CD207+CD1a+ cells circulate in pediatric patients with active Langerhans cell histiocytosis

CD207+CD1a+ cells circulate in pediatric patients with active Langerhans cell histiocytosis
Langerhans cell histiocytosis (LCH) is seen as a myeloid neoplasm with an important inflammatory component. Pathological CD207+CD1a+cells are found in the lesions among other cell types. This study investigated whether these cells could also be found circulating in the blood in active (AD) and non-active (NAD) disease patients. Further cytokines were measured that had been previously associated with LCH.
Twenty-two patients with LCH were recruited form a single center about half having active disease (AD) and the other half non-active disease (NAD). Plasma, peripheral blood mononuclear cells, and further biochemical values were collected. Flow cytometry was used to differentiate circulating cells. Cytokines were measured in the plasma. AD patients were compared with NAD and healthy adults. Plasma of AD LCH patients was incubated with healthy donor monocytes.
CD207+CD1a+cells were found in the peripheral blood of only AD LCH patients but not NAD LCH patients, healthy adults, umbilical cord blood, or patients affected with disseminated juvenile xanthogranuloma (a non-LCH inflammatory disease). CD11b+ cells were also increased. Previously identified cytokines associated with LCH thymic stromal lymphopoietin (TSLP) and transforming growth factor b (TGF-b) plasma levels were increased in patients with AD LCH compared to NAD LCH. When incubating plasma from AD LCH patients with monocytes of healthy adults, appearance of CD11b+ and CD207+ cells was noted. The authors concluded that CD207+CD1a+cells could be used as markers of AD in LCH.
The sample size used to draw conclusions was small. While the theory is compelling and the findings very promising, they have to be put into the clinical context of LCH patients and measured over time when AD patients become NAD and vice versa.
CD207+CD1a+cells were associated with active disease in LCH patients which is the first time that circulating LCH cells are identified in the peripheral blood and could serve as a disease marker.