IMMUNOPATHOLOGY OF FATAL SOYBEAN DUST-INDUCED ASTHMA

A hypothesis was postulated that the characteristic clinical course of fatal soybean asthma may be reflected by specific immunopathological findings. Seven cases of fatal soybean dust-induced asthma from Barcel ona, Spain were compared with 25 fatal asthma cases from New Zealand, Sections of lung tissue were stained by monoclonal antibodies using st andard streptavidin-biotin peroxidase technique, The following cell ty pes were identified: mast cells, ''activated'' eosinophils, neutrophil s, monocytes/macrophages, CD3+ T-cells and CD8+ T-cells, The positivel y staining cells were counted in the epithelium and the submucosa and their numbers expressed per mm and mm(2), respectively. The airways we re divided into larger (internal perimeter (Pi) > 2 mm) and smaller (P i < 2 mm), Firstly, all airways were studied together; and subsequentl y, larger and smaller airways were studied separately. Differences in the numbers of mast cells, eosinophils, neutrophils and monocytes/macr ophages between the two groups were not significant, The numbers of CD 3+ and CD8+ T-cells were significantly reduced in fatal soybean asthma when all airways were taken together, In larger airways, the differen ce was not significant in the epithelium, but was significant in the s ubmucosa for CD3+ cells, CD8+ cells were significantly reduced in Fata l soybean asthma both in the epithelium and the submucosa, The cell co unts in smaller airways were not significantly different either in the epithelium or in the submucosa for CD3+ cells, The numbers of CD8+ ce lls were not different in the epithelium, but were significantly reduc ed in the submucosa of fatal soybean asthma cases. We conclude that th e numbers of CD3+ and CD8+ T-cells are substantially reduced in fatal soybean asthma, These data together with the clinical features of the fatal attack suggest a different mechanism(s) from that described for most asthma deaths, probably involving anaphylaxis.