Preparation and characterization of new WHO reference reagents for XXXX chorionic gonadotropin and metabolites.

@entity1 @entity1522 @entity7807 @entity1465 @entity535 @entity1735 @entity1520 @entity10399
BACKGROUND: The currently used standards for @entity1 @entity1465 ) contain substantial amounts of contaminating variants of @entity1465 and other impurities. Furthermore, some partially degraded forms of @entity1465 and its subunits have become of potential clinical importance, e.g., "nicked" forms of @entity1465 ( @entity10399 ) and @entity7807 (hCGbetan), which contain cuts in the peptide backbone between @entity1522 44-45 or 47-48 in @entity7807 , and a fragment of @entity7807 (hCGbetacf) consisting of @entity1522 6-40 and 55-92 bound together by @entity1520 bridges. The IFCC appointed a working group with the aim of preparing new standards for @entity1465 and related substances to improve standardization of their immunoassays. METHODS: Large amounts of @entity1465 and its subunits as well as of @entity10399 , hCGbetan, and hCGbetacf were prepared by previously developed purification methods in combination with hydrophobic interaction chromatography and reversed-phase HPLC. Each preparation was characterized on the basis of @entity535 and sequence analyses, @entity1735 composition, and electrophoretic patterns. Immunoassays for relevant contaminating proteins were also performed. RESULTS: The major preparations were homogeneous and free of contaminating proteins. Concentrations of the final preparations were determined by @entity535 analysis. CONCLUSIONS: Calibrated in substance concentrations (mol/L) based on @entity535 analyses, these preparations will facilitate improved standardization of immunoassays for @entity1465 and its metabolites. The six preparations have now been established by the WHO as new 1st Reference Reagents for immunoassays with the following codes: @entity1465 99/688, @entity7807 99/650, hCGalpha 99/720, @entity10399 99/642, hCGbetan 99/692, and hCGbetacf 99/708. In contrast to the 3rd International Standard (75/537), the clinically most important Reference Reagent for @entity1465 (99/688) contains no @entity10399 and negligible amounts of free subunits.
