In vitro studies of T-lymphocyte responses using five different batches of Aspergillus fumigatus antigens, were undertaken in twelve patients with A. fumigatus related lung disease and in three normal controls.
Using a leucocyte migration method, five of the twelve patients showed significant inhibition of leucocyte migration with a migration index of 0·80 or less to A. fumigatus, but in only three was this demonstrated with more than one batch of antigen (one patient with aspergilloma and two with bronchopulmonary aspergillosis).
The same antigens were used in lymphocyte transformation tests. Only two patients, one with aspergilloma and one with bronchopulmonary aspergillosis, showed clearly significant transformation although there were several borderline results.
Only three patients had evidence of delayed skin responses to A. fumigatus antigens in vivo, one with aspergilloma, one with bronchopulmonary aspergillosis and one with atypical bronchopulmonary aspergillosis. Two of these three patients also had one or more positive in vitro test results.
Thus T-lymphocyte sensitization to A. fumigatus as demonstrated by these in vitro methods, although present in occasional patients, was not clearly related to any one particular clinical syndrome in this small group of patients with aspergillus related pulmonary disease. There was, however, one of the three aspergilloma patients with positive lymphocyte transformation to all five batches of antigens and having higher transformation indices than in any other patient. This suggests that lymphocyte studies should be extended in this group.
In contrast to the frequent negative results using A. fumigatus antigens, evidence of T-lymphocyte sensitization to either Candida albicans or Mycobacterium tuberculosis or both, was shown by positive delayed hypersensitivity skin responses and in vitro inhibition of leucocyte migration in the majority of the patients, despite which lymphocyte transformation was often negative. The possibility of impaired capacity to transform is supported by the finding of an impaired response to phytohaemagglutinin (PHA) in four of the twelve cases.