CD45-espressing T-cell subsets in intrathoracic lymph nodes, alveolar compartment and bloodstream of pulmonary sarcoidosis patient

Sarcoidosis involves different immune cells. Endobronchial ultrasound-transbronchial needle aspiration allows sampling of lung-draining lymph nodes (LLNs). Several triggers could induce the accumulation of CD45RA T-cells. Our study aims to evaluate CD45RA-expressing T-cells in LLN, bronchoalveolar lavage (BAL) and peripheral blood (PB) of pulmonary sarcoidosis patients. Sarcoidosis patients who underwent bronchoscopy with BAL, LLN and PB sampling were recruited. They were monitored at Siena University and Perugia Hospital. Multicolour flow cytometry (BD FASCLyric) was performed to assess CD45RA-expressing T-cell subsets identifying CD4+45RA−(Thcm),CD4+45RA+(Them),CD4+CD45RA−CCR6+CCR4+CXCR3−(Th17),CD4+CD45RA−CCR6-CCR4+CXCR3−(Th2),CD4+CD45RA−CCR6-CCR4−CXCR3+(Th1),CD8+45RA−(Tccm),CD8+45RA+(Tcem),CD8+CD45RA−CCR6+CCR4+CXCR3−(Tc17),CD8+45RA−CCR6−CCR4+CXCR3−(Tc2),CD8+45RA−CCR6−CCR4−CXCR3+(Tc1). Thirty-two patients (median age(IQR) 57(52–58)y/o; 59%females; 66%never-smokers) were consecutively enrolled. All patients were in Scadding radiological stage II.PB was enriched in ThemRA(p=0.04), Th2(p=0.02), Th17(p=0.02), CD8(p=0.03) and TcemRA(p<0.01) than BAL. Conversely, Th1(p=0.03) and CD4(p=0.04) were more abundant in LLN than in BAL and PB. Re-expression of CD45RA on T-cells could mean higher activity in the organs targeted by the disease. Thus, inflammation is localised at the site of damage, which recruits cells from the PB where they decrease in favour of the target organ. There has been speculation that changes in the relative content of PB cells may be due to changes in cell production and to selective redistribution to granulomatous foci.