Statistical analysis of splenic colony histology: an attempt to confirm that external factors could affect the channelling of CFUS differentiation.

The aim of this work was to analyze quantitatively experimental data, which suggest that CFUS determination can be manipulated by external fibers. This hypothesis was based on the comparison of the ratio of erythroid to granulocytic spleen colonies generated by normal bone marrow exposed to factors released by either untreated or arabinoside cytosine treated mouse bone marrow. To investigate mechanisms able to produce this modification of spleen colony histology, statistical analysis was performed by testing three different schemes of evolution of the number of splenic colonies according to this histology from normal to treated groups. The total number of colonies per spleen is similar in both groups, but a significant increase of the number of erythroid colonies per spleen and a significant decrease of the number of granulocytic colonies are observed in the treated group as compared to control. Bias due to the used experimental technique are investigated but could not explain the observed differences. A unique mechanism acting on only one committed stem cell population does not fit the experimental data. Although other possible mechanisms are suggested, the experimental observations can be interpreted as the consequence of a shift of CFUS differentiation toward the erythroid pathway at the expense of at least the granulocytic lineage due to some humoral factors, secreted by treated mouse bone marrow.