Circulating factors may be responsible for murine strain-specific responses to mobilizing cytokines.
OBJECTIVE
To determine if circulating factors influence strain-specific responses to administration of hematopoietic stem-cell mobilizing cytokines, a murine model was employed.


METHODS
Plasma aliquots from intact DBA2, Balb/c, and C57Bl/6 mice were injected into intact Balb/c mice prior to delivery of mobilizing cytokines. Control Balb/c mice were injected with mobilizing cytokines alone. Plasma from hemi-body irradiated Balb/c mice, known to inhibit mobilization, was also injected into Balb/c mice. Twenty-four hours later, spleen cells were harvested and assayed for granulocyte-macrophage colony-forming cells (GM-CFC) and high-proliferative-potential colony-forming cells (HPP-CFC). Simultaneously harvested blood aliquots were assayed for CD45(+)/CD34(+) cells using flow cytometric techniques.


RESULTS
Mice receiving plasma from any source demonstrated significant inhibition of mobilization of HPP-CFC and GM-CFC to the spleen as compared to mobilized controls; for HPP-CFC, plasma from C57Bl/6 mice was more inhibitory than plasma from Balb/c (p = 0.001) or from DBA2 mice (p = 0.01), while for GM-CFC, plasma from C57Bl/6 mice was more inhibitory than Balb/c plasma but not more inhibitory than DBA2 plasma. Mice injected with plasma from previously irradiated Balb/c mice exhibited the expected HPP-CFC and GM-CFC mobilization inhibition, which was not statistically different from the inhibition seen in animals that received C57Bl/6 plasma. Mobilization of CD34(+)/CD45(+) cells to the blood also appeared to be inhibited by pretreatment with C57Bl/6 plasma, but not DBA2 plasma.


CONCLUSIONS
These data suggest that strain-specific patterns of mobilization may be influenced by a circulating mobilization inhibitor(s).
Kessinger
A
A
Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Neb., USA. makessin@unmc.edu
Mann
S
S
Murphy
B O
BO
Jackson
J D
JD
Sharp
J G
JG
D000818:Animals; D016913:Blood Component Transfusion; D001854:Bone Marrow Cells / Q000166:cytology; D004921:Erythropoietin / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis; D019650:Hematopoietic Stem Cell Mobilization; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D017619:Hemibody Irradiation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010949:Plasma; D011994:Recombinant Proteins; D013045:Species Specificity; D013154:Spleen / Q000166:cytology; D014184:Transplantation, Homologous; D014185:Transplantation, Isogeneic
D011994:Recombinant Proteins; D004921:Erythropoietin; D016179:Granulocyte Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor