Immunology Quiz on Immune System Effects

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Questions and Answers

What is one of the primary effects of corticosteroids like prednisone and dexamethasone on the immune system?

Promote antibody synthesis and B cell activation

Increase macrophage activation and cytokine production

Enhance T lymphocyte proliferation and response

Dampen inflammation by inhibiting PMN migration (correct)

What is a consequence of immunosuppression induced by agents like cyclosporin A and tacrolimus post-transplant?

Enhanced immune response against encapsulated bacteria

Improved ability to counteract viral infections

Predisposition to infections due to T cell deficiency (correct)

Increased production of natural killer cells

How does splenectomy affect the body's defense against infections with encapsulated organisms?

Decreases the risk of systemic infections significantly

Increases the effectiveness of opsonizing antibodies

Prevents the removal of circulating microorganisms

Raises the risk for infections with encapsulated organisms (correct)

Which of the following immune cells is most affected by corticosteroids leading to decreased antibody responses?

T lymphocytes Signup and view all the answers

What type of infections is a patient at increased risk for following splenectomy?

Infections from encapsulated organisms Signup and view all the answers

What is one classic feature of inflammation?

Dolor Signup and view all the answers

Which type of immunity is specifically trained to recognize and remember pathogens?

Adaptive immunity Signup and view all the answers

Which condition is indicative of primary immunodeficiency?

Pneumonia in a 16-month-old after multiple hospital admissions Signup and view all the answers

What is a potential consequence of complement deficiencies?

Failure of the complement cascade Signup and view all the answers

In what context is a patient's immune status particularly crucial?

Formulating a treatment plan for infections Signup and view all the answers

Which of the following best describes macrophages in the immune system?

They induce cell death of infected or malignant cells. Signup and view all the answers

What type of immunodeficiency may be caused by genetic factors?

Primary immunodeficiency Signup and view all the answers

What type of infections are associated with the loss of early components in the immune system?

Increased Staphylococcal and Streptococcal infections Signup and view all the answers

Which condition is characterized by an inability to kill ingested organisms due to defect in phagocytic cell function?

Chronic Granulomatous Disease Signup and view all the answers

What type of deficiency results in a non-functional immune system due to the failure of B cells, T cells, or NK lymphocytes development?

Subacute Combined Immune Deficiency (SCID) Signup and view all the answers

What type of infections do patients with T cell deficiencies tend to experience?

Viral infections, especially from the herpes family Signup and view all the answers

Which type of disorders result in an increased susceptibility to bacterial infections due to B cell deficiencies?

Bacterial infections Signup and view all the answers

Which type of infections are more likely to occur due to failure in lymphocyte function?

Bacterial and viral infections Signup and view all the answers

What is a consequence of chemotherapy related to immunity?

Inhibition of cell division in rapidly dividing cells Signup and view all the answers

What happens to PMN levels after chemotherapy treatment?

They can remain depressed for 1-4 weeks Signup and view all the answers

What type of infections may lead to severe disease when live vaccines are administered to SCID patients?

Viral infections Signup and view all the answers

What is the primary consequence of defects in phagocytic cell function?

Increased susceptibility to bacterial infections Signup and view all the answers

Study Notes

Immunocompromised Host

Lecture 25
Objectives include reviewing the basics of innate and adaptive immune systems and providing an overview of immune system deficiencies that lead to infectious diseases.
Classic features of inflammation include rubor (redness), calor (heat), tumor (swelling), and dolor (pain).
A patient's immune status (e.g., immunodeficiencies, past infections, vaccination) significantly impacts their clinical presentation.
Examples include a post-kidney transplant patient with Pseudomonas aeruginosa in their urine, a healthy 30-year-old non-smoker with non-resolving pneumonia despite antibiotics, a 16-month-old with frequent pneumonia, and a 56-year-old man bitten by a dog with past lymphoma.

Innate and Adaptive Immunity

Innate immunity involves non-specific defenses, a fast response, and a lack of memory.
- It includes fever, dendritic cells, NK cells, macrophages, epithelial cells, and the complement system.
Adaptive immunity involves a trained immune system, a slower response, and a memory component.
- It includes B cells, plasma cells, antibodies, T helper cells, and T killer cells.
- The difference in these attributes impacts the duration and severity of infections.

Innate Immunity - Barriers and Secretions

Skin has many cell layers, tightly packed cells, and dead outer layers with live inner layers.
Mucous membranes have one to a few layers of cells, moist environment, cells mostly alive, mucous present.
Digestive system secretions (saliva, stomach acid, gastroferritin, bile, intestinal secretions) wash microbes or digest them, preventing microbial use of iron, and eliminating microorganisms using peristalsis, defecation, and vomiting.
Urinary system secretions (urine) eliminate microorganisms via acidity and flushing.
Reproductive system secretions (vaginal, menstrual flow, prostate secretions) inhibit microbes and wash them from the tract.
Cardiovascular system blood flow removes microorganisms from wounds and coagulation prevents pathogen entry.

Innate Immunity - Cells

Macrophages ("big eaters") are phagocytes that engulf and destroy microbes.

Adaptive Immunity - Overview

Antibody-mediated (humoral) immunity involves B cells and plasma cells producing antibodies to neutralize or eliminate pathogens.
Cell-mediated immunity involves T helper and T killer cells directly destroying infected or malignant cells.

Immunodeficiency States

Primary immunodeficiencies are genetic disorders causing immune system deficiencies, such as Chronic Granulomatous Disease, Severe Combined Immunodeficiency (SCID), DiGeorge syndrome, and Bruton-type agammaglobulinemia.
Secondary (acquired) immunodeficiencies are caused by infections, splenectomies, malignancies, chemotherapy, steroids, transplant rejection drugs, poor nutrition, pregnancy, and the newborn period.

Secondary Acquired Immunodeficiencies

Chemotherapy interferes with lymphocyte replication, often leading to temporary neutropenia and increased infection risk.
Corticosteroids damp down inflammation, potentially impairing PMN migration to infection sites and reducing macrophage/dendritic cell function, resulting in increased susceptibility to various infections.

Secondary Acquired Immunodeficiencies (continued)

Post-transplant immunosuppressants like cyclosporine, tacrolimus, and serolimus inhibit cytokine production and T cell function, increasing infection risk.
Splenectomy removal of the spleen reduces the production of opsonizing antibodies, leading to higher risks of infections by encapsulated bacteria (like Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis).
HIV/AIDS is characterized by a progressive decline in CD4+ T cells, increasing susceptibility to opportunistic infections.

Evasion of the Immune Response

Bacteria can evade the immune response by destroying complement components, destroying immunoglobulins (e.g., producing IgA protease), preventing phagocytosis (e.g., encapsulating), and preventing intracellular killing.
Some bacteria change surface antigens rapidly, evading the immune system's targeted response.

Important Topics Beyond Scope

Dysregulation, autoimmunity, and allergy are important parts of the immune system but beyond the scope of this lecture.

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Description

This quiz explores key concepts related to the immune system, focusing on the effects of corticosteroids, the risks associated with immunosuppressive agents, and the impact of splenectomy. Test your knowledge on immune response, inflammation, and immunodeficiencies in a range of scenarios.