SEROLOGICAL ANALYSIS OF PULMONARY AND EXTRAPULMONARY TUBERCULOSIS WITH ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR ANTI-A60 IMMUNOGLOBULINS

IgA, IgG, and IgM antibodies to mycobacterial antigen A60 were measure d by ELISA in blood, pleural fluid, and cerebrospinal fluid from 560 p atients with pulmonary and/or extrapulmonary tuberculosis who were bei ng treated at hospitals in northern China and from 734 uninfected cont rols. Among 529 healthy persons (most of whom had been vaccinated with bacille Calmette-Guerin [BCG] and 287 of whom were tuberculin-positiv e), the rate of false-positive results was negligible; this observatio n ruled out interference of remote BCG vaccination with A60 assays at the chosen cutoff level. Rates of positivity for IgM and IgG, respecti vely, were 80% and 36% among patients with active primary pulmonary tu berculosis, 31% and 88.5% among patients with active postprimary. pulm onary tuberculosis, 0 and 41% among patients with inactive pulmonary t uberculosis, and 30%-61% and 69%-86% among patients with extrapulmonar y tuberculosis. Paired samples of blood and pleural fluid from patient s with pleurisy contained IgA antibody to A60 at equal titers; in cont rast, most patients with tuberculous meningitis (100% of whom had a po sitive ELISA result) had higher levels of IgG antibody to A60 in cereb rospinal fluid than in blood-proof of intrathecal synthesis.