THE INFLUENCE OF AGE AND SEX ON PHAGOCYTE CHEMILUMINESCENCE

The process of ageing is associated with increased susceptibility to i nfection. Phagocytes form the primary defence mechanism against infect ing microorganisms. but the influence of ageing on phagocyte function remains controversial. In this study we have applied a microtitre plat e phagocyte chemiluminescence (CL) assay suitable for clinical use to compare phagocyte oxidative metabolism in younger healthy subjects (ag e 20-60 years) and healthy older (60-70 years) subjects. Polymorphonuc lear leukocytes (PMNL) and monocytes were stimulated using phorbol myr istate acetate (PMA), serum opsonized zymosan (SOZ). and non-opsonized zymosan (ZYM) in the presence of both lucigenin and luminol. Monocyte s showed a higher luminol-enhanced CL response to PMA in males compare d with females in the younger age group. No PMNL differences were obse rved between the sexes. Although no differences were found in relation to age when cells were stimulated with PMA and SOZ, significantly low er background (unstimulated) CL was obtained from PMNL with luminol. P MNL luminol-enhanced CL responses were also lower in response to ZYM. The findings suggest a reduced response of PMNL from older subjects to minimal stimulation. This could be related to abnormalities in the tr iggering of the respiratory burst or myeloperoxidase release due to ag eing. The influence of age and sex should be taken into account in cli nical studies of phagocyte CL.