The dendritic cell-specific CC-chemokine DC-CK1 is expressed by germinal center dendritic cells and attracts CD38-negative mantle zone B lymphocytes

DC-CK1 (CCL18) is a dendritic cell (DC)-specific chemokine expressed in bot h T and B cell areas of secondary lymphoid organs that preferentially attra cts CD45RA(+) T cells. In this study, we further explored the nature of DC- CK1 expressing cells in germinal centers (GCs) of secondary lymphoid organs using a newly developed anti-DC-CK1 mAb. Immunohistochemical analysis demo nstrated a remarkable difference in the number of DC-CK1 expressing cells i n adjacent GCs within one tonsil, implicating that the expression of DC-CK1 in GCs depends on the activation and/or progression stage of the GC reacti on, Using immunohistology and RNA analysis,,ve demonstrated that GCDC are t he source of DC-CK1 production in the GCs, Considering the recently describ ed function of GCDC in (naive) B cell proliferation, isotype switching and Ab production, we investigated the ability of DC-CK1 to attract B lymphocyt es. Here we demonstrate that DC-CK1 is a pertussis toxin-dependent chemoatt ractant for B lymphocytes with a preference in attracting mantle zone (CD38 (-)) B cells. The findings that GCDC produce DC-CK1 and attract mantle zone B cells support a key role for GCDC in the development of GCs and memory B cell formation.