Differential expression of CCR6 by the lesional cells in pulmonary Langerhans cell histiocytosis

Solitary pulmonary Langerhans cell histiocytosis occurs predominantly in young adults, who are frequently heavy smokers. Besides the strong association to smoking, it differs from childhood Langerhans cell histiocytosis as well in that it is a polyclonal disorder, and the lesional Langerhans cells in this form of disease are reported to display mature markers. Thus, in this study we set out to analyse the chemokine receptor expression pattern of CCR6 and CCR7, chemokine receptors associated with immature or mature dendritic cells, respectively. This study is a follow up of a previous report that has shown that in childhood Langerhans cell histiocytosis CD1a LCH cells always express CCR6 and lack CCR7. The current study showed that there is a differential expression of CCR6 in pulmonary Langerhans cell histiocytosis lesions, ranging from lesions with all CD1a LCH cells expressing CCR6, to lesions where there is a partial population of CD1a LCH cells that express CCR6, to lesions where all CD1a LCH cells lack CCR6 expression. In addition, CCR7 was always absent on the CD1a cells even on those LCH cells that lacked CCR6. Thus, in contrast to childhood LCH lesions where LCH cells always express CCR6, pulmonary LCH lesions display a differential pattern of expression of chemokine receptor CCR6.