Radioallergosorbent test (RAST) for measurement of IgG antibodies to Aspergillus fumigatus in sera of patients with different lung diseases.

A radioallergosorbent test (RAST) for measuring human anti-Aspergillus fumigatus (Af) antibodies of the IgG class is described. The use of 125I-labelled animal antibodies against human IgG is compared with the use of 125I-labelled protein A. Under optimal conditions the radioactivity binding ratio between pooled patients' serum and pooled healthy persons' serum is 8-11.5. The immunoblotting technique was used to investigate so-called non-specific binding. The results obtained show that most if not all human sera contain anti-Af antibodies of the IgG type. The difference between pathological and normal immunological response to Af antigens seems to be in the antibody titres rather than in the presence or absence of antibodies to these antigens.