Systemic and local immune phenotype and function of patients with pulmonary sarcoidosis and tuberculosis

Aims: The etiolgy of sarcoidosis unknown, however the histopathological and cytopathological findings and the radiological appearance can mimic tuberculosis (TB). We ascertained whether differences exist in the immunophenotype and antimycobacterial immuneresponses of peripheral blood mononuclear cells (PBMC) and broncho-alveolar mononuclear cells (BALMC) of patients with sarcoidosis and minimal pulmonary tuberculosis.

Methods: Patients were prospectively recruited at the Medical Clinic of the Research Center Borstel and the Hospital Großhansdorf in Germany. Immunophenotyping with monoclonal antibodies against CD3, CD4, CD4/45RA, CD4/45/RO, CD8, CD16, CD19, CD25, CD 38, CD57, HLADR were performed on PBMC and BALMC. In addition, MTB specific enzyme linked immunospot (T-Spot. TB) was performed on PBMC and BALMC. Data from an interim analysis are presented.

Results: 10 patients with sarcoidosis, 7 patients with smear negative pulmonary tuberculosis and 8 patients with other pulmonary diseases were included in the interim analysis. Expression of HLADR on BAL lymphocytes was significantly higher in patients with sarcoidosis than in patients with tuberculosis (p=0.029) and controls (p=0.001) but otherwise expression of immunophenotypical markers was non- characteristical for sarcoidosis. MTB-specific ELISPOT on PBMCs and BALMCs was reactive in 0/0 and 2/10 patients with sarcoidosis in 6/7 and 4/7 patients in TB, and 1/8 and 0/8 controls.

Conclusion: These data are not supportive of an mycobacterial etiology of sarcoidosis