Blockers

The existence of heterophilc antibodies and their potential for causing interference in immunoassays has been known for many years. The potentially devastating effects of false positive assay results on the patient and the medical community have more recently been delineated. The increasing use of the susceptible 2-site immunometric (“sandwich”) assay format has led to growing concern over the problem. For this reason, Scantibodies Laboratory has developed a unique heterophilic blocking reagent (HBR) product line that minimizes the occurrence of heterophilic antibody interference.

 

HETEROPHILIC BLOCKING REAGENT

Qualification Test for Application of HBR
Heterophilic Antibody Interference – What is it?
The Unique Aspects of HBR Over Conventional Blocking Methods
Heterophilic Interference – What is Known?
Heterophilic Antibodies – Sources
Heterophilic Interference – How is it Detected?
What is the Difference between “Heterophilic Antibody” and “HAMA?”
What is a Blocking Reagent?
Characteristics of an Ideal Heterophilic Blocking Reagent
The Scantibodies Heterophilic Blocking Reagent (HBR)
Performance Characteristics
False Positive Identification
Certification
Scantibodies Blocking Reagents for Assay Manufacturers
Scantibodies Blocking Reagents for Clinical Labs, Hospitals, etc.

PRODUCT INFORMATION

SCANTIBODIES PRODUCTS FOR REDUCTION OF FALSE POSITIVES DURING ASSAY DEVELOPMENT

3KG775 – Assay Development Blocking Kit => Directional Insert | MSDS
This Kit is provided as an aid in developing a reagent blocking formulation to eliminate false positive or negative interferences. Components that are included in this kit are useful for both active and passive blocking. The components in this kit have been selected to provide an array of options from which a selection may be made to develop a reagent blocking formulation.

SCANTIBODIES BLOCKING REAGENTS FOR ASSAY MANUFACTURERS (ACTIVE BLOCKERS)

3KC533 Heterophilic Blocking Reagent (HBR), 20 mg/ml => Directional Insert | MSDS
It contains specific murine immunoglobulins that block the heterophilic interaction by active binding to the heterophilic antibodies, which are capable of cross-linking the capture and the detection antibodies used in the immunoassay, resulting in false positive readings. The attachment of HBR-1 to the heterophilic antibodies blocks this cross-linking, and eliminates the interference caused by the heterophilic antibodies in the humoral fluids. In addition to its active blocking, this product is also characteristic of its passive blockage of the heterophilic interaction as well. The HBR is a liquid reagent with a protein concentration of 20 ± 2 mg/ml. The immunoglobulins are dissolved in a phosphate buffer with a pH of 7.4. The immunoglobulins in this product are at a purity of greater than or equal to 95% as shown by SDS-PAGE.
3KC534-075 Heterophilic Blocking Reagent (HBR), 2mg/ml => Directional Insert | MSDS

The HBR contains immunoglobulins of murine origin with specific binders that neutralize by active attachment to the heterophilic antibody. The attachment of HBR to the heterophilic antibodies renders the heterophilic antibodies incapable of cross-linking the capture and the label antibodies in the immunoassay. The HBR is a liquid reagent with a protein concentration of 2 ± 0.1 mg/ml. The immunoglobulins are dissolved in a phosphate buffer with a pH of 7.2 – 7.6. The immunoglobulins in the HBR are at a purity of greater than or equal to 95%.
3KC534 Heterophilic Blocking Reagent 1 (HBR 1), 2mg/ml => Directional Insert | MSDS

The HBR contains immunoglobulins of murine origin with specific binders that neutralize by active attachment to the heterophilic antibody. The attachment of HBR to the heterophilic antibodies renders the heterophilic antibodies incapable of cross-linking the capture and the label antibodies in the immunoassay. The HBR is a liquid reagent with a protein concentration of 2 ± 0.1 mg/ml. The immunoglobulins are dissolved in a phosphate buffer with a pH of 7.0 – 7.4. The immunoglobulins in the HBR are at a purity of greater than or equal to 95%.
3BX484 – HBR-1 , Non Purified => MSDS
This product contains the same heterophilic blocking components of HBR-1 in a non-purified form at a concentration of 2-3g/dL. Therefore, its total protein concentration is higher than HBR-1 Purified due to presence of some non-HBR proteins. Some customers prefer this product that further reduces the non-specific interaction which can lead to falsely elevated results.

3KC535 – HBR-2 , Purified => MSDS
This product represents a variation in formulation with similar essential characteristics compared to HBR-1-Purified. It has a concentration of 7-8 mg/ml.

3KC701 – HBR-3 , Purified => MSDS
Each vial contains approximately 4 mg of immunoglobulins. This product represents a variation in formulation with similar essential characteristics compared to HBR-1 Purified. The special formulation is designed to enhance its blocking capability at a lower concentration of immunoglobulins.

3KC542 – HBR-6 , Purified => MSDS
Each vial of HBR-6 contains approximately 10 mg of immunoglobulins. This HBR-6 is specially formulated to enhance its heterophilic blocking ability. The immunoglobulins in this reagent are at a purity of greater than or equal to 95%.

3KC564 – HBR-9 , Purified => MSDS
The HBR-9 is also one of our newly formulated products developed as an alternative for the HBR Plus, 3KC545. It contains immunoglobulins with different characteristics. It is specially formulated for application for immunoassays in which both the capture and detection antibodies are of murine origin. Like HBR Plus, this product is characteristics for its active as well as passive blocking efficacy. Each vial of this product contains approximately 20 mg of immunoglobulins, which are at a purity of greater than 90%.

3KC565 – HBR-11 , Purified => MSDS
The HBR-11 is also one of our newly formulated products. This product is formulated with murine immunoglobulins. In addition to the products listed above, the HBR-11 provides our customers with more selection for heterophilic blockage. Each vial of this product contains approximately 20 mg of immunoglobulins, which are at a purity of greater than 90%.

3KC545 – HBR-Plus , Purified => MSDS
The HBR Plus is one of our newly formulated products developed as an alternative for HBR-1. This product is compounded with immunoglobulins with different characteristics. Therefore, in addition to its active blocking characteristics, the special formulation and production procedures enhance its efficacy in its passive blocking ability as well. Each vial of this HBR Plus contains approximately 20 mg of immunoglobulins.

PASSIVE BLOCKERS

Mouse IgG acts as a passive heterophilic blocker that neutralizes a subpopulation of the heterophilic antibody and reduces the heterophilic interactions. In addition, Mouse IgG also increases the free IgG concentration in an assay system and reduces the non-specific interaction that results in falsely elevated analyte concentrations. It is an inexpensive blocker that works well in a good number of assay formats. However, it does not have the active blocking ability as HBR does. Therefore, Mouse IgG may not be powerful enough to completely block certain strong heterophilic interactions.
3BM245 – Mouse lgG, Purified => MSDS
This product is affinity-purified from normal mouse serum at a concentration of 10-12 mg/ml. It contains all the normal subclasses of mouse IgG, and is provided at a purity of greater than or equal to 95%, as determined by SDS-PAGE. Mouse IgG has known characteristics for passive blocking efficacy which makes it a good choice for a heterophilic blockage at a lower cost. Therefore, it is recommended for heterophilic blockage in immunoassays in which both the capture and detection antibodies are of murine origin.

3BM845 – Mouse lgG, Purified, Concentrated => MSDS
This is a more concentrated (>35 mg/ml) version of our Mouse IgG.

SCANTIBODIES BLOCKING REAGENTS FOR CLINICAL LABS, HOSPITALS, ETC…

3IX761 Nonspecific Antibody Blocking Tube (NABT) => Directional Insert
The NABT contains immunoglobulins. The non-specific antibodies in the serum or plasma samples bind to these immunoglobulins and are blocked from interfering in antibody detection immunoassays. Each tube contains enough reagent to inactivate the non-specific antibodies in 500 ?L of sample. The reagent is in the form of a lyophilized pellet at the bottom of the tube. The NABT allows for the rapid and simple elimination of false positive non-specific antibody interference in plasma or serum for detection assays (i.e., anti-HCV, HIV, Toxoplasmosis, Rubella, CMV. Herpes. Tg, TPO, etc.). The NABT is used as a sample treatment in preparation for testing. It can either be used in conjunction with the initial assay or in a secondary confirmation assay. NABT represents a sample pretreatment/second assay intended to confirm or disqualify the original FDA licensed non pretreatment assay result. The assay result from the pretreatment is NEVER TO BE USED AS A REPORTABLE RESULT. The pretreatment is only a confirmation aid designed to assist the lab to know whether to report the original non pretreatment assay result. In other words, if the pretreatment assay result is the same as the original assay result the original result is reported. However, if the pretreatment sample assay result is lower than the original result, the original result is not reported and the sample is submitted for further study for potential false positive assay interference.
3IX762 – Heterophilic Blocking Tubes (HBT) => Directional Insert

The HBT contains a unique blocking reagent composed of specific binders which inactivate heterophilic antibodies. Once the specific binders have bound to the heterophilic antibodies, the antibodies are no longer able to cause immunoassay interference. The reagent is in the form of a lyophilized pellet at the bottom of the tube. Each tube contains enough reagent to inactivate the heterophilic antibodies in 500 ?L of sample. The HBT allows for the rapid and simple elimination of false positive heterophilic interference in plasma or serum for immunoassays (i.e., FSH, LH, Prolactin, TSH, Ferritin, CEA, AFP, hCG, HBsAg, CK-MB, CA 1251, CA 19-9 , NSE, etc.). HBT represents a sample pretreatment/second assay intended to confirm or disqualify the original FDA licensed non pretreatment assay result. The assay result from the pretreatment is NEVER TO BE USED AS A REPORTABLE RESULT. The pretreatment is only a confirmation aid designed to assist the lab to know whether to report the original non pretreatment assay result. In other words, if the pretreatment assay result is the same as the original assay result the original result is reported. However, if the pretreatment sample assay result is lower than the original result, the original result is not reported and the sample is submitted for further study for potential false positive assay interference.

For pricing details or to arrange for a FREE sample of HBR, please contact Scantibodies Laboratory