Abnormal erythroid differentiation in neonatal bcl-6-deficient mice

Objective The bcl-6 proto-oncogene is ubiquitously expressed in various tissues. Since we found out the smaller number of TER119+ cells in the spleen of neonatal bcl-6-deficient (bcl-6−/−) mice compared with that of control (bcl-6+/+) littermates, we studied functions of bcl-6 in differentiation of erythroid lineage cells. Materials and methods Erythroblasts in the definitive erythropoiesis were separated into four subsets using anti-TER119 and anti-CD71 mAbs. The cell number and property of these four subsets in spleens of neonatal bcl-6+/+ and bcl-6−/− mice were examined using a flow cytometry. Results bcl-6 mRNA expression was detected in the TER119highCD71high subset, which is morphologically equivalent to basophilic erythroblasts, by reverse-transcribed polymerase chain reaction. High percentages of cells in the TER119lowCD71high and TER119highCD71high subsets were in the cell cycle. The cell number of the TER119highCD71high subset in the spleen and the percentage of reticulocytes in the peripheral blood of neonatal bcl-6−/− mice were significantly lower than those of neonatal bcl-6+/+ mice. However, the percentage of apoptotic cells and that of cells in the cell cycle in the TER119highCD71high subset of bcl-6−/− mice were similar to those of bcl-6+/+ mice. Conclusion bcl-6 detected in the TER119highCD71high subset of erythroblasts in the spleen of neonatal mice may be required to retain the erythroblasts in the cell proliferation stage.