Opinion: redefining the role of the physician in laboratory medicine in the context of emerging technologies, personalised medicine and patient autonomy ('4P medicine')

The role of clinical pathologists or laboratory-based physicians is being challenged on several fronts—exponential advances in technology, increasing patient autonomy exercised in the right to directly request tests and the use of non-medical specialists as substitutes. In response, clinical pathologists have focused their energies on the pre-analytical and postanalytical phases of Laboratory Medicine thus emphasising their essential role in individualised medical interpretation of complex laboratory results. Across the European Union, the role of medical doctors is enshrined in the Medical Act. This paper highlights the relevance of this act to patient welfare and the need to strengthen training programmes to prevent an erosion in the quality of Laboratory Medicine provided to patients and their physicians.

Sequential fetal serum β2-microglobulin to predict postnatal renal function in bilateral or low urinary tract obstruction

OBJECTIVE

Fetal serum β2-microglobulin has been shown to predict postnatal renal outcome in cases of fetal obstructive uropathy. We assessed the value of serial measurements of fetal serum β2-microglobulin in the prediction of postnatal renal outcome.

METHODS

We retrospectively studied renal outcome in 42 fetuses with bilateral or low urinary tract obstruction that had fetal blood sampling on at least two occasions to assay serum levels of β2-microglobulin. Amniotic fluid volume at the time of each sampling was recorded. We classified renal outcome as either favorable (when postnatal renal function was normal) or adverse (when postnatal chronic renal failure occurred or when renal dysplasia at autopsy was noted). A β2-microglobulin cut-off of 5 mg/L and amniotic fluid index of 5 cm were used to predict postnatal renal outcome.

RESULTS

Renal outcome was adverse in 28 cases and favorable in 14. In 12 (28.6%) cases, fetal serum β2-microglobulin concentration differed between the first and last measurement. Prediction of postnatal renal outcome was correct in 11 of these cases based on the last β2-microglobulin measurement. The sensitivity of β2-microglobulin in predicting renal outcome was significantly higher (P = 0.005) when using the last rather than the first measurement (96.4% vs 64.3%), with similar specificity for both measurements (85.7% vs 78.6%, non-significant). The sensitivity of amniotic fluid volume was also significantly higher (P = 0.005) when using the last rather than the first measurement (75.0% vs 35.7%), with similar specificity for both measurements (64.3% vs 71.4%, non-significant).

CONCLUSION

Sequential measurement of serum β2-microglobulin, performed for adverse ultrasound findings, such as renal parenchymal abnormality or decreasing amniotic fluid volume, predicts postnatal renal outcome more accurately than does a single assay. This may be due to possible worsening of renal injury with increasing duration of urinary tract obstruction. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

A concurrent ultra-fractionated radiation therapy and temozolomide treatment: A promising therapy for newly diagnosed, inoperable glioblastoma

We report on a phase II clinical trial to determine the effect of a concurrent ultra-fractionated radiotherapy and temozolomide treatment in inoperable glioblastoma patients. A phase II study opened; patients over 18 years of age who were able to give informed consent and had histologically proven, newly diagnosed inoperable diagnosed and supratentorial glioblastoma were eligible. Three doses of 0.75 Gy spaced apart by at least 4 hr were delivered daily, 5 days a week for six consecutive weeks for a total of 67.5 Gy. Chemotherapy was administered during the same period, which consisted of temozolomide given at a dose of 75 mg/m(2) for 7 days a week. After a 4-week break, chemotherapy was resumed for up to six cycles of adjuvant temozolomide treatment, given every 28 days, according to the standard 5-day regimen. Tolerance and toxicity were the primary endpoints; survival and progression-free survival were the secondary endpoints. In total, 40 patients were enrolled in this study, 29 men and 11 women. The median age was 58 years, and the median Karnofsky performance status was 80. The concomitant ultra-fractionated radiotherapy and temozolomide treatment was well tolerated. Complete responses were seen in four patients, and partial responses were reported in seven patients. The median survival from the initial diagnosis was 16 months. Several long-term survivors were noted. Concurrent ultra-fractionated radiation therapy and temozolomide treatment are well accepted by the patients. The results showed encouraging survival rates for these unfavorable patients.

Screening for Latent Tuberculosis Infection in Patients with Chronic Inflammatory Arthritis: Discrepancies Between Tuberculin Skin Test and Interferon-γ Release Assay Results

Objective.

Screening for latent tuberculosis infection (LTBI) is mandatory before initiating biologics in patients with chronic inflammatory arthritis (CIA). However, few studies have evaluated the discrepancies between the results of tuberculin skin test (TST) and interferon-γ release assays (IGRA) in these patients. The purpose of our study was to investigate factors associated with TST and IGRA results in a large cohort of patients with CIA before the introduction of biologics.

Methods.

A total of 563 consecutive patients with CIA (293 rheumatoid arthritis, 270 spondyloarthritis) and eligible for biologics were prospectively enrolled. Demographic, clinical, and biological data were recorded. Risk factors for LTBI were assessed. All patients underwent a TST, a chest radiograph, and an IGRA test (T-SPOT.TB).

Results.

Agreement between the 2 tests was low (κ = 0.16). The bacillus Calmette-Guerin (BCG) status was significantly associated with discordance between the 2 tests (p = 0.004). The TST positivity rate was 34.8%. Factors associated with a negative TST were female sex (p = 0.02) and immunosuppressive treatment (p = 0.003). The only LTBI risk factor associated with TST positivity was an abnormal chest radiograph (p = 0.02). T-SPOT.TB was positive in 21.7% of patients and indeterminate in 15.6%. Previous active TB and chest radiograph abnormalities were associated with IGRA positivity (p = 0.008 and p = 3.9 × 10−5, respectively). The BCG vaccination was associated with negative IGRA (p = 3 × 10−4). Indeterminate IGRA results were associated with age, C-reactive protein, and immunosuppressive treatment (p = 0.005, 0.007, and 0.004, respectively).

Conclusion.

Our data support the combined use of T-SPOT.TB and TST in patients with CIA before biologics introduction. However, despite these good diagnostic values, indeterminate results may complicate the use of IGRA.

A position paper of the EFLM Committee on Education and Training and Working Group on Distance Education Programmes/E-Learning: developing an e-learning platform for the education of stakeholders in laboratory medicine

The progress of information and communication technologies has strongly influenced changes in healthcare and laboratory medicine. E-learning, the learning or teaching through electronic means, contributes to the effective knowledge translation in medicine and healthcare, which is an essential element of a modern healthcare system and for the improvement of patient care. E-learning also represents a great vector for the transfer knowledge into laboratory practice, stimulate multidisciplinary interactions, enhance continuing professional development and promote laboratory medicine. The European Federation of Laboratory Medicine (EFLM) has initiated a distance learning program and the development of a collaborative network for e-learning. The EFLM dedicated working group encourages the organization of distance education programs and e-learning courses as well as critically evaluate information from courses, lectures and documents including electronic learning tools. The objectives of the present paper are to provide some specifications for distance learning and be compatible with laboratory medicine practices.

Combination biomarkers to diagnose sepsis in the critically ill patient

RATIONALE

Although the outcome of sepsis benefits from the prompt administration of appropriate antibiotics on correct diagnosis, the assessment of infection in critically ill patients is often a challenge for clinicians. In this setting, simple biomarkers, especially when used in combination, could prove useful.

OBJECTIVES

To determine the usefulness of combination biomarkers to diagnose sepsis.

METHODS

Three hundred consecutive patients were enrolled to construct a biologic score that was next validated in an independent prospective cohort of 79 critically ill patients from another center.

MEASUREMENT AND MAIN RESULTS

Plasma concentrations of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) and procalcitonin (PCT) were assayed, and the expression of the high-affinity immunoglobulin-Fc fragment receptor I (FcγRI) CD64 on neutrophils (polymorphonuclear [PMN] CD64 index) in flow cytometry was measured. A "bioscore" combining these biomarkers was constructed. Serum concentrations of PCT and sTREM-1 and the PMN CD64 index were higher in patients with sepsis compared with all others (P < 0.001 for the three markers). These biomarkers were all independent predictors of infection, the best receiver-operating characteristic curve being obtained for the PMN CD64 index. The performance of the bioscore, better than that of each individual biomarker, was externally confirmed in the validation cohort.

CONCLUSIONS

This prospective study, including inceptive and validation cohorts of unselected intensive care unit patients, demonstrates the high performance of a bioscore combining the PMN CD64 index together with PCT and sTREM-1 serum levels in diagnosing sepsis in the critically ill patient.

Maternal exposure to air pollution before and during pregnancy related to changes in newborn's cord blood lymphocyte subpopulations. The EDEN study cohort

Background

Toxicants can cross the placenta and expose the developing fetus to chemical contamination leading to possible adverse health effects, by potentially inducing alterations in immune competence. Our aim was to investigate the impacts of maternal exposure to air pollution before and during pregnancy on newborn's immune system.

Methods

Exposure to background particulate matter less than 10 μm in diameter (PM₁₀) and nitrogen dioxide (NO₂) was assessed in 370 women three months before and during pregnancy using monitoring stations. Personal exposure to four volatile organic compounds (VOCs) was measured in a subsample of 56 non-smoking women with a diffusive air sampler during the second trimester of pregnancy. Cord blood was analyzed at birth by multi-parameter flow cytometry to determine lymphocyte subsets.

Results

Among other immunophenotypic changes in cord blood, decreases in the CD4+CD25+ T-cell percentage of 0.82% (p = 0.01), 0.71% (p = 0.04), 0.88% (p = 0.02), and 0.59% (p = 0.04) for a 10 μg/m³ increase in PM₁₀ levels three months before and during the first, second and third trimester of pregnancy, respectively, were observed after adjusting for confounders. A similar decrease in CD4+CD25+ T-cell percentage was observed in association with personal exposure to benzene. A similar trend was observed between NO₂ exposure and CD4+CD25+ T-cell percentage; however the association was stronger between NO₂ exposure and an increased percentage of CD8+ T-cells.

Conclusions

These data suggest that maternal exposure to air pollution before and during pregnancy may alter the immune competence in offspring thus increasing the child's risk of developing health conditions later in life, including asthma and allergies.

Elevated synovial expression of triggering receptor expressed on myeloid cells 1 in patients with septic arthritis or rheumatoid arthritis

OBJECTIVE

To determine whether synovial expression of triggering receptor expressed on myeloid cells 1 (TREM-1) is upregulated in patients with distinct types of inflammatory or non-inflammatory arthritis.

METHODS

Synovial fluid (SF) samples were analysed for levels of soluble TREM-1 (sTREM; n = 132), tumour necrosis factor alpha (TNFalpha, n = 78) and leucocyte TREM-1 messenger RNA (n = 48). Synovial tissue from four rheumatoid arthritis (RA) patients, two patients with Crohn's-associated arthritis, one patient with ankylosing spondylitis and one patient with osteoarthritis were examined for TREM-1 expression by immunohistology, and three of the RA samples were also analysed by Western blotting.

RESULTS

Synovial fluid sTREM-1 levels in septic arthritis and RA were similar to each other and were each greater than those in gouty arthritis, non-septic/non-RA inflammatory arthritis and non-inflammatory arthritis. Synovial fluid TNFalpha and sTREM-1 levels correlated with each other, and sTREM-1 and leucocyte TREM-1 mRNA levels each correlated with SF leucocyte counts. TREM-1 in RA was expressed in situ in synovial tissue by cells of myelomonocytic lineage but was not detectably expressed in control osteoarthritis synovial tissue.

CONCLUSIONS

Synovial TREM-1 expression is increased in septic arthritis and RA. In patients with acute inflammatory arthritis, elevated SF sTREM-1 levels may point the clinician to a diagnosis of septic arthritis or RA. In RA patients, targeting TREM-1 may have therapeutic benefits by reducing local proinflammatory cytokine and chemokine release.

Optimisation of biochemical condition and substrates in vitro for tissue engineering of ligament

In this work, we analysed the effect of growth factors on in vitro cell proliferation and collagens synthesis by fibroblasts cultured for 72 h on different substrates (silicon sheet with or without 1% gelatin, and glass as control surface) for ligament tissue engineering. A human fibroblast cell line (CRL-2703) was used. The synthesis of type I and type III collagens were evaluated qualitatively and quantitatively by RT-PCR and confocal microscopy, respectively. Cell proliferation was evaluated by two methods: (1) MTT assay (2) cell cycle analysis. It was found that PDGF-AB stimulate the proliferation of fibroblast cultured on gelatin coated silicon sheet in dose dependant manner with a maximum effect at 10 ng ml(-1). The exogenous TGF-beta1 induced the expression of type I and type III collagens in a dose and substrate-dependant manner. We deduce from this work that biochemical conditions and substrates have an important impact for optimisation of the tissue neo synthesis.

Effect of cyclic stretching and foetal bovine serum (FBS) on proliferation and extra cellular matrix synthesis of fibroblast

It is well known today that mechanical forces are one of the important factors that induce a variety of cellular responses including morphological changes, protein synthesis, and gene expression and which are involve in tissue remodelling. We studied the effect of uniaxial cyclic stretching on the proliferation, collagens, and tenascin C mRNA expression of fibroblasts under different concentrations of foetal bovine serum. Proliferation was studied by cell cycle analysis, mRNA expression of collagen and tenascin C was studied by RT-PCR. Human fibroblasts were grown in silicon sheet coated with 1% gelatin. Cyclic stretching (5% elongation) was applied at 0.5 Hz (30 cycle/min), for 24 h with two concentrations of the serum (0.5%, 10% FBS). We showed that stretching enhances the synthesis of collagen and tenascin C, but do not act on the proliferation. In contrast, higher concentration of serum enhances the proliferation. These findings suggest that both mechanical stretching and serum concentration can modulate proliferation and extra cellular matrix synthesis in human fibroblasts.

Time-course of sTREM (soluble triggering receptor expressed on myeloid cells)-1, procalcitonin, and C-reactive protein plasma concentrations during sepsis

OBJECTIVE

To describe the course of plasma sTREM (soluble triggering receptor expressed on myeloid cells)-1, procalcitonin (PCT), and C-reactive protein (CRP) concentrations during sepsis and their clinical informative value in predicting outcome.

DESIGN

Prospective, noninterventional study.

SETTING

Medical adult intensive care unit at a university hospital in France.

PATIENTS

Sixty-three critically ill patients with sepsis, severe sepsis, or septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Soluble TREM-1 concentrations were significantly lower at admission in nonsurvivors (n = 21) than in survivors (n = 42) (94 [30-258] vs. 154 [52-435] pg/mL, p = .02), whereas PCT levels were higher among nonsurvivors (19.2 [0.3-179] vs. 2.4 (0-254) pg/mL, p = .001). CRP levels did not differ between the two groups of patients. Plasma PCT and CRP decreased during the 14-day period of study in both survivors and nonsurvivors. Conversely, sTREM-1 plasma concentrations remained stable or even increased in nonsurviving patients and decreased in survivors. An elevated baseline sTREM-1 level was found to be an independent protective factor with an odds of dying of 0.1 (95% confidence interval, 0.1-0.8).

CONCLUSION

A progressive decline of plasma sTREM-1 concentration indicates a favorable clinical evolution during the recovery phase of sepsis. In addition, baseline sTREM-1 level may prove useful in predicting outcome of septic patients.

Measurement of faecal immunoglobulin a levels in young children

A nephelometric immunoassay was developed to quantify immunoglobulin A (IgA) in children's stools. This method enables IgA in faecal protein extracts to be measured over a large range of concentrations (1.61-51.50 mg/L) with good accuracy (linear recovery in dilution-overloading assay) and precision (within- and between-run coefficients of variation (CVs) of 1-6%). An excellent recovery (105%) was obtained in stool samples overloaded by purified colostral IgA, demonstrating that the method used for faecal IgA extraction is adapted, not to induce significant IgA degradation, and probably allow a complete extraction of IgA. The amount of faecal IgA, as determined in stool samples from 125 children (6-24 months old), was an average of 14 mg per 100 g of stools (about 10% of the total protein stool content), with large individual variation (3-30 mg per 100 g of stools). No correlation was observed between faecal IgA amounts and the children's age or sex. Such an immunoassay could enable exhaustive noninvasive investigations of the maturation of the intestinal immune system, as well as accurate studies of the effect of oral dietary supplementation on IgA regulation.

Soluble triggering receptor expressed on myeloid cells and the diagnosis of pneumonia

BACKGROUND

The diagnosis and treatment of bacterial pneumonia in patients who are receiving mechanical ventilation remain a difficult challenge. The triggering receptor expressed on myeloid cells (TREM-1) is a member of the immunoglobulin superfamily, and its expression on phagocytes is specifically up-regulated by microbial products. The presence of soluble TREM-1 (sTREM-1) in bronchoalveolar-lavage fluid from patients receiving mechanical ventilation may be an indicator of pneumonia.

METHODS

We conducted a prospective study of 148 patients receiving mechanical ventilation in whom infectious pneumonia was suspected. A rapid immunoblot technique was used to measure sTREM-1 in bronchoalveolar-lavage fluid. Two independent intensivists who were unaware of the results of the sTREM-1 assay determined whether community-acquired pneumonia and ventilator-associated pneumonia were present or absent.

RESULTS

The final diagnosis was community-acquired pneumonia in 38 patients, ventilator-associated pneumonia in 46 patients, and no pneumonia in 64 patients. The presence of sTREM-1 by itself was more accurate than any clinical findings or laboratory values in identifying the presence of bacterial or fungal pneumonia (likelihood ratio, 10.38; sensitivity, 98 percent; specificity, 90 percent). In multiple logistic-regression analysis, the presence of sTREM-1 was the strongest independent predictor of pneumonia (odds ratio, 41.5).

CONCLUSIONS

In patients receiving mechanical ventilation, rapid detection of sTREM-1 in bronchoalveolar-lavage fluid may be useful in establishing or excluding the diagnosis of bacterial or fungal pneumonia.

[What are the antigenic targets in the ovary?]

The ovary can be the target of an autoimmune disease involving many different autoantigens. The clinical feature of this disease often results in premature ovarian failure or infertility and may be either isolated or associated with other autoimmune pathologies, especially with adrenal autoimmunity. The diagnosis of an autoimmune mechanism relies on the presence of anti-ovarian antibodies, whose prevalence is quite variable according to the different methods used to detect them, and to the different stages of the disease. In addition, their clinical significance is not always clear, as to their pathologic or epiphenomenal nature. However, the study of these autoantibodies has led to the identification of some of their antigenic targets which have to be known for a better understanding of the pathologic mechanisms involved. This paper reviews anti-steroid producing cells, anti-gonadotrophin receptor, anti-gonadotrophin, anti-corpus luteum, anti-zona pellucida and anti-oocyte antibodies.

Anticorps anti-ovaires et fécondation in vitro : cause ou conséquence ?

OBJECTIVES

To assess anti-ovarian antibodies (AOA) in serum samples at various times of in vitro fertilization (IVF) attempts to determine whether ovarian stimulation could result in the production of such autoantibodies in women.

PATIENTS AND METHODS

Prospective study on 134 patients and 138 IVF cycles using a classical long protocol. For each attempt, four serum samples were obtained, respectively, at the onset of downrelation (S1), end of downregulation (S13), after 7 days of follicular stimulation (S21) and the day of follicular puncture (SP). Five hundred and fifty two samples were tested with an enzyme-linked immunosorbent assay for three isotypes (IgG, IgA, IgM) of AOA.

RESULTS

In the whole group, mean concentrations of AOA for each isotype were compared group by group: S1-S13, S1-S21, S1-SP, S13-S21, S13-SP, S21-SP. Not any significant difference was observed whatever the isotype considered.

DISCUSSION AND CONCLUSION

This study shows the absence of influence of endogenous or exogenous ovarian stimulation by gonadotropins on anti-ovarian autoimmunity.

The increased histamine release in ischaemic heart disease patients undergoing coronaroangiography is not mediated by specific IgE

BACKGROUND

The release of histamine by iodinated contrast media (ICM) is higher in coronary artery disease patients than in noncoronary patients during coronary angiogram.

METHODS

Eighty-eight patients who underwent a coronary angiography were classified either as having coronary artery disease or as noncoronary patients. Histamine concentration was higher than the 6.8 nM upper limit in 7 cases (group 1), of whom six were coronary artery disease patients. We compared the IgE and complement fractions in plasma of these patients to two control groups with normal histamine blood level, one (group 2) with and the other (group 3) without coronary artery disease.

RESULTS

No difference of total IgE and C(3c) and C(4) complement fractions was found among the three groups. Anti-ioxaglate IgE-RIA was positive in only one patient from group 1. The affinity of drug-IgE binding in the serum of this patient was very low (Kd: 18.7 mM). The level of anti-ICM IgE detected by ioxitalamate- and iomeprol-Sepharose RIA was significantly higher in groups 2 and 3 than in group 1.

CONCLUSIONS

The higher histamine release in ischaemic heart disease patients undergoing coronaroangiography is not mediated by IgE or complement activation. Further studies are needed to investigate the implication of histamine release factors.

Changes in the mannan binding lectin (MBL) concentration in human milk during lactation

The mannan binding lectin (MBL) activates the complement system by the lectin pathway after the recognition of some structural motifs (saccharides) present on the surface of microorganisms. MBL has been mostly identified and quantified in human serum by ELISA or microparticle immunonephelometry assays. This article reports the MBL levels as assessed by a microparticle immunonephelometric assay in 76 human milk samples. Immunonephelometry was performed using skim-milk samples diluted 20 times over a calibration range of 0.07-4.82 mg/L. MBL is indeed present in human milk and its concentration decreases significantly during development from colostrum (0.55+/-0.09 mg/L) to transitional (0.18+/-0.02 mg/L) and mature milk (0.17+/-0.02 mg/L). This innate molecule may be involved in the primary defenses of the mammary gland and the neonate, whose immune system is immature. The high levels observed during the first days of lactation support the hypothesis that this molecule plays a key role in limiting the colonization of the newborn gut by pathogens.

Expression of IL-2alpha and IL-2beta receptors on the membrane surface of human sperm

Cytokines are secreted proteins that act as local immunological mediators. Increased seminal cytokine concentrations are associated with fertility problems. The purpose of the present study was to investigate the presence of IL-2alpha, and IL-2beta receptors on fresh and isolated sperm by flow cytometry and transmission electron microscopy. Twenty sperm samples from oligospermic men were incubated with CD25, a mouse monoclonal antibody specific for IL-2alpha-chain receptor, and CD122, a mouse monoclonal antibody specific for IL-2beta-chain receptor. The strong initial fluorescence intensity and, subsequently, a labeling index yielded by CD25 and CD122 decreased in sperm centrifuged on a Percoll gradient (p < .05). The expression of CD25 and CD122 correlated negatively with fresh sperm concentration, but in sperm centrifuged on a Percoll gradient there was no correlation. Labeling with CD25 and CD122 antibody was evident on the head and the middle piece in fresh sperm, while in sperm centrifuged on a Percoll gradient a weak labeling was observed only on the principal piece. The authors have identified and localized cytokine receptors on human sperm for the first time. Cytokine receptors may be involved in the regulation of pathophysiological events in sperm cell functions and male infertility. The exact pathway involved in modulation of these receptors requires further investigation. These results contribute to the understanding of cytokine-sperm relationships.

Changes in lactoferrin and lysozyme levels in human milk during the first twelve weeks of lactation

Changes in the lactoferrin and lysozyme concentration of human milk during lactation were determined by microparticle-enhanced nephelometric immunoassays of 360 milk samples collected from 64 lactating volunteers. These 360 samples were colostrum from days 1 to 5 postpartum (142 samples), transitional milk from days 6 to 14 (106 samples), and 112 mature milk samples obtained from days 15 to 28 (34 samples), from days 29 to 56 (50 samples) and from days 57 to 84 postpartum (28 samples). The concentration and percentage of lactoferrin vs. total protein were found to be significantly higher in colostrum (5.8 g/L, 27%) than in transitional milk (3.1 g/L, 22%) or day 15 to 28 mature milk (2.0 g/L, 19%), then increased in day 29 to 56 mature milk (2.2 g/L, 22%) and day 57 to 84 mature milk (3.3 g/L, 30%). The concentration of lysozyme decreased from colostrum (0.37 g/L) to transitional milk (0.27g/L) and day 15 to 28 mature milk (0.24 g/L), then increased in day 29 to 56 mature milk (0.33 g/L) and was highest in day 57 to 84 mature milk (0.89 g/L). The percentage of lysozyme vs. total protein was found to be always rising during lactation: colostrum, 2%; transitional milk, 2%; days 15 to 28, 2%; days 29 to 56, 3%; and days 57 to 84 mature milk, 8%.

Nonenveloped nucleocapsids of hepatitis C virus in the serum of infected patients

One of the characteristics of hepatitis C virus (HCV) is the high incidence of persistent infection. HCV core protein, in addition to forming the viral nucleocapsid, has multiple regulatory functions in host-cell transcription, apoptosis, cell transformation, and lipid metabolism and may play a role in suppressing host immune response. This protein is thought to be present in the bloodstream of the infected host as the nucleocapsid of infectious, enveloped virions. This study provides evidence that viral particles with the physicochemical, morphological, and antigenic properties of nonenveloped HCV nucleocapsids are present in the plasma of HCV-infected individuals. These particles have a buoyant density of 1.32 to 1.34 g/ml in CsCl, are heterogeneous in size (with predominance of particles 38 to 43 or 54 to 62 nm in diameter on electron microscopy), and express on their surface epitopes located in amino acids 24 to 68 of the core protein. Similar nucleocapsid-like particles are also produced in insect cells infected with recombinant baculovirus bearing cDNA for structural HCV proteins. HCV core particles isolated from plasma were used to generate anti-core monoclonal antibodies (MAbs). These MAbs stained HCV core in the cytoplasm of hepatocytes from experimentally infected chimpanzees in the acute phase of the infection. These chimpanzees had concomitantly HCV core antigen in serum. These findings suggest that overproduction of nonenveloped nucleocapsids and their release into the bloodstream are properties of HCV morphogenesis. The presence of circulating cores in serum and accumulation of the core protein in liver cells during the early phase of infection may contribute to the persistence of HCV and its many immunopathological effects in the infected host.