Allergic Diseases

Archive for the 'Allergy and Immunology Questions and Answer' Category

Question: What two signals are required to activate naive T cells?

Sunday, May 18th, 2008

Answer: The first signal is provided by antigenic peptides displayed in MHC molecules. The second is provided by one or more costimulatory molecule produced by the antigen-presenting cell, in response to molecules displayed by pathogens. If these costimulatory signaling molecules are not present, the T cell-MHC interaction may alternatively cause the T cell to undergo […]

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Question: How does cell-mediated immunity work?

Saturday, May 17th, 2008

Answer: Cell-mediated immunity involves the action of T cells. CD8+ cytolytic T cells can kill target cells directly. CD4+ helper cells can activate macrophages to become more effective at killing the organisms they ingest. This process is also considered to be cell-mediated immunity, although, again, a cell of the innate system carries out the ultimate […]

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Question: How does humoral immunity work?

Friday, May 16th, 2008

Answer: Humoral immunity involves antibodies, produced by B cells. Terminally differentiated B cells, called plasma cells, produce most of the antibodies. Humoral immune responses defend the host against extracellular bacteria and toxins. Blocking antibodies can prevent the adherence of bacteria, viruses, or toxins to host cells. Antibodies can activate complement through the classical pathway and […]

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Question: What is the major disadvantage of the adaptive immune system?

Wednesday, February 6th, 2008

Answer: The disadvantage of the adaptive immunes response is that the required expansion process takes time after the first encounter with antigen, in some cases more than 2 weeks. Many infectious agents can cause death or severe disability in less time than it takes the adaptive immune system to mobilize a specific response. This disadvantage […]

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Question: What is the major advantage of the adaptive immune system?

Wednesday, February 6th, 2008

Answer: The distinct advantage of the adaptive immune system is its ability to select B cells and T cells that have high-affinity receptors for new antigens and to stimulate them to replicate and provide a specific, fine-tuned response to foreign invaders. Reference:  Abbas AK, Lichtman AH: Cellular and Molecular Immunology, 5th ed. Philadelphia, W.B. Saunders, […]

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Question: What are the major components of the adaptive immune system? How do they work?

Tuesday, February 5th, 2008

Answer: The adaptive immune system includes elements such as the B lymphocytes that make antibodies and T lymphocytes that provide the effector elements of antigen-specific cell-mediated immune responses. Elements of the adaptive immune system display a large repertoire (e.g., tens of millions) of specific antigen receptors that are generated by DNA rearrangements. Each lymphocyte and […]

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Question: What are the major components of the innate immune system?

Tuesday, February 5th, 2008

Answer: Neutrophils, monocytes, macrophages, eosinophils, basophils, mast cells, natural killer (NK) cells, complement proteins, and acute-phase reactants. All of these elements have germline-encoded receptors that recognize motifs commonly present on microbes. Reference:  Rich RR, Fleisher TA, Shearer WT, et al: Clinical Immunology, Principles and Practice, 2nd ed. St. Louis, Mosby, 2001.

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Question: Which is the first line of defense against infection?

Tuesday, February 5th, 2008

Answer: Innate immunity is the first line of defense against infection because its elements are already present in the circulation and can respond immediately to microbial invasion. However, the innate system has no memory; on subsequent exposure to the same antigen, the response is no greater, no faster, and no more effective than it was […]

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Question: Name the two major divisions of the immune system. Which is older?

Tuesday, February 5th, 2008

Answer: The immune system can be considered to have two major divisions: the innate immune system and the adaptive or cognitive immune system. The innate immune system is phylogenetically older. Reference: Adkinson NF, Yunginger A, Busse W, et al (eds): Middleton’s Allergy: Principles and Practice, 6th ed. St. Louis, Mosby, 2004.

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Question: Does Glutamine-enriched enteral nutrition in very low-birth-weight infants decreased the incidence of atopic dermatitis?

Thursday, December 13th, 2007

Answer: Glutamine-enriched enteral nutrition in very low-birth-weight infants decreased the incidence of atopic dermatitis during the first year of life but had no effect on the incidence of bronchial hyperreactivity and infectious diseases during the first year of life. The authors determined the effect of glutamine-enriched enteral nutrition in very low-birth-weight infants on the incidence […]

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