Effect of patient immunodeficiencies on the diagnostic performance of serological assays to detect Aspergillus-specific antibodies in chronic pulmonary aspergillosis.
Respir Med 2021;
178:106290. [PMID:
33529993 PMCID:
PMC7957343 DOI:
10.1016/j.rmed.2020.106290]
[Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/25/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022]
Abstract
Background
Prevalence of chronic pulmonary aspergillosis (CPA) is ~3 million patients worldwide, and detection of Aspergillus-specific antibody is a critical diagnostic component. Some patients with CPA have subtle immune deficits possibly contributing to poor Aspergillus antibody production and false negative results.
Materials/methods
We analyzed patient data from 167 cases of clinically confirmed CPA previously evaluated by ImmunoCAP Aspergillus-specific IgG EIA, Bordier ELISA and LDBio Aspergillus IgG/IgM ICT lateral flow assay, to identify deficiencies in: mannose binding lectin (MBL), IgG, IgA, IgM, IFN gamma, IL12 or IL17 production, and/or low cell marker counts (CD4, CD19, CD56). We defined patients as ‘sero-negative’ if ImmunoCAP Aspergillus IgG was consistently and repeatedly negative (<40 mg A/L). ‘Sero-positive’ was defined as all other CPA cases.
Results
We found the rate of false negatives by ImmunoCAP Aspergillus IgG EIA (n = 23) to be more prevalent in patients with immunodeficiency markers, especially multiple defects. MBL deficiency combined with low CD19 cells (p < 0.001), pneumococcal antibody levels (p = 0.043), IgM (p = 0.047) or three combined (p = 0.001–0.018) or all four together (p = 0.018) were significant. The performance LDBio Aspergillus IgG/IgM ICT appears to be relatively unaffected by immunodeficiency (92.7% of ImmunoCap sero-negatives were positive). The Bordier assay performed significantly better than the ImmunoCAP assay (P = 0.0016) for sero-negative CPA cases.
Conclusions
In select cases of CPA, ImmunoCAP EIA yields a false negative result, making serological diagnosis difficult. ImmunoCAP false negatives are more prevalent in patients with multiple immunological defects, who may still be positive with the LDBio Aspergillus ICT or Bordier EIA.
Low or undetectable Aspergillus IgG is associated with, usually, several minor immunological defects.
Aspergillus IgG/IgM lateral flow assay is more sensitive than ImmunoCAP for CPA with or without subtle immunodeficiency.
CPA patients may have Aspergillus IgG detectable with different assays.
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