Components of Immune System MCQs

Mature Dendritic cells Mature B-cells and T-cells before antigenic exposure are called naive-B and T cells respectively. Sequence of events in activation of naive T cells. Immature dendritic cells in the epidermis are called langerhans cell. These immature dendritic cells (langerhans cells) capture the antigen in the epidermis. After capturing the antigen these cells secrete cytokines. These cytokines cause loss of adhesiveness of langerhans cells. Langerhans cells separate from each other and migrate into lymphatic vessels. In lymphatic vessel, maturation of langerhans cells takes place. Then these mature langerhans dendritic cells reach to naive T cells in the lymph nodes and present antigen to these cells and activate them.

Hereditary angioedema is caused by deficient levels of C1 inhibitor. This reduces the ability to control activation of the classical pathway. Autosomal-dominant inheritance Gene locus: SERPING1(C1 inhibitor) on chromosome 11 Excessive spontaneous activation of classical complement pathway (especially C2) causing local inflammation of gastrointestinal and respiratory tracts. Swelling of tracheal and bronchial passages can be life-threatening. Nutrition-based immunodeficiencies are not does not presents with severely reduced levels of specific cell types or related molecules. Paroxysmal nocturnal hemoglobinuria is caused by a deficiency of CD59. Wiskott-Aldrich syndrome is caused by a deficiency of the Wiskott-Aldrich syndrome protein. Reference: Ananthanarayan and Paniker's Textbook of Microbiology 10th edition Chapter 19, Pg 187-190

Lysozyme is present in tears, saliva, human breast milk and respiratory mucus secretions. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils (PMNs). Reduced lysozyme levels have been associated with bronchopulmonary dysplasia in newborns. In certain cancers (especially myelomonocytic leukemia) excessive production of lysozyme by cancer cells can lead to toxic levels of lysozyme in the blood. High lysozyme blood levels can lead to kidney failure and low blood potassium. It is used as a marker of sarcoidosis disease activity and is suitable for disease monitoring. (Sensitive but less specific) Reference: Ananthanarayan and Paniker's Textbook of Microbiology 12th edition Chapter 14, Page Number: 175

CRP is an acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages, adipocytes and T cells. Plasma half-life of CRP: It is 19 hours. This half-life is constant in all medical conditions. Therefore, the only factor that affects the level of CRP in blood is only its rate of production. Reference: Ananthanarayan and Paniker's Textbook of Microbiology 12th edition Chapter 14, Pg 175

Ans. is 'a' i.e., A, B, C . Class I HLA comprises A, B and C loci.

Complement component C3 is crucial for opsonization, a process where pathogens are tagged for easier recognition and engulfment by phagocytes like macrophages and neutrophils. A deficiency in C3 impairs this process, leading to increased susceptibility to bacterial infections. While C3 is important for opsonization, it does not directly affect interferon production, T cell activation, or the barrier function of the skin. Key Takeaway: Deficiency in complement component C3 primarily affects the phagocytosis of pathogens due to impaired opsonization. Tags: INICET 2022 | Clinical Tag Line: Hard / Clinical Reference: Shastri, A. (2023). Immunology: Chapter 13on Complement System, pp. 163-167.

The optimal timing to commence ART in HIV-infected patients with TB is relatively complex. It must balance the risk of morbidity and mortality in very advanced HIV disease with the potential occurrence of additive toxicities, drug-drug interactions, and TB-associated immune reconstitution inflammatory syndrome (IRIS). The current World Health Organization guidelines recommend that ART should be started as soon as possible "within the first 8 weeks" of starting anti-tubercular treatment and within the first 2 weeks for patients who have CD4 cell counts less than 50 cells/mm 3 Reference- https://aidsrestherapy.biomedcentral.com/articles/10.1186/s12981-016-0106-y

Toll-like receptors (TLRs) are a type of pattern recognition receptor that recognizes and binds to pathogen-associated molecular patterns (PAMPs) on pathogens. This recognition helps initiate the immune response. B cells and T cells are part of the adaptive immune system, while NK cells are involved in killing infected or cancerous cells, not in recognizing PAMPs. Key Takeaway: TLRs play a critical role in the innate immune system by detecting and responding to pathogens through PAMP recognition. Tags: FMGE 2023 Tag Line: Moderate Reference: Shastri, A., & Bhatt, S. (2023). Essential Microbiology . Chapter 9: Immunity, pg.133.