CD31 + , CD38 + , CD44 + , and CD103 + lymphocytes in peripheral blood, bronchoalveolar lavage fluid and lung biopsy tissue in sarcoid patients and controls.

Background: The mechanisms driving the transition from inflammation to fibrosis in sarcoidosis patients are poorly understood; prognostic features are lacking. Immune cell profiling may provide insights into pathogenesis and prognostic factors of the disease. This study aimed to establish associations in simultaneous of lymphocyte subset profiles in the blood, bronchoalveolar lavage fluid (BALF), and lung biopsy tissue in the patients with newly diagnosed sarcoidosis.

Methods: A total of 71 sarcoid patients (SPs) and 20 healthy controls (HCs) were enrolled into the study. CD31, CD38, CD44, CD103 positive T lymphocytes in blood and BALF were analysed. Additionally, the densities of CD4, CD8, CD38, CD44, CD103 positive cells in lung tissue biopsies were estimated by digital image analysis.

Results: Main findings: (I) increase of percentage of CD3+ CD4+ CD38+ in BALF and blood, and increase of percentage of CD3+ CD4+ CD44+ in BALF in Löfgren syndrome patients comparing with patients without Löfgren syndrome, (II) increase of percentage of CD3+ CD4+ 103+ in BALF and in blood in patients without Löfgren syndrome (comparing with Löfgren syndrome patients) and increase of percentage of CD3+ CD4+ 103+ in BALF and in blood in more advanced sarcoidosis stage. (III) Increasing percentage of BALF CD3+ CD4+ CD31+ in sarcoidosis patients when comparing with controls independently of presence of Löfgren syndrome, smoking status or stage of sarcoidosis. Several significant correlations were found.

Conclusions: Lymphocyte subpopulations in blood, BALF, and lung tissue were substantially different in SPs at the time of diagnosis compared to HCs. CD3+ CD4+ CD31+ in BALF might be a potential supporting marker for the diagnosis of sarcoidosis. CD3+ CD4+ CD38+ in BALF and blood and CD3+ CD4+ CD44+ in BALF may be markers of the acute immune response in sarcoidosis patients. CD4+ CD103+ T-cells in BALF and in blood are markers of the persistent immune response in sarcoidosis patients and are potential prognostic features of the chronic course of this disease.