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Canine cyclic hematopoiesis (CH) involves fluctuating progenitor cells, granulocytic (CFU-c) and erythrocytic (ERC). These fluctuations suggest CH is a hemopoietic stem cell disorder, with humoral factors and blood cells cycling as a consequence.
Area of Science:
- Hematology
- Stem Cell Biology
- Canine Research
Background:
- Canine cyclic hematopoiesis (CH) is characterized by cyclical fluctuations in blood cell counts.
- Progenitor cells, including granulocytic (colony-forming units in culture, CFU-c) and erythrocytic (erythropoietin-responsive cells, ERC), exhibit cyclical behavior in CH.
- Previous studies indicate these progenitor cell populations fluctuate in parallel during the CH cycle.
Purpose of the Study:
- To investigate the behavior of granulocytic (CFU-c) and erythrocytic (ERC) progenitor cells in canine cyclic hematopoiesis (CH).
- To examine the relationship between progenitor cell fluctuations, humoral factors, and peripheral blood cell changes in CH.
- To evaluate the sensitivity of CFU-c to different serum conditions and their proliferation rates during the CH cycle.
Main Methods:
- Analysis of granulocytic (CFU-c) and erythrocytic (ERC) progenitor cell fluctuations in canine cyclic hematopoiesis (CH).
- Assessment of serum erythroid-stimulating activity and subsequent reticulocytosis.
- Evaluation of CFU-c sensitivity to normal and stimulated sera, and their proliferation rates throughout the CH cycle.
Main Results:
- Both CFU-c and ERC progenitor cells fluctuate in parallel during the CH cycle.
- A rise in serum erythroid-stimulating activity precedes the ERC cycle, followed by reticulocytosis.
- CFU-c demonstrate differential sensitivity to sera and exhibit fluctuating proliferation rates, varying from above to below normal levels.
Conclusions:
- The observed fluctuations in progenitor cells and their response to humoral factors support the hypothesis that CH is a disorder of hemopoietic stem cells.
- The cycling of humoral factors and peripheral blood cells in CH may be a consequence of the underlying stem cell defect.
- These findings contribute to understanding the pathogenesis of canine cyclic hematopoiesis.
Abstract:
Granulocytic (colony-forming units in culture, or CFU-c) and erythrocytic (erythropoietin-responsive cells, or ERC) progenitor cells in canine cyclic hematopoiesis (CH) have been shown to fluctuate over the cycle and in the same phases as one another. The ERC cycle is preceded by 3 or 4 days by a rise in serum erythroid-stimulating activity and is followed by a reticulocytosis. During the cycle CFU-c show a differential sensitivity to two sera, one normal and one containing elevated amounts of colony-stimulating activity. The proliferation rate of CFU-c also fluctuates from well above normal to considerably less than normal over the cycle. These results are discussed in the light of present knowledge of the pathogenesis of canine CH. We suggest that these results support the contention that CH is a disorder of hemopoietic stem cells and that the cycling of humoral factors and peripheral blood cells may follow as a consequence.