Expression of mouse CLEC-2 has been reported on circulating CD11b(high) Gr1(high) myeloid cells and dendritic cells (DCs) under basal conditions, as well as on a variety of leucocyte subsets following inflammatory stimuli or in vitro cell culture. However, previous studies assessing CLEC-2 expression failed to use CLEC-2-deficient mice as negative controls and instead relying heavily on single antibody clones. Here, we generated CLEC-2-deficient adult mice using two independent approaches and employed two anti-mouse CLEC-2 antibody clones to investigate surface expression on haematopoietic cells from peripheral blood and secondary lymphoid organs (SLOs). We rule out constitutive CLEC-2 expression on resting DCs and show that CLEC-2 is up-regulated in response to LPS-induced systemic inflammation in a small subset of activated DCs isolated from the mesenteric lymph nodes but not the spleen. Moreover, we demonstrate for the first time that peripheral blood B lymphocytes present exogenously derived CLEC-2 and suggest that both circulating B lymphocytes and CD11b(high) Gr1(high) myeloid cells lose CLEC-2 following entry into SLOs. These results have significant implications for our understanding of CLEC-2 physiological functions This article is protected by copyright. All rights reserved.