The chemokine CCL21 protects normal marrow progenitors from ara-C cytotoxicity

Purpose: Chemokines are a family of small proteins that regulate leukocyte infiltration into inflamed tissue and play key roles in the pathogenesis of many diseases. Some chemokines can also reversibly inhibit the proliferation of hematopoietic progenitors. We have previously found that the chemokine CCL21 (Exodus-2/SLC/6Ckine/TCA4) is a potent inhibitor of the proliferation of normal hematopoietic progenitors. In this study we sought to determine whether this inhibition of proliferation could be therapeutically exploited by protecting normal marrow progenitors from the cytotoxicity of the S phase-active chemotherapeutic agent Ara-C. Methods: Untreated and CCL21-pretreated mice were given doses of Ara-C that are toxic to marrow myeloid progenitors. The recovery of these myeloid progenitors was analyzed by colony formation assays. Results: It was found that pretreatment with small doses of CCL21 prevented the death of normal murine marrow progenitors from the toxic effects of Ara-C. Conclusions: The chemokine CCL21 may be able to prevent Ara-C myelosuppression during acute leukemia induction chemotherapy, and thereby decrease morbidity and mortality of such therapy, and shorten hospital stays.