Immune function and vaccine responses in healthy advanced elderly patients

Background: Decline in immune function has been reported to predictably acc ompany advancing age. However, to our knowledge, few studies have specifica lly characterized the rapidly expanding advanced elderly population or cont rolled adequately for concurrent diseases. Objective: To assess whether successfully reaching an advanced age in good health is associated with preserved immune function. Methods: We prospectively compared in vivo with in vitro variables of immun e function in 29 healthy, independently living elderly subjects (mean age, 80 years; age range, 75-103 years) and in 21 healthy young control subjects (mean age, 29 years, age range, 25-35 years) in a Veterans Affairs Medical Center. Results: In vivo, among elderly and young subjects, numbers of total white blood cells, monocytes, lymphocytes, and lymphocyte subsets (CD4(+) and CD8 (+) T lymphocytes and CD20(+) B cells) were similar, as were levels of tota l serum IgG and IgM. Only levels of serum IgA were higher in the elderly su bjects (3.0 vs 1.7 g/L; P=.001). Functionally, both groups showed vigorous responses to protein (tetanus and diphtheria toxoids) and polysaccharide (2 3-valent pneumococcal) vaccines. Although levers varied, the fold increases in vaccine antigen-specific IgG were not significantly different in young and elderly subjects, and the avidities of IgG to pneumococcal polysacchari des 14 and 19F were similar before and after vaccination. In vitro, prolife rative responses of blood mononuclear cells to T-lymphocyte and B-cell mito gens (pokeweed mitogen, Staphylococcus aureus Cowan strain I, and S aureus Cowan strain I plus interleukin 2), and lipopolysaccharide-induced producti on of tumor necrosis factor alpha, were comparable in elderly vs young subj ects. Conclusion: Successful aging, defined by reaching an advanced age with one' s overall health intact, may be associated with preserved immune function a nd adequate responses to vaccines.