Expression of blood dendritic cell antigens (BDCAs) by CD1a+ human pulmonary cells

Myeloid and plasmacytoid dendritic cell (DC) subsets have been recently identified in the human lung based on their differential expression of Blood DC Antigens 1-3 (BDCAs). We investigated the expression of these antigens by isolated human pulmonary CD1a(+) DCs, namely Langerhan's cells.

Using an in vitro cell culture system we successfully isolated a population of relatively pure (>70%) CD1a(+) cells from human lung tissue (n=5 subject samples) and stained these with antibodies against the myeloid DC markers BDCA1 (CD1c) and BDCA3 (CD303), the plasmacytoid DC marker BDCA2 (CD141), the Langerhan's cell marker Langerin and the maturation marker CD83.

Among different subject samples, the isolated CD1a(+) cells showed variable expression of Langerin, BDCAs and CD83. Interestingly, in two subject samples, which contained >70% CD83(+) mature CD1a(+) cells, >50% of the cells were positive for all of the BDCAs.

We conclude that isolated pulmonary CD1a(+) DCs in vitro have the capacity to express both myeloid and plasmacytoid BDCA markers and that rather than subset restriction in pulmonary DCs, a significant degree of flexibility/plasticity can be induced, albeit experimentally.