T-Iymphocytes with T-cell antigen receptor (TCR) comprising ay chain and a 5 chain (y5+ T cells) are believed to be involved in the immune reaction to mycobacterial antigens, and they have been found in increased proportions in sarcoid patients. We evaluated the proportions of y5+ T-Iymphocytes and of two major y5+ subpopulations, the V51+ and the V52+ T-cell subsets, in 10 normal blood donors, in 15 patients with tuberculosis (TB), seven of whom had pleural effusion (PE), and in 12 patients with pulmonary sarcoidosis (PS), nine of whom underwent bronchoalveolar lavage (BAl). T-cell subsets were evaluated in peripheral blood (PBl) of all subjects and in PE from patients with TB and in BAl from patients with PS. Compared with normal blood donors, patients with TB had increased proportions of PBl CD3+ y5+ T cells (6±10/0 versus 14±30/0 of CD3+ T cells, p< 0.05) because of the presence of four patients who had an increase (respectively, 18.3, 22.0, 24.2, and 35.40/0 of CD3+ T cells) of y5+ T cells. In patients with TB and PE, y5+ T cells were 7.9±2.70/0, a value not different from that in the tubercular PBl and in normal PBl. Although patients with PS had proportions of PBl y5+ T cells (9.2±3.40/0) similar to those in normal PBl, two patients had increased (35 and 310/0) PBl y5+ T-Iymphocytes. The proportions of y5+ T cells in sarcoid lung recovered by BAl were similar to those in PBl from patients with PS (3.0±0.8% of CD3+ T cells, p> 0.05). Among y5+ T-cell subsets, V52+ T-Iymphocytes were 73±90/0 of total y5+ T cells in PBl of normal subjects, similar to PBl and PE of patients with TB and to PBl and BAl of patients with PS. However, in the patients with TB or PS with an expansion of PBl y5+ T cells, V52+ T cells were> 90% of y5+ T cells, and they were increased also as absolute numbers of cells/ul of PBl, whereas the proportions of V51+ T cells were similar to normal values. The expansion of y5+ T cells with identical variable regions in some patients with PS and TB may be due to similar immunopathogenetic processes and/or it may represent a type of immune reaction of a subgroup of patients. Balbi B, Valle MT, Oddera S, Giunti D, Manca F, Rossi GA, Allegra L. T-Iymphocytes with y5+ V52+ antigen receptors are present in increased proportions in a fraction of patients with tuberculosis or with sarcoidosis. Am Rev Respir Dis 1993; 148: 1685-90.

Tuberculosisand sarcoidosis are granulomatous disorders characterized by the accumulation of T-Iymphocytes in the affected organs. In tuberculosis, T-Iymphocytes recognizing mycobacterial antigens are activated and proliferate. As a result, at least part of the T-Iymphocytes recruited in the affected tissues are specific for mycobacterial antigens (1-3). Similarly, in pulmonary sarcoidosis T-Iymphocytes are activated, possibly reacting toward a yet unknown antigen (s), and compartmentalize different T-cell subsets in the lung (4-7). T-Iymphocytes interact with antigens