Crossed affinoimmunoelectrophoresis using concanavalin A and Aleuria aurantia lectin as diantennary glycan- and fucose-specific affinocomponents, respectively, was applied to study changes in the concentration and glycosylation of the acute phase protein alpha 1-acid glycoprotein (AGP) in sera obtained from patients with hyperimmunoglobulinemia D and periodic fever syndrome. Increases in concentration of AGP compared to control values were found not only during attacks, but also during remissions. Compared to healthy controls, the presence of diantennary glycan-containing glycoforms of AGP also increased during febrile attacks, while no changes were found during remissions. A continuous high degree of alpha 1-->3 fucosylation was accompanied by a continuous high expression of sialyl Lewisx on AGP. Despite the clinical picture of recurrent febrile attacks with asymptomatic intervals, these studies indicate that hyperimmunoglobulinemia D should be considered a condition of persistent inflammation.