The Relationship of Prognostic Factors with Regulatory T Cells in Langerhans Cell Histiocytosis

Abstract

Aim: Langerhans cell histiocytosis (LCH), is a clonal disorder characterized by abnormal proliferation of dendritic cells, which has an intense inflammatory microenvironment. There is limited information about contribution of microenvironment to this rare disease. We aimed to compare regulatory T cells in microenvironment and BRAFV600E mutation with prognostic data. Material and Methods: Overall, 26 cases were included to the study. The number FOXP3+ regulatory T cell (Treg) and presence of BRAFV600E mutation were assessed according to age, gender, localization, unifocal or multifocal, involvement of organ at risk, and recurrence status in a histochemical manner. Results: The number of adult cases was higher than pediatric cases. Bone was the most common localization, and 81% of cases were unifocal. Risk organ involvement was observed in 3 cases, 2 of which showed recurrence. It was found that the number of FOXP3+ Tregs was higher in adults, those with unifocal localization, and those with bone involvement. In addition, the number of FOXP3+ Tregs was higher in the group with recurrence than those without recurrence. BRAFV600E mutation was higher in children when compared to adults (p=0.003), but, no significant correlation was found when compared with remaining prognostic parameters (p>0.05). Conclusion: Although BRAFV600E mutation is more common in pediatric patients, it can also be seen in adult patients. The number of FOXP3+ Tregs is proportional to CD3+ and CD4+ cells. T cells, which present at varying rates in microenvironment, play an essential role in the pathogenesis of LCH.