Th1 cytokine pattern in sarcoidosis is expressed by bronchoalveolar CD4+ and CD8+ T cells

Abstract

The pathogenesis of pulmonary sarcoidosis has been related to an increased production of Th1-like cytokines. However, cytokine expression in sarcoidosis has not been systematically studied at a single-cell level. We therefore investigated the expression of IL-2, IL-4, IL-13, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) intracellularly in bronchoalveolar lavage (BAL) and peripheral blood CD3+ T lymphocytes from patients with pulmonary sarcoidosis (radiologic stage II-III, n = 8) and normal controls (n = 9) by flow cytometry. In contrast to IL-4 and IL-13, the percentage of T lymphocytes expressing intracellular IL-2 (49.3 +/- 21.3% versus 14.5 +/- 15.6%), IFN-gamma (75.5 +/- 14.9% versus 32.6 +/- 18.7%) and TNF-alpha (68.3 +/- 18.7% versus 36.8 +/- 20.8%) was significantly higher in patients with sarcoidosis than in normal controls (each P < 0.005). In contrast to BAL lymphocytes, expression of these cytokines in peripheral blood lymphocytes did not differ between patients with sarcoidosis and normal controls. Close correlations were observed between the percentages of BAL lymphocytes expressing intracellular IL-2, IFN-gamma and TNF-alpha, but not for IL-4 or IL-13. Analysis of the expression of these cytokines in T lymphocyte subsets revealed IL-2, IFN-gamma, and TNF-alpha in CD4+ as well as CD8+ T lymphocytes, suggesting a contribution of TC1 cells to the production of proinflammatory cytokines in sarcoidosis. We conclude that a Th1-like cytokine pattern can be observed in CD4+ as well as in CD8+ BAL T lymphocytes in patients with pulmonary sarcoidosis.

Fig. 1

Comparison of intracellular cytokine expression in patients with sarcoidosis (S) and healthy volunteers (N). (a) Relative mean fluorescence (RFI) of IL-2 in bronchoalveolar lavage (BAL) and peripheral blood lymphocytes (CD3⁺). (b) Percentage of IL-2⁺ BAL and peripheral blood lymphocytes (CD3⁺). (c) RFI of IFN-γ in BAL and peripheral blood lymphocytes (CD3⁺). (d) Percentage of IFN-γ⁺ BAL and peripheral blood lymphocytes. (e) RFI of tumour necrosis factor-alpha (TNF-α) in BAL and peripheral blood lymphocytes (CD3⁺). (f) Percentage of TNF-α⁺ BAL and peripheral blood lymphocytes. **P < 0·005; *P < 0·05.

Fig. 2

Correlations between IL-2⁺, IFN-γ⁺, and tumour necrosis factor-alpha (TNF-α)⁺ bronchoalveolar lavage (BAL) lymphocytes (CD3⁺) in patients with sarcoidosis (•) and healthy volunteers (○). (a) Correlation between IFN-γ⁺ and IL-2⁺ cells. (b) Correlation between TNF-α⁺ and IL-2⁺ cells. (c) Correlation between TNF-α⁺ and IFN-γ⁺ cells.

Fig. 3

Percentage of IL-2⁺, IFN-γ⁺, tumour necrosis factor-alpha (TNF-α)⁺ bronchoalveolar lavage (BAL) T lymphocytes of patients with sarcoidosis separated according to CD4⁺ and CD8⁺ phenotype.

Fig. 4

Correlation between IL-2 relative mean fluorescence (RFI) of bronchoalveolar lavage (BAL) T lymphocytes and total BAL T lymphocyte count of patients with sarcoidosis (•) and healthy volunteers (○) (r = 0·82, P = 0·042).

Fig. 5

Correlation between the IL-2 relative mean fluorescence (RFI) of bronchoalveolar lavage (BAL) T lymphocytes and total lung capacity (TLC percentage of predicted) in patients with sarcoidosis (•) and healthy volunteers (○) (r = −0·67, P = 0·006).