Serological diagnosis of Mycobacterium avium complex lung diseases by enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen

Abstract

Introduction There is an increasing trend worldwide in the incidence of Mycobacterium avium complex pulmonary diseases (MAC-PD) and the diagnosis is sometimes complicated. Recently, an enzyme immunoassay (EIA) kit that detects serum IgA antibody against MAC-specific glycopeptidolipid (GPL) core antigen had been developed and found to be useful in discriminating MAC-PD from other lung diseases. The antibody was subsequently also found to be elevated in patients suffering Mycobacterium abscessus pulmonary diseases (MAB-PD). This study is to evaluate this EIA kit in the serological diagnosis of MAC-PD in Hong Kong Chinese patients. Methods The study was conducted in Grantham Hospital, Hong Kong between July 2017 and July 2018. Assay of the IgA antibody level using the EIA kit was done on blood samples collected from patients suffering from MAC-PD, MAB-PD, pulmonary tuberculosis and other lung diseases. Results There were 100 subjects recruited into the study, among which 11 were excluded. By using the cut-off value 0.7 U/mL provided by the manufacturer, the sensitivity and specificity for diagnosis were 73.7% and 77.6% for MAC-PD; 50% and 77.6% for MAB-PD. By receiver operating characteristic curves analysis, new cut-off for MAC-PD and MAB-PD were calculated as 1.771 U/mL and 0.172 U/m, respectively. The sensitivity and specificity were 68.4% and 86.2% for MAC-PD, whereas 66.7% and 72.4% for MAB-PD. Conclusions Our study showed that the enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen could help to distinguishing MAC and M. abscessus pulmonary diseases from pulmonary tuberculosis and other lung diseases among Hong Kong Chinese patients. Further larger scale studies in our local population for the usefulness of this antibody test in the diagnosis and monitoring of MAC and M. abscessus lung diseases might be warranted.

IgA Serological Response for the Diagnosis of Mycobacterium abscessus Infections in Patients with Cystic Fibrosis

“…Unlike the only test measuring IgA to detect Mabs infection published to date ( 10 , 14 – 16 ), our IgA ELISA was able to differentiate Mabs from Mav/Mchm-infections, but not from Mint-infections although the number of patients was small. Our assay is based on the recognition of Mabs proteins or extracts while the older test is based on detection of antibodies recognizing the GPL core antigen of M. avium .…”

“…With this reagent, they were able to detect patients infected with M. abscessus or Mycobacterium massiliense without differentiating them from other mycobacteria belonging to the avium complex, whereas they differentiated those with M. tuberculosis , linked to the fact that GPLs exist only in non-tuberculous mycobacterials (NTMs). The same reagent (Tauns Laboratories) was used in three recent studies in 2020 ( 14 – 16 ) to identify patients infected with M. abscessus . Although, this assay did not allow the differentiation of sera from patients infected with M. abscessus complex mycobacteria or with the M. avium species complex (MAC), it predicted a favorable outcome, revealing a decrease over time of antibody level in surgically treated patients ( 15 ).…”

Patient with Adult T-cell Leukemia and Lung Infection Caused by <i>Mycobacterium abscessus</i>: Successful Treatment with Intensive Chemotherapy Followed by Haploidentical Hematopoietic Stem Cell Transplantation

“…In general, MABC can be detected within seven days (11). MABC antigens can crossreact with anti-MAC antibodies (11)(12)(13).…”

T-cell deficiency and hyperinflammatory monocyte responses associate with Mycobacterium avium complex lung disease

“…Diagnosis of MAC lung disease is often challenging due to difficulties in collecting sputum and differentiating between MAC colonization and lung disease ( 19 ). Efforts to improve MAC diagnostics included skin tests ( 20 , 21 ) and serodiagnostics ( 22 – 24 ). However, immunologic tests which accurately diagnose MAC, predict disease progression, or assess the success of treatment are not currently available.…”