30 Questions
What is the primary characteristic that makes a molecule an effective antigen?
Foreignness to the host
Which of the following is NOT a property that makes a molecule a more effective antigen?
Ability to induce an immune response on its own
What is the main difference between high molecular weight and low molecular weight antigens?
High molecular weight antigens can induce an immune response on their own, while low molecular weight antigens cannot
What is the main function of an antigenic determinant or epitope?
To bind to antigen-specific membrane receptors on lymphocytes or secreted antibodies
Which of the following is NOT a factor that determines the antigenicity of a molecule?
Ability to induce an inflammatory response
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
What is the primary function of MHC class I molecules?
Regulation of immune responses to intracellular parasites
What is the structure of an MHC class I molecule?
α1, α2, α3, and β2 macroglobulin
What is the primary function of MHC class II molecules?
Regulation of immune responses to exogenous antigens
What is the structure of an MHC class II molecule?
2α chains (α1, α2) and 2β (β1, β2)
Which T cell type is activated by MHC class I molecules?
CD8+ T cells
Which T cell type is activated by MHC class II molecules?
CD4+ T cells
What are the two types of antigenic determinants described in the text?
Conformational and sequential determinants
Which type of antigenic determinant is mainly recognized by T cells according to the text?
Sequential determinants
What is the chemical nature of antigens described as being very good immunogens in the text?
Proteins
Which type of antigen has entered the body from the outside, for example by inhalation, ingestion, or injection?
Exogenous antigens
What are the examples of bacterial antigens mentioned in the text?
Somatic antigen (O), Capsular antigen, Flagellar Ag (H)
Which type of antigen is described as being poorly immunogenic?
Nucleic acids
Which of the following is the mechanism by which immature dendritic cells take up large molecular or microbe antigens?
Phagocytosis
Which receptor-mediated process is used by macrophages to take up low levels of particulate or soluble antigens?
Receptor-mediated pinocytosis
Which of the following is the first step in antigen processing?
Degradation of externally- or internally-derived antigen into short peptide sequences
Which MHC molecule is involved in the presentation of exogenous antigens to CD4+ T cells (Th)?
MHC class II
Where does the association of peptides with MHC class II molecules take place?
Lysosome and endosome
Which of the following receptors are involved in the uptake of exogenous antigens?
All of the above
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.
Which of the following statements about superantigens is correct?
Superantigens are produced by some pathogenic viruses and bacteria, likely as a defense mechanism.
What is a key difference between conventional T-dependent antigens and superantigens?
Superantigens activate a larger fraction of T-cells than conventional antigens.
Which of the following bacterial toxins are examples of superantigens?
All of the above.
What is a requirement for T-cell response to microbial antigens?
Microbial antigens must be transported to the lymph nodes to encounter T-cells.
What is the primary reason for the systemic toxicity caused by superantigens?
The massive T-cell activation and release of large amounts of cytokines.
Test your knowledge on high and low molecular weight antigens, incomplete antigens, and the properties that make molecules effective antigens. Learn about the role of carrier molecules in inducing immune responses.
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