Frequent Detection of Anti-Tubercular-Glycolipid-IgG and -IgA Antibodies in Healthcare Workers with Latent Tuberculosis Infection in the Philippines

Abstract EN

Anti-tubercular-glycolipid-IgG (TBGL-IgG) and -IgA (TBGL-IgA) antibodies, and the QuantiFERON-TB Gold test (QFT) were compared in healthcare workers (HCWs, n=31) and asymptomatic human immunodeficiency virus-carriers (HIV-AC, n=56) in Manila.

In HCWs, 48%, 51%, and 19% were positive in QFT, TBGL-IgG, and -IgA, respectively.

The TBGL-IgG positivity was significantly higher (P=0.02) in QFT-positive than QFT-negative HCWs.

Both TBGL-IgG- and -IgA-positive cases were only found in QFT-positive HCWs (27%).

The plasma IFN-γ levels positively correlated with TBGL-IgA titers (r=0.74, P=0.005), but not TBGL-IgG titers in this group, indicating that mucosal immunity is involved in LTBI in immunocompetent individuals.

The QFT positivity in HIV-AC was 31% in those with CD4+ cell counts >350/μL and 12.5% in low CD4 group (<350/μL).

59 % and 29% were positive for TBGL-IgG and -IgA, respectively, in HIV-AC, but no association was found between QFT and TBGL assays.

TBGL-IgG-positive rates in QFT-positive and QFT-negative HIV-AC were 61% and 58%, and those of TBGL-IgA were 23% and 30%, respectively.

The titers of TBGL-IgA were associated with serum IgA (P=0.02) in HIV-AC.

Elevations of TBGL-IgG and -IgA were related to latent tuberculosis infection in HCWs, but careful interpretation is necessary in HIV-AC.