Effect of age on concentrations of serum antibodies to viral, bacterial, and food antigens in elderly Swiss people.

Serum antibody concentrations to two viral, five bacterial, and two food antigens were investigated in 307 elderly Swiss subjects, and the hypothesis of whether serum antibody titers decreased with age was tested. The cross-sectional part of the study consisted of 216 unselected consecutive patients hospitalized in one geriatric hospital. The patients were divided into two age groups (65 to 84 and 85 to 102 years old), and their antibody titers were compared. No age-related decreases in antibody titers were observed. The members of the two age groups were well matched for medical diagnosis and nutritional and inflammatory status. The prospective part of the study consisted of 91 healthy elderly subjects living in the community; they were 71 to 76 years old when they were enrolled in the study. Their serum antibody status was measured at the beginning of the study and 4 years later. We observed a significant decrease in diphtheria antitoxin levels and a significant increase in antibody titer to the capsular polysaccharide of Streptococcus pneumoniae. No change in antibody titer to rotavirus, respiratory syncytial virus, lipopolysaccharide of Escherichia coli, C polysaccharide of S. pneumoniae, or the polyribosyl-ribitol phosphate of Haemophilus influenzae was observed. Thus, no signs of B-cell immunosenescence were seen in these two groups of elderly Swiss people.