Antimycobacterial antibodies in pleural effusions.

We devised a dot blot assay to evaluate the IgG and IgA response to P32, a recently isolated antigen specific to mycobacteria. Pleural fluids and the corresponding sera were tested, obtained from five patients with pleural tuberculosis proven by direct examination and/or culture and from 14 patients with pleural effusions of other origins. We measured the total IgG and IgA levels in all samples and determined the anti-P32 titer after adjusting IgG and IgA respectively to the same levels in all samples. Those pleural fluids and sera from tuberculous patients contained a higher proportion of anti-P32 antibodies than samples obtained from nontuberculous control subjects; in those patients, the proportion of anti-P32 antibodies was generally higher in pleural effusion fluid than in serum.