Murine mammary carcinoma 4T1 induces a leukemoid reaction with splenomegaly: association with tumor-derived growth factors

Exp Mol Pathol. 2007 Feb;82(1):12-24. doi: 10.1016/j.yexmp.2006.06.007. Epub 2006 Aug 17.


A leukemoid reaction with granulocytosis and splenomegaly has been observed in animals and humans with a variety of tumors. We have employed four color flow cytometry to characterize the leukemoid reaction induced by the transplantable mouse mammary carcinoma 4T1 in female BALB/c mice. Gr-1(+) myeloid cells with the morphology of granulocytes increased in peripheral blood from <15% pre-transplant to nearly 80% of total CD45(+) leukocytes at four weeks post-transplant. Though the granulocyte:lymphocyte ratio increased markedly, the absolute numbers of CD19(+) B lymphocytes, CD4(+) and CD8(+) T lymphocytes, and the CD4/CD8 ratio in peripheral blood did not change significantly. Femurs from tumor-bearing mice showed myeloid hyperplasia of the fatty marrow. There was a notable increase in cells with a Gr-1(dim)/CD11b(bright) immature granulocyte phenotype, and these cells were also found in peripheral blood and spleen. Spleen weights had increased 8.5-fold by four weeks post-tumor transplant, mainly due to granulocytic hyperplasia. Cultured 4T1 tumor cells constitutively expressed mRNA for the myeloid colony-stimulating factors G-CSF and GM-CSF, and IFN-gamma-inducible M-CSF transcripts were also detected. Tumors excised from mice had transcripts for G-CSF and GM-CSF, but only G-CSF protein was found in high levels in serum of tumor-bearing mice. These data demonstrate that 4T1 tumor-bearing mice exhibit a leukemoid reaction that apparently is caused by the production of colony-stimulating factors produced by the tumor. The 4T1 tumor may serve as an excellent model for the study of this reaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Marrow / pathology
  • Colony-Stimulating Factors
  • Female
  • Flow Cytometry
  • Granulocyte Colony-Stimulating Factor / blood
  • Granulocyte-Macrophage Colony-Stimulating Factor / blood
  • Granulocytes / pathology
  • Leukemoid Reaction / etiology*
  • Lymphocytes / pathology
  • Mammary Neoplasms, Experimental / complications*
  • Mammary Neoplasms, Experimental / metabolism*
  • Mammary Neoplasms, Experimental / pathology
  • Mice
  • Mice, Inbred BALB C
  • Neoplasm Transplantation
  • Reverse Transcriptase Polymerase Chain Reaction
  • Splenomegaly / etiology*


  • Colony-Stimulating Factors
  • Granulocyte Colony-Stimulating Factor
  • Granulocyte-Macrophage Colony-Stimulating Factor