T cells activate the tumor necrosis factor-alpha system during hemodialysis, resulting in tachyphylaxis.
BACKGROUND
The immunosuppressive state of hemodialysis (HD) patients is accompanied by activation of antigen-presenting cell-derived cytokines, for example, tumor necrosis factor-alpha (TNF-alpha), which are required for T-cell activation. To test whether an activated TNF-alpha system results in impaired T-cell response in these patients, we analyzed parameters of their antigen-presenting cell (APC) function (for example, TNF-alpha system) and T-cell function [for example, interleukin-2 (IL-2) system].


METHODS
By quantitative flow cytometry, the expression of the TNF-receptor 2 (TNF-R2 = CD120b) and the alpha and beta chain of the IL-2 receptor (IL-2R; CD25, CD122) was measured. Using reverse transcriptase-polymerase chain reaction, the mRNA for TNF-alpha, IL-2, and IL-2R were determined. Phyto-hemagglutinin (PHA)- and IL-2-stimulated proliferation and cytokine production were measured. Biological activity of soluble receptors was measured by adding recombinant cytokines to the patient's plasma.


RESULTS
CD120b expression was significantly increased in HD patients, whereas CD25 and CD122 was comparable to controls. In contrast to mRNA for IL-2 and IL-2R, mRNA for TNF-alpha was increased in HD. This resulted in significantly increased TNF-alpha levels in HD patients. In peripheral blood of HD patients, high levels of soluble TNF-R (R1 and R2) and IL-2R were found. These receptors were capable of binding 40% of added TNF-alpha and 55% of added IL-2. PHA-induced TNF-alpha production by T cells from HD patients was significantly lower, while their PHA-stimulated IL-2 production and proliferation capacity by T cells were comparable to controls.


CONCLUSIONS
We conclude that although the TNF-alpha system is activated during HD, the TNF-alpha production of T cells is impaired, suggesting that tachyphylaxis of T cells occurs for TNF-alpha, as their proliferative capacity and IL-2 production capacity do not imply an intrinsic T-cell defect.
Department of Internal Medicine, University Hospital Rotterdam-Dijkzigt, Rotterdam, The Netherlands. vanRiemsdijk@inw2.azr.nl
I C
IC
van Riemsdijk
C C
CC
Baan
E H
EH
Loonen
C J
CJ
Knoop
G
G
Navarro Betonico
H G
HG
Niesters
R
R
Zietse
W
W
Weimar
D000368:Aged; D002455:Cell Division; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007121:Immunocompetence; D007376:Interleukin-2 / Q000097:blood / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology; D012333:RNA, Messenger / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D012016:Reference Values; D006435:Renal Dialysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012995:Solubility; D013601:T-Lymphocytes / Q000378:metabolism / Q000502:physiology*; D013618:Tachyphylaxis / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D007376:Interleukin-2; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha