Sarcoidosis Th17 cells are ESAT-6 antigen specific but demonstrate reduced IFN-γ expression.
BACKGROUND
Sarcoidosis is a granulomatous disease of unknown etiology. Many patients with sarcoidosis demonstrate antigen-specific immunity to mycobacterial virulence factors. Th-17 cells are crucial to the immune response in granulomatous inflammation, and have recently been shown to be present in greater numbers in the peripheral blood and bronchoalveolar lavage (BAL) fluid (BALF) of sarcoidosis patients than healthy controls. It is unclear whether Th-17 cells in sarcoidosis are specific for mycobacterial antigens, or whether they have similar functionality to control Th-17 cells.


METHODS
Flow cytometry was used to determine the numbers of Th-17 cells present in the peripheral blood and BALF of patients with sarcoidosis, the percentage of Th-17 cells that were specific to the mycobacterial virulence factor ESAT-6, and as well as to assess IFN-γ expression in Th-17 cells following polyclonal stimulation.


RESULTS
Patients with sarcoidosis had greater numbers of Th-17 cells in the peripheral blood and BALF than controls and produced significantly more extracellular IL-17A (p = 0.03 and p = 0.02, respectively). ESAT-6 specific Th-17 cells were present in both peripheral blood and BALF of sarcoidosis patients (p < 0.001 and p = 0.03, respectively). After polyclonal stimulation, Th-17 cells from sarcoidosis patients produced less IFN-γ than healthy controls.


CONCLUSIONS
Patients with sarcoidosis have mycobacterial antigen-specific Th-17 cells peripherally and in sites of active sarcoidosis involvement. Despite the Th1 immunophenotype of sarcoidosis immunology, the Th-17 cells have reduced IFN-γ expression, compared to healthy controls. This reduction in immunity may contribute to sarcoidosis pathogenesis.
Division of Allergy, Pulmonary and Critical Care Medicine, Vanderbilt University Medical School, Nashville, TN 37232-2363, USA. Bradley.Richmond@vanderbilt.edu
Bradley W
BW
Richmond
Kristen
K
Ploetze
Joan
J
Isom
Isfahan
I
Chambers-Harris
Nicole A
NA
Braun
Thyneice
T
Taylor
Susamma
S
Abraham
Yolanda
Y
Mageto
Dan A
DA
Culver
Kyra A
KA
Oswald-Richter
Wonder P
WP
Drake
D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis*; D020381:Interleukin-17 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D012507:Sarcoidosis / Q000276:immunology* / Q000378:metabolism*; D018417:Th1 Cells / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology* / Q000378:metabolism
D000942:Antigens, Bacterial; C525005:ESAT-6 antigen, Mycobacterium leprae; D020381:Interleukin-17; D016692:Receptors, Antigen, T-Cell, gamma-delta; D007371:Interferon-gamma