Bone-marrow eosinophilia in the mouse. I. Eosinophil leukocyte levels in untreated mice.

The number of eosinophil leukocytes in the bone marrow of untreated mice (Cpb:SE) has been shown to vary widely. A systematic investigation of this variability is reported here. The study was done a) within a group of mice, b) within groups of mice at roughly 3-month intervals, and c) within a group over a time course. The following are the most important results of this study: 1. Analysis of variance of eosinophils/1000 cells in 165 mice over a 35-day period showed that the results were consistent with the assumption that there are no changes during this interval (P is less than 0.05). 2. The number of eosinophils/1000 cells found in the various groups are not directly comparable; the mean number for the four groups investigated at intervals of about 3 months differed by a factor of up to 3. 3. On the basis of the variability found, the number of eosinophils/1000 cells in the bone marrow of a given untreated mouse in a group to be investigated cannot be reliably predicted. At a 99 per cent confidence level, the value would lie between 5 and 139.