FURTHER CONSIDERATIONS TOWARDS AN IMMUNOLOGIC THEORY OF AGING

Aging may be due to long-term minor-grade histo-incompatibility reactions among the body's populations of cells. This theory does not require the concept of "loss of vitality" of individual cells, and attributes aging to intercellular rather than intracellular processes. Data already available suggest the existence of age-related immunologic disharmony which may be auto-immune in nature. Model experiments in which one or two lymphoid systems differing at weak loci are placed in opposition appear to lead to accelerated aging as judged by life span and disease pattern. A number of the "classic" gerontologic experiments or observations withstand re-interpretation in terms of immunologic theory. Several ways in which immune reactions might actually cause aging are discussed. Certain "problems" which the theory does not take well into account are outlined. Finally, the prediction is made that so-called hybrid vigor has been misunderstood in terms of true physiologic aging, and that crosses between sufficiently long-lived inbred mouse strains will show reduced life span.