Lecture 8.1 - The immunocompromised host

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Questions and Answers

What is the primary cause of immunodeficiency in an immunocompromised host?

Malnutrition and stress

Defect in one or more components of the immune system (correct)

Infection by a microorganism

Aging process

What is the characteristic of primary immunodeficiency diseases?

Intrinsic or congenital defect, passed on from generation to generation (correct)

Acquired through environmental factors

Caused by malnutrition and stress

Developed through random mutations

What is the result of B cell defects in immunodeficiency?

Increased production of complement proteins

Reduced production of antibodies (correct)

Increased production of cytotoxic T cells

Enhanced phagocytic activity

Which of the following is an example of secondary immunodeficiency?

HIV infection Signup and view all the answers

What is the role of Zinc in immunodeficiency?

Important for the maturation of B and T lymphocytes Signup and view all the answers

Which of the following is NOT a characteristic of primary immunodeficiency?

Acquired through environmental factors Signup and view all the answers

What is the result of T cell defects in immunodeficiency?

Reduced production of cytotoxic and helper T cells Signup and view all the answers

Which of the following is an example of a primary immunodeficiency disease?

X-linked agammaglobulinemia Signup and view all the answers

What is a common consequence of delayed diagnosis of primary immunodeficiency diseases?

Permanent tissue/organ damage Signup and view all the answers

Which of the following is NOT a cause of decreased production of immune components?

Protein-losing conditions Signup and view all the answers

What is the average time frame from the onset of symptoms to diagnosis for primary immunodeficiency diseases?

1-25 years Signup and view all the answers

What is a common risk factor for septic complications in patients with haematological malignancies?

Untreated febrile neutropenia Signup and view all the answers

Why is there a need for better diagnostic criteria for immunodeficiency diseases?

To improve awareness of immunodeficiency diseases in medical school/training Signup and view all the answers

What is a consequence of chemotherapy-induced damage to mucosal barriers in patients with haematological malignancies?

Increased susceptibility to infections Signup and view all the answers

What percentage of patients with primary immunodeficiency diseases are diagnosed after the age of 18?

>60% Signup and view all the answers

What is the primary goal of empiric antibiotic therapy in patients with suspected febrile neutropenia?

To prevent septic complications Signup and view all the answers

What is the consequence of a defective B cell?

Production of the wrong antibodies or no antibodies at all Signup and view all the answers

Which type of immunodeficiency is associated with autoimmune diseases?

IgA deficiency Signup and view all the answers

What does the acronym 'SPUR' stand for in the context of immunodeficiency?

Severe, Persistent, Unusual, Rare Signup and view all the answers

What is the primary goal of immunoglobulin replacement therapy?

To achieve serum IgG levels > 8g/l Signup and view all the answers

Which of the following is a type of primary immunodeficiency disorder?

Hyper-IgM syndrome Signup and view all the answers

What is the success rate of haematopoietic stem cell therapy (HSCT) in treating Severe Combined Immunodeficiency (SCID)?

90% Signup and view all the answers

What is the primary reason for using UV-irradiated CMV negative blood products in patients with severe PID?

To prevent CMV transmission, which was common in liver transplants Signup and view all the answers

What is the characteristic of X-linked agammaglobulinemia (XLA)?

Absence of mature B cells leading to severe antibody deficiency Signup and view all the answers

Study Notes

Immunocompromised Host

A state in which the immune system is unable to respond appropriately and effectively to infectious microorganisms
Caused by a defect in one or more components of the immune system

Types of Immunodeficiencies

Primary immunodeficiency
Secondary immunodeficiency

Primary Immunodeficiency

Over 100 primary immune deficiency diseases
Caused by intrinsic or congenital defect, single gene defect, or random error during development
Passed on from generation to generation
Problems with:
- B cells: reduction in antibody production
- T cells: reduction in Cytotoxic and helper T cells
- Both B and T cells
- Complement: opsonins, perforins, etc.
- Phagocytes/phagocytosis: control of infections is not efficient

Secondary Immunodeficiency

Acquired, caused by a number of factors:
- Malnutrition (e.g., zinc important in maturation of B and T lymphocytes)
- Stress
- Cancer (cancer itself or side effect of chemotherapy)
- Side effect of medications (corticosteroids, chemotherapy, surgery, anaesthetics)
- Infection (HIV)

How is a Host Immunocompromised?

Primary immunodeficiency: congenital, due to intrinsic gene defect
- Missing protein, missing cell, or non-functional components
Secondary immunodeficiency: acquired, due to underlying disease/treatment
- HIV, chemotherapy, etc.

Immunodeficiency Caused by Antibody Defects

B cells may not work properly, may not carry out its function, or may not be fully developed
Production of wrong antibodies or no antibodies at all, defective B cell
IgA is found in mucous membranes of the body, IgA deficiency associated with autoimmune diseases

Immunodeficiency Caused by T Cell Defects

Defects in T cell function or development

Immunodeficiency Caused by Defects in Phagocytosis

Defects in phagocytosis, control of infections is not efficient

When to Suspect Immunodeficiency

Infections suggesting underlying immune deficiency defined as "SPUR":
- Severe
- Persistent
- Unusual
- Recurrent

The 10 Warning Signs of PIDs (Primary Immunodeficiency Diseases)

Management of PIDs

Supportive treatment:
- Infection prevention (prophylactic antimicrobials)
- Treat infections promptly and aggressively
- Nutrition support
- Use UV-irradiated CMV-negative blood products only
- Avoid live attenuated vaccines in patients with severe PID (SCID)
Specific treatment:
- Regular immunoglobulin therapy (IVIg or SCIg)
- SCID: Haematopoietic stem cell therapy (HSCT, 90% success)
Comorbidities:
- Autoimmune disease and malignancies
- Organ damage (lung function assessment)
- Avoid non-essential exposure to radiation

Immunoglobulin Replacement Therapy

Goal: serum IgG > 8g/l, life-long treatment
Different formulations: IvIg, ScIg (young patients)
Conditions: CVID, XLA, Hyper-IgM syndrome, etc.

Why is Immunodeficiency an Unmet Clinical Problem?

Large spectrum of immunodeficiencies
Failure to recognize and diagnose
1-25 years from the onset of symptoms to diagnosis for primary immunodeficiency diseases
> 60% of patients will be 18 years old or older when diagnosis is made
> 40% of them will have permanent tissue/organ damage by the time they are diagnosed

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Description

Understand the concept of immunocompromised hosts and the different types of immunodeficiencies, including primary and secondary immunodeficiency diseases.