Forty-seven allophenic mice of three different types (C57BL/6 in equilibrium (A X SJL), C57BL/6 in equilibrium (CBA X CBA/H-T6), and C57BL/6 in equilibrium DBA/1) were analyzed for changes in their peripheral white blood cell composition and hemoglobin composition with age. It was found that 10 of the 47 mice showed significant changes termed "chimeric drift" in one or the other or both of these parameters. These 10 mice were classified as unstable chimeras, as opposed to the 37 stable chimeras, which showed no apparent chimeric drift. There was an excellent correlation of peripheral white blood cell and hemoglobin compositions of the stable chimeras. However, the unstable chimeras showed little or no correlation of these two markers. Possible mechanisms of chimeric drift are discussed.
Aging Animals