Role of fibrocytes and endothelial progenitor cells among low-differentiated CD34+ cells in the progression of lung sarcoidosis

BACKGROUND: Sarcoidosis is a multisystemic granulomatous disease with still unknown etiology. Our previous studies showed a significantly higher percentage of CD34 + cells in the peripheral blood in patients with sarcoidosis (SA) compared to the control group. The objective of the present study was to characterized of the CD34 + cell population in peripheral blood in patients with SA with reference to the control group. Moreover in patients with SA, fibrocytes and endothelial cells were analysed and their relationship to the fibrosis process based on assessment of diffusing capacity for carbon monoxide (DLCO). METHODS: Data from patients diagnosed with SA at Military Institute of Medicine (Warsaw, Poland) between January 2018 and December 2019 were collected and analysed ongoing basis. Peripheral blood was collected from 26 patients with newly diagnosed pulmonary SA and 16 healthy subjects. The immunomagnetic method and flow cytometry were used. Among the CD34+ progenitor cells were assessed: low-differentiated cells, hematopoietic progenitor cells and endothelial progenitor cells. The Statistica 12.0 software was used for a statistical analysis. RESULTS: We observed a significantly higher percentage of low-differentiated cells (13.8 vs. 2.3, P = 0.001) and endothelial cells (0.3 vs. 0.0, P = 0.001) in patients with SA compared to the control group. In the study group the median proportion of fibrocytes was 1.877% (0.983–2.340) in patients with DLCO< 80%, while in patients with DLCO> 80% was 0.795% (0.139–1.951) (P = 0.72). The median proportion of endothelial progenitor cells was higher in patients with DLCO< 80%: 0.889% (0.391–1.741), than in patients with DLCO> 80%: 0.451% (0.177–0.857) (P = 0.44). CONCLUSIONS: In conclusion we demonstrated for the first time the immunophenotype of peripheral CD34 + cells with the degree of their differentiation. The study confirmed the involvement of low differentiated cells and endothelial cells in patients with SA.