A human whole blood model of LPS-mediated suppression of T cell activation.
BACKGROUND
Lipopolysaccharide (LPS) is the main initiator of the early signaling events leading to sepsis caused by Gram-negative bacteria. Late stages of sepsis are associated with impairments of T lymphocyte function, a condition associated with nosocomial infection and poor outcome. The molecular basis for septic immunosuppression is not fully understood.


METHODS
Human whole blood was incubated ex vivo with purified LPS. Cytokine responses and T cell proliferation were assessed, and the role of cyclic 3',5'-adenosine monophosphate (cAMP) in T cell suppression by LPS was studied using a cAMP-antagonist (Rp-8-Br-cAMPS).


RESULTS
Adding LPS (0.01 to 10 microg/ml) to human blood ex vivo caused a release of prostaglandin E2 (PGE2) in a concentration- and time-dependent manner, with maximal levels of PGE2 obtained with 10 microg LPS per ml blood after 10 hours of incubation. Adding PGE2-concentrations ranging from 0.03 to 10 microM to purified T cells completely abrogated T cell activation and proliferative response, which was largely reversed by adding Rp-8-Br-cAMPS. Peripheral blood mononuclear cells (PBMC) and T cells harvested from whole blood cultured in the presence of LPS ex vivo showed attenuated proliferative response (30-70%) (purified T cells and PBMC) and reduced IL-2 production (85%) upon T cell receptor (TCR)/CD3 activation with anti-CD3. The proliferation in T cells and PBMC was in part restored by Rp-8-Br-cAMPS.


CONCLUSIONS
The human whole blood model of LPS-mediated T lymphocyte suppression described in this paper is time and cost efficient, as well as easy to use.
Yaqub
Sheraz
S
Department of Medical Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Norway. sherez.yaquib@basalmmed.uio.no
Solhaug
Vigdis
V
Vang
Torkel
T
Solberg
Rigmor
R
Aasen
Ansgar
A
Taskén
Kjetil
K
Wang
Jacob E
JE
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000097:blood; D017868:Cyclic AMP-Dependent Protein Kinases / Q000097:blood; D015232:Dinoprostone / Q000097:blood / Q000494:pharmacology; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000097:blood; D008070:Lipopolysaccharides / Q000633:toxicity*; D008213:Lymphocyte Activation / Q000187:drug effects*; D018448:Models, Immunological; D018805:Sepsis / Q000097:blood / Q000209:etiology / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology
C105593:8-bromoadenosine-3',5'-cyclic monophosphorothioate; D007376:Interleukin-2; D008070:Lipopolysaccharides; D013873:Thionucleotides; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone