Sodium caseinate induces mouse granulopoiesis.

OBJECTIVE AND DESIGN: Sodium caseinate (CasNa) induces differentiation and M-CSF production in mouse band granulocytes in vitro; however, it is not yet known if this molecule can also induce the proliferation and activation of the granulocyte lineage in vivo. In this work we evaluated the induction in vivo of granulopoiesis and the activation of granulocytes in mice treated with CasNa. MATERIAL OR SUBJECTS: BALB/c male mice 8-12 weeks old were used. TREATMENT: The animals were inoculated intraperitoneally with 1 ml of CasNa (10% in PBS p/v) four times (every 48 h). METHODS: Granulocyte proliferation was evaluated by flow cytometry; activation was evaluated by phagocytic indices. The cytokine was measured using an ELISA assay. RESULTS: We show that CasNa increased bone marrow granulopoiesis percentage (38.35 ± 10.88 vs. 64.94 ± 34.14 BrdU+/Gr-1+ cells) and the granulocytes generated presented increased phagocytic indices (0.3 ± 0.1 vs. 0.6 ± 0.11, p < 0.05). We also show that G-CSF (974 ± 411 vs. 3189 ± 350 pg/ml, p < 0.05) and GM-CSF increased in serum, but only G-CSF in bone marrow plasma. CONCLUSIONS: CasNa induces granulopoiesis with functional granulocytes, suggesting that this molecule could be an innate immune system activator.

[Stem cell factor (SCF) supports granulocyte progenitor survival in mouse bone marrow cultures]. / El factor de células totipotenciales (stem cell factor; SCF) sostiene la supervivencia de progenitores de granulocitos en cultivos de médula ósea de ratón.

The regulation of cell differentiation and cell death in crucial to the generation of hematopoietic cells both in vitro and in vivo. The biologic role of stem cell factor (SCF) in hematopoietic cell development is not well known. We monitored the survival, proliferation and differentiation of mouse hematopoietic cells in culture in the presence of SCF. Examination of colony formation, MTT and thymidine killing of mouse bone marrow indicated that SCF is mainly a survival factor. Our results show that SCF maintains cells in a "undifferentiated" state. Committed granulocytic and monocytic progenitors (CFU-GM) survive for seven days in the presence of SCF alone, under conditions where no maturing granulocytic monocytic cells could be recovered. On transfer to GM-CSF containing cultures, these cells proliferate and differentiate terminally. Together, our data indicate that SCF induces survival in hematopoietic progenitors. Furthermore, SCF favors the survival of granulocytic progenitors over that of monocytic progenitors. In the absence of later acting factors such as GM-CSF, cells that progress beyond the CFU-GM stage lose c-kit expression and die by default. Hence, lack of cell expansion in the presence of SCF by itself is due to constant cell proliferation and survival, which is counterbalanced by cell death. In contrast, the presence of both SCF and GM-CSF allows for the continuous survival and expansion of hematopoietic progenitor cells in culture, as well as favoring their terminal differentiation along granulocytic and monocytic pathways. Furthermore, GM-CSF induces colonies of macrophages that produce G-CSF and IL-6, two molecules involved in granulopoiesis, and these in turn stimulate granulocyte colony formation. Finally, our data suggest that survival signals by SCF are crucial during the differentiative process of granulocytes, giving strength to deterministic model.