International collaborative study to evaluate and calibrate two recombinant L chain Ferritin preparations for use as a WHO International Standard

Abstract Objectives To evaluate and calibrate two candidate preparations for the 4th International Standard for Ferritin (Human, Recombinant) (codes: 19/118 and 19/162) against the 3rd International Standard for Ferritin (Human, Recombinant) (code: 94/572), and three serum commutability samples in an international collaborative study involving 12 laboratories in nine countries. Methods Eleven of the 12 participating laboratories performed Ferritin quantitation using automated assay platforms and one laboratory used a manual ELISA kit. Results There was better overall agreement between all laboratories and between assay methods for the potency of preparation 19/118 than for preparation 19/162. The overall geometric mean potency (from all methods) of the candidate 4th International Standard, 19/118, was 10.5 µg/ampoule, with inter-laboratory variability, expressed as % geometric coefficient of variation (GCV), of 4.7%. Accelerated stability studies have predicted both 19/118 and 19/162 to be very stable for long term storage at −20 °C. Conclusions The candidate 4th International Standard for Ferritin (Human, Recombinant) (19/118) has been shown to be immunologically similar to the 3rd International Standard for Ferritin (Human, Recombinant) (94/572). It was recommended to and accepted by the WHO Expert Committee on Biological Standardization that 19/118 be established as the 4th International Standard for Ferritin (Human, Recombinant) with an assigned potency of 10.5 µg/ampoule and expanded uncertainty limits 10.2–10.8 µg/ampoule (95% confidence; k=2.23).

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International collaborative study to evaluate a recombinant L ferritin preparation as an International Standard

Clinical Chemistry ◽

10.1093/clinchem/43.9.1582 ◽

1997 ◽

Vol 43 (9) ◽

pp. 1582-1587 ◽

Cited By ~ 22

Author(s):

Susan J Thorpe ◽

Dawn Walker ◽

Paolo Arosio ◽

Alan Heath ◽

James D Cook ◽

...

Keyword(s):

Collaborative Study ◽

Expert Committee ◽

Immunological Reactivity ◽

International Standard ◽

Accelerated Degradation ◽

Wide Range ◽

Biological Standardization ◽

International Collaborative ◽

Degradation Studies ◽

International Collaborative Study

Abstract A recombinant L ferritin preparation, lyophilized in ampoules and designated 94/572, was evaluated by 18 laboratories in 9 countries for its suitability as an International Standard (IS). The preparation was assayed in a wide range of in-house and commercial immunoassays against the 2nd IS for ferritin (of spleen origin; 80/578). The immunological reactivity of the recombinant material was similar to that of the 2nd IS for ferritin in the majority of assays and demonstrated adequate stability in accelerated degradation studies. On the basis of the results presented here, the WHO Expert Committee on Biological Standardization established 94/572 as the 3rd IS for ferritin, recombinant.

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An International Standard for holotranscobalamin (holoTC): international collaborative study to assign a holoTC value to the International Standard for vitamin B12 and serum folate

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2015-1167 ◽

2016 ◽

Vol 54 (9) ◽

pp. 1467-1472 ◽

Cited By ~ 6

Author(s):

Susan J. Thorpe ◽

Peter Rigsby ◽

Graham Roberts ◽

Anne Lee ◽

Malcolm Hamilton ◽

...

Keyword(s):

Vitamin B12 ◽

Collaborative Study ◽

World Health ◽

Serum Folate ◽

Expert Committee ◽

Specific Marker ◽

Serum Samples ◽

International Standard ◽

International Collaborative ◽

International Collaborative Study

AbstractBackground:Investigation of possible B12 and folate deficiencies requires measurement of these vitamins in serum. There is evidence that holotranscobalamin (holoTC), the active portion of B12 available to cells, is a more specific marker of early B12 deficiency than total B12. The availability of immunoassays for holoTC prompted an international collaborative study to assign a holoTC value to the World Health Organization (WHO) 1st International Standard (IS) for vitamin B12 and serum folate, 03/178.Methods:The IS, 03/178, and three serum samples with different holoTC levels were assayed by 12 laboratories in eight countries using manual and automated immunoassays for holoTC; one laboratory additionally performed an in-house assay. Fourteen sets of data were analysed.Results:Overall, the IS, 03/178, and the three serum samples demonstrated assay linearity and parallelism. An overall geometric mean (GM) holoTC value of 106.8 pmol/L was obtained for 03/178, with an inter-laboratory geometric coefficient of variation (GCV) of 10.5%. There was a reduction in inter-laboratory variability when the holoTC levels in the serum samples were determined relative to the IS with an assigned holoTC value rather than to the assays’ calibration. Accelerated degradation studies showed that 03/178 was sufficiently stable to serve as an IS for holoTC.Conclusions:The WHO Expert Committee on Biological Standardization endorsed the proposal to assign a holoTC value of 107 pmol/L to 03/178, corresponding to 0.107 pmol per ampoule, for use as the 1st IS for vitamin B12, serum folate, and holoTC.

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An International Standard for whole blood folate: evaluation of a lyophilised haemolysate in an international collaborative study

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm.2004.090 ◽

2004 ◽

Vol 42 (5) ◽

Cited By ~ 17

Author(s):

Susan J. Thorpe ◽

Dawn Sands ◽

Alan B. Heath ◽

Malcolm S. Hamilton ◽

Sheena Blackmore ◽

...

Keyword(s):

Whole Blood ◽

Collaborative Study ◽

World Health ◽

Expert Committee ◽

International Standard ◽

Accelerated Degradation ◽

Biological Standardization ◽

The World ◽

Health Organization ◽

International Collaborative Study

AbstractFolate measurements, particularly for whole blood, show wide inter-laboratory and inter-methodology variability. This variability appears to be due in part to the lack of internationally accepted reference materials. A whole blood haemolysate, lyophilised in ampoules and designated 95/528, was therefore evaluated by 15 laboratories in five countries for its suitability as an International Standard (IS) for whole blood folate. The preparation was assayed using a variety of microbiological and protein-binding methodologies against local standards and calibrators. A consensus folate content was assigned to 95/528. The inclusion of three whole blood samples in the study with widely differing folate levels demonstrated a considerable reduction in inter-laboratory variability when the folate content of the samples was determined relative to the proposed IS 95/528 rather than to laboratories' local standards and calibrators. Accelerated degradation studies indicated that the folate content of 95/528 is stable when stored at −20°C. On the basis of the results presented here, the World Health Organization Expert Committee on Biological Standardization established 95/528 as an IS for whole blood folate.

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Characterization of Reference Materials for Human Antiserum to Pertussis Antigens by an International Collaborative Study

Clinical and Vaccine Immunology ◽

10.1128/cvi.00372-08 ◽

2008 ◽

Vol 16 (3) ◽

pp. 303-311 ◽

Cited By ~ 50

Author(s):

Dorothy Xing ◽

Carl Heinz Wirsing von König ◽

Penny Newland ◽

Marion Riffelmann ◽

Bruce D. Meade ◽

...

Keyword(s):

Collaborative Study ◽

International Standards ◽

World Health ◽

Enzyme Linked Immunosorbent Assay ◽

Expert Committee ◽

International Standard ◽

Reference Serum ◽

International Collaborative ◽

International Collaborative Study

ABSTRACT Enzyme-linked immunosorbent assay (ELISA) has been widely used to evaluate antibody responses to pertussis vaccination and infection. A common reference serum is essential for the standardization of these assays. However, no internationally recognized reference serum is available. At the request of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), a set of four candidate international standards has been prepared. These candidate materials have been assessed for suitability and compared to the widely used U.S. reference pertussis antiserum (human) lot 3, lot 4, and lot 5 by 22 laboratories from 15 countries in an international collaborative study. Laboratories measured immunoglobulin G (IgG) and IgA antibodies to pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and fimbriae (Fim2&3) using their established immunoassays. The results of this study showed each of the four candidates to be suitable as an international standard. With the agreement of the participants, a recommendation has been made to the ECBS that the candidate material coded 06/140 be established as the First International Standard for pertussis antiserum (human), with the following assigned international units (IU): IgG anti-PT, 335 IU/ampoule; IgA anti-PT, 65 IU/ampoule; IgG anti-FHA, 130 IU/ampoule; IgA anti-FHA, 65 IU/ampoule; IgG anti-PRN, 65 IU/ampoule; and IgA anti-PRN, 42 IU/ampoule. No formal units have been proposed for anti-Fim2&3 because most assays used a mixture of fimbrial antigens. In addition, the candidate material coded 06/142 has been proposed as a WHO working preparation for characterization of assay systems.

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A Collaborative Study Designed to Establish the 4th International Standard for Heparin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661160 ◽

1984 ◽

Vol 52 (02) ◽

pp. 148-153 ◽

Cited By ~ 14

Author(s):

D P Thomas ◽

A D Curtis ◽

T W Barrowcliffe

Keyword(s):

Collaborative Study ◽

International Standard ◽

Thrombin Inhibition ◽

Freeze Dried ◽

Assay Methods ◽

The Mean ◽

International Collaborative ◽

International Collaborative Study

SummaryAn international collaborative study, in which 22 laboratories participated, was carried out to establish a replacement for the International Standard for Heparin. A total of 248 assays were analyzed, including APTT, thrombin inhibition and anti-Xa assays, as well as pharmacopoeial assays. Overall, there was less than 5% difference in the mean potency estimates of the candidate preparations, by all assay methods. The freeze-dried preparation 82/502 demonstrated the closest parallelism by bioassay to the existing standard and was established by WHO as the 4th International Standard for Heparin, with an assigned unitage of 1780 i.u. per ampoule.

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