Enzyme-linked immunosorbent assay (ELISA) for antibodies to purified protein derivative of tuberculin (PPD). IgM-, IgA- and IgG- anti-PPD antibodies in active pulmonary tuberculosis.

Enzyme-linked immunosorbent assay (ELISA) was developed for IgM, IgA and IgG antibodies against purified protein derivative of tuberculin (PPD). PPD antibodies of 44 patients with active pulmonary tuberculosis were measured at admission to hospital. The control material consisted of 35 healthy blood donors. The mean antibody levels in all three immunoglobulin classes correlated to the extent of the tuberculous infection, i.e. the severer the disease the higher the mean antibody level. The mean antibody levels also were significantly higher in the tuberculosis patients than in the controls, the only exception was specific IgA antibodies in the patients with minimal disease. ELISA-positivity of the patients, i.e. positive result in at least one immunoglobulin class was as follows: 33% of the grade I, 64% of the grade II and 100% of the grade II patients.