Expression and function of histamine H4 receptor in mouse splenic dendritic cells

Abstract

Dendritic cells (DC) are the master regulators of the immune system. DCs act as ‘‘sentinels’’ and they are the most potent antigen-presenting cells specialized for capture, transport, processing and presentation of antigens [1]. During these activities numerous factors may influence their functions. Histamine is one of these mediators released from neighboring mast cells, basophils, and even from the DCs themselves [2]. Histamine exerts its physiological functions through four different G protein-linked receptors: H1R, H2R, H3R, and the recently discovered H4R [3]. In contrast to other histamine receptors, H4R expression shows tissue specificity, it is mainly found in immune cells, e.g. mast cells, eosinophils, T cells, and DCs. Very recently, it has also been detected in the mouse central nervous system [4]. H4R expression has been investigated mainly on the mRNA level, and it has been also described in murine bone marrow-derived DCs. The involvement of H4R in the regulation of DC chemotaxis and cytokine production has been newly published [5]. We have studied the expression of H4R protein in mouse splenic DCs and its possible role in a major DC function, namely antigen presentation.