Determination of humoral immunoglobulins M and G directed against mycobacterial antigen 60 failed to diagnose primary tuberculosis and mycobacterial adenitis in children

Abstract

The serodiagnosis of primary tuberculosis (TB) and mycobacterial adenitis in children was tried using the Anda-Tb tests (Anda Biologicals, France) that measure immunoglobulins (Ig) M and G directed against mycobacterial antigen 60 (A60) by enzyme-linked immunosorbent assay. The 188 cases studied included 81 healthy or mycobacteria-unrelated diseased children with no reaction to tuberculin skin test (STN); 9 recent BCG vaccination (BCG); 35 asymptomatic (AsTB), 29 symptomatic (STB) primary TB and 11 adenitis caused by atypical mycobacteria from the group avium-intracellulare-scrofulaceum (MAIS) tested before treatment; and 23 past primary TB tested at different times after completion of specific treatment (past TB). The individual IgM and IgG levels largely overlapped whatever the clinical status of the children. Setting the normal upper limit at the 95th percentile of the STN values, which by definition gives 95% specificity, the highest IgM sensitivity was found in past TB (35%), AsTB showing 23%, STB 17%, and MAIS 18% sensitivity. IgG sensitivity was also the highest in past TB (26%) and was equal to 6, 14, and 9% in AsTB, STB, and MAIS, respectively. Positive and negative predictive values and the test efficiency (63 and 62% for IgM and IgG, respectively) were far too low. Combining positivity for IgM and/or IgG did not improve the results. In our study, the anti-A60 IgM and IgG measurements using the Anda-Tb tests in primary TB and mycobacterial adenitis in children did not prove of any diagnostic help.