Screening of the HLDA9 panel on peripheral blood dendritic cell populations.

Dendritic cells (DC) are a heterogeneous population of bone marrow derived leucocytes that are essential in the initiation of primary T lymphocyte responses. DC are identified as Lineage negative, HLA-DR(+) blood cells that can be further subdivided by CD11c to distinguish CD11c(+) DC and the CD11c(-) plasmacytoid DC. Plasmacytoid DC are the primary IFNα producing cells and express CD303, CD304 and CD123. The CD11c(+) myeloid DC can be divided into populations by CD1c, CD16 and CD141 expression. Despite DC being a functionally unique population, they share many cell surface antigens with myeloid lineage cells and B lymphocytes. We used flow cytometry to screen fresh human blood DC populations with the HLDA9 panel of 63 directly labelled mAb which included mAb specific for a number of B lymphocyte antigens. Of this panel, 23 mAb did not bind Lin(-)HLA-DR(+) DC and 10 bound all four populations. Eight mAb bound to the three CD11c(+) DC populations whilst no mAb tested bound to only pDC. Some of the mAb expected to bind to DC populations failed in this analysis. Overall, this screening highlighted similarities between the CD11c(+) DC subsets and the relatively immature state of peripheral blood DC.