[Superoxide generation by neutrophils as defence mechanisms in elderly]

We investigated superoxide generation by polymorphonuclear leukocytes (PMNs) stimulated with various species of bacteria in order to clarify the species-specific immunocompromised status in the elderly. We studied 66 elderly patients (ranged 66 to 89 year-old; mean 77-year-old) and 26 young healthy volunteers (ranged 25 to 3-year-old; mean 31-year-old) as a control group. The elderly patients were divided into two groups, i.e., the malignancy group and the benign group. Peripheral blood was prepared from each host and diluted. The activity of superoxide generation by PMNs was determined by means of chemiluminescence method. PMNs were stimulated with the standard stimulants; i.e., phorbol myristate acetate (PMA) and zymosan (ZY), and four bacterial species; i.e., Escherichia coli, Psudomona aeruginosa, Staphylococcus aureus and Candida albicans. The activity of superoxide generation by PMNs in the malignancy group was significantly lower than that in the control group (p < 0.05). Furthermore, the activity of superoxide generation by PMNs in the malignancy group and the benign group stimulated with C. albicans were significantly lower than those in the control group (p < 0.05). These results indicate that the elderly are in an immunocompromised status especially against fungus such as C. albicans.