Laboratory Tests for Immunity Disorders

Study Notes

Laboratory Tests for Inborn Errors of Immunity

Immunological Assessment
- Complete Blood Count (CBC): Evaluates white blood cell (WBC) count, hemoglobin, and platelets.
- T-Cell and B-Cell Analysis: Flow cytometry used to enumerate T- and B-lymphocyte populations.
- Immunoglobulin Levels: Measurement of serum IgG, IgA, IgM, and IgE concentrations to assess antibody production.
Functional Assays
- Lymphocyte Proliferation Assays: Measure the response of lymphocytes to mitogens (e.g., pokeweed mitogen) or antigens to assess functionality.
- Cytokine Production Assays: Evaluation of cytokine release in response to stimulation (e.g., IL-2, IFN-γ).
- Neutrophil Function Tests: Assess ability of neutrophils to phagocytose and generate reactive oxygen species (e.g., nitroblue tetrazolium test).
Genetic Testing
- Next-Generation Sequencing (NGS): Identify mutations in genes associated with immune disorders.
- Targeted Gene Panels: Focus on specific genes related to known inborn errors of immunity.
- Whole Exome Sequencing (WES): Comprehensive analysis of exons to detect rare genetic variants.
Metabolic Tests
- Enzyme Activity Assays: Evaluate enzymatic function in conditions like adenosine deaminase deficiency.
- Urinary Organic Acids: Screening for metabolic byproducts indicative of inherited metabolic disorders affecting immunity.
Complement System Evaluation
- Complement Levels: Measure components (C1q, C3, C4, etc.) of the complement system to identify deficiencies.
- Complement Function Tests: Hemolytic assays (CH50, AH50) to assess functional capacity of the complement system.
Additional Considerations
- Skin Testing: Assess delayed-type hypersensitivity responses.
- Microbiological Cultures: Identify recurrent infections and potential opportunistic pathogens.
- Immunization History: Evaluate response to vaccines as part of immune function assessment.

Understanding these laboratory tests helps diagnose and manage patients with inborn errors of immunity effectively.

Immunological Assessment

Complete Blood Count (CBC): Evaluates the number of white blood cells (WBCs), hemoglobin, and platelets in the blood.
T-Cell and B-Cell Analysis: Measures the number of T-lymphocytes and B-lymphocytes using flow cytometry.
Immunoglobulin Levels: Determines the concentration of circulating antibodies, including immunoglobulins G (IgG), A (IgA), M (IgM), and E (IgE).

### Functional Assays

Lymphocyte Proliferation Assays: Evaluates the ability of lymphocytes to multiply in response to stimulation from mitogens (e.g., pokeweed mitogen) or antigens.
Cytokine Production Assays: Measures the release of various cytokines (e.g., IL-2, IFN-γ) from lymphocytes following stimulation.
Neutrophil Function Tests: Assesses the ability of neutrophils to engulf and destroy bacteria, which involves phagocytosis and the production of reactive oxygen species (ROS).

Genetic Testing

Next-Generation Sequencing (NGS): Can be used to identify mutations in multiple genes associated with immune system disorders.
Targeted Gene Panels: Focuses on examining a specific set of genes known to be involved in particular inborn errors of immunity.
Whole Exome Sequencing (WES): Analyzes the majority of protein-coding regions (exons) in the genome to detect rare genetic variants.

Metabolic Tests

Enzyme Activity Assays: Evaluates the functionality of specific enzymes implicated in various immune disorders.
Urinary Organic Acids: Screens for abnormal metabolic byproducts in urine that can indicate inherited metabolic disorders impacting the immune system.

Complement System Evaluation

Complement Levels: Measures the concentrations of various components within the complement system (e.g., C1q, C3, C4).
Complement Function Tests: Uses hemolytic assays (CH50, AH50) to assess the overall functional capacity of the complement system.

Additional Considerations

Skin Testing: Evaluates the response to allergens and assesses delayed-type hypersensitivity, a type of immune response.
Microbiological Cultures: Detects the presence of infectious agents and potential opportunistic pathogens.
Immunization History: Provides information about the effectiveness of previous vaccinations and a patient's response.

Description

This quiz covers essential laboratory tests used to diagnose inborn errors of immunity. Explore various immunological assessments, functional assays, and genetic testing methods that are critical for evaluating immune disorders. Test your knowledge on the techniques and their applications in clinical settings.