The acute phase response: overview and evidence of roles for both transcriptional and post-transcriptional mechanisms.
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Acute-Phase Proteins↗
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Effect of aseptic abscesses in protein-deficient rats on the relationship between interleukin-6 and the acute-phase protein, alpha 2-macroglobulin.
1. Rats established on a normal (20% protein) diet or a protein-deficient (3% protein) diet were given either a subcutaneous injection of turpentine (5 ml/kg), which induces formation of aseptic abscesses, or saline. Plasma samples were obtained at timed intervals (0-14 days) after the injection for determination of albumin, total protein, alpha 2-macroglobulin (a major acute-phase protein in the rat) and interleukin-6 concentrations. The magnitude and pattern of the acute-phase protein response was then compared with the local inflammatory reaction, assessed histologically, and with changes in the circulating concentration of interleukin-6, which is an important mediator of the acute-phase protein response. 2. After turpentine injection there was an early fall in the plasma albumin and total protein concentrations in both normal and protein-deficient rats. After 12 h the total protein concentration increased in both groups of animals reaching a peak at about 48 h, whereas the plasma albumin concentration continued to fall reaching a minimum at 48 h. The main alpha 2-macroglobulin response was delayed and attenuated in the protein-deficient rats (onset 9 versus 24 h, peak concentration 8.95 +/- 0.5 versus 5.33 +/- 0.75 g/l, P < 0.01, and area under the concentration-time curve 18.43 +/- 2.13 versus 7.96 +/- 1.48 g/l-1 days, P < 0.01, in the normal group and protein-deficient group, respectively). 3. The circulating interleukin-6 concentration showed a transient early rise at 1 h, and was followed by a larger more sustained peak at 6-48 h.(ABSTRACT TRUNCATED AT 250 WORDS)
Abscess↗
Radioimmunoassay of human C-reactive protein and levels in normal sera.
C-reactive protein (CRP) has been considered an acute-phase protein which appears only during reactions of tissue injury or inflammation. We report here the quantitation of CRP levels in normal adults and neonates made possible by the development of a sensitive and precise radioimmunoassay for human CRP which enables the detection of 3 ng. per milliliter. Serum levels in 153 healthy blood donors ranged from 68 to 8,200 ng. per milliliter, with a median value of 580 ng. per milliliter (mean = 1,340 ng. per milliliter). CRP levels in 24 normal cord serum samples ranged from 10 to 370 ng. per milliliter, with a median value of 70 ng. per milliliter (mean = 109 ng. per milliliter). CRP levels in 246 individuals evaluated for autoimmune diseases ranged to 256,000 ng. per milliliter with a median value of 13,000 ng. per milliliter (mean = 38,000 ng. per milliliter). No individual lacking CRP was detected. Thus, CRP can be considered a component of normal serum which only increases dramatically in concentration during inflammation.
Adult↗
A new function for ceruloplasmin as an acute-phase reactant in inflammation: a scavenger of superoxide anion radicals.
In summary, purified human ceruloplasmin inhibits several reactions mediated by superoxide anion in a fashion consistent with an ability to scavenge this free radical. It must be pointed out, however, that on a weight basis, the superoxide-scavenging activity of ceruloplasmin is substantially less than that of purified human erythrocyte superoxide dismutase. Nevertheless, since superoxide dismutase is almost exclusively an intracellular enzyme, ceruloplasmin probably represents the major circulating scavenger of superoxide anion radicals. The level of superoxide dismutase in human plasma has been reported to be 0.7 microgram/ml. It is not clear, however, how this was measured. We have found that concentrations of plasma exceeding 10% (v/v) interfere significantly with the assays routinely employed for detecting superoxide-scavenging activity. Consequently, we have not yet been able to quantify the superoxide-scavenging activity of either ceruloplasmin or superoxide dismutase in whole human plasma. Thus, we can only speculate that under conditions where levels of ceruloplasmin are markedly elevated, as during pregnancy, during acute infections, or in association with inflammatory diseases (such as rheumatoid arthritis), this acute-phase reactant may play a major role as a circulating scavenger of oxygen-derived free radicals.
Ceruloplasmin↗
Induction of the acute-phase serum protein SAA requires both RNA and protein synthesis.
SAA is a normal acute-phase serum protein which has been identified by its cross-reaction with antibodies to the amyloid A fibril protein, AA, that is associated with secondary amyloidosis. The induction of SAA by bacterial lipopolysaccharide (LPS) has been studied with 3 inhibitors of protein synthesis: cycloheximide, actinomycin D, and galactosamine. Each of the 3 agents when administered simultaneously with LPS completely abolishes induction of SAA for at least 6 h. They are all significantly effective when given 1.5 h after LPS but 3 h after LPS the inhibitory effect of actinomycin D on SAA induction is markedly reduced. Cycloheximide alone can also induce significant concentration of SAA, but a longer time is required than for LPS. Thus it appears that the acute-phase SAA response is characterized by both RNA and protein synthesis which is initiated by the acute-phase inducing agent and which precedes the appearance of elevated SAA concentrations in the serum.
Amyloid↗
Improved continuous-flow (SMAC) determination of serum albumin.
The albumin values determined by the bromcresol green methods do not compare well with values by more specific methods for albumin determination. The discrepancies have been related to, among other things, acute-phase reactants and are especially pronounced in the lower albumin range. These disadvantages are also inherent in a routine continuous-flow method for albumin (SMAC). The bromcresol green method has been improved considerably by shortening the reaction time before the absorbance is measured, as is described here. The modified method yields values that better agree with those by more specific methods and an influence of acute-phase reactants is no longer observed.
Autoanalysis↗
Isolation of the etiologic agent of Korean Hemorrhagic fever.
Lung tissues from 73 rodents (Apodemus agrarius coreae) gave specific immunofluorescent reactions when they reacted with sera from patients convalescing from Korean hemorrhagic fever. Similar staaining was observed in the lungs of A. agrarius inoculated with acute-phase sera obtained from two patients with this disease. The unidentified agent was successfully propagated in adult A. agrarius through eight passages representing a cumulative dilution of greater than 10(-17). Experimentally inoculated rodents developed specific fluorescent antigen in the lung, kidney, liver, parotid glands, and bladder. Organs, especially lungs, were positive beginning 10 days and continuing through 69 days after inoculation. The agent could not be cultivated in several types of cell cultures nor in laboratory animals. No fluorescence was observed when infected A. agrarius lung tissues were reacted with antisera to Marburg virus, Ebola virus, and serval arenaviruses. Diagnostic increases in immunofluorescent antibodies occurred in 113 of 116 severe and 11 of 34 milder cases of clinically suspected Korean hemorrhagic fever. Antibodies were present during the first week of symptoms, reached a peak at the end of the second week, and persisted for up to 14 years. Convalescent-phase sera from four persons suffering a similar disease in the Soviet Union were also positive for antibodies.
Animals↗
[Acute-phase proteins in women with a copper IUD (author's transl)].
Acute-phase (AP) proteins haptoglobin, alpha1-antitrypsin and C-reactive protein were measured in 50 women before and 10 to 30 weeks after insertion of a copper T-200. No statistically significant increase in AP proteins was found. Since these proteins are synthesized in the liver, the results indicate the lack of a systemic humoral reaction of the organism in women with a copper-containing IUD.
C-Reactive Protein↗
Agarose gel filtration of concentrated fecal extracts containing virus-like particles associated with hepatitis A.
Virus-like particles shown to be associated with hepatitis A infection were recently visualized by immune electron microscopy in human and chimpanzee acute-phase fecal extracts. Agarose gel filtration of concentrated chimpanzee fecal extracts containing those 27-nm diameter particles separated more than 99% of the high molecular weight fecal impurities into two major peaks as determined by absorbance at 280 and 260 nm. The hepatitis A-associated particles were found between these two peaks by both immune electron microscopy and a new immunoradiometric assay.
Animals↗
Systematic Proteome Profiling of Maternal Plasma for Development of Preeclampsia Biomarkers.
Preeclampsia (PE) is a hypertensive disorder of pregnancy with various clinical symptoms. However, traditional markers for the disease including high blood pressure and proteinuria are poor indicators of the related adverse outcomes. Here, we performed systematic proteome profiling of plasma samples obtained from pregnant women with PE to identify clinically effective diagnostic biomarkers. Proteome profiling was performed using TMT-based liquid chromatography-mass spectrometry (LC-MS/MS) followed by subsequent verification by multiple reaction monitoring (MRM) analysis on normal and PE maternal plasma samples. Functional annotations of differentially expressed proteins (DEPs) in PE were predicted using bioinformatic tools. The diagnostic accuracies of the biomarkers for PE were estimated according to the area under the receiver-operating characteristics curve (AUC). A total of 1307 proteins were identified, and 870 proteins of them were quantified from plasma samples. Significant differences were evident in 138 DEPs, including 71 upregulated DEPs and 67 downregulated DEPs in the PE group, compared with those in the control group. Upregulated proteins were significantly associated with biological processes including platelet degranulation, proteolysis, lipoprotein metabolism, and cholesterol efflux. Biological processes including blood coagulation and acute-phase response were enriched for down-regulated proteins. Of these, 40 proteins were subsequently validated in an independent cohort of 26 PE patients and 29 healthy controls. APOM, LCN2, and QSOX1 showed high diagnostic accuracies for PE detection (AUC >0.9 and p < 0.001, for all) as validated by MRM and ELISA. Our data demonstrate that three plasma biomarkers, identified by systematic proteomic profiling, present a possibility for the assessment of PE, independent of the clinical characteristics of pregnant women.
Humans↗
The in vitro interactions of rat pancreatic elastase and normal and inflammatory ray serum.
The partition of labelled rat pancreatic elastase (EC 3.4.21.11) between the different protease inhibitors of rat plasma was studied at different levels of saturation of the inhibitors of rat plasma was studied at different levels of saturation of the inhibitor capacity of plasma with the enzyme. The reaction mixtures were analysed by immunoelectrophoretic methods utilizing specific antisera against the different inhibitors and by gel filtration on Sephadex G-200. Rat serum was shown to contain four elastase binding proteins. alpha 1-antitrypsin, alpha 1-macroglobulin and alpha 2-acute phase protein and alpha 1-inhibitor 3 which exhibits immunologic cross-reaction with human inter-alpha-trypsin inhibitor and is of similar molecular weight. With minute amounts of labelled elastase the partition among the binding protein was alpha 1-macroglobulin 60%, alpha 1-antitrypsin 24% and alpha 1-I3 16%. The 60% value of alpha 1-M bound radioactivity in normal serum corresponds to the sum of alpha 1-M and alpha 2-AP labelling in inflammatory serum.
Acute-Phase Proteins↗
Effect of human cord and postoperative serum on experimental inflammation in the rat.
Human cord and postoperative serum depressed the oedema provoked by mediators of the inflammatory reaction such as bradykinin, histamine, serotonin and prostaglandin E2 and also the experimental inflammation caused by carrageenin. Normal human and pregnancy serum did not have such an effect. In two cases of open neural tube defect, one of anencephaly and another of spina bifida, human amniotic fluid also had a strongly depressing effect on the experimental oedema provoked by serotonin. Human amniotic fluid from normal pregnancies did not inhibit this experimental inflammation. A protein-fraction of mol. wt 30,000--100,000 has been isolated from the inhibiting sera and shows the anti-inflammatory activity to be dose-related towards all the oedema-provoking substances used. Immunological studies showed that the inhibiting factor could be a protein in the pre-albuminic region, while alpha-foetoprotein did not appear to be responsible for the anti-inflammatory activity. Our conclusion is that human serum contains a protein of foetal origin with an acute-phase character and strong anti-inflammatory activities analogous to rat alpha 2-macrofoetoprotein.
Amniotic Fluid↗
Evidence for lipopolysaccharide binding in human granulosa-luteal cells.
We investigated whether human granulosa-luteal (GL) cells exhibited lipopolysaccharide (LPS)-binding protein, and the response of follicular aspirate cells to LPS in vitro. Follicular aspirates taken from a human in-vitro fertilization and gamete intra-fallopian-tube transfer programme were subjected to Percoll gradients in order to isolate an enriched population of GL cells. GL cells exhibited specific LPS-binding protein, detected by autoradiography of the cellular lysate on SDS-PAGE after the cells were specifically labelled with a radioiodinated, photoactivable and reducible LPS derivative. LPS binding to the cells was also detected by the appearance of immunofluorescence associated with the cellular membrane when incubated with a fluorescent conjugated LPS receptor antibody. Ninety-four per cent of the cells exhibiting immunofluorescent LPS-binding protein were also positive for the steroidogenic enzyme 3 beta-hydroxysteroid dehydrogenase, as detected by cytochemistry. In order to detect a response to LPS, the enriched population of GL cells were cultured in vitro in the presence or absence of LPS; after 16 h of culture, tumour necrosis factor-alpha (TNF) mRNA was detected by reverse transcription-polymerase chain reaction and Southern blot analysis of the amplified cDNA. The expression of TNF mRNA was enhanced when the cells were cultured in the presence of LPS, which also significantly enhanced TNF secretion into the media during the 16-h period. These results reveal that GL cells exhibit LPS-binding protein and thus increased TNF secretion occurs in response to LPS in follicular aspirate cells. The source of ovarian TNF may be leukocytes, macrophages and/or GL cells.
3-Hydroxysteroid Dehydrogenases↗
Conformational flexibility of the serum amyloid precursor SAA.
SAA is a normal acute-phase serum protein and is thought to be the precursor of amyloid protein AA which is deposited as insoluble beta-pleated sheet fibrils in secondary amyloidosis. Native SAA has a molecular weight of 160,000 and has not been isolated; it has been most frequently purified as a species (designated SAAL) of 12,500 mol. wt. by gel filtration in dissociating solutions. The conformational properties of SAA proteins in patients with and without amyloidosis have been compared in an effort to determine the factors involved in the induction of the beta-pleated sheet conformation in the amyloid SAA protein prior to fibril deposition. Amyloid and nonamyloid SAA proteins are similar in that they readily undergo conformational changes which result in the formation of heterogenous mol. wt. SAA species and in an increased exposure of antigenic determinants which cross-react with AA fibril proteins. Amyloid and nonamyloid SAA are different, however, in that amyloid SAA is more resistant to dissociation to SAAL. Amyloid SAAL, while similar to nonamyloid SAAL in immunoreactivity, shows a greater tendency toward aggregation. The relative resistance of both amyloid SAA and SAAL to complete dissociation may play an important role in amyloid fibril formation from these precursors.
Amyloid↗
Acute-phase proteins from the liver and enzymes from myocardial infarction; a quantitative relationship.
In 14 patients with acute myocardial infarction (M.I.) not having any other disease, the possible quantitative relationship between enzymes from M.I. and changes in concentration of acute phase reactants coming from the liver were studied. The patients were followed up until 1 1/2 years after M.I. and comparison of baseline-protein values took place using a control group of 18 healthy individuals. Quantitation of protein changes was done by planimetric determination of the area under the concentration curve and by taking peak values. The myocardial infarction was quantitatively estimated by mathematical analysis of the time course of alpha-hydroxybutyrate dehydrogenase (alpha-HBDH) plasma concentrations and by taking peak values. A quantitative relationship with enzymatic infarct size was found for haptoglobin, alpha1-acid glycoprotein, alpha1-antitrypsin, C-reactive protein, fibrinogen and E.S.R. Albumin and transferrin did not show a negative quantitative relationship with enzymatic infarct size. Humoral factors originating from the site of tissue injury and evoking in proportion a positive acute phase reaction by the liver are probably the basis for this observed quantitative relationship.
Acute Disease↗
Saliva versus lesion swabs for PCR diagnosis of acute-phase clade Ib mpox in Uganda: a prospective matched hospital cohort study.
BACKGROUND: As clade Ib mpox expands through HIV-affected populations in east and central Africa, diagnostic specimen selection should balance accuracy, accessibility, and operational feasibility in outbreak settings. Here, we aimed to compare the diagnostic performance of matched plasma, saliva, genital, anal, and skin specimens during the acute rash phase of clade Ib mpox to identify clinically practical and high-yield sampling approaches for outbreak response and clinical care. METHODS: We conducted a prospective cohort study of 155 adults (median age 30 years, IQR 25-36) hospitalised at Uganda's national mpox referral hospital. The specimens were collected between March 3 and April 10, 2025, during the clade Ib outbreak. All participants were admitted with suspected mpox and were subsequently confirmed by MPXV PCR. We collected 836 clinical specimens (acid citrate dextrose plasma, saliva, genital swabs, anal swabs, and skin swabs) during the acute phase (visit 1; 14 days [SD 2] after systemic symptom onset) and at approximately 3 months (visit 2). A matched acute-phase subset (n=80) provided concurrent plasma, saliva, genital, and skin specimens for within-participant comparisons. MPXV DNA was quantified by F3L real-time quantitative PCR, and cycle threshold (Ct) values were compared using paired Wilcoxon signed-rank tests. Whole-genome sequencing of selected acute specimens confirmed clade assignment. FINDINGS: In the matched subset at visit 1, PCR positivity was high in saliva (78 [98%] of 80), skin swabs (78 [98%] of 80), and genital swabs (77 [96%] of 80). Results for the saliva closely mirrored genital and skin swab results, supporting saliva as a high-yield alternative when lesion sampling is painful, operationally difficult, or unacceptable. Plasma had substantially lower sensitivity (34 [43%] of 80) and showed poor agreement with mucocutaneous compartments. At 3 months, persistent MPXV DNA was rare (ten [9%] of 109) and clustered among people with HIV, including the only two participants with persistent plasma positivity. All sequenced genomes clustered within clade Ib. INTERPRETATION: During the established rash phase (14 days [SD 2] after onset), saliva provides diagnostic yield similar to that provided by lesion swabs for clade Ib mpox in this hospitalised cohort. These findings are restricted to this sampling window; further studies are needed to define performance in prodromal, pre-rash, and asymptomatic infection. FUNDING: CEPI through its Centralised Laboratory Network.
Adult↗
Hepatitis "C" antigen in non-A, non-B post-transfusion hepatitis.
Evidence for a new hepatitis-specific antigen has been obtained from double immunodiffusion assays between acute and convalescent sera obtained from patients with non-A, non-B post-transfusion hepatitis. The designation hepatitis C (HC) antigen is proposed. HC was found in the acute-phase sera of all 13 non-A, non-B post-transfusion hepatitis patients with longer incubation and duration periods (type 2) tested, but only transiently in 4 out of 10 acutephase sera obtained from patients with type 1 non-A, non-B hepatitis, with shorter incubation and duration periods. The antigen was also detected in 2 out of 16 single specimens obtained during the acute phase from acute hepatitis patients who had not received a blood-transfusion. This suggests presence of a carrier state. No patients with alcoholic hepatitis and no healthy blood-donor carried HC antigen. The antigen seems distinct from those of hepatitis A and B (surface and core). It migrated in the serum beta-globulin region and had a buoyant density of 1.30 and a molecular weight between 100 000 and 300 000. Antibodies against HC antigen were found in only 30% of the type-2 non-A, non-B post-transfusion hepatitis patients and did not persist for long. However, these antibodies were directed specifically against HC antigen and moved in a manner similar to 7S globulin on rate-zonal centrifugation.
Acute Disease↗
Cell-mediated immunity to Epstein-Barr-virus-transformed lymphoblastoid cells in acute infectious mononucleosis.
Mononuclear peripheral blood leukocytes from 21 patients with infectious mononucleosis and 16 healthy controls were tested in a 51Cr-release assay for cytotoxicity against two human lymphoblastoid cell lines derived from the same donor. One line contained the Epstein-Barr virus (EBV); the other did not. Acute-phase leukocytes were significantly more cytotoxic against the EBV-infected cell line than were control leukocytes. Mean (+/- S.E.) lysis at a leukocyte-target-cell ratio of 100:1 was 10.6 +/- 1.6 per cent for patients and 3.4 +/- 0.6 per cent for controls (P less than 0.0005). Cytotoxicity correlated with the percentage of atypical lymphocytes. Cells of three patients with acute mononucleosis-like illnesses failed to show killing activity above those of normal controls. Cytotoxicity against the EBV-negative line was not significantly different for each group. The finding of cytotoxic cells in infectious-mononucleosis patients with atypical lymphocytes suggests that these cells operate in vivo to limit the proliferation of altered EBV-transformed B lymphoblasts.
Acute Disease↗