Complement-induced solubilization of C-reactive protein-pneumococcal C-polysaccharide precipitates: evidence for covalent binding of complement proteins to C-reactive protein and to pneumococcal C-polysaccharide

Insoluble precipitates between C-reactive protein and pneumococcal C-polysaccharide were solubilized by fresh but not heat-inactivated human serum. Solubilization was dependent on the C-reactive protein to C-polysaccharide ratio and the serum concentration and proceeded optimally at 37 degrees C. On 12 to 30% sucrose density gradients solubilized complexes sedimented as a broad peak between the 7S region and the bottom of the tube. In C2-deficient human serum, solubilization was delayed by 30 min and then proceeded at a slow rate. Immunoprecipitation experiments indicated that C3, C4, C5, and to a lesser extent C1q were deposited on solubilized complexes. After dissociating solubilized complexes with EDTA, a considerable percentage of C-polysaccharide coprecipitated with C3, C4, and C5, whereas C-reactive protein coprecipitated with only C3. SDS-PAGE analysis of solubilized precipitates indicated the formation of covalent complexes between fragments of C3 and both C-polysaccharide and C-reactive protein.

Interactions of C-reactive protein with lymphoid cells

The interactions between CRP and peripheral blood lymphocytes were investigated. CRP, in the presence of an appropriate ligand, bound saturably to a small percentage of normal PBL. The characteristics and optimal conditions for this binding were defined using several different assay systems. CRP was found to bind preferentially to cells with the IgG FcR. Binding was increased in the presence of acute phase sera, and higher numbers of cells binding CRP were observed in acute phase individuals. CRP and CRP-CPS had minimal effects upon lymphocyte responsiveness in vitro, although enhancing effects on MLC and CMC reactions, and a slight blastogenic effect, were observed. CRP antigenicity was detected on a small percentage of PBL, and treatment of PBL with anti-CRP and complement led to loss of NK reactivity, suggesting a possible association of CRP with this function. The functional expression of binding of CRP complexes, the relationship of the CRP-binding site to surface CRP antigenicity and the FcR, and the role of these factors in lymphocyte functions such as NK reactivity and recognition, are yet to be determined.

Interaction of very low density lipoproteins (VLDL) with rabbit C-reactive protein

Rabbit CRP is similar to human CRP in structure, kinetics of appearance, and binding reactivities to phosphate esters and cationic polymers. CRP in rabbit acute-phase serum migrates either with gamma or with beta, pre-beta electrophoretic mobility, and distinct gamma- and beta-migrating species can be observed simultaneously in some sera. The present study shows that beta-CRP in serum is converted to gamma mobility during isolation and purification. Normal, acute-phase, or CRP-depleted acute-phase rabbit serum restores the beta mobility of purified gamma-CRP, a conversion that does not occur in the presence of EDTA. Serum CRP fails to adsorb to DEAE-cellulose but does adsorb to CM-cellulose, from which it elutes as gamma-mobility antigen. Chelation by EDTA or flotation and removal of lipoproteins from acute phase rabbit serum produces a gamma-mobility CRP that adsorbs to the anion-exchange resin. Lipid-containing fractions from ion-exchange columns as well as VLDL (but not LDL or HDL) isolated by ultracentrifugation change the mobility of purified CRP from gamma to beta, pre-beta. These changes in mobility are not observed in the presence of EDTA or phosphocholine. In acute-phase rabbit serum with CRP of both beta and gamma mobility, the beta form has a higher m.w. and is lipid-associated, whereas the gamma form is a lower m.w., lipid-poor molecule. These results suggest that in serum the association of CRP with lipoproteins, particularly VLDL, is responsible for its beta, pre-beta electrophoretic mobility. Further studies of the association of CRP with lipoprotein in relation to lipoprotein metabolism may provide insight into the biological role of CRP.

Serum concanavalin-A binding in rheumatoid arthritis

A nephelometric assay of concanavalin-A binding of serum acute phase proteins (con-A binding) has been used in cross-sectional and sequential studies of disease activity in rheumatoid arthritis (RA). Con-A binding correlated well with blood viscosity, C-reactive protein, and other individual acute phase reactants in patients with active RA. Twenty-four patients were treated for 6 months with D-penicillamine and assessed clinically and seriologically. Clinical improvement was accompanied by significant falls in both C-reactive protein and con-A binding, although the serological changes did not always occur in parallel in individual patients. The advantages of this simple, cheap assay of acute phase proteins are discussed.

Reduced amyloid-A-degrading activity in serum in amyloidosis associated with rheumatoid arthritis

The ability to degrade amyloid A fibrils was studied in the serum of 31 patients with amyloidosis associated with rheumatoid arthritis, 33 patients with rheumatoid arthritis without amyloidosis, and 47 healthy controls. Fibrillar amyloid A protein and the radial diffusion method were used. The mean degrading activity in serum was significantly lower in patients with rheumatoid arthritis complicated by amyloidosis (58 +/- 19% SD of the activity in a pooled sample of sera from 100 healthy blood donors used as standard) than in patients with rheumatoid arthritis alone (78 +/- 14%; p less than 0.001) or controls (99 +/- 19%; p less than 0.001). Alpha 1-antitrypsin, concentrations of which were raised in both groups of patients, inhibited the degrading activity in serum even in low concentrations. A negative correlation between degrading activity and alpha 1-antitrypsin concentrations was observed. These findings suggest that reduced amyloid-A-degrading activity is due to inhibition rather than to deficiency of enzyme.

The amylase-to-creatinine clearance ratio--a non-specific response to acute illness?

It was felt that the apparent specificity of the amylase-to-creatine clearance ratio (ACCR) in several previous studies of pancreatitis might reflect a failure to utilize adequately ill control subjects. The ACCR and the renal clearances of beta 2-microglobulin (B2-m), similarly related to creatinine (BCCR) as well as the urinary concentration of albumin, were compared in 27 patients with acute pancreatitis, 8 with a perforated peptic ulcer and 7 with mild biliary colic, during the first 5 days in hospital. Acute pancreatitis was graded as mild (6), moderate (14) or severe (7), using a combination of clinical data, diagnostic peritoneal lavage and multiple criteria. Further assessment of the severity of the acute illness was obtained from measurement of C-reactive protein (C-RP). Lowest C-RP levels were found in the patients with mild pancreatitis and biliary colic, and highest levels in the patients with severe pancreatitis and perforated ulcer (P less than 0.002). Similarly, ACCR and BCCR levels were significantly lower in the two mild groups than in the two severe ones (P less than 0.01 and less than 0.002 respectively), although plasma amylase was raised only in patients with pancreatitis and plasma B2-m was similar in all groups. Electrophoresis of urine showed dense bands of tubuloprotein in patients from both severe groups. Urine albumin was higher in severe pancreatitis than in perforated ulcer (P less than 0.1), perhaps indicating a more specific glomerular lesion in pancreatitis. Thus a rise in amylase clearance appeared to be related to the severity of the acute illness, and may be a component of a non-specific tubuloproteinuria. In this study patients with a perforated peptic ulcer had increases in ACCR similar to those seen in patients with severe pancreatitis, and we are therefore doubtful whether ACCR has any role in the clinical diagnosis of pancreatic disease.

A remarkable increase of superoxide dismutase activity in synovial fluid of patients with rheumatoid arthritis

Superoxide dismutase activities in the synovial fluid of patients with rheumatoid arthritis and osteoarthritis were determined by the technique of McCord and Fridovich. The superoxide dismutase activity from the rheumatoid arthritis group was found to be remarkably higher than that from the osteoarthritis group. The high superoxide dismutase activity of rheumatoid arthritis is correlated with the severity of the disease. A significant correlation was also found between C-reactive protein and superoxide dismutase activity. These observations suggest that superoxide dismutase activity is a manifestation of the acute inflammatory stage of rheumatoid arthritis.

Prognostic significance of serum CRP levels and lymphoid cell infiltrates in human breast cancer

As part of a major study to identify prognostic factors for human breast cancer we evaluated serum C-reactive protein (CRP) concentration and extent of lymphocytic infiltration of the tumor as prognostic markers. Elevated serum CRP concentrations were present in a higher proportion of patients with stage IV disease, the presence of metastasis, and the presence of leukocytic infiltration of the primary tumor. CRP levels did not correlate with the length of the disease-free interval following surgery, the histopathological grade of the tumor, or lymph node involvement. Although serum CRP levels and the presence of a lymphoid cell infiltrate correlated with each other, neither measure was a useful prognostic indicator.

Binding of C-reactive protein to human lymphocytes. II. Interaction with a subset of cells bearing the Fc receptor

In the preceding paper we reported that C-reactive protein (CRP) in the presence of a multimeric binding specificity such as C-polysaccharide (CPS) binds to a small percentage of peripheral blood lymphocytes (PBL). In the present paper additional methods for demonstrating this binding were developed and utilized to help characterize the CRP-binding cell. Heat-modified CRP and E-CPS-CRP each were found to bind to a similar percentage of PBL by microscopic visualization, and an identical degree of binding was observed by cytofluorimetric analysis. Multiple marker studies indicated that CRP-binding cells are found in the T cell, B cell, and null cell categories in a ratio of 2:1:1, respectively. Preferential overlap was seen with IgG FcR-bearing cells, which accounted for 70% of the CRP-binding cells; however, only 12% of the FcR cells bound CRP. These studies indicate that CRP-binding cells predominantly represent a subset of cells bearing FcR, and these cells have the morphologic characteristics of large granular lymphocytes. CRP in the presence of CPS bound to cells of multiple human and murine cultured lines shown to have IgG FcR reactivity, but showed lesser or no binding to cell lines negative for FcR. The precise morphologic and functional characterization of the CRP-binding cells and the nature of the binding site are yet to be established.

Binding of C-reactive protein to human lymphocytes. I. Requirement for a binding specificity

Our laboratory previously reported that C-reactive protein (CRP) binds selectively to T lymphocytes and inhibits certain of their reactivities in vitro. However, these findings could not be repeated using more highly purified CRP preparations even under a variety of experimental conditions. Purified CRP alone did not bind to peripheral blood lymphocytes (PBL); however, in the presence of a ligand such as pneumococcal C-polysaccharide (CPS), CRP binding was readily detectable both by immunofluorescence and by a radioassay established for this purpose. The optimal concentration of CRP, ratio of CRP:CPS, and time and temperature for reactivity were determined using both assays. A markedly enhanced rate of binding was observed after pre-equilibration of CRP with calcium. A small percentage (mean 3.0%; range 0.5 to 8.0%) of PBL bound complexed CRP, and saturation was reached with 200 microgram CRP/ml. Reactivity of CRP with a multimeric form of phosphocholine (PC) (KLH-PC44) led to binding comparable to that observed with CPS, whereas monomeric PC inhibited the binding. Thus, in the presence of a multimeric binding specificity, CRP binds to a small fraction of peripheral blood lymphocytes, which are characterized in the accompanying paper.

Complement in pneumococcal infections with varying degrees of severity

Complement component levels (Clq, Cls, C4, C3, factor B and properdin) and C1 subcomponent complexes (C1r-C1s, C1-r-C1-, C1-r-C1-s-C1 inactivator, 1A) were studied in 16 adults with pneumococcal infections varying severity. Patients with fulminant disease and signs of septic shock showed pronounced hypocomplementemia. In patients with pneumococcal pneumonia or meningitis elevated levels of C1-r-C1-s-C1- IA complexes indicated activation of C1, despite normal levels of C1q, C1s, C4 and C3. Moderately decreased properdin values suggested involvement of the alternative pathway. In adults with pneumococcal otitis no changes in the complement profile was found. In contrast, pronounced aberrations of the C1 subcomponents were earlier demonstrated in children with otitis.

Inhibitory effect of C-reactive protein on alternative C pathway activation by liposomes and Streptococcus pneumoniae

C-reactive protein (CRP) is an acute phase serum protein found associated with damaged tissue at sites of inflammation. CRP bound to multivalent phosphocholine-containing or polycationic ligands activates C by the classical pathway. We have previously described liposomes of a particular lipid composition that are able both to activate the alternative pathway of C and to bind CRP. In addition many strains of Streptococcus pneumoniae activate the alternative pathway. We have shown CRP binding to these bacteria as well. Because antibody to an activating surface in many cases enhances alternative pathway activation, we tested CRP for a similar function in these systems. Our results indicate that, in contrast to antibody, CRP inhibits alternative pathway activation. This inhibition by CRP is apparently restricted to surfaces that bind CRP. Thus, CRP binding to membrane or bacterial surfaces can convert them from alternative pathway activation to classical pathway activation.

Reactivity of human C-reactive protein with positively charged liposomes

Interaction of CRP with liposomes was studied by agglutination, complement consumption, and the binding assay. Liposomes composed of phosphatidylcholine and stearylamine were agglutinated with CRP. The interaction of CRP and liposomes was further demonstrated by the consumption of hemolytic complement activity. Stearylamine could be substituted by cetyltrimethylammonium bromide, indicating that positively charged molecules were required for the interaction. Agglutination of liposomes caused by CRP was dependent on the fatty acid composition of phosphatidylcholine, cholesterol content and temperature. Differential scanning calorimetry measurement revealed that both the agglutination of liposomes and the consumption of complement caused by CRP required the fluid state of membranes. Particle electrophoresis measurement showed that stearylamine in fluid state membranes was more dispersed than in rigid state membranes indicating that lateral distribution of stearylamine affected the reactivity of liposomes. The mode of complement activation by the interaction of CRP with positively charged liposomes was similar to that observed in the system of protamine and heparin.

Binding reactivity of C-reactive protein for polycations. II. Modulatory effects of calcium and phosphocholine

C-reactive protein previously was shown to selectively and reversibly precipitate with certain small polymers of arginine and lysine. In the present report, calcium was shown to inhibit this reactivity in a dose-dependent manner, in direct contrast to the requirement for calcium for precipitation of CRP with C-polysaccharide. However, in the presence of phosphocholine, CRP rapidly precipitated and formed stable complexes with the polycationic polymers in the otherwise inhibitory calcium concentrations. alpha-Glycerol-phosphocholine, unlike phosphocholine, did not reverse this inhibitory effect. These results extend the characterization of the binding reactivity of CRP for polycations and suggest a relationship between this binding site and the sites for calcium and phosphocholine. We propose that CRP-polycation interactions in the presence of phosphocholine may have physiologic significance during the acute inflammatory process.

[Stress-metabolism after myocardial infarction-demonstrated by means of the behaviour of plasma proteins with short half-life (author's transl)]

The kinetics of plasma proteins with short half-life during stress-metabolism in patients after myocardial infarction with and without clinical complications and after angina pectoris were compared. The acute-phase proteins alpha1-antitrypsin, C-reactive protein (CRP), fibrinogen, haptoglobin, and the transport proteins prealbumin and transferrin were analyzed with the method of radial immunodiffusion. Whereas angina pectoris doesn't influence the protein kinetics, one can recognize after myocardial infarction a continuous increase of the acute-phase proteins to maxima between the 3rd and 5th day after the attack. Parallel to these changes, the transport proteins decrease with subsequent increase. The changes, which are similar to those seen after surgical trauma, are dependent on the severity of illness, and can be used as prognostic parameters. During stress metabolism, the concentrations of the proteins depending on nutrition, prealbumin and transferrin, are modified by the type and severity of stress, and by nutritional influences. The mechanisms of these changes and the consequences for their use as diagnostic parameters are discussed.

Interaction of C-reactive protein with artificial phosphatidylcholine bilayers and complement

We have examined the interaction of C-reactive protein (CRP) with model membranes and complement. Binding of CRP to multilamellar liposomes or unilamellar vesicles of egg-phosphatidylcholine required the presence of lysophosphatide in the bilayer. The binding was Ca++-dependent, could be inhibited by phosphocholine, and resulted in activation of the classical complement pathway. A weak interaction between CRP and agarose was observed, which was also CA++-dependent and could be inhibited by phosphocholine and galactose. In addition, incorporation of galactocyl cerebroside in phosphatidylcholine:lysophosphatidylcholine liposomes enhanced the binding of CRP. Binding constants of 1.9 X 10(-5) M and 7.1 X 10(-5) M were calculated for liposomes containing and lacking the glycolipid, respectively. Furthermore, CRP bound to galactocyl cerebroside-containing liposomes bound approximately twice as much C1q as the same amount of CRP bound to liposomes lacking the glycolipid. We conclude that: 1) An alteration of the normal organization of phosphatidylcholine bilayers is necessary for binding of CRP. 2) The presence of galactosyl residues on the surface of the bilayer enhances the binding of CRP, perhaps through interaction with a putative secondary binding site on the protein.

Serial study of C-reactive protein during infection in leukaemia

Serum C-reactive protein was studied serially by a 1-hour laser nephelometric assay in 25 patients with leukaemia who developed 34 episodes of infection. The serum level rose above, or by, 100mg/l in 29 of the episodes. Serial measurement of this acute-phase reactant was of value in detecting infection in the neutropenic patient and in monitoring the response to antibiotic therapy.

Interaction of C-reactive protein with liposomes. III. Membrane requirements for binding

We have previously presented a model for CRP-membrane interactions using liposomes composed of dimyristoyl phosphatidylcholine (DMPC), cholesterol (CHOL), stearylamine (SA), and galactosyl ceramide. We have shown that the interaction of cRP with these liposomes in the presence of human serum results in consumption of hemolytic C and membrane lysis. In the present paper we have directly examined the binding reaction between CRP and liposomes using radiolabeled CRP. We have found that this binding is more characteristic of CRP interactions with polycations than CRP interactions with phosphocholine- (PC) containing molecules. CRP binding to liposomes was dependent on the presence of SA in the membrane and could occur with dimyristoyl phosphatidylethanolamine in place of DMPC. The binding was not inhibited by ethylenediaminetetraacetate (EDTA) but could be inhibited by CaCl2, whereas CRP binding to PC-Sepharose was inhibited by EDTA and required CaCl2. We have further examined the effects of changes in membrane composition on CRP binding to liposomes. In liposomes with a limiting density of SA, we found increased CRP binding with changes in composition that would increase membrane fluidity. In most cases, the amount of CRP binding correlated with the amount of C activation observed previously. However, increasing the amount of CHOL in the membrane was found to increase C activation while decreasing CRP binding. These findings indicate that CRP binding to membranes and subsequent C activation can occur through cationic molecules as well as phospholipids.

A biochemical comparison of alclofenac and D-penicillamine in rheumatoid arthritis

In view of the claim that alclofenac has a specific antirheumatoid action a detailed biochemical study has been made over a 6-month period of 2 groups of patients with rheumatoid arthritis receiving either alclofenac or D-penicillamine for the first time. We found no biochemical evidence and little clinical evidence that alclofenac had a 'penicillamine-like' effect in rheumatoid arthritis.

Value of serum C-reactive protein measurement in the investigation of fever in systemic lupus erythematosus

The concentration of C-reactive protein (CRP) in the sera of patients with systemic lupus erythematosus (SLE) was higher when the disease was active than when it was inactive, but was only markedly raised in patients suffering from identifiable microbial infection. CRP levels greater than 60 mg/l suggest the presence of intercurrent infection and may therefore be a valuable aid to the differential diagnosis of pyrexia in SLE.

Elevated serum beta 2-microglobulin levels and C1q-binding immune complexes in sarcoidosis

Serum beta 2 microglobulin levels were found significantly higher (3.05 +/- 0.98 mg/l) in 32 sarcoidosis patients without renal dysfunction than in normal controls (1.54 +/- 0.22 mg/l). Low levels of C1q-binding immune complexes were detected in 70% of patient's sera, despite the absence of extra-thoracic manifestations. C-reactive protein was detected in 55% of sarcoidosis sera. Neither C1q-binding immune complexes nor C-reactive protein were correlated with beta 2 microglobulin levels. Beta 2 microglobulin raised during relapses and fell under efficient corticosteroid treatment. Beta 2 microglobulin would represent a possible biological marker of disease activity.

Interactions of C-reactive protein and complement with liposomes. II. Influence of membrane composition

We found previoulsy that interaction of C-reactive protein (CRP) with liposomal model membranes resulted in complement(C)-dependent membrane damage. In the present study, we investigated the influence of membrane composition on the interactions of CRP and C with liposomes. Adsorption experiments showed that binding of CRP was greatest to strongly positive liposomes. A lesser, but still substantial, extent of CRP binding also was observed with negative liposomes, but negligible amounts of CRP bound to neutral or weakly positive liposomes. CRP-mediated consumption of hemolytic C, and C-dependent glucose release from liposomes both were strongly influenced by liposomal charge, positive being superior to negative. Glucose release and, to a lesser extent, consumption of hemolytic C were inversely related to phospholipid fatty acyl chain length. Phospholipid fatty acyl unsaturation and liposomal cholesterol concentration both had strong influences on C consumption and glucose release. The data suggest that CRP-mediated C consumption and membrane damage require an optimum membrane fluidity. Complement damage in the presence of CRP was enhanced by certain sphingolipids and also by digalactosyl diglyceride, but not by sphingomyelin. Our results thus demonstrate that CRP-mediated C consumption and C-dependent membrane damage both are influenced by the liposomal membrane composition.

Control of the acute phase response. Demonstration of C-reactive protein synthesis and secretion by hepatocytes during acute inflammation in the rabbit

To determine the cell of origin of C-reactive protein (CRP) and to cast light on the mechanisms leading to the acute phase response, we used an immunoenzymatic technique to visualize this protein in livers from rabbits at intervals after intramuscular injection of turpentine. CRP was detected only in hepatocytes. 8 h after turpentine injection, CRP was demonstrated in occasional periportal hepatocytes. With time, larger numbers of positive cells were detected successively in perilobular, midlobular, and centrilobular areas. On electron microscopy, CRP was detected in rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), and Golgi apparatus (GA). When colchicine was administered to inhibit cellular secretion of CRP, intensity of reaction and number of CRP-containing hepatocytes were substantially greater than without colchicine, but the sequence of intralobular distribution was similar. At peak serum response 38 h after turpentine injection, CRP could be demonstrated in most hepatocytes. Electron microscopic studies showed accumulation of CRP on membranes and lumina of RER, SER, GA, and in cytoplasmic vacuoles. These findings indicate that CRP is produced by progressively increasing numbers of hepatocytes after inflammatory stimulus and suggest that a mediator, acting initially in portal zones, is responsible for recruitment of cells to CRP production.

Salazopyrin in rheumatoid arthritis

After a 12-week preliminary period of observation 32 patients with consistently active rheumatoid arthritis (RA) were treated for up to 22 weeks with salazopyrin. Seven patients could not tolerate the drug. The remaining 25 patients had a marked improvement in subjective clinical state and significant falls in serum C-reactive protein and the erythrocyte sedimentation rate 6 weeks after treatment began. The improvement was maintained after 22 weeks. The results strongly suggest that further trials with this drug in RA are needed.

Lymphocytes binding C-reactive protein during acute rheumatic fever

Lymphocytes binding C-reactive protein (CRP) were studied in 31 patients with acute rheumatic fever and 30 controls who were children. Marked elevations in both proportions and absolute numbers of CRP-binding lymphocytes were recorded in rheumatic fever (P less than 0.001). No clear correlation was noted between plasma CRP as quantitated by radioimmunoassay and proportions or numbers of CRP-binding cells. Double-labeling experiments indicated that 60-80% of CRP-binding lymphocytes also showed Fc receptors reacting with fluorescein-conjugated IgG aggregates. Passage of lymphocytes over Ig--anti-IgG columns, removed cells bearing surface Ig but not CRP-binding lymphocytes. Studies of T-cell subpopulations indicated no overlap between Tmicron- and CRP-binding cells; however about half of Tgamma-cells showed concurrent CRP binding. "Active" T-cell rosetting cells did not bind CRP. A 12-15-h incubation of lymphocytes at 37 degrees C in 5% CO2-air showed persistence of CRP binding in substantial proportions of cells particularly in acute rheumatic fever. CRP-binding lymphocytes may represent a marker for immunologically committed cells in acute rheumatic fever.

Comparative clinical study of protein SAP (amyloid P component) and C-reactive protein in serum

The serum concentration of protein SAP (amyloid P component) has been measured for the first time in a substantial series of normal individuals and patients with various diseases, and the results contrasted with the levels of the related protein C-reactive protein (CRP). The mean +/- s.d. concentration of protein SAP was 43 +/- 14 microgram/ml in seventy-six normal men, 33 +/- 10 microgram/ml in eighty-six normal women and 4 +/- 2 microgram/ml in thirty-six normal cord sera. Unlike CRP, whick is a major acute phase reactant, protein SAP was only slightly elevated in inflammatory and neoplastic diseases in which CRP was greatly increased. The level of protein SAP was significantly depressed in patients with hepatic disease, suggesting that its measurement might be of value in their management.

Changes in human serum amyloid A and C-reactive protein after etiocholanolone-induced inflammation

Secondary amyloidosis is a complication of diseases characterized by recurrent acute inflammation. In this study, a standardized stimulus which induced fever and inflammation was given to six normal subjects (19-24 yr old) to follow the fluctuation in concentration of serum amyloid A (SAA), the precursor of the secondary amyloid fibril protein. After a single intramuscular injection of etiocholanolone (0.3 mg/kg), blood samples were drawn twice a day for 12 days for determination of SAA by solid phase radioimmunoassay. From a base line of <100 mug/ml, the SAA concentration began rising within 12 h to a maximum value at about 48 h of 1,350-1,800 mug/ml in three males and 380-900 mug/ml in three females and returned to base line by 4-5 days. The SAA response showed a similar time response to C-reactive protein (CRP), a well-documented acute phase protein which was assayed semiquantitatively by capillary tube precipitin reaction. CRP, but not SAA, showed a quantitative correlation with the amount of fever induced by etiocholanolone. One subject exhibited a second rise in SAA and CRP concentrations after acute over-indulgence with alcohol, suggesting that acute liver damage may have caused an acute phase reaction. Thus, a controlled episode of fever and inflammation produced a prompt and prolonged elevation of SAA and CRP concentrations. Unlike SAA, CRP has not been implicated in the pathogenesis of amyloidosis, although its relationship to the P component of amyloid has recently been established.

Control of the acute phase response. Serum C-reactive protein kinetics after acute myocardial infarction

In order to investigate the magnitude and kinetics of the C-reactive protein (CRP) response after differing degrees of tissue injury, we studied changes in serum concentration of this acute phase protein in 19 patients after mild or extensive acute myocardial infarction. An increase in serum CRP concentration was seen in all patients. The rate of increase in concentration was found to be exponential, with a mean hourly rate constant for the entire group of patients of 0.085 (doubling time, 8.2 h). Patients with extensive infarction attained mean serum CRP levels about 4 times as great as did patients with mild infarction. No difference could be shown in the mean rate constant between these groups, the greater CRP response in the former group resulting principally from a more protracted period of rise in serum CRP concentration. A lag period before serum CRP levels began to rise was noted in only 4 of the 13 patients in whom this could be assessed. 7 of 10 patients with presumed unstable angina (coronary insufficiency) showed no rise in CRP concentration, while a small increase as noted in 3 patients. The data suggest that acute tissue injury, such as myocardial infarction, rapidly leads to acceleration in synthesis of CRP, and that the duration of this period of acceleration is related to the extent of tissue injury.

Anti-fab' antibodies in human sera. II. A study of their possible association with C-reactive protein, rheumatoid and anticomplementary factors

The present study was undertaken to determine whether a relationship could be found between Fab' antibodies and the occurrence of C-reactive protein, rheumatoid and anticomplementary factors in the serum of patients with malignancies and other illnesses. The findings argue against the possibility that Fab' antibody activity is associated with a single disease entity. The very frequent occurrence of Fab' antibodies in hospital patients as opposed to healthy blood donors implies that their function is probably indirectly related to other immunological events. There is evidence to suggest that Fab' antibodies may serve as a mechanism for clearing immune complexes.

A critique of some of the current concepts on the immunopathogenesis of rheumatoid arthritis

The interaction of polycations produced during tissue damage and C-reactive protein, and the enzymatic degradation of complement components may be positive mechanisms augmenting immune-complex/complement damage, while reduced phagocytosis and reduced chemotaxis may be negative mechanisms. In cell-mediated immunity, systems consisting of C-reactive protein, proteases, prostaglandins and immune complexes are all potentially capable of negative feedback control.

Modifications of serum glycoproteins the days following a prolonged physical exercise and the influence of physical training

Eight male subjects (mean age 24.1 +/- 2.6 years) performed at intervals of 2 weeks successively a 3 h and two 2 h runs of different running speed. The days following the running there were moderate elevations of C-reactive protein, haptoglobin, alpha-1-acid glycoprotein, coeruloplasmin, transferrin, alpha-1-antitrypsin and plasminogen. There were small or no changes of albumin, alpha-2-macroglobulin and hemopexin. The elevations of the "acute phase reactants" were examined in three male subjects following a 2 h run before and after an endurance training period of 9 weeks. This demonstrated a decreased acute phase response after training as illustrated by the changes of C-reactive protein, haptoglobin and alpha-1-acid glycoprotein in spite of higher posttraining running speeds. Well-trained athletes have elevated levels of the serum protease inhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and C1-inhibitor. These antiproteolytic glycoproteins might limit exercise-induced inflammatory reactions.

Interactions of C-reactive protein and complement with liposomes

Interactions between C-reactive protein (CRP) and liposomal model membranes containing phosphatidylcholine were investigated. These interactions, in the presence of human serum, resulted in consumption of each of the components of the classical complement pathway (C1-C9) and also resulted in complement-dependent damage and release of trapped glucose from certain types of liposomes. CRP-initiated lysis of liposomes was strongly dependent upon membrane lipid composition. Optimal activity occurred with positively charged liposomes containing galactosylceramide (galactocerebroside); positively charged liposomes lacking galactocerebroside released much less glucose, while negatively charged liposomes, either with or without galactocerebroside, did not release glucose at all. Glucose release was inhibited by free phosphocholine. Lesser, but significant, "background" glucose release independent of the presence of CRP also was observed with positively charged liposomes containing galactocerebroside, and this was associated with marked preferential consumption of the later-acting complement components (C3-C9). C2-deficient human serum failed to support CRP-dependent glucose release, but glucose release was observed upon reconstitution of the serum with C2. Guinea pig complement also did not support CRP-mediated glucose release, but upon addition of human C1q substantial glucose release was observed. We conclude that (i) CRP can sensitize appropriate liposomes for complement-dependent damage via the primary complement pathway starting at the level of C1q; (ii) of those studied, liposomes that are most susceptible to membrane damage contain phosphatidylcholine, have a positive charge, and contain a ceramide glycolipid; and (iii) such liposomes also are sensitive, although to a much lesser degree, to complement-dependent lysis initiated in the absence of CRP and involving consumption of terminal in excess of early acting complement components.

Circulating immune complexes after renal transplantation. Correlation of increased 125I-Clq binding activity with acute rejection characterized by fibrin deposition in the kidney

To assess the role of circulating immune complexes in the pathogenesis of acute rejection, sera were measured for such complexes by the (125)I-C1(q) binding assay in 45 normal subjects, 24 allografted patients undergoing acute rejection, and in 11 allografted patients in a quiescent phase. Increased C1(q)-binding activity (C1(q)-BA) was detected in 14 patients with acute rejection, 9 of whom had renal biopsies showing fibrin deposition in the vasculature together with cellular infiltrates in the tubulo-interstitial structures; renal histology was not available in the other 5 patients. The other 10 patients with acute rejection, whose biopsies showed only cellular infiltrates, and the 11 patients in a quiescent phase posttransplantation did not have increased levels of serum C1(q)-BA. Of the group with increased serum C1(q)-BA, serial studies in eight patients showed a correlation between increased serum C1(q)-BA and the occurrence of rejection; with reversal by therapy, serum C1(q)-BA returned to within normal levels. Complexes from six patients were analyzed by sucrose density gradient ultracentrifugation to have sedimentation coefficients ranging from 15S to 18.4S. After acid dissociation and analysis by double-diffusion techniques, C1(q)-reactive complexes were shown to contain IgG. Immunofluorescent studies done in five renal biopsies from this group revealed granular deposits of immunoglobulin, and (or) less frequently, of complement in the glomeruli or the tubular basement membranes. The findings suggest that circulating immune complexes may mediate the type of acute rejection characterized by fibrin deposition in the kidney. The role of circulating immune complexes arising from the recipient's original kidney disease could be excluded in 10 patients with humoral rejection, inasmuch as the underlying renal pathology was of a "nonimmunologic" nature; this was corroborated by sequential studies in six patients in whom circulating immune complexes could not be demonstrated before rejection. The participation of administered antilymphocyte globulin (ALG) as an antigen also appears to be excluded in four patients, two who were not given ALG, and in two of whom episodes of rejection occurred unrelated temporally to ALG administration.

Biochemical markers in human breast cancer

Nineteen biochemical parameters, most of which have been individually advocated as tumour-index-substances for breast cancer, were measured in 51 patients with breast disease, 42 of whom had active breast cancer. Seven of these parameters were raised in more than half of the 17 patients of the series with overt metastases; these were serum ferritin (88%), C-reactive protein (87%), carcinoembryonic antigen (81%), acid glycoprotein (75%), total alkaline phosphatase (64%), sialyl transferase (56%), andthe urinary hydroxyproline/creatinine ratio (73%). The incidence of biochemical abnormalities in patients in this group compared favourably with the results of physical methods of detecting metastases. 7 of 16 further patients without evidence of distant metastases, but who had a poor prognosis as judged by histology of the primary tumour and axillary lymph-nodes, had abnormalities of at least one of the seven parameters. 3 of these patients have relapsed within a year of mastectomy. The results suggest that these biochemical tests could assist in monitoring metastatic disease and could indicate at the time of mastectomy, patients who might benefit from immediate systemic therapy in addition to local treatment of their breast carcinomas.

Complement activation by interaction of polyanions and polycations. III. Complement activation by interaction of multiple polyanious and polycations is the presence of C-reactive protein

Interactions between heparin and protamine previously were found to result in activation of the complement (C) system. In the present investigation, this interaction was shown to result in the binding of purified C1, and this was markedly enhanced in the presence of C-reactive protein (CRP). CRP also enhanced C consumption during heparin-protamine interactions in whole serum, and in the presence of CRP depletion of C components C1-3 was observed. Similar C1 binding and C consumption in the presence of CRP were seen upon the interaction of multiple additional polyanions including DNA, ENA, hyaluronic acid, chondroitin sulfate, and dextran sulfate with the polycations protamine sulfate and poly-L-lysine. These effects were observed with CRP concentrations well within the range found in normal human sera and considerably less than those found in most acute phase sera. We suggest, therefore, C activation by polyanion-polycation interactions in the presence of CRP may be important to certain reactions of host defense and inflammation.