LYMPHOCYTES-T AND ACTIVATED EOSINOPHILS IN AIRWAY MUCOSA IN FATAL ASTHMA AND CYSTIC-FIBROSIS

With the use of monoclonal antibodies (mAb) and immunohistology, the numbers of phenotypically distinct cells infiltrating lung tissue from 15 postmortem (PM) cases of fatal asthma were quantified and compared with 6 cases of cystic fibrosis (CF) (three postmortem, three transplant) and 10 nonasthmatic cases of sudden death matched for age and sex. Tissue eosinophilia was significantly greater (p<0.001) in the fatal asthma group than in the CF or sudden death controls. In asthma, approximately 40% of the eosinophilic infiltrate was EG2 positive (an indication of eosinophil activation and secretion of eosinophil cationic protein). The numbers of eosinophils and EG2 positive cells were significantly elevated in the subjects with acute severe asthma who had had a duration of terminal illness exceeding, as compared with less than, 24 h (p<0.05). When compared with the sudden death controls, there were increases in the numbers of Dako L C positive cells (i.e., CD45 positive "total leukocytes") in both fatal asthma and CF (p<0.01 and 0.05, respectively). The mean number of MT-1 positive (T) cells in the asthma and CF groups was approximately twice that of the control (p<0.05 and 0.01, respectively). The mean number of MB2 positive (B) cells was similar for both the asthma and sudden death control groups but was significantly increased In CF (p<0.05). The average T:B cell ratios were 6:1, 1:1, and 2:1 in the fatal asthma, CF, and control groups, respectively. The results support a role for the T lymphocyte in the pathogenesis of fatal asthma and CF. However, the high numbers of B cells and the low numbers of eosinophils in CF distinguish CF from asthma. Asthma in contrast is characterized by a high T.B cell ratio and the presence in airway tissue of relatively large numbers of "activated" eosinophils.