Neuroendocrine—Thymus Interactions During Development and Aging. In: Grossman CJ, editor. Bilateral Communication Between the Endocrine and Immune Systems. New York: Springer; 1994. pp. 158-82. [DOI: 10.1007/978-1-4612-2616-1_8]

Natural immunity and bone and muscle remodelling hormones in the elderly

Increasing evidence has demonstrated that the immune system is closely integrated with two other physiological systems: endocrine and nervous. They communicate through circulating humoral factors such as cytokines, hormones and neurotransmitters. We undertook a cross-sectional analysis in a group of elderly subjects over 90 years to demonstrate that a functional relationship exists among the number and cytolytic activities of NK cells, bone and muscle remodelling hormones, anthropometric parameters and physical ability. Peripheral blood samples collected from 62, 90-106 years-old subjects underwent biochemical (bone and muscle remodelling hormone levels) and immunological determinations (Natural Killer cell distribution and activity), anthropometric and functional assessment. Significant associations were found among NK cell number and cytolytic activity and serum concentrations of vitamin D, anthropometric parameters, while functional independence in daily activity was only associated with NK cell number. In general a high level of physical ability was correlated with preserved body stores and vitamin D levels. In conclusion, our results stress the importance of nutritional evaluation in the clinical assessment of elderly people. The magnitude of the NK immune response, which constitutes the first line of defence against infected and neoplastic cells, is best preserved in oldest-old people with the best hormonal parameters and nutritional measures.

Age-dependent decrease of beta-adrenoceptor density in the submandibular glands of mice and its modulation by the thymus

Beta-adrenergic receptors were characterized in submandibular glands of ageing mice and old mice grafted with a neonatal thymus. No statistically significant changes of receptor affinity were found in the animal models investigated. On the contrary, receptor density showed a progressive decrease with advancing age. The age-related decrease has been found partially corrected in thymus-grafted old animals, which show a statistically significant recovery of receptor density when compared to their untreated littermates. Receptor modulation can be responsible for the age-related impairment and the thymus-dependent correction of beta-adrenergic responsiveness of submandibular glands previously observed in vivo. Hormonal balance and thyroid hormones, in particular, are suggested as being involved in the age- and thymus-dependent regulation of receptor density. In the accompanying Appendix, we describe the mathematical method used to calculate both specific and nonspecific binding from total binding data.