Abstract
In vitro phagocytic action of neutrophiles was compared between the aged and they young and following results were obtained.
1. Generally, the phagocytic action of neutrophiles in the aged was inferior to thatt of the young.
2. The phagocytic action of neutrophiles in the aged was especially low on a short: period cultivation and its gradually increased with the elapse of time, but it was always lower than that of the young.
From the above mentioned observations, it is considered that the fall in phagocytic action of neutrophiles plays an important role in the fall of the resistance of the aged against diseases.
