Diagnosis of invasive aspergillosis by passive hemagglutination assay of antibody.

Sheep red cells treated with concanavalin A and sensitized with a partially purified aspergillus antigen were used to detect antibody to Aspergillus by passive hemagglutination (PHA). Sera from eight patients with aspergillomas or allergic aspergillosis had PHA titers of greater than or equal to 1:800 and antibody detectable by immunodiffusion (ID). Of 122 hospitalized cancer patients without invasive aspergillosis, 118 had titers of less than or equal to 1:80, 86 of < 1:10, two of 1:160, and two of 1:320. None had antibody by ID. Antibody was detectable by PHA in sera from 12 of 14 healthy microbiology laboratory workers. Of 55 cancer patients who had sera available for testing within two weeks before diagnosis of invasive aspergillosis, 18 patients seroconverted: 13 by both PHA and ID, two by PHA alone, and three by ID alone. PHA titers rose from < 1:10 to between 1:40 and 1:1,280. In immunosuppressed patients who were at risk of developing invasive aspergillosis, the appearance of antibody correlated with the diagnosis of invasive aspergillosis.