Thymic dependency of the humoral regulation of CFU-s proliferation in mice bearing a CSF-producing tumor.
A better understanding of the mechanisms involved in the proliferation of splenic colony-forming units (CFU-s) during tumor growth is important for the prevention of bone marrow aplasia during chemotherapy. The in vivo growth of EMT6 cells, a colony-stimulating factor-secreting mammary tumor, in BALB/c and nude mice resulted in splenomegaly and an increase in the number of splenic granulocyte/macrophage colony-forming cells (GM-CFC). Proliferation of CFU-s, observed in BALB/c mice but not in nude mice, most likely resulted from combined direct and indirect actions of factors secreted by tumor and host cells (in particular helper T cells). These factors were detectable in the serum immediately following tumor cell injection. Thus, the GM-CFC response to factors secreted by the EMT6 tumors is thymus-independent while the CFU-s response is dependent upon the presence of T cells. Finally, we show that EMT6 tumor growth had no effect on the determination of CFU-s differentiation toward the various myeloid cell lineages.
D000818:Animals; D002469:Cell Separation; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors / Q000378:metabolism*; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000378:metabolism*; D007377:Interleukin-3 / Q000032:analysis; D007700:Kinetics; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D013234:Stem Cells / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology*
D003115:Colony-Stimulating Factors; D006133:Growth Substances; D007377:Interleukin-3; D016178:Granulocyte-Macrophage Colony-Stimulating Factor