Immunosuppression after endotoxin shock: the result of multiple anti-inflammatory factors.
OBJECTIVE
Endotoxin induced suppression of cellular immune function is thought to contribute to septic complications in trauma patients. A rabbit model of endotoxemia was used to determine the relative roles of the anti-inflammatory factors interleukin-4 (IL-4), interleukin-10 (IL-10), transforming growth factor beta1 (TGFbeta1), and prostaglandin E2 (PGE2) in addition to other factors, in inducing immunosuppression.


METHODS
T-cell suppressive factors (TSF) in serum ultrafiltrates were separated and tested for the presence of the known suppressive factors PGE2, IL-4, IL-10, and TGFbeta1.


METHODS
New Zealand rabbits were injected with 50 microg/kg of purified Escherichia coli lipopolysaccharide. Animals were exsanguinated after 48 hours and serum was separated by ultrafiltration (cutoff 50 kd), TSK HW-40 size exclusion chromatography, and Q-Sepharose anion exchange chromatography. TSF activities of chromatographic fractions and serum samples were measured with a mitogen induced in vitro T-cell proliferation assay. Levels of PGE2, IL-4, IL-10, and TGFbeta1 were measured with enzyme immunoassays.


RESULTS
Serum TSF activity, and levels of PGE2, IL-4, IL-10, and TGFbeta1 were increased after endotoxemia. Size exclusion chromatography revealed three major fractions (TSF1-3) with up to 600 times more TSF activity compared with controls. IL-4 and IL-10 were found in TSF1 and TSF3. Further separation of TSF1 by anion exchange chromatography revealed a total of eight different T-cell suppressive factors. TGFbeta1 probably remained in the retentate after ultrafiltration, while PGE2 eluted at a higher retention time. The known anti-inflammatory factors TGFbeta1, IL-10, IL-4, and PGE2 only accounted for 13% of the total serum TSF activity of 614 U/mL.


CONCLUSIONS
Lipopolysaccharide shock results in the release of multiple T-cell suppressive factors in addition to known immunosuppressive factors, all of which contribute to the anti-inflammatory response.
Junger
W G
WG
Department of Surgery, Division of Trauma, University of California San Diego, 92103-8236, USA.
Hoyt
D B
DB
Liu
F C
FC
Loomis
W H
WH
Coimbra
R
R
D000818:Animals; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D015232:Dinoprostone / Q000276:immunology*; D004195:Disease Models, Animal; D004927:Escherichia coli Infections / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology*; D016753:Interleukin-10 / Q000276:immunology*; D015847:Interleukin-4 / Q000276:immunology*; D008297:Male; D011817:Rabbits; D012772:Shock, Septic / Q000276:immunology*; D013491:Suppressor Factors, Immunologic / Q000032:analysis; D016212:Transforming Growth Factor beta / Q000276:immunology*
D013491:Suppressor Factors, Immunologic; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D015847:Interleukin-4; D015232:Dinoprostone