This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Innate Immune Cell Behavior”.
1. What is another term used for Innate Immunity?
a) Native immunity
b) Specific immunity
c) Automated immunity
d) Collateral immunity
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Explanation: Innate immune has a lot of terms till date such as native immunity, natural immunity as well as it is sometimes also referred to as inborn immunity. This type of immunity is the natural immunity that is present in our body by birth. This immunity is the first part of the body to detect invaders such as viruses, bacteria, parasites or toxins. It also helps in sensing any kind of trauma.
2. Which chemokine is responsible for the allergen-induced eosinophil response?
a) Eotaxin-1
b) Eotaxin-2
c) Eotaxin-3
d) Eotaxin-4
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Explanation: Eotaxin-1 is the chemokine responsible for allergen-induced eosinophil response. This response takes place due to the enrolment of gastrointestinal eosinophils. Eosinophils, by definition, act as multifunctional leukocytes which play a very important role in pathogenesis. This affects various allergic infections and diseases.
3. The innate immune system is composed of only physical barriers.
a) True
b) False
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Explanation: The innate immune system is composed of physical as well as some chemical barriers to respond against the invaders in our body. The examples of physical barriers are skin and mucous membrane while some examples of chemical barriers are antimicrobial peptides and some reactive oxygen species along with innate immune cells and soluble mediators.
4. Which of the following does NOT belong to the antimicrobial peptide family?
a) Defensins
b) Cathelicidin
c) Statins
d) Peptidins
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Explanation: Antimicrobial peptides (AMPs) are essential components of the innate immune response, which contribute to the first line of defence against infections. In humans, AMPs are classified into three main families: defensins (α and β), cathelicidin, and statins. AMPs have a wide spectrum of antimicrobial activity, exerting their functions through electrostatic interactions between their positive charge and the negative charge that certain pathogens have on their cell wall.
5. What is the approximate time span for the monocytes to circulate once released in the bloodstream?
a) 24 hours
b) 48 hours
c) 72 hours
d) 60 hours
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Explanation: Monocytes are cells that develop in the bone marrow and they are released into the bloodstream to circulate for approximately 72 hours. After the circulation is complete, then they emigrate to different tissues where they differentiate into macrophages or DCs (dendritic cells). Monocytes have a greater involvement in the innate immune response against pathogens and during the inflammatory processes.
6. Which of the following is NOT a surface receptor possessed by macrophages to carry out innate response?
a) Toll-like receptors
b) NOD-like receptors
c) Scavenger receptors
d) T cell receptors
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Explanation: Macrophages produce a wide range of surface receptors which give them the ability to recognize exogenous as well as endogenous ligands in order to respond to the invading pathogens. These are a group of receptors which are as follows: Toll-like receptors (TLRs), NOD-like receptors, scavenger receptors, retinoic acid-inducible gene (RIG)-I family and lectins.
7. Which of the following type of macrophages are found in almost all tissues?
a) Resident macrophages
b) Inflammatory macrophages
c) Innate macrophages
d) Adaptive macrophages
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Explanation: Monocytes differentiate into macrophages after the circulation is completed in the bloodstream. Macrophages are heterogeneous cell population, such as effector cells of the innate immune system, which play an important role in a host’s defence and inflammation. In general, macrophages can be divided into two populations: resident and inflammatory macrophages. Resident macrophages are found in almost all tissues and contribute to their development, as well as immunological surveillance, homeostasis, and tissue repair. On the other hand, inflammatory macrophages are derived from circulatory monocytes and rapidly infiltrate tissues compromised by injury or infection.
8. Which type of cells represent an important link between innate and adaptive immune system?
a) Macrophages
b) Somatic cells
c) Dendritic cells
d) Mast cells
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Explanation: Dendritic Cells (DCs) represent an important link between innate and adaptive immunity. DCs are heterogeneous population of antigen-presenting cells that are crucial to initiate and polarize the immune response. Although, all DCs are capable of capturing, processing, and presenting antigens to T cells, DCs subtypes differ in origin, location, migration patterns, and specialized immunological roles.
9. How is granulopoiesis graduated?
a) Myeloblasts (MB) ➔ Promyelocytes (PM) ➔ Myelocytes ➔ Metamyelocytes (MM)
b) Myelocytes ➔ Promyelocytes (PM) ➔ Myeloblasts (MB) ➔ Metamyelocytes (MM)
c) Promyelocytes (PM) ➔ Myelocytes ➔ Metamyelocytes (MM) ➔ Myeloblasts (MB)
d) Myeloblasts (MB) ➔ Metamyelocytes (MM) ➔ Myelocytes ➔ Promyelocytes (PM)
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Explanation: The granulopoiesis is initiated by neutrophils which are one of the important factors of the Innate Immune System. This process occurs in the bone marrow and is initiated when the neutrophils myeloblasts (MB) develop in promyelocytes (PM), characterized by a round nucleus and presence of azurophil granules. Further they mature into myelocytes with specific granules, maturing to metamyelocytes (MM). These are the cells composed by a nucleus with kidney form. Metamyelocytes further mature to band cells (CB) and in segmented cells (CS) also known as polymorphonuclear cells (PMNs).
10. Which of the following factor does NOT contribute for the development of eosinophils for regulating the Innate Immune response?
a) IL-3
b) IL-5
c) GM-CSF
d) IL-2
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Explanation: Eosinophils are produced in the bone marrow from pluripotent stem cells, which first differentiate into a precursor for basophils and eosinophils and then differentiate into an eosinophilic lineage. IL-3, IL-5, and GM-CSF are particularly important in regulating the eosinophils development. Out of these three cytokines, IL-5 is the most specific for the eosinophilic lineage and is responsible for the selective differentiation and release of eosinophils from the bone marrow into the peripheral circulation. IL-5 plays a critical role in the eosinophils production.
11. Which of the following cells are considered to be “sentinels” of innate immune system?
a) Eosinophils
b) Basophils
c) Macrophages
d) Mast cells
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Explanation: Mast cells are one of the most important types of cells which reside in the tissues that are associated with CD34+ hematopoietic progenitor cells. These cells appear in granulated structure and form. These cells are present by birth as immature cells and they further mature by the process of differentiation and proliferation that is completed in the vascularised tissues. Hence these cells are associated with innate immune system. These cells are said to be the first cells in the body to recognize antigens and foreign particles. As a result, they are known as sentinels of innate immune system.
Sanfoundry Global Education & Learning Series – Immunology.
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