Determination of alpha-fetoprotein concentration based on liquid-phase binding assay using anion exchange chromatography and sulfated peptide introduced antibody

Alpha-fetoprotein: Past, present, and future

Alpha-fetoprotein (AFP) is a glycoprotein that plays an important role in immune regulation with critical involvement in early human development and maintaining the immune balance during pregnancy. Postfetal development, the regulatory mechanisms controlling AFP undergo a shift and AFP gene transcription is suppressed. Instead, these enhancers refocus their activity to maintain albumin gene transcription throughout adulthood. During the postnatal period, AFP expression can increase in the setting of hepatocyte injury, regeneration, and malignant transformation. It is the first oncoprotein discovered and is routinely used as part of a screening strategy for HCC. AFP has been shown to be a powerful prognostic biomarker, and multiple HCC prognosis models confirmed the independent prognostic utility of AFP. AFP is also a useful predictive biomarker for monitoring the treatment response of HCC. In addition to its role as a biomarker, AFP plays important roles in immune modulation to promote tumorigenesis and thus has been investigated as a therapeutic target in HCC. In this review article, we aim to provide an overview of AFP, encompassing the discovery, biological role, and utility as an HCC biomarker in combination with other biomarkers and how it impacts clinical practice and future direction.

Biochemistry and biomedicine of quantum dots: from biodetection to bioimaging, drug discovery, diagnostics, and therapy

According to recent research, nanotechnology based on quantum dots (QDs) has been widely applied in the field of bioimaging, drug delivery, and drug analysis. Therefore, it has become one of the major forces driving basic and applied research. The application of nanotechnology in bioimaging has been of concern. Through in vitro labeling, it was found that luminescent QDs possess many properties such as narrow emission, broad UV excitation, bright fluorescence, and high photostability. The QDs also show great potential in whole-body imaging. The QDs can be combined with biomolecules, and hence, they can be used for targeted drug delivery and diagnosis. The characteristics of QDs make them useful for application in pharmacy and pharmacology. This review focuses on various applications of QDs, especially in imaging, drug delivery, pharmaceutical analysis, photothermal therapy, biochips, and targeted surgery. Finally, conclusions are made by providing some critical challenges and a perspective of how this field can be expected to develop in the future.

STATEMENT OF SIGNIFICANCE

Quantum dots (QDs) is an emerging field of interdisciplinary subject that involves physics, chemistry, materialogy, biology, medicine, and so on. In addition, nanotechnology based on QDs has been applied in depth in biochemistry and biomedicine. Some forward-looking fields emphatically reflected in some extremely vital areas that possess inspiring potential applicable prospects, such as immunoassay, DNA analysis, biological monitoring, drug discovery, in vitro labelling, in vivo imaging, and tumor target are closely connected to human life and health and has been the top and forefront in science and technology to date. Furthermore, this review has not only involved the traditional biochemical detection but also particularly emphasized its potential applications in life science and biomedicine.

Clinical Assay for AFP-L3 by Using Multiple Reaction Monitoring-Mass Spectrometry for Diagnosing Hepatocellular Carcinoma

BACKGROUND

Lens culinaris agglutinin-reactive fraction of α-fetoprotein (AFP-L3) is a serum biomarker for hepatocellular carcinoma (HCC). AFP-L3 is typically measured by liquid-phase binding assay (LiBA). However, LiBA does not always reflect AFP-L3 concentrations because of its low analytical sensitivity. Thus, we aimed to develop an analytically sensitive multiple reaction monitoring-mass spectrometry (MRM-MS) assay to quantify AFP-L3 in serum.

METHODS

The assay entailed the addition of a stable isotope-labeled internal standard protein analog, the enrichment of AFP using a monoclonal antibody, the fractionation of AFP-L3 using L. culinaris agglutinin lectin, deglycosylation, trypsin digestion, online desalting, and MRM-MS analysis. The performance of the MRM-MS assay was compared with that of LiBA in 400 human serum samples (100 chronic hepatitis, 100 liver cirrhosis, and 200 HCC). Integrated multinational guidelines were followed to validate the assay for clinical implementation.

RESULTS

The lower limit of quantification of the MRM-MS assay (0.051 ng/mL) for AFP-L3 was less than that of LiBA (0.300 ng/mL). Thus, AFP-L3, which was not observed by LiBA in HCC samples (n = 39), was detected by the MRM-MS assay, improving the clinical value of AFP-L3 as a biomarker by switching to a more analytical sensitive platform. The method was validated, meeting all the criteria in integrated multinational guidelines.

CONCLUSIONS

Because of the lower incidence of false-negative findings, the MRM-MS assay is more suitable than LiBA for early detection of HCC.

Molybdenum carbide nanotubes: a novel multifunctional material for label-free electrochemical immunosensing

Herein, a multifunctional nanoarchitecture has been developed by integrating well-crystalline molybdenum carbide (Mo2C) nanotubes and an electrochemical indicator - thionin (TH). The Mo2C nanotubes were synthesized through the self-degradable template method and high-temperature calcination, and their structure and morphology were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Due to the high electrocatalytic properties, excellent conductivity and highly active surface area of Mo2C nanotubes, the Mo2C-based material was used as a nanocarrier to load TH molecules for the development of a label-free electrochemical immunosensor for α-fetoprotein (AFP) detection. The decorated TH probe on the Mo2C nanotubes not only acted as a bridging molecule to effectively capture and immobilize primary anti-AFP on the Mo2C nanotubes, but also acted as a signal indicator for the detection of AFP. The proposed immunosensor exhibited excellent selectivity (with a detection limit of 3 pg mL(-1)), high stability and good reproducibility by combining the unique structure and features of the Mo2C nanotubes. Furthermore, this sensing platform was finally used for the detection of AFP in human serum with satisfactory results. Therefore, the Mo2C nanotubes can be considered as a candidate carbon material for fabrication of simple, label-free and ultrasensitive electrochemical sensors, broadening the application of this material.

Biomarkers for the early diagnosis of bacterial infection and the surveillance of hepatocellular carcinoma in cirrhosis

The early detection of bacterial infections and hepatocellular carcinoma (HCC) could ameliorate the prognosis of cirrhosis. C-reactive protein and procalcitonin are under investigation in the setting of cirrhosis as markers of sepsis. In the attempt to discriminate bacterial infection from systemic inflammation, the role of novel biomarkers such as lypopolysaccharide binding-protein, mid-regional fragment of pro-adrenomedullin and delta neutrophil index are currently in development. Concerning HCC, many studies attempted to evaluate biomarkers in the hope of ameliorating the accuracy of the surveillance based on ultrasound. The use of α-fetoprotein (AFP) has been extensively investigated, as well as other biomarkers expressed in the serum of HCC patients like lens culinaris agglutinin-reactive fraction of AFP, des-γ-carboxy prothrombin, glypican-3, α-l-fucosidase and their combined use.

Improvement of the Lectin-Antibody Enzyme Immunoassay of the Alphafetoprotein Carbohydrate Chain for Automation with the Enzyme Immunoassay Robot

The lectin-antibody enzyme immunoassay of the alphafetoprotein-L3 carbohydrate chain, a tumor marker of liver cancer, has not been automated. We improved the technique of the assay for automation. Consequently, alphafetoprotein-L3 and total alphafetoprotein were detected with two lectins using an automatic paramagnetic bead handling robot. This indicates that the improved method is potentially applicable to the automated enzyme immunoassay robot.

Changes in highly sensitive alpha-fetoprotein for the prediction of the outcome in patients with hepatocellular carcinoma after hepatectomy

We investigated changes in highly sensitive lens culinaris agglutinin A-reactive fraction of alpha-fetoprotein (hsAFP-L3) measured using a novel method and its predictive ability for prognosis in patients with hepatocellular carcinoma (HCC) who underwent curative hepatectomy, comparing to other HCC tumor markers, that is, AFP, des-gamma-carboxy prothrombin (DCP), and AFP-L3 measured with conventional method (cAFP-L3). AFP, DCP, and AFP-L3 including both cAFP-L3 and hsAFP-L3 were measured before and after curative hepatectomy in 187 patients. The percentage of patients with elevated tumor marker levels pre- and postoperatively was compared, and recurrence-free and overall survival rates were analyzed based on changes in tumor markers. The percentages of patients with elevated AFP, DCP, and cAFP-L3 decreased postoperatively. In contrast, the percentage of patients with elevated hsAFP-L3 did not decrease postoperatively. Both recurrence-free and overall survival rates were significantly lower in patients whose tumor marker levels remained elevated postoperatively than patients without tumor marker elevation postoperatively. Recurrence-free and overall survival rates of patients in whom hsAFP-L3 became elevated postoperatively despite normal preoperative hsAFP-L3 levels were significantly lower than those of patients with normal hsAFP-L3 postoperatively, and were similar to those of patients with persistent elevation. Preoperative elevations of AFP, DCP, and cAFP normalized in many patients postoperatively, but not for hsAFP-L3. The elevation of hsAFP-L3 identifies patients with poor prognosis despite the normalization of AFP and DCP.

High-sensitivity Lens culinaris agglutinin-reactive alpha-fetoprotein assay predicts early detection of hepatocellular carcinoma

BACKGROUND

Prognosis of patients with hepatocellular carcinoma (HCC) remains poor because HCC is frequently diagnosed late. Therefore, regular surveillance has been recommended to detect HCC at the early stage when curative treatments can be applied. HCC biomarkers, including Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3), are widely used for surveillance in Japan. A newly developed immunoassay system measures AFP-L3 % with high sensitivity. This retrospective study aimed to evaluate clinical utility of high-sensitivity AFP-L3 (hs-AFP-L3) as a predictor of early stage HCC in surveillance at a single site.

METHODS

Of consecutive 2830 patients in the surveillance between 2000 and 2009, 104 HCC-developed and 104 non-HCC patients were selected by eligibility criteria and propensity score matching. Samples were obtained from the HCC patients who had blood drawn annually for 3 years prior to HCC diagnosis.

RESULTS

In the present study, hs-AFP-L3 was elevated 1 year prior to diagnosis in 34.3 % of patients. The survival rate of patients with the hs-AFP-L3 ≥ 7 % at 1 year prior to diagnosis was significantly lower than that of patients with hs-AFP-L3 < 7 %.

CONCLUSIONS

Elevation of hs-AFP-L3 was early predictive of development of HCC even at low AFP levels and in absence of ultrasound findings of suspicious HCC. The hs-AFP-L3 should be added to surveillance programs with US because elevated hs-AFP-L3 may be a trigger to perform enhanced imaging modalities for confirmation of HCC.

Lens culinaris agglutinin-reactive α-fetoprotein decline after transcatheter arterial chemoembolization in patients with hepatocellular carcinoma predicts survival

BACKGROUND

Lens culinaris agglutinin-reactive α-fetoprotein (AFP-L3) is a fucosylated fraction of AFP that is highly specific for hepatocellular carcinoma (HCC). We studied the relationship between AFP-L3 response and treatment outcome in terms of radiologic response and overall survival in patients undergoing transcatheter arterial chemoembolization (TACE).

METHODS

We retrospectively analyzed 152 patients with advanced HCC undergoing TACE. Serum AFP-L3 and AFP levels were measured simultaneously with a novel lectin dual-label time-resolved immunofluorometric assay (lectin dual-label TRFIA). AFP-L3 response was defined as a ≥20% reduction in AFP-L3 level after a minimum of 2 cycles of chemotherapy.

RESULTS

A total of 47 AFP-L3 responders had improved median overall survival of 42.9 months compared with 15.4 months in nonresponders (P<0.0001), and AFP-L3 response was strongly associated with radiologic response (P<0.0001). The combination of AFP-L3 response and serum AFP response provided further prognostic information. On multivariate analysis, the prognostic value of AFP-L3 response was independent of maximum tumor diameter and BCLC stage.

CONCLUSION

A significant reduction in AFP-L3 in patients with advanced HCC is an important predictor of survival. Achieving an AFP-L3 response should be one of the therapeutic intents of TACE.

Highly sensitive AFP-L3% assay is useful for predicting recurrence of hepatocellular carcinoma after curative treatment pre- and postoperatively

AIM

  The micro-total analysis system (µTAS), a fully automated immunoassay system using microchip capillary electrophoresis, is highly sensitive and able to quickly assay the AFP-L3%. The clinical usefulness of this system was studied.

METHODS

  We retrospectively enrolled 250 patients who underwent curative treatment for primary hepatocellular carcinoma (HCC) (93 patients underwent hepatic resection and 157, radiofrequency ablation [RFA]).

RESULTS

  The sensitivity for µTAS AFP-L3% was 40.3% at the cutoff value of 5% in a range of AFP less than 20 ng/mL where the conventional method was unable to determine AFP-L3%. The sensitivity for AFP-L3% remained high even at stage I and at tumor size less than 2 cm (42.5% and 46.0%, respectively). Recurrence rate of patients with AFP-L3% greater than 5% was significantly higher than that of patients with less than 5% (P = 0.001). Furthermore, in resected patients, the postoperative AFP-L3% remained elevated with value greater than 5% was related to HCC recurrence (P = 0.001). Multivariate analysis revealed that multiple tumors (P = 0.004), preoperative AFP-L3% greater than 5% (P = 0.003), albumin less than 3.5 g/dL (P = 0.008), and RFA (P = 0.003) were significant prognostic factors of recurrence.

CONCLUSIONS

  The µTAS was found to be a highly sensitive assay for AFP-L3% in patients with curative treatment of HCC. A cutoff value of 5% was useful for predicting recurrence after the curative treatment and detecting small tumors and early stage HCC. Additionally, postoperative AFP-L3% was found to be a prognostic factor of HCC recurrence.

Clinical utility of highly sensitive Lens culinaris agglutinin-reactive alpha-fetoprotein in hepatocellular carcinoma patients with alpha-fetoprotein <20 ng/mL

The Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3) has been used as a diagnostic and prognostic marker of hepatocellular carcinoma (HCC). The analytical sensitivity of a conventional method for AFP-L3% is not sufficient in patients with a low AFP level. This study was performed to determine the clinical utility of a newly developed highly sensitive AFP-L3% (hs-AFP-L3%) assay in patients with an AFP level <20 ng/mL. In the cohort study, serum samples obtained from 270 patients with newly diagnosed HCC before treatment and 396 patients with chronic liver disease at Ogaki Municipal Hospital, in both of which the AFP level was <20 ng/mL, were measured for conventional AFP-L3% (c-AFP-L3%), hs-AFP-L3% and des-gamma-carboxy prothrombin (DCP). Diagnostic sensitivity and specificity of hs-AFP-L3% at a cut-off level of 5% were 41.5% and 85.1%, respectively, significantly increasing the sensitivity from 7.0% for c-AFP-L3%. Multivariate analysis identified hs-AFP-L3% as an independent factor associated with reduced long-term survival. The survival rate of patients with high hs-AFP-L3% (≥ 5%) before treatment was significantly poorer than that of patients with low hs-AFP-L3% (<5%) (P < 0.001). In patients with AFP <20 ng/mL, measurements of AFP-L3% by the highly sensitive method before treatment were more useful for diagnosis and prognosis of HCC than by the conventional method.

Gold nanoparticles based chemiluminescent resonance energy transfer for immunoassay of alpha fetoprotein cancer marker

In this paper, we report a new strategy of chemiluminescence resonance energy transfer (CRET) by using gold nanoparticles (AuNPs) as efficient long-range energy acceptor in sandwich immunoassays. In the design of CRET system, we chose the highly sensitive chemiluminescence (CL) reaction of luminol and hydrogen peroxide catalysed by horseradish peroxidase (HRP) because the CL spectrum of luminol (λ(max) 425 nm) partially overlaps with the visible absorption bands of AuNPs. On the basis of CRET strategy, we developed a sandwich immunoassay of alpha fetoprotein (AFP) cancer marker. In immunoassay, two antibodies (anti-AFP-1 and anti-AFP-2) were conjugated to AuNPs and horseradish peroxidase (HRP), respectively. The sandwich-type immunoreactions between the AFP (antigen) and the two different antibodies bridged the donors (luminol) and acceptors (AuNPs), which led to the occurrence of CRET from luminol to AuNPs upon chemiluminescent reaction. We observed that the quenching of chemiluminescence signal depended linearly on the AFP concentration within a range of concentration from 5 to 70 ng mL(-1) and the detection limit of AFP was 2.5 ng mL(-1). Our method was successfully applied for determination of AFP levels in sera from cancer patients, and the results were in good agreement with ELISA assays. This approach is expected to be extended to other assay designs, that is, using other antibodies, analytes, chemiluminescent substance, and even other metallic nanoparticles.

Evaluation for clinical utility of GPC3, measured by a commercially available ELISA kit with Glypican-3 (GPC3) antibody, as a serological and histological marker for hepatocellular carcinoma

AIMS

We evaluated the clinical utility of glypican-3 (GPC3), which has been proposed as a potential novel tumor marker for hepatocellular carcinoma (HCC), as a serological and histological marker for HCC.

METHODS

The serum GPC3 level was compared between 200 patients with HCC and 200 patients with chronic liver disease (CLD). In addition, the expression of GPC3 was examined with immunohistochemistry on 38 resected specimens from patients with HCC. A commercially available GPC3 antibody was used for these analyses.

RESULTS

The median values of serum GPC3 in patients with HCC and with CLD were 924.8 pg/mL and 1161.6 pg/mL, respectively. We found no elevation of serum GPC3 level in patients with HCC in comparison with those with CLD; rather the level was higher in patients with CLD (P < 0.0001). In immunohistochemical analysis, 14 of 38 (36.9%) HCC tissues were positive for GPC3, whereas no corresponding non-cancerous tissue was positive. The positivity for GPC3 tended to increase with pathologic decreased differentiation of HCC.

CONCLUSIONS

We did not find serum GPC3 level, measured by a commercially available ELISA kit with GPC3 antibody, to be useful in the diagnosis of HCC. However, we did observe increased GPC3 staining in HCC tissue with moderate or poor differentiation, suggesting that GPC3 is produced by HCC tumors. This lack of utility could have been due to the measuring procedure used in the present study. Further evaluation of GPC3 in HCC with other measuring procedures is needed.

Utility of Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein and des-gamma-carboxy prothrombin, alone or in combination, as biomarkers for hepatocellular carcinoma

BACKGROUND & AIMS

Des-gamma-carboxy prothrombin (DCP) and Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3) are surveillance markers used to detect hepatocellular carcinoma (HCC) in Japan. This study evaluated their utility, alone or in combination, in a North American population.

METHODS

Patients with hepatitis C virus-related cirrhosis were followed up prospectively for 2 years.

RESULTS

Of 372 patients, HCC developed in 34 of 298 who were free of HCC at entry. The overall sensitivity, specificity, and positive and negative predictive values for only AFP (>20 ng/mL) were 61%, 71%, 34%, and 88%, respectively; for only AFP-L3% (>10) were 37%, 92%, 52%, and 85%, respectively; and for only DCP (>7.5 ng/mL) were 39%, 90%, 48%, and 86%, respectively. Values increased when AFP values were combined with AFP-L3% and DCP to 77%, 59%, 32%, and 91%, respectively. Among patients with increases in AFP levels to 20 to 200 ng/mL, AFP-L3% and DCP were highly specific markers (86.6% and 90.2%, respectively). Of 29 HCC patients with AFP levels less than 20 ng/mL, 13 had increased levels of AFP-L3% or DCP. Increased alanine aminotransferase levels were associated with increased total AFP but not AFP-L3% or DCP levels. Both AFP-L3%- and DCP-positive patients showed significant differences in lower cumulative HCC-free rates compared with the overall group (P < .0001 and P = .0005, respectively).

CONCLUSIONS

AFP-L3% and DCP levels have higher correlation values with an absence of HCC, as well as a higher specificity and negative predictive value, than total AFP. Although this combination of markers only marginally improves surveillance for early HCC, it could identify individuals with negative imaging results who would benefit from follow-up evaluation.

Clinical utility of AFP-L3% measurement in North American patients with HCV-related cirrhosis

BACKGROUND AND AIMS

Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3%) has been reported to be useful in the early detection of hepatocellular carcinoma (HCC) in Japan. The aim of this prospective study was to compare the clinical utility of AFP-L3% with that of total AFP in North American patients.

METHODS

Patients with chronic hepatitis (CH) C virus-related cirrhosis from 7 clinical sites were prospectively followed every 3-6 months for 2 yr.

RESULTS

Of the 372 patients evaluated, 40 had hepatitis C virus-related HCC at entry and 332 entered the prospective trial. Of the latter, 34 developed HCC and 298 remained free of HCC. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for AFP were 60.8%, 71.1%, 34.4%, and 88.0% with a cutoff of 20 ng/mL and 21.6%, 98.7%, 80.0%, and 83.5% with a cutoff of 200 ng/mL, compared to 36.5%, 91.6%, 51.9%, and 85.3% for AFP-L3% with a cutoff of 10%. In those with an elevated AFP (20-200 ng/mL), AFP-L3% had a specificity of 86.6% and an NPV of 80.7%. Multivariate analysis identified AFP, AFP-L3%, and age as independent predictors of HCC. Elevated AFP-L3% was associated with a lower cumulative HCC-free rate at 2 yr (58.9%) than was AFP (82.0%, P= 0.01).

CONCLUSIONS

The incidence of HCC was significantly higher in patients with elevated AFP-L3% than in those with elevated AFP. The high specificity of AFP-L3% persisted among patients with elevated AFP (20-200 ng/mL) and suggests that AFP-L3% has clinical utility in HCV patients with AFP of 20-200 ng/mL.

Clinical evaluation of lens culinaris agglutinin-reactive alpha-fetoprotein and des-gamma-carboxy prothrombin in histologically proven hepatocellular carcinoma in the United States

There is no established clinical role for the lens culinaris agglutinin-reactive fraction of alpha-fetoprotein (AFP-L3%) and des-gamma-carboxy prothrombin (DCP) in the management of the U.S. hepatocellular carcinoma (HCC) patient population. In order to clarify the clinical usefulness and characteristics of AFP-L3% and DCP, a prospective study was performed on United States patients having histologically proven hepatocellular carcinoma. Ninety-nine histologically proven HCC patients, who were diagnosed with unresectable cancer between July 1999 and March 2001 at the Liver Cancer Center of the University of Pittsburgh Medical Center, were included for analysis. The sensitivity of AFP-L3%, DCP, and AFP was 61.6%, 72.7%, and 67.7%, respectively. The highest sensitivity, 85.9%, was obtained in the combination of three markers. Statistically significant differences were observed for portal vein invasion in AFP-L3% and AFP levels (P = 0.0059 and P = 0.0360, respectively). DCP was significantly associated with metastasis (P = 0.0368). There were significant associations between AFP-L3% and AFP results and patient survival (P = 0.0150 and P = 0.0020, respectively). AFP-L3%, platelet count,and albumin showed a significant difference with respect to outcomes on Cox's proportional hazard model (P = 0.0059, P = 0.0073, and P = 0.0265, respectively). The combination of AFP-L3%, DCP, and AFP was determined to be superior for detection of HCC compared with each marker alone or to other combinations. AFP-L3% was significantly related to portal vein invasion and patient outcomes and appears to be a useful prognostic marker for HCC.

Simultaneous Determination of α-Fetoprotein and Free β-Human Chorionic Gonadotropin by Element-Tagged Immunoassay with Detection by Inductively Coupled Plasma Mass Spectrometry

Background: An inductively coupled plasma mass spectrometry (ICP-MS)-based immunoassay has been proposed independently by Baranov et al. (Anal Chem 2002;74:1629–36) and our group, but the applicability of this method for multianalyte analysis in clinical samples has not been fully illustrated. We developed a dual-label immunoassay method for the simultaneous determination of α-fetoprotein (AFP) and free β-human chorionic gonadotropin (hCGβ) in human serum.

Methods: Monoclonal antibodies immobilized on microtiter plates captured AFP and hCGβ, which were detected by use of Eu3+-labeled anti-AFP and Sm3+-labeled anti-hCGβ monoclonal antibodies. Eu3+ and Sm3+ were dissociated from the immunocomplex with HNO3 solution (10 mL/L) and delivered by peristaltic pump to the ICP mass spectrometer.

Results: The measurable ranges of AFP and hCGβ were 4.6–500 and 5.0–170 μg/L, respectively, with detection limits of 1.2 and 1.7 μg/L (3 SD above mean of zero calibrator), respectively. The intraassay imprecision (CV) for AFP was 8.3%, 4.0%, and 2.7% at 16.3, 86, and 354 μg/L, respectively, and the interassay CV was 10%, 5.7%, and 3.5%. For hCGβ, the intraassay CV was 5.4%, 6.4%, and 3.1%, respectively, at 10.5, 45.2, and 105 μg/L, and the interassay CV was 7.2%, 8.0%, and 3.7%. Comparison with IRMAs for AFP and hCGβ yielded correlation coefficients (r2) of 0.97 and 0.95.

Conclusions: Two proteins can be measured simultaneously by immunoassays using two rare earth elemental tags (Eu3+ and Sm3+) and ICP-MS detection. The multielement capability and the multiple potential elemental labels make ICP-MS attractive for multianalyte immunoassays. Implementation of ICP-MS-linked immunoassays may be relatively straightforward because the labeling and immunoreaction procedures have been well developed for clinical time-resolved immunofluorometric assays.

Simultaneous determination of percentage of Lens culinaris agglutinin-reactive alpha-fetoprotein and alpha-fetoprotein concentration using the LiBASys clinical auto-analyzer

BACKGROUND

Lens culinaris agglutinin (LCA)-reactive alpha-fetoprotein (AFP-L3) percentage of total AFP concentration [(AFP-L3/total AFP)x100] has been used as an effective marker for earlier diagnosis, for assessment of therapeutic effects and for predicting the prognosis of hepatocellular carcinoma (HCC).

METHODS

A new clinical automatic analyzer, the "LiBASys", and an assay kit for the simultaneous determination of AFP-L3 percentage and concentration of AFP in human serum were developed. LiBASys performed automatic re-measurement and also met stat samples. Both AFP-L3 percentage and AFP concentration were calculated simultaneously and printed out continuously every 3.4 min per test.

RESULTS

A linear dose-response relationship was observed up to 1000 ng/ml AFP concentration. The detection limit and functional sensitivity of LCA-nonreactive AFP (AFP-L1) and AFP-L3 concentrations were 0.4 and 0.8 ng/ml, and 0.4 and 1.0 ng/ml, respectively. Interassay CVs of AFP-L3 percentage and AFP concentration ranged from 2.8% to 13.4% and 2.6% to 4.6%, respectively. Assay results exhibited good correlations with those of commercially available lectin-affinity electrophoresis (r=0.984) for AFP-L3 percentage and with the RIA method (r=0.999) for AFP concentration.

CONCLUSIONS

This method simultaneously yields both qualitative and quantitative results for AFP-L3 percentage and AFP concentration.

AFP-L3: a new generation of tumor marker for hepatocellular carcinoma

BACKGROUND

Alpha-fetoprotein (AFP) from hepatocellular carcinoma (HCC) displays differential affinity to lectin Lens culinaris agglutinin (LCA) compared to that from chronic hepatitis/liver cirrhosis. According to their binding capability to LCA, total AFP can be separated into three different glycoforms, AFP-L1, AFP-L2, and AFP-L3. AFP-L1 is the non-LCA-bound fraction, which constitutes the major glycoform of AFP in serum of chronic hepatitis and liver cirrhosis. AFP-L3 is the LCA-bound fraction of AFP. It has been reported that malignant liver cells produce AFP-L3, even when HCC is at its early stages, and especially when the tumor mass is supplied by the hepatic artery. Clinical research has determined that AFP-L3 is a highly specific marker for HCC. The AFP-L3 can be detected in the serum of approximately 35% of the patients with small HCC (<2 cm). The AFP-L3-positive HCC has potential for rapid growth and early metastasis. Compared to imaging techniques, it has been shown to have 9-12 months of lead-time in early HCC recognition. Combined sensitivity of AFP-L3 for HCC is 56%, with a specificity of >95%.

METHODS

Automated assay for measuring AFP-L3 has been developed and introduced in clinical use. The new automated method for measurement of ALP-L3 is based on liquid phase binding of the AFP-L3 glycoform with LCA and two specific monoclonal antibodies labeled with peroxidase and polysulfated tyrosine peptide, respectively.

CONCLUSION

AFP-L3 is a new generation of tumor marker for HCC and yields useful information on HCC for clinical decision making.