Open AccessA Novel Role of Complement in Mobilization: Immunodeficient Mice Are Poor Granulocyte‐Colony Stimulating Factor Mobilizers Because They Lack Complement‐Activating Immunoglobulins
Author(s) -
Reca Ryan,
Cramer Daniel,
Yan Jun,
Laughlin Mary J.,
JanowskaWieczorek Anna,
Ratajczak Janina,
Ratajczak Mariusz Z.
Publication year - 2007
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1634/stemcells.2007-0525
Subject(s) - mobilization , biology , alternative complement pathway , complement system , haematopoiesis , zymosan , immunology , progenitor cell , complement component 5 , granulocyte , bone marrow , antibody , stem cell , microbiology and biotechnology , biochemistry , archaeology , in vitro , history
Complement (C) and innate immunity emerge as important and underappreciated modulators of mobilization of hematopoietic stem/progenitor cells (HSPC). We reported that (a) C becomes activated in bone marrow (BM) during granulocyte–colony‐stimulating factor (G‐CSF)‐induced mobilization by the classic immunoglobulin (Ig)‐dependent pathway and that (b) C3 cleavage fragments increase the responsiveness of HSPC to a stromal derived factor‐1 gradient. Since patients suffering from severe combined immunodeficiency (SCID) mobilize poorly, we hypothesized that this could be directly linked to the lack of C activating Ig in these patients. In the current study to better elucidate the role of C activation in HSPC mobilization, we mobilized mice that lack Ig (RAG2, SCID, and Jh) by G‐CSF or zymosan, compounds that activate C by the classic Ig‐dependent and the alternative Ig‐independent pathways, respectively. In addition, we evaluated mobilization in C5‐deficient animals. Mobilization was evaluated by measuring the number of colony‐forming unit‐granulocyte macrophage and leukocytes circulating in peripheral blood. We found that (a) G‐CSF‐ but not zymosan‐induced mobilization was severely reduced in RAG2, SCID, and Jh mice; (b) impaired G‐CSF‐induced mobilization was restored after infusion of purified wild‐type Ig; and (c) mobilization was severely reduced in C5‐deficient mice. These data provide strong evidence that the C system plays a pivotal role in mobilization of HSPC and that egress of HSPC from BM occurs as part of an immune response. Disclosure of potential conflicts of interest is found at the end of this article.