BCR/IFCC reference material for plasma proteins (CRM 470)

doi:10.1016/S0009-9120(98)00035-6

Clinical Biochemistry

Volume 31, Issue 6, August 1998, Pages 459-465

https://doi.org/10.1016/S0009-9120(98)00035-6 Get rights and content

Introduction

Several different reference materials for plasma proteins have been in use worldwide over the last 10 to 15 years. The introduction in the late 1960s of the World Health Organization (WHO), International Reference Preparation for Serum Immunoglobulins G A and M, code numbered 67/86 and in the late 1970s of the First WHO International Reference Preparation of Six Human Serum Proteins for Immunoassay (WHO 6HSP) and the United States National Reference Preparation for Specific Human Serum Proteins (USNRP) 1, 2, 3, 4, 5, 6, greatly improved the measurement of plasma proteins. Despite this, quality control surveys in Western Europe and the United States during the late 1980s and early 1990s showed that values for some proteins varied by as much as 100%, depending on the calibrator used. The reasons for this problem were complex, but several studies showed that the use of a single, international reference material by all manufacturers and laboratories reduced the variability to a large degree (7).

These observations led to the establishment of the International Federation of Clinical Chemistry (IFCC) Working Group on Plasma Protein Standardization in 1988 (later to become a committee of the Scientific Division) and the initiation of a program to prepare a new international reference material for plasma proteins, which has now been produced by the Community Bureau of References of the Commission of the European Communities (BCR): BCR CRM 470 8, 9. The project was managed by the Committee on Plasma Protein Standardization of the IFCC, and the College of American Pathologists (CAP), the major providers of plasma protein reference materials in the USA, have adopted the standard. The material was certified by BCR as a certified reference material (CRM 470) and released jointly with the CAP in mid-1993, after FDA approval with values assigned for transthyretin (prealbumin), α₁-acid glycoprotein (orosomucoid), α₁-antitrypsin (α₁-protease inhibitor), α₁-antichymotrypsin (assigned in a subsequent campaign) and transferrin against purified protein preparations. Values for albumin, ceruloplasmin, haptoglobin, α₂-macroglobulin, C3, C4, IgG, IgA, IgM have been assigned against WHO 6HSP in International Units and against USNRP in mass units. Values for C-reactive protein have been assigned from the WHO CRP standard. The basis of CRM 470 is shown in Figure 1.

Section snippets

Preparation of CRM 470

Extensive testing of the procedures to be used for the production of CRM 470 was undertaken in a number of pilot batches and they were shown to result in a clear material that could be used in all common methods of immunoassay. Accelerated degradation studies showed no significant change in protein concentration in samples of the lyophilised material stored at 45°C for 1 year. Every effort was made to ensure that the serum matrix used for this reference material contained proteins in a similar

Production of pure proteins for value assignment

International reference materials with values assigned against purified and highly characterized proteins are desirable. The IFCC Working Group on Plasma Proteins, during the early 1980s, produced three purified plasma proteins: transthyretin (prealbumin), α₁-acid glycoprotein (orosomucoid), and transferrin using mild purification methods that did not damage the proteins and with high recoveries, which are the best guarantee that subfractionation has not taken place. Recoveries were 85% for

Primary reference materials used for value transfer

Because of the availability of only a few such proteins and the urgent need for a new international reference material, it was decided to calibrate CRM 470 for the other proteins against the relevant WHO materials for International Units (IU) and against the best available materials for mass/volume units. For the majority of proteins this was the United States National Reference Preparation for Serum Proteins (USNRP Lot No. 12-0575C), from the Centers for Disease Control and Prevention

Value assignment

The analyses for value assignment of albumin, ceruloplasmin, haptoglobin, α₂-macroglobulin, C3, C4, IgG, IgA, and IgM were performed by 27 laboratories in Europe, the United States, and Japan. The data from all these laboratories showed agreement and statistical evaluation showed that it was homogeneous and could be merged. For the purified proteins α₁-acid glycoprotein (orosomucoid), α₁-antitrypsin (α₁-protease inhibitor), transferrin, transthyretin (prealbumin), and C-reactive protein values

Reference ranges based on CRM 470

Conversion to the new reference material has resulted in significant changes in reference values for some proteins, (notably, IgM, α₁-acid-glycoprotein, α₁-antitrypsin, transthyretin, and transferrin). The establishment of new reference ranges will take a considerable amount of time and in the interim several professional societies and diagnostic companies have agreed to use consensus reference ranges based on studies that have already been undertaken Table 2, 10.

Impact of the availability of CRM 470 on performance of protein analyses

Quality control schemes in various European countries have shown a considerable improvement in the results of protein analysis since the introduction of CRM 470.

Results for IgM measurement from the External Quality Assurance in Laboratory Medicine in Sweden are shown in Figure 6. It can be seen that there is a steady improvement in between-laboratory CV over late 1994 to mid 1995 resulting from the gradual introduction of CRM 470. Figure 7 shows the results for haptoglobin over a similar

Availability and use of CRM 470

CRM 470 has been released in Europe by the Community Bureau of Reference (now the Measurement and Testing program) of the Commission of the European Communities and has been approved by the FDA for distribution in the United States by CAP. It is available together with the protocols and statistical analysis used for the value assignment upon request from BCR, Commission of the European Communities, Directorate General for Science, Research & Development, DG X11/C/5, Measuring & Testing

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References (11)

D.S. Rowe et al.
A research standard for human serum immunoglobulins IgG, IgA and IgM
Bull Wld Hlth Org
(1970)
D.S. Rowe et al.
An international reference preparation for human serum immunoglobulins G, A and Mcontent of immunoglobulins by weight
Bull Wld Hlth Org
(1972)
C.B. Reimer et al.
Progress towards international reference standards for human serum proteins
J Biol Stand
(1978)
C.B. Reimer et al.
Collaborative calibration of three established reference preparations for specific proteins in human sera as secondary standards for IgA, IgM and IgG
J Biol Stand
(1981)
C.B. Reimer et al.
Collaborative calibration of the U.S. National and the College of American Pathologists reference preparations for specific serum proteins
Am J Clin Pathol
(1982)

There are more references available in the full text version of this article.

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InvitedBCR/IFCC reference material for plasma proteins (CRM 470)

Introduction

Section snippets

Preparation of CRM 470

Production of pure proteins for value assignment

Primary reference materials used for value transfer

Value assignment

Reference ranges based on CRM 470

Impact of the availability of CRM 470 on performance of protein analyses

Availability and use of CRM 470

First page preview

A research standard for human serum immunoglobulins IgG, IgA and IgM

Bull Wld Hlth Org

An international reference preparation for human serum immunoglobulins G, A and Mcontent of immunoglobulins by weight

Bull Wld Hlth Org

Progress towards international reference standards for human serum proteins

J Biol Stand

Collaborative calibration of three established reference preparations for specific proteins in human sera as secondary standards for IgA, IgM and IgG

J Biol Stand

Collaborative calibration of the U.S. National and the College of American Pathologists reference preparations for specific serum proteins

Am J Clin Pathol

Invited
BCR/IFCC reference material for plasma proteins (CRM 470)