AVIDITY OF ASPERGILLUS-UMBROSUS IGG ANTIBODIES IN FARMERS LUNG-DISEASE

Farmer's lung disease (FL), the commonest form of allergic alveolitis caused by repeated inhalation of mouldy hay, is associated with exposu re to the fungus Aspergillus umbrosus among Finnish farmers. The antig en-binding avidity of A. umbrosus-specific IgG antibodies was measured in 12 FL patients in acute phases of initial and recurrent attacks an d during 1 year follow up as well as in 12 healthy farmers and five he althy urban controls. The farmers' groups were further divided into tw o subgroups: subjects with short exposure (<7 years) and subjects with long exposure (>25 years). During the first acute phase FL patients w ith long exposure exhibited a high avidity of A. umbrosus-specific IgG antibodies that remained high during the 1 year follow up, although t he A. umbrosus-specific IgG antibody titre decreased. A re-exposure to mouldy hay leading to a recurrence further enhanced the maturation of the antibody avidity, so that an even higher A. umbrosus-specific IgG avidity with a less significant increase of antibody titre occurred t han during the first acute attack. Notably higher Ige antibody avidity was observed in FL patients with long exposure than in healthy Farmer s or in healthy controls.