the answers

What is the primary reason for the systemic toxicity caused by superantigens?

The massive T-cell activation and release of large amounts of cytokines. Signup and view all the answers