EXPRESSION OF THE CD23 MOLECULE ON ALVEOL AR MACROPHAGES AND IN SERUMIN EXTRINSIC ALLERGIC ALVEOLITIS

Patients wit extrinsic allergic alveolitis (EAA) exhibit increased exp ression of CD23 on alveolar macrophages in BAL. In serum elevated leve ls of soluble CD23 can be detected compared to patients with allergic asthma and healthy controls. We hypothesize that CD23 is cleaved from the cell surface of alveolar macrophages by a proteolytic process and released into peripheral blood. Cytokines like IFN gamma which are pro duced under conditions of lymphocytic alveolitis in EAA might be invol ved in this mechanism. Since total IgE and anti-IgE-antibodies are not significantly elevated in EAA the CD23 molecule might play a role as a mediator for T-cell- and monocyte activation under circumstances of this disease.