Peripheral blood lymphocytes display reduced K+ channel activity in aged humans

Effect of malnutrition on K+ current in T lymphocytes

Severe malnutrition in children is frequently associated with infectious diseases. Animal models have been useful for studying the effects of malnutrition. One of the immunosuppressive mechanisms of malnutrition is inhibition of the activation of T lymphocytes. The voltage-dependent K(V) potassium channels are vital for the activation of T lymphocytes. The blockade of K(V) channels inhibits the activation of T lymphocytes. Malnutrition could affect the suitable synthesis of K(V) channels in T lymphocytes, producing changes in the magnitude and/or dependency of the voltage of the K+ current. We reported a significant decrease in the K+ current and activation to a 20 mV more positive membrane potential in T lymphocytes of rats with severe malnutrition. These results indicate that the diminution in the K+ conductance by alteration of K(V) channels in severe malnutrition is one of the mechanisms that inhibit the activation of T lymphocytes.

Neutrophil immunity of the elderly

Due to age-related changes of the immune system, elderly people are more susceptible to microbial infections than the young. Most research concerning immune senescence has been done on T and B cells, yet the first cells to migrate into microbe-infected tissue are neutrophils, which phagocytose and kill the pathogens. Long regarded as mere phagocytes, the neutrophils' importance for the immune response has been recognized in current publications, which acknowledge them an active participation in the cytokine network. Similarities in the symptoms of patients with genetical neutrophil deficiencies and those of the elderly indicate a leading role of neutrophils in the effects of immune senescence. While the number of circulating neutrophils remains unaltered in the elderly compared with young controls, phagocytosis and intracellular killing have been reported impaired. Oddly enough, the results for various stimuli differed: while some showed a decrease in neutrophil activation, the response to others remained unaltered. More research needs to be done on this, preferably using preparations of high purity to exclude monocytic interventions. Elucidation of immune deficiencies caused by neutrophil senescence can be an important contribution to a healthier elderly population.

Experimental gerontology in Hungary

Gerontological research has some past and sporadically also some highlights in Hungary, but its present state can be easily deduced from the following data. During the last 12 years and more, well over 10,000 Hungarian scientific papers have been published in well-recognized national or international journals. Altogether approximately 1% of them have been classified as gerontological publications from Hungary. This low figure shows that gerontology has low priority and--unfortunately low support--in Hungary. This statement does not intend to downgrade Hungarian gerontologists, however points out that the Hungarian trends are not far from those of European or world wide interest in aging. Despite the recognition that we have to accept the inevitable fact that industrial societies will have (they already have) an aging population with all the social and medical problems arising, the focus of interest is wide from this significant and interesting (sub)population, which is neglected (sometimes even despised); yet everybody is absolutely eager to join this club. The average of the Hungarian research achievements and publication activities are among the better European achievements. There are some highlights and new trends even initiated by some outstanding Hungarian scientists, yet the overall weight of gerontology research is still an orphan in the Hungarian scientific life. We deal in this short and far from complete summary almost exclusively with experimental gerontology. We have to apologize if we have not included everybody, who also contributed even significantly to this field because the time for the preparation of this overview was short.

Biogerontological research in Canada

There is an ever increasing interest in the study of the aging process. This review is aimed to make an overview of the biological aging research in Canada. I will summarize, to the best of my knowledge, the biological aging research undertaken actually in Canadian institutions dealing with various aspects of this research using many different experimental approaches, models from animals to humans and a huge array of techniques. The biological aging research is developing continuously in Canada, however, it is very important that we assist in a near future to its huge explosion if we would respond to the needs of an ever increasing aging population. Initiatives recently proposed by the Canadian government concerning the creation of Canadian Institutes on Health Research will provide good opportunities to establish a performant, cost-effective, and innovative biological aging research.

Cellular distribution of protein kinase C isozymes in CD3-mediated stimulation of human T lymphocytes with aging

Protein kinase C (PKC) is involved in a variety of cellular responses, such as the expression and secretion of IL-2, the regulation of cytotoxic killing and cell proliferation. It is known that these immune functions are altered with aging. Here, we show that anti-CD3-triggered T cell proliferation is significantly decreased with aging and that H7, an inhibitor of PKC, impairs the anti-CD3-induced T cell proliferation in a differential manner, lymphocytes of healthy young subjects being more sensitive to the PKC inhibitor than those of elderly subjects. We examined (Western blot) the presence and the cellular distribution of PKC isozymes in T lymphocytes of healthy young and elderly subjects in the resting state and after anti-CD3 mAb stimulation using antibodies directed against PKC alpha, beta, delta, epsilon and zeta isoforms in the cytosol and the plasma membrane fractions. These five PKC isotypes were present in human T cells of young and elderly subjects. However, their distribution between the cytosolic and membrane fractions varied according to the isozymes and the age of the subjects. In resting lymphocytes of young subjects, all the PKC isozymes were found in the cytosolic fraction, except PKC-zeta. In resting lymphocytes of elderly subjects PKC-zeta and -epsilon were almost equally distributed between the cytosolic and the membrane fractions, whereas PKC-alpha and -zeta were mainly found in the membrane fraction and PKC-beta was almost exclusively located in the cytosolic fraction. The translocation of PKC-alpha, -beta, -delta and -epsilon could be observed under anti-CD3 mAb stimulation in lymphocytes of young subjects, while in the case of elderly subjects only the PKC beta isoform was translocated. Our results suggest tha the decreased availability of cytosolic PKC may contribute to the diminished PKC-dependent responses to CD3-triggered stimulation of human T lymphocytes with aging.