CIRCULATING CD207+ CD1A+ MYELOID CELLS DELINEATE A NEW CELLULAR SCORE IN LANGERHANS CELL HISTIOCYTOSIS

OLEXEN CINTHIA M; ROSSO, DIEGO A.; NOWAK, WANDA; FORTUNATI DANIELA; DALLA VECHIA GUIDO LUIS; ERRASTI ANDREA E*; CARRERA SILVA EUGENIO A*

Mar del Plata

Congreso; Reunión Conjunta SAIC-SAI-SAFIS 2022; 2022

Langerhans cell histiocytosis (LCH) is a neoplasm inflammatory dis- order characterized by accumulation of CD207+ and CD1a+ cells in almost any tissue with putative myeloid precursors circulating in the blood. Currently, there is a lack of prognostic markers to follow-up patients, monitor disease reactivation or treatment response. Our aim was to set a standardized method to screen circulating CD207+ and CD1a+ cells in a drop of blood of patients with LCH and monitor them during follow up. Employing flow cytometry, 202 independent blood sampling including follow up from patients with LCH and 23 controls were examined. A standardized cellular score was defined by measuring CD207+ and CD1a+ expression in monocytes and dendritic cells, based on CD11b, CD14, CD11c, and CD1c subsets, giving a unique value for each sample. To test the trajectory of the cellular score associate with biochemical parameters and clinical outcome we examine some patients with at least 6 independent sampling including bone, multisystem and skin compromise. A ROC curve was used to validate the scoring system (AUC: 0.849) with a threshold value obtained with Youden ́s test (Y index: 14), defining the presence of circulating CD207+CD1a+ cells. A positive correla- tion between the cellular score and sCD40L, sIL-2Ra, and CXCL12 molecules in plasma was also found. During the follow-up, circu- lating CD207+CD1a+ cells were evidenced just before the clinical manifestation in bone compromise. The patient with multisystem involvement showed circulating cells just before bone reactivation and during the clinical manifestation. The patient with skin involve- ment, have also circulating cells before and/or during at least one of the clinical reactivations. We have set a cellular score based on the presence of circulating CD207 and CD1a cells that could help with prognostic accuracy, early reactivation, and follow-up with minimal invasiveness.