Can Quotient demonstrate metrological traceability of the Anti-D quantitation value to a recognised standard?
Quotient manufacture products designed to test the sensitivity of immunohaematology test systems which contain Anti-D at a level of <0.1IU/mL as recommended in BCSH Guidelines for pre transfusion compatibility procedures in blood transfusion laboratories.
The products are prepared from pooled human plasma containing Anti-D which undergoes quantitation to determine the antibody concentration in IU/mL. Based on the quantitation result the anti-D is then accurately diluted to achieve a level of <0.1 IU/mL in the final product.
Quantitation is carried out prior to the final dilution of the plasma to ensure that the concentration of the antibody is within the linear range of the quantitation assay to allow accurate measurement. Levels of Anti-D at or below 0.1 IU/mL are not considered to be within the linear range of the assay and therefore are not measured directly.
Quantitation of the Anti-D is carried out by an accredited laboratory which utilises a standard curve prepared from the British Working Standard Anti-D (73/515) and therefore Quotient sensitivity control products containing Anti-D below 0.1IU/mL are metrologically traceable to 73/515 Anti-D British Working Standard (NIBSC).
Do you have suggestions or cautions for a new user with your products?
In order to assure clear demonstration of weak D and partial D antigens, our Anti-D reagents have potentiators that may exhibit a false positive reaction if the reagents or relevant samples are tested at 18°C or below. These reactions are easy to identify, as they generally weaken at 37°C.
Our Anti-N and Anti-M reagents are very quick, requiring a short 5 minute incubation, at 20 – 25C. It is important that the reagents are at room temperature prior to testing. If these reagents are removed from the refrigerator and used immediately, it is likely that the incubation temperature will not be correct, and weak false positives may be seen.
The Anti-M reagent reacts optimally at pH 8.5 and is extremely sensitive to pH to allow for the testing to be completed with only 5 minutes of incubation. Buffered saline will affect pH levels, so be sure to utilize red cells suspended in unbuffered/ unstabilized normal saline.
Some manufacturers do not include Anti-A,B in their reagent Anti-A,B and instead mix Anti-A and Anti-B together, does Quotient’s product contain actual Anti-A,B?
Yes, Anti-A,B is included in the Quotient reagent so it will detect most weak subgroups of A, especially Ax. The reagent is an excellent choice for rechecking units and provides the information you need when attempting to resolve ABO discrepancies that are the result of weak subgroups of A.
What is all the hype about cell lines? As long as the reagent works, why should I care about cell lines?
Cell lines indicate the “pedigree” of the cells producing the antibody used in a monoclonal reagent. Each cell line actually has its own specificity and you will occasionally see differences between the reactions from different cell lines for the same antibody specificity. AABB Standards requires that IRLs have two examples of some antisera. The laboratory staff needs to determine the cell lines used in the reagents they purchase to make sure they have two examples because it is not unusual for multiple manufacturers to utilize the same cell line. Quotient primarily utilizes cell lines that have not been previously distributed in the United States and can aid IRLs in meeting this requirement.
Is it possible to have Quotient Anti-D reagents from different cell lines, one that is appropriate for most transfusion patients and one capable of weak D testing for say cord blood?
Yes, there are two ALBAclone® product combinations that would meet your need. The Anti-D alpha is appropriate for most transfusion patients, while our Anti-D blend is from a different cell line but can detect weak-D through IAT. Additionally, our Anti-D beta also would be appropriate for transfusion patients, while the Anti-D optimum is from a different cell line and can detect weak D at immediate spin.
Currently we perform "weak D testing" on all the patient samples we test, which of your Anti-Ds should we consider using?
The ALBAclone® Anti-D blend is our most comparable alternative to the reagents you are currently using. The Anti-D blend is an all-round product that can be read at immediate spin, then incubated and taken through the indirect antiglobulin test (IAT) to detect weak D.