Higher levels of interleukin IL-17 and antigen-specific IL-17 responses in pulmonary sarcoidosis patients with Löfgren's syndrome.

Sarcoidosis is a granulomatous disorder of unknown aetiology. The presence of Mycobacterium tuberculosis catalase-peroxidase (mKatG) in sarcoidosis tissue has been reported. T helper type 1 (Th1) responses against mKatG have previously been observed. However, little is known about interleukin (IL)-17 and Th17 responses in sarcoidosis. Here, we investigated the levels of IL-17 and frequencies of IL-17-producing cells responding to mKatG in sarcoidosis patients with different prognosis. Peripheral blood and bronchoalveolar lavage (BAL) cells were obtained from sarcoidosis patients with or without Löfgren's syndrome (often associated with spontaneous recovery), and also stratified according to human leucocyte antigen (HLA) type. Cells producing IL-17 and interferon (IFN)-γ after stimulation with mKatG were enumerated by enzyme-linked immunospot (ELISPOT). The level of IL-17 in the BAL fluid of sarcoidosis patients and healthy controls was measured by quantitative immuno-polymerase chain reaction (qIPCR). We also performed flow cytometry and immunohistochemistry for further characterization of IL-17 expression. Patients with Löfgren's syndrome had a higher frequency of IL-17-producing cells responding to mKatG in BAL fluid compared to patients without Löfgren's syndrome (P < 0·05). The HLA-DR3(+) sarcoidosis patients with Löfgren's syndrome (known to have a particularly good prognosis) also had a clearly higher level of IL-17 in BAL fluid compared to healthy controls and sarcoidosis patients without Löfgren's syndrome (P < 0·01) and (P < 0·05), respectively. No such difference between patient groups was observed with regard to IFN-γ and not with regard to either cytokine in peripheral blood. These findings suggest that IL-17-producing cells may be a useful biomarker for the prognosis of sarcoidosis and play a role in the spontaneous recovery typical of patients with Löfgren's syndrome.

Indoleamine 2,3-dioxygenase is expressed in the endometrium of cycling mice throughout the oestrous cycle.

Indoleamine 2,3-dioxygenase (IDO), an enzyme responsible for tryptophan catabolism, is thought to be required to prevent the rejection of the allogenic fetus by maternal T cells and to protect against intra- and extra-cellular pathogens. Consequently, we studied the expression of IDO in the endometrium of female Balb/c mice during the oestrous cycle. At each phase, the endometrium was peeled away and the relative expression of IDO mRNA was detected by semi-quantitative RT-PCR. The presence of IDO protein was confirmed in each phase by Western blotting and immunohistochemistry. Our results showed that IDO is expressed in the endometrium of cycling mice during all the phases of oestrous cycle. The expression of IDO was highest at the oestrus and lowest at the dioestrus. By means of Western blotting and immunohistochemistry, we obtained evidence that IDO protein is synthesised in the endometrium of cycling mice throughout the oestrous cycle. In accordance with RT-PCR results, IDO protein was predominant at the oestrus phase. IDO protein was mainly localised in the glandular and luminal epithelial cells. Our results support the concept of IDO providing a mechanism of innate immunity to protect from ascending infections of the female reproductive tract. In addition, considering the fact that mating only occurs during the oestrus phase, the high expression of IDO in this phase is likely to be a mechanism that induces immunological tolerance of the fetus.