| Popis: |
There are numerous medical problems that become more prevalent with increasing age. Among these are increased incidence of cancer, infectious diseases, and autoimmune syndromes (Makinodan & Kay, 1980). The increase in all three of these conditions can be explained by changes in regulation of immune response. Changes in immune response with increasing age have been observed and confirmed repeatedly since 1967 (Pisciotta et al., 1967). These changes include atrophy of the site of maturation of the T cell—the thymus (Weksler et al., 1978), decreased ability to mount a delayed-type hypersensitivity reaction to various stimuli including tuberculin (Girard et al., 1977), and a generalized decreased ability of lymphocytes to respond to foreign stimuli as exemplified by reduced proliferation (Sohnle et al., 1982). An excellent review article outlining the history of these studies was written by Makinodan and Kay (1980). Although the decreases in T-cell immunity observed in animal models, particularly mice, are fairly consistent, there are a number of conflicting reports in humans, however. There are some scientifically sound explanations for these conflicts. First, the health of the subjects may be a major factor. Changes observed in the elderly may reflect the effects of underlying disease rather than of the aging process. Unless careful consideration is given to the health of individuals, the effect of “age” on immune parameters cannot be evaluated. |
