Laboratory Tests for Immunity Disorders

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.