Specificity of antibodies and tuberculin response after occupational exposure to tuberculosis

Specific antibody levels and delayed-type hypersensitivity skin responses to antigens of Mycobacterium tuberculosis in 39 hospital staff who were heavily exposed to tuberculosis (TB) were compared with those in 36 factory employees from Indonesia. Antibody levels to the TB68 epitope of the 14-kDa antigen were significantly greater, while titers to the TB23 (19-kDa) and TB72 (38-kDa) epitopes and lipoarabinomannan (LAM) were lower in exposed than in nonexposed subjects (all P less than .02). The intensity of tuberculin responses correlated positively with anti-LAM and negatively with anti-19-kDa antibody levels. Possible reasons for the selective humoral response of chronically exposed healthy subjects to the 14-kDa antigen, but not to other antigens immunogenic in patients with tuberculosis, are discussed.