[Specific antibody-forming cells in bronchoalveolar lavage fluid of patients with summer-type hypersensitivity pneumonitis--detection by enzyme-linked immunospot (ELISPOT)].

Antigen-specific antibody-forming cells (AFCs) were assessed in bronchoalveolar lavage (BAL) fluid of patients with summer-type hypersensitivity pneumonitis by the method of enzyme-linked immunospot (ELISPOT). Both Cryptococcus- and Trichosporon-specific AFCs of isotypes of IgG, IgA and IgM were detected in BAL fluid cells. The frequency of isotypes of AFCs was in the order of IgA > IgM > IgG. Antibody activities against both Cryptococcus and Trichosporon antigens were detected in the culture supernatant of BAL cells. A good correlation was observed between the number of AFCs and the degree of antibody activity of culture supernatant of BAL cells, particularly of IgA isotype. For the IgM and IgA isotypes, anti-Cryptococcus antibody activity correlated well with anti-Trichosporon antibody activity (r = 0.98, p < 0.0001). In several cases examined, antigen-specific AFCs were detected in in vitro culture of peripheral blood mononuclear cells of patients after stimulation with PWM. In the present study, we demonstrated that Cryptococcus neoformans and Trichosporon cutaneum antigen-specific AFCs were present in the lungs of patients with summer-type hypersensitivity pneumonitis, and the antibodies secreted therefrom reacted with both these antigens. The presence of memory B cells was also suggested in the peripheral blood of patients.