Activator-bound C1 is less susceptible to inactivation by C1 inhibition than is fluid-phase C1

Parameters that influence the effective interaction of C1 with the serum regulatory glycoprotein C1 Inhibitor were investigated. C1 that bound to activator particles EAC4 or EA was strikingly less susceptible to inactivation by C1 Inhibitor than was fluid-phase C1. By using the conventional hemolytic assay, the concentrations of C1 Inhibitor required for inhibition of C1 bound to EAC4 were 1000-fold higher than those required for fluid-phase C1. With EA as the activator (and indicator) particle, 17- to 75-fold higher concentrations of C1 Inhibitor were required to inhibit bound vs free C1. These findings suggest that, on binding to these particulate immune complexes, the domain of the C1 molecule capable of interacting with C1 Inhibitor is less available for binding than when C1 is in fluid phase. Alternatively, the conformation of C1 may be altered when bound to EA or EAC4, resulting in a lower association constant of C1 Inhibitor for C1. As assessed by inhibition of classical complement pathway hemolysis, the inhibition of the enzymatic activity of C1 by C1 Inhibitor (both in the fluid phase and particle-bound) was markedly dependent on the concentration of the reactants. Incubation of C1 and C1 Inhibitor at serum concentrations resulted in the inhibition of more than 10 times the amount of C1 hemolytic activity than that which occurred when the same ratio of components was incubated at the more dilute concentrations used in the conventional hemolytic assays. These findings have allowed for the development of a more sensitive and rapid assay for C1 Inhibitor function.

Serum profiles of the regulatory complement proteins during the progression of renal damage in human glomerulonephritis

Persistent activation of the complement system after escape from control by the regulatory proteins results in an excessive release of split products with inflammatory properties. Serum levels of the regulatory proteins of the complement system (Cl-INH, H, I and AT III) were assayed by the radial immunodiffusion technique in 521 serum samples from 124 patients with idiopathic chronic glomerulonephritis divided into two groups: 81 cases with normal renal function (NRF), and 43 cases with deteriorated renal function (DRF). Significant high mean levels of Cl-INH, H, I and AT III were found in patients with NRF, when they were compared with DRF patient groups. Positive correlations between the regulatory proteins and the corresponding complement components were found in patients with NRF, whereas they were reduced considerably in patients with DRF. Serial measurement of the control proteins showed a decay of the levels of Cl-INH, H and I in patients with progressive impairment of renal function. The presence of high levels of regulatory proteins suggest that a control mechanism may occur in patients with NRF; measurement of these proteins could, therefore, be of prognostic value, as the presence of high levels are indicative of a block of the complement system.

Plasma factor XIII and some other haemostasis parameters in patients with diabetic angiopathy

Since intravascular and endoparietal fibrin deposition is thought to be involved in the development of atherosclerosis, we measured factor XIII activity and its subunit 'a' and 'b' concentrations against a background of other haemostasis parameters in diabetics with angiopathy and in 2 control groups (healthy subjects and diabetics without vascular complications). Diabetics with angiopathy revealed a significant increase of factor XIII activity as well as its subunit concentrations. They also had significantly elevated anti-thrombin III, alpha 2 macroglobulin, alpha 1 antitrypsin, C1 inhibitor, fibrinogen, FDP concentrations and prolongation of euglobulin lysis time. The highest factor XIII levels were found in diabetics with renal failure. We suppose that increased factor XIII level and other observed changes of haemostasis in patients with diabetic angiopathy might promote intravascular and endoparietal fibrin deposition and contribute to the development of atherosclerotic complications of diabetes.

Inhibitors of coagulation-fibrinolysis system and platelet function in patients with vertigo

Eight parameters of blood coagulation and fibrinolysis, i.e., the levels of fibrinogen, plasminogen, fibrinogen and/or fibrin-degradation products (FDP), alpha 2-macroglobulin, alpha 1-antitrypsin, CI-inactivator, antiplasmin activity and antithrombin activity, were measured in patients with vertigo. Furthermore, the ADP- and collagen-induced platelet aggregations were determined. The results were compared with those for healthy adults. The antiplasmin activity was significantly reduced (p is less than 0.001), the antithrombin activity was significantly reduced (p is less than 0.001) and the platelet aggregation significantly increased (p is less than 0.001), but the levels of fibrinogen, plasminogen, FDP, alpha 2-macroglobulin, alpha 1-antitrypsin and CI-inactivator were not significantly altered. The importance of the coagulation-fibrinolysis system and platelet function in patients with vertigo is discussed.

Disseminated intravascular coagulation and antiprotease activity in acute human pancreatitis

The coagulation and fibrinolytic systems were analysed parallel to the clinical evaluation in 27 attacks of acute human pancreatitis of different severity. Consumptive coagulopathy was evident from decreased platelet counts, decreased prothrombin values and consumption of fibrinogen during the first days in severe attacks. Fibrinolysis was suggested by decreased plasminogen values and the presence of fibrinogen degradation products. All main protease inhibitors of the two systems showed protease-antiprotease complexation and lower functional than quantitative values. Functional levels of the protease inhibitors were almost zero in the peritoneal fluid in severe attacks. It is concluded that severe acute pancreatitis results in consumptive coagulopathy and fibrinolysis together with a local antiprotease deficiency. All the changes are closely correlated to the severity of the disease.

Elevated plasmin-alpha 2-antiplasmin complex levels in hereditary angioedema: evidence for the in vivo efficiency of the intrinsic fibrinolytic system

The contact activation and fibrinolytic systems were assessed in 5 patients with hereditary angioedema (HAE). Reductions in F XII levels and increase in kallikrein-like activity in some patients indicated activation of the contact (intrinsic) system of coagulation. A great increase in plasmin-alpha 2-antiplasmin complex in all subjects indicated that in this disease, there is a constantly ongoing fibrinolysis. Since C1-inhibitor, the deficient protein in HAE, is a poor inhibitor of the well-known extrinsic (tissue-type) plasminogen activator, but the major inhibitor of the contact activation system and a related in vitro phenomenon termed intrinsic fibrinolysis, our data show that this fibrinolytic system is also sometimes operating efficiently in vivo. Furthermore, the known clinical data on HAE are compatible with a role of intrinsic fibrinolysis in the pathophysiology of this disease.

[Nonspecific immunity factors and elimination of circulating immune complexes in patients with myocardial infarct in the 1st phase of rehabilitation]

A considerable increment of humoral immunity parameters was demonstrated during the 3d-5th week after the onset of myocardial infarction (MI). The levels of IgG and IgE were increased, and those of circulating immune complexes (CIC), decreased significantly in patients with their first diagnosed infarction, as compared to those with repeated MI. Patients with repeated MI showed significantly reduced blood C3c, C4 and the phagocyte index in the presence of high blood levels of CIC and C-reactive protein, as compared to patients with primary infarction. The results are indicative of a considerable activation of the complement and the phagocytic system and CIC elimination in patients with their first MI diagnosis, and the absence of such a stimulation in repeated MI cases.

Synthesis of C1 inhibitor (C1-INA) by a human monocyte-like cell line, U937

Human monocytes are known to synthesize many of the components of complement, including C1-INA. In this report we demonstrate that the human monocyte-like cell line U937 is also capable of synthesizing functional C1-INA. This was shown in several ways, including 1) incorporation of tritiated amino acids into antigenic C1-INA, immunoprecipitation, and detection by fluorography; 2) a sensitive ELISA, which allowed quantitation of antigenic C1-INA in cell lysates, and 3) a C2-dependent hemolytic assay in which the functional activity of U937 C1-INA was assayed. Data from the ELISA indicate that U937 cells contain between 2.1 to 12.8 ng of C1-INA per 1 X 10(6) cells. Furthermore, fluorescence-activated cell sorter analysis revealed that approximately 16% of U937 cells carry C1-INA as a surface bound antigen. Other proteins found to be synthesized by U937 cells include C1r, C8, and possibly alpha-2-macroglobulin. These results suggest that the U937 cell line could be a convenient and valuable model for the study of monocyte C1-INA synthesis and physiology.

Plasma plasmin inhibitors in Duchenne-type progressive muscular dystrophy

In our previous research, we found that the level of the plasminogen activity in the plasma from Duchenne-type patients with progressive muscular dystrophy was higher than of the normal boys, though the level of the plasmin inhibitors was lower. Therefore, in the present study, we investigated the differences in the fractions of plasmin inhibitors. The subjects were nine patients (the average age being 17.1 years) who had been diagnosed, by clinical and biochemical tests, as having PMD; serving as controls were normal boys (the average age being 15 years), the patients' mothers, and the mothers of the normal boys. The plasmin inhibitors were separated from plasma using lysine-Sepharose columns according to the method of Urita et al. The determination was performed based on the method of Aoyagi et al. and an immunoreactive assay. The results were as follows: (1) No significant differences were seen between patients with PMD and control subjects with respect to either alpha 1-antichymotrypsin, antithrombin III, and alpha 1-antitrypsin or alpha 2-macroglobulin and inter-alpha-trypsin inhibitors. These results suggested that the low level of plasmin inhibitors in patients was due to the low activity of the C1 inactivator. (2) The patients with PMD showed lower values than the normal boys in the levels of C1 inactivator in plasma; similarly, the mothers of these patients showed lower values than the normal mothers.

Determination of C1s-C1 inhibitor complexes in plasma by means of an enzyme linked immunosorbent assay

An enzyme linked differential antibody immunosorbent assay for the quantitation of the C1s-C1 inhibitor complex has been developed. A study of the assays' performance under various conditions has shown that before use in the assay, it is imperative to remove competing forms of C1s from the samples to be tested. This is conveniently achieved in human plasma or serum by polyethylene glycol precipitation of the C1qrs, since the C1s-C1 inhibitor complex remains soluble and can be assayed in the supernatant solution. The detection limit of the assay in the plasma milieu is 0.1 mg/l, and the concentrations of the C1s-C1 inhibitor complex were found to be 1 mg/l in citrated plasma and 2 mg/l in serum. Activation of the fibrinolytic system in vivo does not seem to result in any appreciable C1 activation, since there was no concomitant major change in the plasma concentration of the C1s-C1 inhibitor complex.

Sperm antibodies, immunoglobulins, and complement in human follicular fluid

The levels of immunoglobulins (IgG, IgA, IgM), complement (C3, C4, C1EI) and sperm antibodies were determined in plasma and follicular fluid samples from 26 patients undergoing in vitro fertilization (IVF) treatment. The results show that IgG, IgA, C3, C4, and C1EI concentrations in follicular fluid are similar to plasma concentrations (63.1-96.1% of plasma levels). The follicular fluid concentration of IgM was severely reduced, however, being only approximately 10% of plasma concentrations. Sperm antibody titres were compared in three patients using sperm agglutination, immobilization, and immunobead binding. The titres in plasma and follicular fluid were similar, apart from antibodies of IgM class, which were undetectable in follicular fluid.

Involvement of complement in psoriasis and atopic dermatitis--measurement of C3a and C5a, C3, C4 and C1 inactivator

Normal complement components and activation products were determined in the peripheral blood of 35 patients with atopic dermatitis (AD) and 24 patients with psoriasis at a mild to intermediate stage. None of the patients had received systemic or local steroid therapy 6 weeks prior to blood collection. Levels of C3, C4 and C1 inactivator (C1 INA) were determined in serum by radial immunodiffusion, whereas C3a and C5a levels were measured by radioimmunoassay. In comparison to healthy non-atopic controls, the levels of C3, C4 and C1 INA were found to be significantly increased in both diseases. No substantial differences were detected between patients with psoriasis vulgaris and psoriasis guttata, which suggests that the dissimilarities found were not due to preceding or concomitant infections. In AD, there was a tendency towards increased C3a levels, whereas in psoriasis, C3a levels were significantly increased. In both diseases, no measurable amounts of C5a could be detected. The results indicate that, in both AD and psoriasis, the complement participates in the inflammatory process. Elevated levels of C3a suggest that there is a continuous activation of the complement system leading to the generation of inflammatory mediators.

Evaluation of euglobulin methods for the study of blood fibrinolytic activity: results for patients with rheumatoid arthritis and in the postoperative period

Euglobulin fractionation is a frequently employed pretreatment of plasma for the determination of fibrinolytic activity. The fractionation procedure suffers from possible in vitro artifacts, e.g., variable precipitation of C1-inactivator. This is illustrated by the following two situations. It is shown that increased amounts of C1-inactivator not related to an increased plasma concentration are present in euglobulin fractions in cases of classic rheumatoid arthritis. Similarly, postoperatively, a disproportional increase in C1-inactivator in euglobulin fractions occurs. In both cases, an artificially reduced fibrinolytic activity is recorded due to increased inhibition by C1-inactivator. This is circumvented and recognized by adding sodium flufenamate or C1s-esterase to euglobulin fractions to uniformly eliminate C1-inactivator. Two specific assays for tissue-type plasminogen activator activity in euglobulin fractions (as C1-inactivator-resistant activator activity and a parabolic rate assay on a synthetic substrate) correlate excellently (r = 0.8728; p less than 0.001; n = 108). The first mentioned is corrected for variable endogenous C1-inactivator; the latter assay is found to be insensitive to inhibition by C1-inactivator. It is concluded that with euglobulin methods a misinterpretation of blood fibrinolytic activity is possible in rheumatoid arthritis patients. In the postoperative period, the fibrinolytic shutdown concerns tissue-type plasminogen activator activity; the pattern of the shutdown can be misjudged in using traditional euglobulin methods.

Immunological variables and acute-phase reactants in patients with ankylosing spondylitis (Bechterew's syndrome) and their relatives

Serum and EDTA blood from 120 patients with ankylosing spondylitis (Bechterew's syndrome) and serum from 138 first-degree relatives of patients and from 42 adult blood donors were investigated. Increased serum concentrations of IgA and IgG and complement factors C3 and C4 were found in total groups of HLA B27-positive male or female patients compared with controls or relatives. The men had higher serum concentration of IgA and complement factors than the women, whereas IgM concentration was higher in the women. These patterns were found in controls, in relatives and in patients. Increased concentrations of IgA and of C4 were characteristic of all patients whereas IgG and IgM and C3 concentrations were likewise elevated in patients with peripheral joint arthritis/arthropathy. Increased levels of circulating immune complexes (CIC) were associated with peripheral joint arthritis and were strongly correlated with IgG or CRP concentrations in serum. Total haemolytic complement activity in serum was negatively correlated with concentrations of CIC or CRP indicating complement activation in patients with such complexes. No differences in serum concentrations of Ig or complement factor concentrations were seen between HLA B27-positive and negative relatives with normal sacro-iliac joints or between relatives and controls. Strong mutual correlations were seen among IgG, IgM, complement factors, CRP, SAA, sedimentation rate and alpha 2-macroglobulin. When the present findings were combined with our previous results it turned out that AS, and psoriasis with or without arthropathy, and acute anterior uveitis (AAU) in combination with sacro-iliitis, may be described as IgA-related conditions and that increased serum C4 was related to sacro-iliitis in all these disorders.

Evaluation of the degree of desialylation of serum C1-inactivator and haemopexin

The calibration curves for evaluating the degree of desialylation of C1-inactivator (sialic acid content 12.5%) and haemopexin (sialic acid content 4%) have been plotted. No desialylation of either glycoprotein occurs in normal subjects. In the patients (liver damage) studied, C1-inactivator is often desialylated, whereas haemopexin is not. In a previous report, we had shown that alpha1-acid glycoprotein is more often desialylated than alpha1-antitrypsin. Thus, it appears that the degree of desialylation of the sialic acid-rich glycoproteins is a more sensitive index of the severity of hepatic injury than that of the sialic acid-poor glycoproteins. This could be due to a defect in the sialylation process during synthesis.

Activation of blood coagulation, fibrinolytic and kallikrein systems during storage of plasma

This study deals with the question of how blood coagulation, kallikrein and fibrinolytic systems are affected by storage of plasma at +6 degrees C. Blood was collected into citrate phosphate dextrose adenine (CPD) or acid citrate dextrose (ACD) and the plasma samples were stored at +6 degrees C for 35 days. Samples were taken at weekly intervals for assays of various parameters of the different systems. No significant changes were observed in the levels of the main thrombin inhibitor, antithrombin III. At the end of the storage period, however, fibrinopeptide A levels increased markedly, particularly in the ACD plasma, indicating thrombin activation. There was no change in the plasminogen level, but a decrease in the levels of antiplasmin and urokinase inhibitors and an increase in the level of the fibrinogen degradation fragment B beta 15-42 were observed, indicating activation of the fibrinolytic system. The level of antikallikrein activity decreased sharply in ACD plasma; CPD plasma was less affected. This decrease was parallel to the increase in spontaneous proteolytic activity and correlated with the increase in fibrinopeptide A. Prolonged storage of plasma of +6 degrees C thus resulted in the activation of coagulation, fibrinolytic and kallikrein systems and decrease in inhibitors. The activation was much more pronounced in ACD than in CPD plasma.

Plasma prekallikrein, factor XII, antithrombin III, C1(-)-inhibitor and alpha 2-macroglobulin in critically ill patients with suspected disseminated intravascular coagulation (DIC)

In nine patients with suspected disseminated intravascular coagulation (DIC) and five controls, the following analyses were performed on admission and 7-29 hours later: Routine coagulation studies (fibrinogen, platelet count, fibrin(ogen) degradation products, ethanol gelation, reptilase time, Factor V) providing a semiquantitative DIC score, prekallikrein (PK), Factor XII, antithrombin III (AT-III), C1(-)-inhibitor and alpha 2-macroglobulin. Significant correlations were found: PK or AT III with the DIC-score, PK with AT-III and Factor XII, AT-III with Factor XII. The changes (expressed as a percentage of normal plasma) of PK and AT-III from the first to the second evaluation were nearly identical. The two patients with rapidly fatal irreversible shock showed the highest DIC score and a pronounced decrease of PK and AT-III, whereas in reversible shock stable or increasing PK and AT-III values were found. The other variables showed an overlap between reversible and irreversible shock. DIC in these shock patients, accompanied by a decrease in PK, probably was mediated via Factor XII activation. PK and AT-III might be of prognostic value in patients with (septic) shock.

Complement inhibitors in normal cornea and aqueous humor

C1 inhibitor, beta 1H and C3b inactivator are important inhibitory proteins that regulate the complement system. These inhibitor proteins were detected by gel double diffusion in eluates from normal corneas, but not in normal aqueous humor. Functional tests of C1 inhibitor and C3b inactivator showed low-to-absent levels of these inhibitory proteins in normal aqueous humor. On the other hand, the mean activities of C1 inhibitor and C3 inactivator in corneas were nearly as high as those in sera, and there were no statistically significant differences between the values. The lower molecular weights of complement inhibitors, relative to other complement components, may account for their higher levels in normal cornea and may tip the balance in favor of inhibition of complement activation in the noninflamed cornea.

[Immune complex and complement levels in spontaneous abortions and normal pregnancy]

We gave attention to the following as specific immunological tolerance factors in pregnancy: a) the serum levels of circulated immune complex (IC), b) serum complement levels (C1q, C3, C4, C1-Inhibitor). The results were as follows: In spontaneous abortions measured by C1q binding test (Zubler et al.) IC levels did not differ significantly from those in normal pregnancies in the first trimester, but in both cases, IC levels were slightly higher than the levels in nonpregnant women. C1q and C1-Inhibitor levels in normal pregnancies were significantly lower than in nonpregnant women, and both levels in spontaneous abortions were significantly higher than in normal pregnancies. In cases of artificial and spontaneous abortions, increased IC levels were rapidly lowered to the normal range within 7 days after treatment and lowered C1q and C1-Inhibitor levels also returned to the normal range within 7 days. But these trends were more remarkable in artificial abortions. However, C3 and C4 levels did not change after treatment in either case. A negative correlation between complement levels (C1q, C3, C4) and IC levels in the third trimester was demonstrated in our study.

Stage-related correlations between immunoglobulins and complement components in preoperative sera from patients with gastric carcinoma

Immunoglobulins A, G and M and complement components C3, C4 and C1-INH were quantitated in sera taken preoperatively from 168 patients with gastric carcinoma. The values were grouped according to stages (pTNM). The concentrations of C4 and C1-INH increased with advancing stage of disease and were above normal mean values in all stages. The concentration of IgG was below the normal mean value among all the patients and with the lowest concentration in stage III. Concentrations of IgA and C3 were above normal means but without significant relation to stages. There was a positive correlation between the concentrations of IgG and C1-INH in sera from patients with stage IV carcinoma, while the same correlation was negative in stages I-III. Although the results varied among the patients within each stage, the profiles of immunoglobulin and complement concentrations are of value in the preoperative staging of the disease.

C1 inactivator-C1s complexes in inflammatory joint disease

A newly developed enzyme linked immunosorbent assay for the quantitation of C1 inhibitor (C1In)-C1s complexes was used to study activation of the classical pathway of complement in inflammatory joint diseases. Synovial fluid (SF) specimens were obtained from patients with rheumatoid arthritis (RA), other arthritides and non-inflammatory joint effusions. Paired serum (S) samples were obtained in 17 cases. Immune complexes (IC) were measured by the staphylococcal binding assay. C1In-C1s were higher in RA SF samples than in paired RAS samples (P less than 0.01). IC were higher in RA SF than non-RA SF. There was a significant inverse correlation between SF C1In-C1s complexes and SF total haemolytic complement. For all SF samples there was a correlation between IC and C1In-C1s complexes, but for RA SF alone there was no significant correlation between these parameters. There was no correlation between titre of rheumatoid factor and C1In-C1s complexes. These results demonstrate that activation of the classical pathway of complement is the hallmark of rheumatoid synovitis, yet also suggest functional heterogeneity of both circulating and intra-articular IC.

[Complement components, whole complement activity, and circulating immune complexes in neoplastic diseases]

Serum levels of complement components(cc), whole complement activity (CH 50), and circulating immune complexes (IC) were measured in 41 patients with neoplastic diseases. The level of cc was higher than in healthy controls; the levels of C1q, C1INA, C4, C3c, C3ACT, C5, and C9 were statistically higher. In patients with lung cancer, the levels of cc were correlated with the clinical stage as well as the performance status. Both the IC serum level and the incidence of high serum IC levels in lung cancer were higher in stage III and IV than in stage I and II. Serum CH 50 was higher than in healthy controls, but not correlated with the clinical stage.

Heparin-stimulated modification of C1-inhibitor by subcomponent C1s of human complement

C1-inhibitor and C1s form a very stable complex which migrates with an apparent molecular mass of 180 kDa in dodecyl sulfate gel electrophoresis. A small fraction of the inhibitor (100 kDa) was found to be converted to a large (95 kDa) and a small (2 to 5 kDa) fragment during this reaction. It is concluded that C1-inhibitor is modified by C1s in a similar way as are the related plasma inhibitors alpha 1-proteinase inhibitor, antithrombin III and antiplasmin by their specific proteinases. The fraction of modified C1-inhibitor increased when heparin was present during complex formation. This reaction was complete after 15 s and is comparable with the fast heparin induced formation of modified antithrombin III. Treatment with hydroxylamine led to a complete dissociation of the inhibitor-enzyme complex by dodecyl sulfate. The large inhibitor fragment (and not unmodified inhibitor as reported by other authors) was released.

Complement, coagulation and fibrinolytic parameters in hereditary angioedema (HAE)

The intrinsic clotting, the kinin generating and the fibrinolytic systems were investigated in 10 patients with hereditary angioedema (HAE), 10 patients with chronic urticaria and 18 healthy volunteers. In spite of the fact that patients suffering from HAE severely lack C1 INH, neither the intrinsic coagulation nor the fibrinolytic systems are impaired. There was a slight decrease of plasma kallikrein--as already known--and moreover a greater decrease in HMW-kininogen, and increase in Factor XII levels. Furthermore, activation of pre-kallikrein was delayed in these patients. These findings make it apparent that lowered HMW-kininogen levels compensate the lack of C1 INH, thus preventing an enhanced activation of the intrinsic clotting and the fibrinolytic systems.

Effect of nonviable tissue and abscesses on complement depletion and the development of bacteremia

Complement concentrations and blood cultures were compared in 58 patients within 24 hours of injury and weekly thereafter. Extensive amounts of nonviable tissue (n = 40) were associated with a mean depletion of C4, C3, and C5 by 56%, and minor injuries (n = 18) by 22% of normal concentration within 14 hours after injury. The C4, C3, and C5 concentrations returned to normal or above within a week after minor injuries, but not following major injuries. However, C4, c3, and C5 levels remained depressed after major injuries unless necrotic tissue was removed or abscesses were drained. If complement concentration was below 50% of normal for more than a week all patients developed bacteremia. Following debridement or drainage complement returned to normal in 11 patients and blood cultures became negative in seven. Possible consequences by activation and altered availability of complement for chemotaxis, opsonization, and lysis of bacteria have been analyzed and related to the development of bacteremia.

New and rapid functional assay for C1 inhibitor in human plasma

C1 inhibitor (C1-INH) and alpha 2-macroglobulin (alpha 2M) account for over 90% of the inactivation of purified plasma kallikrein by normal human plasma. The rate of kallikrein inactivation is also dependent on the presence of high molecular weight kininogen (HMWK), which forms a reversible complex with kallikrein protecting the active site of the enzyme against inhibitors. By selectively inactivating alpha 2M with methylamine, and eliminating the protective effect of HMWK by dilution, the inactivation of kallikrein by plasma became almost exclusively dependent on C1-INH. Functional C1 inhibitor was assessed by measuring the pseudo-first-order rate constant for the inactivation of kallikrein by diluted methylamine-treated plasma in 29 individuals, including 11 controls, 11 oral contraceptive users, 5 patients with classical hereditary angioedema (HAE), and 2 patients with variant HAE. Over a wide range of concentrations, an excellent correlation (r = 0.90) was observed between functional and antigenic C1-INH among controls, oral contraceptive users, and patients with classical HAE. This new functional assay for C1-INH can be performed in less than 3 hr with commercially available reagents. Therefore, this assay will be helpful for the diagnosis and management of conditions associated with the deficiency of C1-INH, such as HAE.

A rapid method for functional determination of C1 esterase inhibitor in plasma

A functional determination of C1 esterase inhibitor (C1 INH) can be easily performed with an amidolytic assay by monitoring the inactivation of plasma kallikrein. In patients with urticaria as well as in healthy donors kallikrein inactivation, determined as the ratio of kallikrein activity at t60/t15, was found to be 0.47 +/- 0.06; in patients with hereditary angioneurotic edema (HANE). However, it amounted to 0.80 +/- 0.06. There was a good correlation between the inactivation rate of kallikrein and the protein levels of C1 INH (r = -0.93, p less than 0.001). In patients with HANE, levels of plasma kallikrein were slightly decreased (mean = 0.37 +/- 0.11 U/ml, normal mean = 0.47 +/- 0.09 U/ml), but still sufficient for monitoring kallikrein inactivation. In the case of one patient with functionally inactive C1 INH protein, the inactivation of kallikrein was impaired as in the conventional form of the disease.

[Studies on relationship between complement and blood coagulation system in toxemia of pregnancy (author's transl)]

Presence of chronic DIC (disseminated intravascular coagulation) eliciting an impeded blood coagulation has been postulated of late as one of the etiology causing toxemia of pregnancy, for which studies have been immunologically made. These theories remain unestablished. In this regard, the role of complement in blood coagulation has been noted, and their correlation is being elucidated. The author introduced a concept of complement to etiological theory of an impeded blood coagulation origin, by which toxemia of pregnancy was studied with emphasis placed on their correlation. The results obtained are as follow: 1) Thrombin and thromboplastin allowed in vitro to decreases the potency of complement, and the lowering also was seen even in the case of simultaneous supplement of urokinase and plasminogen. 2) The decrease also was periodically seen in rabbit's DIC experimentally made. 3) An increase in CH50, C3, C4, and factor B of normal pregnancy were of significance when compared with those of the control (p less than 0.001), while C1 inactivator decreased significantly (p less than 0.001). 4) CH50 was 52.2 +/- 2.4U/ml in severe toxemia, a decrease being of significance (p less than 0.01) as compared with that in third trimester of normal pregnancy. Those other parameters which tended to decrease included hemolytic activity of alternative pathway (AP-CH50), C4, and factor B except C1 inactivator with a trend being high.

Complement factors and acute phase reactants in the Guillain-Barré syndrome

The concentrations of C3, C4, C1 inactivator, C3 proactivator and orosomucoid were determined in sera from 13 patients with Guillain-Barré syndrome. The most severely affected patients had the highest levels of C3, C4 and orosomucoid in the acute phase with a slight decline over the following 3-8 weeks. The mildly affected patients had complement concentrations in the upper normal range. In the group of patients with the highest concentrations of C3, C4 and orosomucoid, 4 out of 6 developed residual weakness, while residual weakness was only found in 1 out of 7 with normal concentrations. The measurement of C3 and C4 may, therefore, be of value in estimating the severity and prognosis in the early phase of the disease.

Complement levels in cigarette smokers: elevation of serum concentrations of C5, C9, and C1-inhibitor

Serum levels of 13 individual complement component and control proteins were measured in 25 male cigarette smokers and 25 male non-smokers. A significant elevation of the mean serum levels of C5, C9 and C1-inhibitor was demonstrated for the smokers while levels of C1q, C2, C4, C3, C6, C8, Factor B, properdin, C3b inactivator and beta 1H did not differ significantly between the two groups. Serum level of C9 in individual smokers correlated significantly with both the present amount of consumption and cumulative consumption, while C5 level correlated with present consumption. The complement profile in the cigarette smoker is similar to that observed in certain inflammatory conditions. The elevation of C5, C9 and C1-inhibitor levels may reflect the presence of a low grade inflammatory process in the cigarette smoker.

[Hereditary angioedema: description of a sibship and review]

Report on a newly recognized sibship with hereditary angioedema (HAE). The 27 persons investigated include 8 with decreased concentrations of C-1INH and C4 in the Serum. Three of these are children without symptoms of HAE. Five patients have characteristic attacks of HAE, some of which are predominantly abdominal. The effects of treatment with danazol in 4 patients are described. HAE is briefly reviewed with special reference to pathogenesis and treatment.

First component of complement and thrombosis

The previous demonstration of an association between the collagen-like region of C1q (subcomponent of the first component of complement) and human platelets and of the inhibitory properties of C1q on platelet adhesion and aggregation to or by collagen has led us to consider the first component of complement as a possible modulator of the platelet-collagen interaction. Since collagen represents a major component of the vessel wall, the modification of C1 could play a role in the development of thrombosis. We have therefore studied two patients with abnormalities of complement (low or undetectable C1, C4, C2 and deficiency in C1 inhibitor) who presented with acquired angioneurotic oedema. Both patients had a history of multiple episodes of arterial and/or venous thrombosis. Platelet associated C1q was decreased or undetectable, and this condition was associated with a specific increase of collagen induced aggregation thereby suggesting a possible mechanism for the recurrent thromboembolic episodes.

Complement inhibitors and immunoconglutinins in ulcerative colitis and Crohn's disease

The serum concentrations of the complement inactivators C1INH, C3bINA and beta 1H have been determined in patients with ulcerative colitis and Crohn's disease and their correlation with C3 and properdin factor B examined. The incidence of immunoconglutinins (1K) in these patients was investigated. Raised serum concentrations of C1INH and C3bINA have been found in patients with active disease, but no significant alteration was found in serum concentration of beta 1H. An increasing incidence of positive 1K titres was found with increased length of disease history. These results suggest continuing complement activation in these diseases.

Changes in complement and coagulation factors in a patient suffering a severe anaphylactoid reaction to injected contrast material: some considerations of pathogenesis

A patient, suffering a severe anaphylactoid reaction to contrast material injected for an intravenous pyelogram, developed a consumption coagulopathy and evidence of complement activation. Precontrast complement values suggested that the patient had been processing complement via the classical pathway, perhaps as a consequence of an earlier protracted Klebsiella infection. Following contrast injection, a precipitous fall in hemolytic complement (CH50) and in the concentration of the C1 esterase inhibitor (C1INH) developed, as well as a diminution in C4 and C3 with the evolution of C3 conversion products. The possible role that these changes might play in the pathogenesis of idiosyncratic reactions to contrast media is considered.

Rapid fibrinolysis, augmented Hageman factor (factor XII) titers, and decreased C1 esterase inhibitor titers in women taking oral contraceptives

The use of OCAs has been associated with multiple hemostatic abnormalities and an increased risk of thromboembolic disease. These changes have been attributed to increased synthesis of various clotting factors and decreased titers of antithrombin III. Paradoxically, enhanced in vitro fibrinolytic activity is also found in plasmas of women using OCAs. The present study demonstrates marked elevation of both procoagulant and antigenic HF titers in plasmas of women using OCAs, accompanied by a simultaneous decrease in plasma C-1-INH concentration. Titers of plasma prekallikrein, HMW kininogen, PTA, and alpha 2-Pl were unchanged. The rate of kaolin-assisted fibrinolysis was related directly to the titer of HF and inversely to C-1-INH concentration. Further, the addition of human HF to normal plasma enhanced fibrinolytic activity to a degree similar to that observed in plasmas of women taking OCAs. These data suggest that the increase in plasma HF concentration may participate in the phenomenon of enhanced in vitro fibrinolysis associated with OCA use, possibly augmented by diminished inhibitory control by C-1-INH. The relationship of these phenomena to the increased incidence of thrombosis is not known.

treatment of hereditary angio-oedema by low dose attenuated androgens: disassociation of clinical response from levels of C1 esterase inhibitor and C4

Nine patients with hereditary angio-oedema (H.A.E.) with a deficiency of C1 esterase inhibitor (C1 INH), have been treated with low dose attenuated androgenic drugs, with complete control of their disease. The C1 esterase inhibitor and C4 levels became normal in only one patient. It is concluded that H.A.E. can be controlled in the absence of correction of the reduced levels of C1 INH and C4. The mode of action of these drugs appears to be more complex than is generally realized.