[Studies of neutrophil function in the elderly: especially analysis of bedridden patients and patients with bacterial...

To evaluate the host defense function in the elderly, chemotaxis and chemiluminescence (CL) were assessed as indicators of neutrophil function in healthy and bedridden subjects as well as in patients with bacterial infection. In addition, humoral host defensive factors were also investigated. 1) The differences in chemotaxis and CL between healthy elderly subjects and healthy adults were slight. Neutrophil function showed little decrease with aging. 2) Plasma fibronectin (PFN) values in bedridden patients were lower than in healthy elderly subjects. 3) Chemotaxis and CL in patients in the acute phase of bacterial infection were higher than those of healthy elderly subjects regardless of whether these patients were bedridden or not. CL was slightly lower in bedridden patients than in non-bedridden patients. CL and body temperature were positively correlated in the acute phase of bacterial infection. Among the humoral defensive factors, PFN revealed lowered values in the acute phase of bacterial infection. 4) As the infection healed, chemotaxis and CL decreased, while PFN rose to normal. In the complement system, CH50 increased slightly as the infection healed. From these results, we concluded that neutrophil function in elderly subjects, regardless of whether they were bedridden or not, is enhanced by infection. Responses to infection of bedridden patients were slightly weaker than those of non-bedridden subjects.