RESPONSE OF BLOOD-PLATELETS TO PROTEUS-MIRABILIS LIPOPOLYSACCHARIDE

The effects of the lipopolysaccharide (LPS) of Proteus mirabilis on th e production of thiobarbituric acid reactive substances (TBARS) and th e generation of superoxide radicals (O-2(-)) by pig blood platelets we re studied in vitro. The effect of LPS on TBARS formation in platelets was dependent on the concentration of endotoxin. LPS at concentration s above 0.1 mu g/10(8) platelets caused the production of TBARS concom itant with the generation of superoxide radicals. The responses of pla telets to LPS suggest that endotoxin, like thrombin (a strong platelet s agonist), stimulates an enzymatic cascade of platelet arachidonate v ia cyclooxygenase and produces thromboxane A(2) (TXA(2)) concomitant w ith malonyldialdehyde (MDA).