IS THE DIFFERENT T-HELPER CELL-ACTIVITY IN SARCOIDOSIS AND EXTRINSIC ALLERGIC ALVEOLITIS ALSO REFLECTED BY THE CELLULAR BRONCHOALVEOLAR LAVAGE FLUID PROFILE

Background - Sarcoidosis is generally characterized by a CD4(+) lympho cyte predominance in bronchoalveolar lavage fluid (BALF), whereas in e xtrinsic allergic alveolitis (EAA) a CD8(+) lymphocyte predominance is found. However, we have previously demonstrated an increase in CD4(+) lymphocytes in BALF obtained from EAA patients as well. The aim of th is study was to evaluate whether in sarcoidosis and EAA the BALF cellu lar profile - even without the help of cytokine detection - might refl ect differences in the CD4(+) T-lymphocyte subpopulations, i.e. T help er (TH)-1 and TH2 lymphocytes. Methods - For this purpose, we analyzed BALF analysis results obtained from 77 nonsmoking patients with histo logically proven sarcoidosis and 54 nonsmoking patients suffering from EAA. Results Patients with EAA showed the highest mean absolute numbe rs of lymphocytes, CD8(+) as well as CD4(+) T lymphocytes, whereas the percentage of CD4(+) T lymphocytes in BALF was low. In contrast, pati ents with sarcoidosis showed the lowest absolute and relative number o f CD8(+) T lymphocytes, the highest percentage of CD4(+) T lymphocytes and CD4(+)/CD8(+) ratio. Moreover, patients with Lofgren's syndrome d emonstrated an alveolitis suggesting a TH1 lymphocyte-subset-like pred ominant related profile, characterized by lower numbers of eosinophils and mast cells, whereas sarcoidosis patients with respiratory symptom s formed a more mixed TH1/TH2 pattern. Patients with EAA showed a cell ular BALE profile suggesting a functional predominance of TH2 lymphocy tes. Conclusion - These preliminary data suggest a different distribut ion of the CD4(+) T lymphocyte subtypes characterized by a functional heterogeneity of CD4(+) T lymphocytes between - as well as within - th ese various pulmonary disorders. The exact role of this imbalance of T H1 and TH2-like activity in the lung with regard to the pathogenesis a nd prognosis needs to be further elucidated.