GAMMA DELTA T-LYMPHOCYTES IN THE BLOOD OF PATIENTS WITH SARCOIDOSIS/

Background - Gamma/delta T Iymphocytes are thought to have a role in g ranulomatous immune responses at peripheral sites of antigen contact s uch as the gut, skin and lung. The aim of this study was to determine if gamma/delta T lymphocytes are increased in the peripheral blood of patients with active sarcoidosis. Methods - Peripheral blood from 21 u ntreated patients with a new presentation of sarcoidosis (12M, 9F), 20 normal volunteers (12M, 8F), and 12 patients with cavitary pulmonary tuberculosis were subjected to Ficoll Hypaque separation and flow cyto metry analysis using monoclonal antibodies to CD3, 4, 8, 25, HLA-DR an d gamma/delta T cell receptor. Results - All patients with sarcoidosis had compatible chest radiographs and all were Mantoux negative in spi te ofprevious BCG vaccination. In all but one patient histological exa mination showed non-caseating granuloma. There was no difference in th e mean percentage or absolute numbers of gamma/delta positive peripher al blood lymphocytes between the three populations. Thirteen patients with sarcoidosis had an absolute Iymphopenia and the mean percentage o f CD3 positive peripheral blood lymphocytes in the group with sarcoido sis was lower than the other two groups. The percentage of CD25 and HL A-DR positive cells was higher in the group with sarcoidosis, supporti ng the fact that these patients had active disease. Conclusions - Gamm a/delta T Iymphocytes are not increased in the peripheral blood of pat ients with sarcoidosis and are unlikely to have a role in the pathogen esis of this disease.