Examination of the immunoglobulin classes involved in the serological response of pregnant sheep to Aspergillus fumigatus.

Pregnant sheep inoculated with Aspergillus fumigatus conidia developed agglutinating and precipitating antibodies for mycelial antigens. The agglutinins were initially exclusively of the IgM class, but were later supplemented by IgG antibodies, although IgM production was usually sustained throughout the serological response. Precipitins active in the immunodiffusion test were of the IgG class. They developed later in the immune response than agglutinins and declined more rapidly. The precipitins and IgG agglutinins were more closely associated with recent active infection than IgM agglutinins.