The hypotension and disseminated intravascular coagulation (DIC) in bacteremia is thought to be mediated by the combined actions of cytokines, prostaglandins, and complement. The contact system, via the release of bradykinin and the activation of Factor XI, has been postulated to be contributing to the observed hypotension and DIC. Using a mAb to Factor XII (C6B7), we blocked the activation of the contact system in an established experimental baboon model in which Escherichia coli was infused to produce lethal bacteremia with hypotension. The untreated group (n = 5) displayed contact activation, manifested by a significant decrease in high molecular weight kininogen (HK) and a significant increase in a2macroglobulin-kallikrein complexes (a2M-Kal). The C6B7-treated group (n = 5) showed an inactivation of Factor XII and the changes in HK and a2M-Kal complexes were prevented. Both groups developed DIC manifested by a decrease in platelet, fibrinogen, and Factor V levels. The untreated group developed irreversible hypotension. The treated group experienced an initial hypotension that was reversed and extended the life of the animals. This study suggests that irreversible hypotension correlates with prolonged activation of the contact system, and specific antibody therapy can modulate both the pathophysiological and biochemical changes. (J. Clin. Invest. 1993.91:61-68.) Key words: septic shock * bradykinin * prekallikrein * high molecular weight kininogen * a2-macroglobulin Introduction Activation of the kallikrein-kinin system concomitant with hypotension has been demonstrated to occur in humans ( 1, 2) and in a lethal baboon model (3) during gram-negative bacteremia. The consequences ofcontact activation include the generation of kallikrein, which releases bradykinin from high molecular weight kininogen (HK),' and the generation of Factor

SummaryThrombosis of the ovarian vein is a remarkable process occuring within a few days of labor in 1:500-1:2000 women. Its presentation is characterized by fever, abdominal pain and occasionally by a palpable abdominal mass that in earlier years sometimes lead to explorative laparotomy. With the advent of modern imaging techniques the diagnosis can be made relatively easily. The pathogenesis has been attributed to an infectious process expanding from the uterus to the right ovarian vein and stasis. A predisposition towards thrombosis has not been so far explored. In this study we retrospectively analysed the clinical features, diagnosis and treatment of 22 patients with objective documentation of post partum ovarian vein thrombosis (POVT) and assessed potential risk factors. In 11 of the 22 patients (50%) inherited prothrombotic risk factors were detected as follows: 4 were heterozygous for factor V G1691 A, 2 had protein S deficiency, one had protein S deficiency and was heterozygous for factor V G1691A, and 4 were homozygous for MTHFR C677T. Eight of the 11 patients who bore a prothrombotic predisposition underwent cesarean section. Taken together, the data suggest that POVT may result from the combined effect of an infection, cesarean section and a prothrombotic tendency.

Because plasma kallikrein activates human neutrophils, and in plasma prekallikrein (PK)

Activation of the contact system has been documented in severe sepsis and hereditary angioedema, but a sensitive, specific, and quantitative assay for assessing the degree of involvement of this proteolytic enzyme cascade is not yet available. We have developed a quantitative sandwich enzyme-linked immunosorbent assay (ELISA) for the alpha 2- macroglobulin-kallikrein (alpha 2M-Kal) complex using an F(ab')2 derivative of a monospecific polyclonal antibody against alpha 2 M as the capture antibody and a unique murine monoclonal antibody, 13G11, against the heavy chain of kallikrein as the detector antibody. The assay does not detect complexes in normal plasma but reacts with complexes generated by activating normal plasma with dextran sulfate at 4 degrees C in a range of 5 to 375 nmol/L. A close correlation of the ELISA with an amidolytic assay for alpha 2M-Kal was documented. Patients with sepsis syndrome but negative bacterial blood cultures did not show elevated plasma complexes, whereas a majority of those with positive blood cultures did show modest elevation and a single patient with septic shock showed a very high level of alpha 2M-Kal complex. Similarly, a patient with classic hereditary angioedema (HAE) showed increased concentration of complexes on three separate occasions during attacks but normal levels between attacks. Two other HAE patients did not show elevated levels at quiescent periods. The ELISA for alpha 2M- Kal appears to be sensitive, specific, and quantitative, and it can be used to reflect the degree of contact system activation in human sepsis and in HAE attacks.

The objective of this study was to determine the role of the kallikrein- kinin system in healthy humans after intravenous administration of either Escherichia coli endotoxin or saline. We studied a total of 18 healthy nonsmoking volunteers, 23 to 38 years old, in an open-label study at the Critical Care Medicine Department, Clinical Center, National Institutes of Health (Bethesda, MD) in which some of the patients served as their own controls. After baseline data collection, the subjects received intravenously either E coli endotoxin (n = 15, 4 ng/kg of body weight) or saline (n = 8, controls). Signs, symptoms, systemic blood pressure, factor XII, plasma prekallikrein (PK), factor XI (FXI), antithrombin III (AT-III), high molecular weight kininogen (HK), and alpha 2-macroglobulin-kallikrein complexes were measured at baseline and 1, 2, 3, 5, and 24 hours after injection of either saline or endotoxin. After infusion of endotoxin, we found the functional plasma levels of FXI decreased at 2 hours (P < .05) and at 5 hours (P < .05). Functional PK was significantly depressed by 2 hours (P < .05), at 5 hours (P < .05), and at 24 hours (P < .01), whereas the PK antigen was only low at 5 hours (P < .05). These changes were accompanied by a significant increase in circulating alpha 2-macroglobulin-kallikrein complexes at 3 hours (P < .05) and 5 hours (P < .01). No significant changes occurred in the plasma levels of factor XII or HK. We concluded that clinical response to intravenous endotoxin in healthy human volunteers is associated with activation of the kallikrein-kinin systems. Further investigation is needed with specific inhibitors of the kallikrein-kinin system to define its primary or secondary role in the endotoxin-mediated reactions.