LYMPHOCYTE CAMP AND AGING - SIGNIFICANCE OF SUBSET COMPOSITION, PLASMA NORADRENALINE, REGULAR PHYSICAL-TRAINING AND LONG-TERM SMOKING

1. We studied 37 healthy men at rest in the supine position to examine the effect of ageing, smoking and physical training on beta(2)-adreno ceptor function, plasma catecholamines and the proportions of various lymphocyte subsets. 2. In 14 young subjects the proportion of natural killer cells was correlated with cAMP production in lymphocytes and in versely correlated with plasma noradrenaline level. 3. In 16 elderly n on-smokers plasma noradrenaline was negatively correlated with the nat ural killer cell subset CD3-CD16+. Lymphocyte cAMP responses did not d iffer between young and elderly non-smokers, whereas plasma noradrenal ine increased slightly but significantly with age, Physical training d id not influence either plasma noradrenaline or adrenaline at rest or cAMP in lymphocytes. 4. In seven elderly long-term smokers cAMP produc tion and the viability of lymphocytes were reduced, Plasma noradrenali ne attained its highest values in long-term smokers. 5. It is conclude d that cAMP production and plasma noradrenaline are related to lymphoc yte subset composition. The greater the proportion of natural killer c ells and related subsets, the higher is cAMP production and the lower is plasma noradrenaline, Thus, the inverse correlation between lymphoc yte cAMP and plasma noradrenaline is indirect and most likely mediated by variability in lymphocyte subset composition. In elderly subjects, reduced cAMP production was observed in long-term smokers, and this a bnormality was probably due to a reduced viability of lymphocytes and especially of natural killer cells. The negative correlation between t he proportion of natural killer cells and plasma noradrenaline at rest contrasts with a well-known mobilizing effect of adrenaline on natura l killer cells.