Novel evidence that the mannan-binding lectin pathway of complement activation plays a pivotal role in triggering mobilization of hematopoietic stem/progenitor cells by activation of both the complement and coagulation cascades

Hematopoietic stem progenitor cells (HSPCs) circulate at low levels in peripheral blood (PB) and follow changes in circadian rhythm. 1 Evidence has accumulated that their egress from stem cell niches is significantly augmented in a complement cascade (ComC)-dependent manner. 2 The number of HSPCs circulating in PB increases during infection, tissue or organ injuries and particularly after administration of pharmacological drugs, such as granulocyte-colony stimulating factor (G-CSF) or the CXCR4 receptor antagonist AMD3100, and pharmacological mobilization is a means to obtaining HSPCs for hematopoietic transplants. 3 However, the mobilization process is still not well understood.