Table 6.
Quality and standardization control stratification of inborn errors of immunity (IEI) assessment nonfunctional immunoassays.
| IEI categories | Nonfunctional immunoassay | Method | Method standardization | Quality control program | Reference range (including early age groups) |
|---|---|---|---|---|---|
| Predominantly antibody deficiencies | IgG, IgM and IgA | Nephelometry or turbidimetry | Standardized | Established | Standardized |
| IgD | ELISA | Standardized | Established | Nonstandardized | |
| IgE | ELISA or fluorimetry | Standardized | Established | Few initiatives | |
| IgG subclasses | Nephelometry or turbidimetry | Standardized | Established | Standardized | |
| Salivary IgA | ELISA | Few initiatives | Unestablished | Few initiatives | |
| Vaccine response against tetanus toxoid | ELISA | Standardized | Unestablished | Few initiatives | |
| Vaccine response against diphtheria toxoid | ELISA | Standardized | Unestablished | Few initiatives | |
| Vaccine response against measles | ELISA | Standardized | Unestablished | Standardized | |
| Vaccine response against mumps | ELISA | Standardized | Unestablished | Standardized | |
| In vivo vaccine response against Streptococcus pneumoniae | ELISA | Standardized | Established | Standardized | |
| Multiplex | Standardized | Unestablished | Nonstandardized | ||
| Isohemagglutinins | Hemagglutination | Standardized | Unestablished | Few initiatives | |
| B cells (CD19+ or CD20+) | Flow cytometry | Standardized | Established | Standardized | |
| B cell immune phenotyping | Flow cytometry | Few initiatives | Unestablished | Few initiatives | |
| Intracellular BTK expression | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| Defective cell surface CVID-related protein expression | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| Combined immunodeficiencies | TREC | qRT-PCR | Standardized | Unestablished | Few initiatives |
| CD4+/CD8+ T cells | Flow cytometry | Standardized | Established | Standardized | |
| T cell immune phenotyping | Flow cytometry | Few initiatives | Unestablished | Few initiatives | |
| Th17 immunophenotyping | Flow cytometry | Nonstandardized | Unestablished | Few initiatives | |
| Intracellular Wiskott-Aldrich protein expression | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| Defective cell surface or intracellular SCID-related protein expression | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| ADA-1 erythrocyte activity | Fluorometry, spectrophotometry | Nonstandardized | Unestablished | Nonstandardized | |
| PNP erythrocyte activity | LCTMS, ECA | Nonstandardized | Unestablished | Nonstandardized | |
| Diseases of immune dysregulation | Soluble CD25 | ELISA, chemoluminescence | Standardized | Unestablished | Few initiatives |
| Defective intracellular HLH-related protein expression (PRF1, SAP/SH2DIA, XIAP) | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| Double negative TCRα/β circulating T cells (DNT) | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized | |
| IL-10 | ELISA, ALBIA | Standardized | Unestablished | Few initiatives | |
| IL-18 | ELISA, ALBIA | Standardized | Unestablished | Few initiatives | |
| Soluble FASL | ELISA, ALBIA | Standardized | Unestablished | Few initiatives | |
| B12 vitamin | ELISA | Standardized | Established | Standardized | |
| Defects in phagocytes, intrinsic and innate immunity | Cell surface protein expression: IFNγ-R1 and IFNγ-R2 | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized |
| Cell surface protein expression: CD18, CD11a/CD11b/CD11c, CD15 | Flow cytometry | Nonstandardized | Unestablished | Nonstandardized |
The main methodologies platforms used for each test are also presented. Standardization and quality control stratification for each test are rated as: “standardized/established”, in the case of robust, clear data available; “few initiatives”, in the case of only reports or low-numbered uncontrolled case series available; or “nonstandardized/unestablished”, in the case of no trustworthy data available.
ADA-1, adenosine deaminase-1; ALBIA, addressable laser bead immunoassay; ECA, enzymatic colorimetric assay; ELISA, enzyme-linked immunosorbent assay; HLH, hemophagocytic lymphohystiocytosis; LCTMS, liquid chromatography-tandem mass spectrometry; PNP, purine nucleoside phosphorylase; PRF1, perforin 1; SAP/SH2DIA, SLAM-associated protein/SH2 domain–containing protein 1A; TREC, T cell receptor excision circles; XIAP, X-linked inhibitor of apoptosis.