Questions and Answers
What type of disorder is Crohn's disease?
Which of the following is a form of hypersensitivity reaction?
What characterizes ulcerative colitis?
Which of these is not a factor contributing to IBD?
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What is the largest independent risk factor for IBD?
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Which condition leads to a lack of new T cells and affects antibody production?
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Up to what fraction of patients with CD have a first-degree relative with the disease?
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What type of infections does HIV infection predispose individuals to?
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Which therapy is used to inhibit the entry of HIV into the host cell?
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What kind of inflammatory response can superantigens cause?
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Which chromosomes have been identified with susceptibility loci for UC and CD?
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HAART combined with IL-2 mainly aims to:
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What is a significant immunological consequence of HIV infection?
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Which problem is associated with HIV vaccines?
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Which of the following is not a factor leading to acquired immunodeficiency?
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What is a common result of protein-calorie malnutrition related to the immune system?
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Which gene is associated with Crohn's disease in white populations?
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What role does the NOD2 protein play in the immune system?
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Where is the NOD2 protein primarily expressed?
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Which type of cells infiltrate the bowel wall in Crohn's disease?
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What does the immune theory of IBD assume?
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What mechanism is excessive with Crohn's disease (CD)?
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Which cytokine's expression is increased in the intestinal mucosa of IBD patients?
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How is inflammation in IBD maintained?
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Study Notes
Acquired Immunodeficiency
- Caused by other diseases or conditions, including aging, protein-calorie malnutrition, cancer treatment, immunosuppressive therapies, and HIV infection.
- HIV infection leads to severe secondary immunodeficiency, causing dysfunction and deficiency of B cells, T cells, and phagocytic cells, and decreased cell-mediated cytotoxicity by natural killer cells.
Immunomodulation
- HAART (Highly Active Antiretroviral Therapy) and IL-2 can reconstitute the immune system and slow apoptosis of HIV-infected cells.
- Chemokine receptor inhibitors can prevent HIV entry into host cells.
- Vaccines, including proteins, DNA, subunit, and recombinant virus (SIV-HIV chimeric virus), can stimulate immune response.
Problems with Immunomodulation
- HIV-1 infection allows the virus to shield itself from recognition by antibodies.
- Low immunogenicity and delayed response due to low CD4+ T cell counts.
- Destruction of CD4+ T cells by vaccine.
- Integration of virus in host genome.
- High rate of virus replication.
- Challenges with vaccine development, including route of exposure and lack of animal models.
Disorders of the Immune System
- Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease.
- Reactions of hypersensitivity, including allergic rhinitis and anaphylaxis.
- Autoimmune diseases, including rheumatoid arthritis and multiple sclerosis.
- Immunodeficiency syndromes, including primary and acquired immunodeficiency.
Inflammatory Bowel Disease (IBD)
- Caused by a dysregulated immune response.
- Two forms: ulcerative colitis (mucosal inflammation confined to the rectum and colon) and Crohn's disease (transmural inflammation of the GI tract).
- Etiologies include dysregulated immune response, host genetics, and environmental factors.
Etiologies of IBD
- Dysregulated immune response.
- Host genetics.
- Environmental factors, including commensals, pathogens, antibiotics, diet, stress, and barrier function.
Infectious Factors
- Certain bacterial strains produce toxins that cause mucosal damage.
- Bacteria produce peptides that cause an influx of inflammatory cells.
- Microbes may elaborate superantigens that stimulate global T lymphocyte stimulation.
Genetic Factors
- Positive family history is a significant risk factor.
- Increased concordance for the disease in monozygotic twins.
- Polygenic disease, with susceptibility loci on multiple chromosomes.
- Linkage mutations have been found on CARD15/NOD2, IBD5, and IBD3 loci.
The Role of NOD2 in the Immune System
- NOD2 recognizes bacterial molecules and stimulates an immune reaction.
- Encodes a protein with two caspase recruitment domains and eleven leucine-rich repeats.
- Expressed in peripheral blood leukocytes.
- Plays a critical role in immune response by recognizing bacterial molecules and activating NF-κB.
Immunological Mechanism of IBD
- The immune system plays a critical role in the pathogenesis of IBD.
- Infiltration of lymphocytes, plasma cells, mast cells, macrophages, and neutrophils in the bowel wall and mucosal layer.
- Inflammation is maintained by an influx of leukocytes from the vascular system into sites of active disease.
- The influx is promoted by expression of adhesion molecules on endothelial cells.
The Immune Theory of IBD
- IBD is caused by an inappropriate reaction of the immune system.
- Potential immunologic mechanisms include both autoimmune and non-autoimmune phenomena.
- Dysregulation of cytokines is a component of IBD.
- Th1 cytokine activity is excessive in CD, while Th2 cytokine activity is excessive in UC.
- Patients have an inappropriate T cell response to antigens from their own intestinal microflora.
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Description
This quiz covers the various causes of acquired immunodeficiency syndrome, including aging, malnutrition, cancer treatment, and HIV infection.
