Immunodeficiency Flashcards
What is the definition of primary immune deficiency?
An intrinsic defect in the immune system.
What is the definition of secondary immune deficiency?
An immune deficiency resulting from an underlying disease.
What are the two main classifications of immunodeficiency?
- Primary
- Secondary
What types of immune deficiencies are included in primary immunodeficiency disorders?
- Innate
- Adaptive
What are some examples of primary disorders of T cell function?
- DiGeorge Syndrome
- Severe Combined Immunodeficiency (SCID)
What are some examples of primary disorders of B cell function?
- X-linked Agammaglobulinemia
- Common Variable Immunodeficiency
- Hyper IgM Syndromes
What are some examples of primary disorders of phagocyte function?
- Chronic Granulomatous Disease
- Leukocyte Adhesion Deficiency
What are some examples of primary disorders of complement function?
- C2 Deficiency
- C3 Deficiency
What are common complications of immune deficiency disorders?
- Recurrent infections
- Autoimmune conditions
- Malignancies
When should primary immunodeficiency be suspected?
- Family history
- Recurrent or chronic infections
- Infections with unusual organisms
- Early-onset eczematous skin rashes
- Early-onset autoimmunity
- Failure to thrive
What type of investigations are used for diagnosing immunodeficiency?
- Quantitative tests
- Qualitative tests
What are some quantitative tests for immunodeficiency?
- FBC with differential
- Immunoglobulin levels
- Flow cytometry for B-cell subset
- Flow cytometry for T-cell subset
What are some qualitative tests for immunodeficiency?
- Functional antibody responses to vaccines
- T-cell proliferation to mitogens
- Neutrophil oxidative burst assay
What is the management strategy for primary immunodeficiency?
- Antimicrobials
- Immunoglobulin replacement therapy
- Haematopoietic stem cell transplant (HSCT)
What is the incidence of primary antibody deficiencies?
4 to 6 per 1,000,000 population.
What age groups are affected by primary antibody deficiencies?
- <4 years
- 4-15 years
- 16-60 years
What is the typical presentation of X-linked Agammaglobulinemia?
- Young boys
- Recurrent pyogenic infections
- Absent circulating B-cells
What are the key features of Hyper IgM syndromes?
- Severe antibody deficiency
- Normal numbers of B cells
- Normal or raised serum IgM levels
What characterizes Common Variable Immunodeficiency?
- Low serum levels of IgG and IgA
- Normal or reduced IgM
- Normal or low numbers of B cells
What is the main association of Selective IgA deficiency?
- Coeliac disease diagnosis
- Anaphylaxis risk with blood products
What is the definition of Combined immune deficiency?
Defects that involve both T- and B-lymphocytes.
What are some examples of disorders associated with Combined immune deficiency?
- DiGeorge Syndrome
- Wiskott-Aldrich Syndrome
What is the mnemonic to remember the features of DiGeorge Syndrome?
CATCH22
What is the triad of symptoms in Wiskott-Aldrich Syndrome?
- Immunodeficiency
- Thrombocytopenia
- Eczema
What is SCID?
Severe Combined Immunodeficiency.
What are the types of SCID?
- Reticular dysgenesis
- Adenosine deaminase deficiency
- Gamma chain deficiency
- RAG1/2 deficiency
What is a common symptom of SCID in infants?
Chronic diarrhoea.
What is the classification of SCID?
Combined deficiency
SCID stands for Severe Combined Immunodeficiency.
What defects are associated with RAG1/2 in SCID?
Autosomal recessive, T – B - NK + SCID, Lack of VDJ recombination
RAG1/2 defects lead to severe immune system impairment.
What is the prevalence of IL7 receptor deficiency in SCID?
24%
IL7 receptor deficiency is one type of SCID with significant prevalence.
What are the types of defects in SCID?
- RAG1/2 defect
- IL7 receptor deficiency
- CD3 delta chain
- CD3 activation failure
These defects lead to T, B, and NK cell deficiencies.
What are the two categories of immunodeficiency?
- Primary
- Secondary
Primary refers to intrinsic defects, while secondary is due to underlying diseases.
What are the professional phagocytic cells?
- Monocyte / Macrophage
- Neutrophils
- Dendritic cells
- Mast cells
These cells play a crucial role in the immune response.
What is a key characteristic of Neutropenia?
Classification
Neutropenia can be classified based on its causes and severity.
What is Leucocyte Adhesion Deficiency (LAD)?
Defect in adherence to endothelial cells, leading to inability to traverse into tissues
Clinical presentations include skin infections and delayed separation of the umbilical cord.
What is the clinical presentation of Chronic Granulomatous Disease?
- Recurrent infections
- Poorly responsive to antibiotics
- Staphylococcal skin infections
This condition is often complicated by granuloma formation.
What is the screening test for Chronic Granulomatous Disease?
Dihydrorhodamine (DHR) test
This test assesses the oxidative burst in phagocytes.
What is hereditary angioedema associated with?
Deficiency of C1 inhibitor, low C4 levels
This condition is a type of primary immunodeficiency.
What are Pattern Recognition Receptors (PRR)?
Receptors that recognize pathogen-associated molecular patterns
PRRs play a critical role in the innate immune response.
What is the impact of malnutrition on immune function?
Decreases production of immune components
Malnutrition can lead to secondary immunodeficiency.
What types of drugs can lead to secondary immunodeficiency?
- Immunosuppressants
- Chemotherapy
These medications can impair the immune system.
What is the key feature of innate immunity?
Includes interaction between PRRs on phagocytes and pathogen-associated molecular patterns
Innate immunity does not improve with repeated exposure.
What are the pathways to activate the complement system?
- Classical pathway
- Alternative pathway
Activation of the complement system is crucial for immune defense.
What accurately describes the complement system?
Ends with a final common pathway leading to bacterial lysis
The complement system plays a vital role in both innate and adaptive immunity.
