![]() |
6th ESACP Congress, Heidelberg, April 7-11, 1999 |
A159
The results of our earlier investigations suggested that the high production
of TNF is associated with a low NK cytotoxic activity. In the present paper
we wondered whether the inhibitory effect of an elevated level of TNF on NK
activity in the elderly is realised by its suppressive action on the
expression of the IL2Ralpha (CD25). Groups of volunteers (50 people each) aged
20-35 and 60-75 were enrolled into the study. The health was graded as
healthy and non-fully healthy. The levels of TNF and Interleukin 2 (IL2)
were measured in the sera and the supernatants of PBMC incubated with K562
cells for 4 h by bioassays. Cytotoxic NK activity was measured by a standard
method with 51Cr. An expression of CD25 molecule was measured on CD16+ cells
from resting and stimulated in vitro by TNF peripheral blood mononuclear
cells (PBMC) and peripheral blood lymphocytes (PBL) by the flow cytometry.
Our results revealed that the healthy people were characterised by a high NK
activity while those non-fully healthy with a low NK response. An anti-TNF
moAb suppressed the NK activity of the elderly low NK responders. Cells of
the young people and the healthy elderly were characterised by a low
secretion of TNF during NK cytotoxic reaction. At the same time a high
amount of the bioactive TNF was released during the NK reaction of the
non-fully healthy elderly. After 48 h of incubation with TNF in vitro, the
increase in CD16+CD25+ (activated NK cells) was significantly higher in the
group of the low NK responders. Our results suggest that the high production
of TNF during NK reaction of the elderly low NK responders is necessary to
maintain this response on the highest possible level through the generation
of CD16+CD25+ cells.
SIGNIFICANCE OF AN OVEREXPRESSION OF TNF FOR THE CYTOTOXIC NK ACTIVITY
AND HEALTH STATUS OF THE ELDERLY
Mysliwski A, Mysliwska J, Bryl E
Department of Histology and Immunology, Medical University of Gdansk,
Poland