Effect of age on different receptors and functions of phagocytic cells

Different tests were performed on 15 young (age between 17 and 39) and 13 older (62-83) subjects. Blood polymorphs and monocytes were separately tested for ingestion of 3 different particle species and stimulation of superoxide anion production. The erythrocyte sedimentation rate and the serum concentrations of 10 proteins possibly related to inflammatory processes were also determined. It is concluded that: Individual variations of phagocyte ability to be stimulated by different cell types are independent processes. Aged people displayed selective decrease of Fc receptor-mediated phagocytosis by granulocytes and possibly selective impairment of nonspecific phagocytosis by monocytes. Further, the IgM level was decreased whereas the IgA, C-reactive protein and erythrocyte sedimentation rate were higher in old people than in young subjects. Correlations were found between the serum concentrations of some protein species and phagocytic function, but further experiments were coincidental (if both parameters were age-related) or revealed some causal link. It is suggested that our procedure provides a simple and reproducible way of testing many independent functions of phagocytic cells.