LUNG IMMUNOPATHOLOGY IN CASES OF SUDDEN ASTHMA DEATH

The histopathology of airway inflammation in rare cases of sudden asph yxic asthma death (SAAD) is unclear. This study examines, for the firs t time, the relative disposition of lymphocyte and macrophage subsets and eosinophils in proximal and distal tissues of such cases. Multiple resection specimens from five cases of SAAD were studied. Tissue bloc ks were obtained at necroscopy and immediately frozen in liquid nitrog en within 18 hours of death (death occurring within 1 h of the onset o f an unprovoked asphyxic asthma attack). After immunohistological stai ning, frozen sections underwent semiquantitative analysis (cell counts per unit area) for T-cells, macrophages and eosinophils using compute rized imaging systems. Subsets of T-cells and macrophages were estimat ed using double immunofluorescence techniques. Variability within samp les, between samples and between cases was compared. These cases of fa tal asthma showed infiltrates of T-cells, macrophages and eosinophils within peribronchial tissues. Distinct from stable asthma, a CD8+ T-ce ll dominance was found, A high proportion of eosinophils were activate d (EG2+), whereas the relative proportion of antigen-presenting cells (RFD1+) did not seem to be abnormal, although numbers of these cells w ere high. These features were seen both in proximal and distal tissues . The variability of these parameters within an individual was 9.4-15. 2%, however, the variability between individual cases was greater. Sud den asphyxic asthma is associated with inflammatory infiltrates both o f proximal and distal lung tissues. In contrast to stable asthma, this infiltrate contains large numbers of CD8+ T-cells, suggesting distinc t qualitative as well as quantitative characteristics in the immunopat hology of sudden asthma death.