This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Pre-Antigen Immune Cell Behavior”.
1. Who described the role of lymphatic endothelial cells to propagate the induction of peripheral tolerance?
a) Edward Jenner
b) Cohen
c) Pasteur
d) Phillipe and Stewart
View Answer
Explanation: Cohen along with his colleagues (in 2010) first stated the theories based on lymphatic endothelial cells with the help of autoimmune regulators. These regulators present them to self-antigens which carries forward to the immune periphery. This entire mechanism takes place in tertiary lymphoid organs as the lymphatic endothelial cells as associated with these organs.
2. Clonal Selection Law states that membrane-bound antigen receptors of B as well as T cells are generated in an antigen-independent genetic process.
a) True
b) False
View Answer
Explanation: Clonal selection theory was stated a long time ago which further developed into a law as it was proved by all the necessary found evidences. The maximum evidences were observed in adaptive immune system. Hence, this law is stated to be associated with adaptive immune system. As a result of this, Clonal Selection Law (CSL) is widely accepted as it consists of BCRs and TCRs that carry forward the adaptive immune responses throughout the human body.
3. Which of the following antigen factor is NOT considered for the activation and proliferation of B and T cells for carrying out the immune response?
a) Route of entry
b) Size and structure
c) Its interaction with respective BCR and TCR
d) Genetic constitution of host
View Answer
Explanation: Depending on antigen parameters like quantity, quality (along with various parameters that determine the antigenic immunogenicity which includes size, structure, ability to induce cytokine responses after binding to non-clonal receptors on antigen-presenting cells, presentability of antigen fragments via major histocompatibility complex (MHC) molecules, etc.) route of entry, place of action in tissues, presence of natural microbial or mixed adjuvants, and the genetic constitution of the host: such interactions may either lead to activation and proliferation of the respective B and T cells that execute the immune response or may lead to differentiation into end stage effector and memory cells. These parameters can also cause induction of tolerance.
4. Which of the following cells/receptors directly react with native antigens?
a) Cell-bound BCRs
b) Naïve T cells
c) CD8+ cytotoxic cells
d) Suppressor CD4+ T cells
View Answer
Explanation: We know that both, BCR and TCR mediate the initiation of adaptive immune response. However, cell-bound BCRs directly react with the native antigen. On the other hand, naïve T cells population including CD8+ cytotoxic cells, suppressor CD4+ T cells (which include Th1, Th2, Th17, Tfh and Tregs) can only participate in adaptive responses after the introduction of antigen is completed and is degraded by various antigen-processing cells which then present antigen fragments on MHC molecules on the cell surface.
5. In the germinal centres (GCs) which cells undergo Tfh-dependent proliferation?
a) B cells
b) T cells
c) B cell receptor
d) T cell receptor
View Answer
Explanation: In the GCs, B cells undergo Tfh-dependent proliferation as well as somatic hypermutations (SMH) in order to participate in secondary responses for activation in presence of humoral antibody. This is accompanied by class-switch recombination (CSR) and immune maturation through selection of higher affinity clones.
6. Which of the following are the earliest immune cells to encounter antigen at the site of injury?
a) Dendritic cells
b) B cells
c) Macrophages
d) Cytotoxic T lymphocytes
View Answer
Explanation: Macrophages are some of the earliest immune cells to encounter antigen at sites of infection or injury. The response to antigenic stimulus is context-dependent but production of inflammatory cytokines is one of the most important function of these cells in the early stages of inflammation. For example, in the case of atherosclerosis, macrophages that infiltrate plaque take up oxidized low-density lipoprotein (ox-LDL) particles and are activated, including upregulation of antigen-presentation genes and increased production of inflammatory cytokines.
7. What is the main role of B cells in immune response?
a) Production of antigen
b) Production of antibodies
c) Recognising the antigen receptor
d) Attracting the antigen to its receptor
View Answer
Explanation: The main role of B cells in an immune response is production of antibodies. B cell presentation of antigen to T cells is one of the most important aspect of this function. These interactions allow B cells to receive survival signals and direct them appropriately to generate high affinity antibody specific to the antigen that is encountered.
8. As an immune response to antigen: Salmonella typhimurium, heterogenous populations of memory B cells retain which antibody isotype linked with BCR (B cell receptor) on cell surface?
a) IgD BCR
b) IgM BCR
c) IgA BCR
d) IgE BCR
View Answer
Explanation: Immune responses to complex antigens like Salmonella typhimurium can develop independently of GC formation in follicles and extrafollicular sites and this response is also accompanied by CSR and SHM-mediated immune maturation. The heterogeneous populations of memory B cells are possibly generated in as well as outside GCs and may retain IgM BCR on their cell surface.
9. Which cells are found in B cell follicles?
a) Follicular T cells
b) Follicular BCR
c) Follicular Tfh cells
d) Follicular dendritic cells
View Answer
Explanation: The most important cells that are found in B cell follicles are the follicular dendritic cells which are also denoted as FDCs. By their name, it suggests that these cells play a very important role in follicular functions which include presentation of antigen on the surface to give rise to immune complexes. FDCs have a long life span hence they are said to be an integral part of B cell follicles.
10. In Sjogren’s syndrome, which type of cells present self-antigens?
a) Skin epithelial cells
b) Follicular cells
c) Salivary gland epithelial cells
d) B cells
View Answer
Explanation: Sjogren’s syndrome is related to drying of eyes as well as mouth. In this syndrome, the patient’s body’s immune system attacks its own healthy cells that produce saliva (in case of mouth) and tears (in case of eyes). It is said that if this syndrome is related to dryness of mouth, the salivary gland epithelial cells (also termed as SGECs) are responsible for presenting self-antigens. To support this evidence various factors including expression of co-stimulatory molecules (such as CD80, CD86 and CD40) and the ability to express adhesion molecules and human leukocyte antigen are observed.
Sanfoundry Global Education & Learning Series – Immunology.
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