Immunoassay
Blocking Reagents
Practical Guide
ISO Certified 13485:2016

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Recommended Blockers
Blockers for interference in sandwich immunoassays
Animal IgG – Passive Blockers

TRU Block™ – Active HAMA & RF Blocker• Suited for mixed species assays (e.g. MAb/PAb)• Suited for double mouse monoclonal assays•	Species of blocker must be the same as the host of
the capture or detection antibody• Removes HAMA, HA & RF interference

Mouse IgGTRU Block™ Ready8001
TRU Block

TRU Block™ Ultra
TRU Block8000
IgM RF
8002 (no azide)

A66186M (9-13mg/mL)
A66185M (50-55mg/mL)
A66189M (45-55mg/mL, No Azide)
A66185M-LY (Lyophilized)

TRU Block™
A66800H

Interfering HA(e.g. HAMA)

Detection Antibody(mouse origin)

TRU Block™ 2
A66802H

AntigenBlocking
BufferCapture Antibody(mouse origin)

Goat IgG
A66200H

Rabbit IgG
A66100H

TRU Block 3
A66803H

Rat IgG
A64391R
A41182R

Sheep IgG
A66400S(70-77mg/mL, Liquid)*Formulations differ in their ratio of various proprietary
ingredients that confers unique blocking characteristics.

Passive blocking reagents work by preventing interfering
antibodies from binding to the capture or detection
antibodies by providing alternate binding sites. Animal IgG(e.g. Goat IgG) can only block one type of interference(e.g. human anti-goat antibodies) so typically more than
one type must be used, depending on the host of both thecapture and detection antibodies. Animal IgG must be addedin excess concentration and the effectiveness depends on
the affinity of interfering antibody for the animal IgG.

™

In double mouse monoclonal assays, a specific blocker isrequired to remove a particular type of HA interference called
human anti-mouse antibodies (HAMA) and Rheumatoid Factor(RF). A HAMA blocker contains a specific binder directedagainst all types of heterophilic interference including HAMAand RF. Once bound to the interfering antibodies, TRU Blockprevents further binding of HA to other assay components
through steric hindrance. Active blockers can typically be usedin lower concentrations than passive blocking reagents, which
minimizes the reduction in assay signal commonly associatedwith passive blockers.

RECOMMENDED CONCENTRATION:•	10x the concentration of the MAb/PAb being used in
the assay (e.g. if 5μg/mL of Ab/conjugate, add 50μg/
mL Animal IgG).
•	Can be added to the sample or conjugate diluent but
ideally should be in contact with the patient sample
before incubation with the assay capture antibody.

RECOMMENDED CONCENTRATION:
For best performance, TRU Block should be included
as part of the sample or conjugate diluent, at arecommended concentration range:
Product

Protein Concentration

Application

TRU Block™
Ready

Single-step dilution withrecommended dilutionof 1:1000 to 1:10

ELISA & LF

TRU Block™ ULTRA

Range: 24-26 mg/mL

ELISA, CLIA & LF

TRU Block™
ULTRA (no azide)

Range: 24-26 mg/mL

ELISA, CLIA & LF

TRU BlockRange: 24-26 mg/mL

ELISA & CLIA

TRU Block™ 2

Range: 24-26 mg/mL

CLIA & LF

TRU Block™ 3

24.3 mg/mL

ELISA

™

2

Blockers Practical Guide

Blockers for Interference in IgM Capture Assays
IgG Absorbent
IgG Absorbent is a purified goat anti-human IgG (GAH IgGFc) Fc fragment designed for the removal of human IgG
and IgG/rheumatoid factor (RF) complexes from serum
prior to testing for specific IgM antibodies in ELISA or otherimmunoassays. Removal of IgG interference has been
demonstrated to significantly increase the sensitivity of IgM
detection in immunoassays. Meridian’s IgG Absorbent istested by immunoelectrophoresis to ensure specificity for
IgG and no cross-reactivity to IgM or IgA. Goat anti-human
IgG (GAH IgG Fc) L15406G.

RECOMMENDED REAGENT:
L15406G Goat anti-human IgG Fc (GAH IgG Fc)
		
Dilute prior to adding to patient sample. 		
		
Recommend diluting 1:10 in PBS.
		Add in a ratio of 1:10 to patient sample
and allow to incubate 5-30 minutes.

IgM Assay Diluent
IgM Assay Diluent is intended for use in qualitative andquantitative assays that detect IgM antibodies. This
diluent is formulated to reduce assay interference from apatient’s IgG antibodies, rheumatoid factor, heterophilic
antibodies, and other non-specific proteins that can affectthe immunoassay results. Blocking proteins within the
IgM Assay Diluent are in high excess and will bind to any
open binding site on the assay solid phase to prevent
binding from interfering factors. When included as a partof a test kit, IgM Assay Diluent can increase the sensitivityof an IgM detection assay.

RECOMMENDED REAGENT:
8120
IgM Assay Diluent		In a separate tube, dilute the patient serum
sample in the IgM Assay diluent at a
1:21 dilution or greater (mix well). The
diluent must be standardized with theother assay components.

Solid Phase Blocking Buffers
J82100B - ELISA Blocking Buffer (PBS, pH7.4)
J82300B - Lateral Flow Blocking Buffer (PBS, pH 7.4)
• Non-mammalian based blockers•	Blocks non-specific binding to a solid phase subtrate toimprove assay sensitivity• Stabilizes bound proteins on microplate/membrane• Increases signal-to-noise ratio• Use at 1x concentration or with further dilution

J16430D - Coating Stabilizer and Blocking Buffer•	Improves stability and function of antigens/proteinsbound to a solid phase•	Ideal for very unstable proteins or for less labile antigens/proteins. Dilute up to 1:1 in the assay’s current blocker• Buffer pH 7.2 ± 0.2
A64801B - Bovine Serum Albumin (BSA)•	Ideal for casein-sensitive antibodies, such as
phospho-specific antibodies• Can be used in ELISA, Western blot, and IHC• Use at 1-5% concentration in PBS at pH 7
• Lyopholized

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3

Recommended Blockers
Isotype Controls & Other Blockers
An isotype control acts as a negative control in flow cytometry and immunohistochemistry
assays by differentiating non-specific background signal from specific antibody signal. In
addition, Human Immunoglobulin can be used to measure the type of immunoglobulin/
isotype in a patient’s sample, as a standard blocking agent, or as a protein coating agent for
applications including immunofluorescence, immunocytochemistry, Western blot, and ELISA.

RECOMMENDED REAGENT:
Human

Mouse

Rat

IgG

IgM

IgG

IgG

• A50170H, IgG• A50168H, IgM• A66186M, IgG• A64391R, IgG• A01696M, IgG2a, kappa• A41182R, IgG• A50175H, IgG (Fc)

IgE

IgA

• A50384H, IgE• A50167H, IgA•	A75671H, IgE, kappa& lambda• A50166H, IgA1, kappa• A50165H, IgA1, lambda

Sheep
IgG
• A66400S, IgG

Isotype controls are primary antibodies that lack specificity to the target antigen, but match the class and type of the primary
antibody used in the application. They act to reduce non-specific binding by the primary/capture antibody through blocking Fc
receptor binding or nonspecific antibody interactions with cellular proteins, carbohydrates, and lipids. The isotype control
antibody should match the primary/capture antibody’s host species, isotype (including heavy chain (IgA, IgG, IgD, IgE, or IgM)
and light chain (kappa or lambda) class) and if relevant, conjugation. In addition, isotype controls should be used at the same
concentration as the primary antibody.

44 | Blockers
Blockers Practical
Practical Guide

Why Use Blockers?
Blockers are used in ELISA and LF assays to reduce interference from proteinsin patient samples that could produce false results and an incorrect diagnosis.
Choosing the best assay format depends on the intended
application of the assay, the type of samples to be analyzed,
the availability of reagents and whether the assay is intended
for a single analysis in one lab, or is intended to be used inmany laboratories by various technicians. Generally, an
immunoassay will fall into one of the following categories:•	
Sandwich Antigen Detection ELISA - designed tomeasure the amount of target antigen/analyte•	
Antibody Capture ELISA - used to screen for
antibodies (e.g: lgG, lgM, lgA & lgE) to a specific target•	Competitive ELISA - detects antigen/analyte present
in a sample and is commonly used when the antigen
is small with only 1-2 epitopes
Several parameters that are critical to assay performanceare common among all of these formats: (1) the choice ofsolid phase (2) the choice of antibodies/antigen and (3) the
choice of blocking agents. In order to produce an assay withhigh sensitivity and specificity, the most critical element isselecting antibodies or antigens that have a highly specificinteraction with the target molecule. However, it is possible
to improve assay sensitivity and specificity with the use ofblocking agents. These blockers work by reducing non-specificbinding resulting in an increase in signal-to-noise ratio.

TYPES OF IMMUNOASSAY SOLID PHASES
Material

Binding
CapacityType of Interaction

Nitrocellulose

High

Hydrophobic, Hydrophilic

PVDF

High

Hydrophobic

Nylon

High

Hydrophobic

Polystyrene

Low

Hydrophobic

Polyvinyl

Low

Hydrophobic

Low

Covalent, Hydrophobic,
Hydrophilic

Plates & Tubes

Derivatized
microtiter plates
Beads
Polystyrene

Moderate

Hydrophobic

Denvatized
Polystyrene

High

Covalent, Hydrophobic,
Hydrophilic

Microparticles

High

Covalent and Hydrophobic

A solid surface which has a high binding capacity but does
not cause damage to the native protein conformation of theimmobilized antigen or antibody is ideal.

Non-specific interactions in an assay can occur (1) between
the solid phase and non-target proteins, which can absorb to
the surface of the solid substrate and (2) between antibodies
within the assay itself and endogenous antibodies present
within a patient’s sample. To prevent non-specific binding,blocking buffers are used after the solid-phase coating step toblock any remaining open binding sites. Other blocking agentsare used in the sample preparation to prevent interfering
antibodies from binding to the assay antibody components.

KEY PERFORMANCE DIFFERENCES BETWEEN MONOCLONAL AND POLYCLONAL ANTIBODIESIn general, a MAb is often chosen as the primary antibody to establish the highest level of specificity in an assay, and a PAb ischosen as the secondary antibody, to amplify the signal via multiple binding events. However, any combination can be used.
All candidate antibodies must be tested together with the intended sample type in order to select the best performers.
Monoclonal antibodies (MAb)

Polyclonal antibodies (PAb)•	Generally produced in mice orrecombinantly, and recognize asingle epitope.

•	Produced in goats, sheep, chicken, rabbits and other animals.

•	Since only one antibody moleculecan bind to the antigen, theinteraction is highly specific but
can lack sensitivity, depending on
the affinity constant.

•	PAbs are able to recognize multiple epitopes on any one antigen which makes
them less sensitive to antigen mutational changes.

•	Polyclonal sera is a heterogeneous composite of antibodies with uniquespecificities. The concentration of specific antibody (PAb) is typically 50-200mg/mL.

•	PAbs are useful when the nature of the antigen is not well known.
However, their quantity is limited by the lifespan of the host animal.

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5Immunoassay formats that
require blockers

Sandwich Antigen Detection Immunoassays

This is a sensitive and robust method which captures the target antigen between two antibodies (capture and detection antibody).
The capture antibody is bound to the solid phase. The antigen-containing sample is applied followed by a wash step to remove
unbound antigen. A detection antibody is added that binds directly to the antigen. The capture and detection antibodies must bindto non-overlapping epitopes on the antigen. Either monoclonal or affinity-purified polyclonal antibodies can be used as capture anddetection. The antigen can be measured with a conjugated detection antibody (direct detection) or a matched set of unlabeleddetection and conjugated secondary antibodies (indirect detection).

Detector
Label

Detection
Antibody

Secondary
Antibody

Detector
Label

Detection
Antibody

Antigen

AntigenCaptureAntibody

CaptureAntibody
Direct Detection

Indirect Detection

Antibody detection Assay (IgG, IgM & IgA)
The antigen is immobilized on the solid phase by direct absorption. The antibody-containing sample is applied followed by awash step. Detection of the antibody can then be performed using an conjugated detection antibody (direct detection) or amatched set of unlabeled detection and conjugated secondary antibodies (indirect detection). Direct detection is shown below.
Detector
Label

Detection
Antibody
Patient’s IgG Ab

Detection
Antibody

Detector
Label

Patient’s IgM Ab

Antigen

AntigenIgG Detection

IgM Detection

Competitive Assay
A competitive binding process between the patient’s target
analyte and labeled antigen (inhibitor antigen). Antibody
specific for the target analyte is coated onto the solid phase.
Patient sample and labeled inhibitor antigen are incubatedwith the pre-coated antibody and compete for binding sites.
Unbound labelled antigen/analyte is removed by washing.
The more analyte in the sample, the less the labelled inhibitor
antigen will bind to the antibody. Therefore, the weaker theassay signal, the higher the concentration of analyte in thepatient sample. This is a common method for small antigens
that have only 1-2 epitopes.

6

Blockers Practical Guide

Detector
Label
Patient
AnalyteInhibitor
AntigenCaptureantibody
Direct Detection

Blocking the Solid Phase
Solid phase quantitative immunoassays such as ELISA, lateral flow and Western blot all
involve the immobilization of antibodies to a surface. Non-specific binding to this surface byother proteins or biomolecules can reduce an assay’s specificity and sensitivity. Solid phase
blocking agents are specifically designed to saturate these unoccupied binding sites toprevent non-specific binding, while enhancing assay sensitivity.
When developing a new immunoassay, the first step is to
optimize the antigen or capture antibody coating conditions
on the solid phase in order to maximize the amount ofprotein coated. After coating, any remaining unoccupied
binding sites must be blocked in order to prevent nonspecific binding of subsequent reactants. An ideal blocking
agent is typically protein-based as it is able to block bothhydrophobic and hydrophilic sites on the solid phase. In
addition, it can serve as a stabilizing agent and prevent
denaturation while proteins react at the surface of the solid
phase. The concentration of the blocker and the amount ofblocking time must be optimized for each assay. Using
inadequate amounts of blocker will result in excessive
background and a reduced signal-to-noise ratio. Using
excessive concentrations of blocker may mask antibodyantigen interactions causing less sensitivity.

IDEAL BLOCKING AGENTS HAVE
THE FOLLOWING CHARACTERISTICS:•	Effectively block nonspecific binding of assay
reactants to the surface of the well•	Do not disrupt the binding of assay componentsthat have been adsorbed to the well•	Act as a stabilizer (prevent denaturation) of
assay reactants on the solid phase•	Do not cross-react with other assay reactants•	Do not possess enzymatic activity that might
contribute to signal generation of the substrateor degradation of the reactants•	Perform consistently across various lots

ELISA without blocking buffer
Unbound debris such as proteins, interfering molecules in thepatient sample, and assay reactant bind to the solid phase andcompete with the specific antigen-antibody reaction causing
background noise and reduction in specific assay signal.

ELISA with blocking buffer
Blocking buffer is designed to bind to open sites on the solid
phase, preventing unbound debris from non-specifically binding.
Detector
Label

Detector
Label

Detection
Antibody
AntigenDetection
Antibody
UnboundDebrisCaptureAntibody

AntigenCaptureAntibody

Blocking
BufferGENERAL BLOCKING PROTOCOL
1.	After coating the solid-phase with primary antibody, add the blocking solution
directly to the wells, beads, blotting membrane or nitrocellulose membrane.
2.	Determine the best concentration of blocker for your assay. Blockers can beused at 1x concentration or diluted.
3.	Determine the optimum incubation temperature and time for proper absorption of
the blockers. Longer times and higher temperature increase the rate of blocking.
Typical temperatures are 25°C - 30°C incubated for 30 minutes to 2 hours.

NOTE: In addition to blocking, it is essential
to perform thorough washes between eachstep. Washing steps are necessary to remove
unbound reagents and decrease backgroundnoise. Insufficient washing will allow highbackground. A common technique is to use adiluted solution of the blocking buffer alongwith some added high-purity detergent.

4. Proceed to wash steps.

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7

Blocking Assay Interference
Background information on Immunoassay interference
Immunoassay interference is a general term for substances that can change theoutcome of an assay by causing a false positive or false negative test result. Examples ofpotentially interfering particles include endogenous antibodies or other binding proteinspresent in a patient sample, polyreactive antibodies or autoantibodies (heterophiles), andhuman anti-animal antibodies.
Interfering substances can have non-specific reactions that disrupt thereaction between the analyte and reagent antibodies in an immunoassay
by either: (1) out-competing the analyte of interest for binding to the assay
antibodies (false negative) or (2) simulta- neously binding to the assay captureand detection antibodies in the absence of any analyte (false positive).
Assays that are inherently vulnerable to interference include double- sandwich
antigen detection assays, competitive assays and lgM capture assays. Specificexamples which have been reported in the literature are assays for ToRCH,
CEA, CA-125, CK-MB, LH, FSH, prolactin, TSH, AFP, cardiac troponin I (cTnl)
and hCG.
The most common type of interference in sandwich and competitive assays isheterophilic antibodies (HA) which are naturally occurring human antibodies
with low affinities that can react with immunoglobulins from different species,
including mouse, goat, rabbit, sheep and chicken. In diagnostic assays, HAs
are able to bind to multiple and seemingly unrelated epitopes to disrupt theassay’s specific antigen-antibody interaction.
Human anti-mouse antibodies (HAMA) is one type of HA interference thatspecifically binds to mouse antibodies. Due to the high use of mousemonoclonal antibodies in commercial diagnostic immunoassays, HAMAinterference is the most widely experienced type. Rheumatoid factor (RF), an
autoantibody that reacts with the patient’s own immunoglobulin (lg), may also
cross-react with animal lg resulting in “RF interference”, which is similar to
HA/HAMA interference. Generally, isotype (Fc region)-specific interfering HA
is more common than idiotype (Fab or binding site)-specific HA.
lgM capture assays generally experience two types of interference. The
first is from high levels of patient lgG antibodies that can compete with lgM
for antigen binding sites on the solid phase. Since lgG antibodies are highly
abundant, representing approximately 75% of serum antibodies in humans,
they can outcompete lgM due to their sheer quantity. The second type ofinterference is caused by lgM RF which can produce false-positive signals
by reacting with the Fc fragment on immunoglobulins. RF are found in 1%
to 4% of the general population and in 75% of adult patients over 65 yearsof age.

TRUE Positive Result
Detection
Antibody
AntigenCaptureAntibody

Blocking
Buffer

FALSE Negative Result

Blocking
BufferInterfering antibody blocks thebinding site on the capture ordetection antibody. Occurs in bothsandwich and competitive assays.

FALSE Positive Result
Interfering
Antibody(HA interference)

Blocking
BufferInterfering antibody binds to boththe capture and detection antibody
even in the absence of the antigen.
Occurs in sandwich assays only.

8

Blockers Practical Guide

Interference in Sandwich Immunoassays
A sandwich immunoassay uses two antibodies (either monoclonal or polyclonal) thatbind to different sites on the antigen or analyte of interest. The capture antibody binding
affinity for the antigen is usually the main determinant of immunoassay sensitivity.
However, human anti-animal immunoglobulin antibodies (HA antibodies) can interferewith this interaction and reduce assay sensitivity and specificity.
Mixed Species Assays
e.g. goat, sheep, rabbit,
rat, chicken, mouse

Double Mouse Monoclonal Assays

Detection Ab

Mouse MAb

Antigene.g. mouse, chicken,
rabbit, rabbit, goat

AntigenBlocking
BufferCapture Ab

For mixed species sandwich assays, the IgG blocker used must be thesame as the host of the capture and detection antibodies. More than
one species of IgG is required when two different antibody species areused in a sandwich assay.

Mouse MAb

Blocking
BufferFor double mouse monoclonal antibody sandwich assays, mouse IgG
in addition to an active HAMA blocker (TRU Block) should be used toremove a specific type of HA interference called human anti-mouse
antibodies (HAMA) and Rheumatoid Factor (RF).

interference in IgM Capture Assays
IgM antibodies are the first type of antibodies produced by the immune system in responseto an infection. Consequently, lgM detection assays have proven to be valuable diagnostic toolsthat assist in identifying early and recent infections. However, lgM antibodies only comprise
5% to 10% of all the antibodies in the body. In contrast, lgG antibodies are the most abundant
immunoglobulin and comprise about 75% to 80%. In order to ensure an lgM assay is bothsensitive and specific, it is necessary to reduce assay interference, especially from the more
plentiful lgG antibodies and other non-specific proteins, such as rheumatoid factors (RF).

Goat Anti-humanIgG or IgM Diluent
Patient IgG

Detection
Antibodies

Detector
Label

Patient’s IgM
AntigenIgM Capture Assay

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9Product List
Abbreviations
Ab

Antibody

IgM

Immunoglobulin M

Aff. Pur.

Affinity Purified

IgY

Immunoglobulin Y

Block

Tested as a blocking agent

LF

Lateral flow

BSA

Bovine Serum Albumin

MAb

Monoclonal antibody

EIA, ELISA

Enzyme Immunoassay

Monospecific	Monospecific when tested byimmunoelectrophoresis

Fc	Fragment crystallizable regionof an antibody

Neat

Whole, unpurified, undiluted antisera

Heavy and light chain in IgG

Neph

Nephelometry

HA

Heterophillic antibodies

PAb

Polyclonal antibody

HAMA

Human anti-mouse antibodies

PBS

Phosphate buffered saline

HRP

Horseradish peroxidase

Purified	Refer to the product COA regarding
the extent of purification and/or
process used

H&L

IEP

Immunoelectrophoresis

IgA

Immunoglobulin A

IgE

Immunoglobulin E

IgG

Immunoglobulin G

TIA

Turbidimetry

Tris	Tris (hydroxymethyl) aminomethanebased-buffer

Animal Serums
Animal serum contains a diverse mixture of proteins which can absorb heterophile interfering agents in various assays.
Animal serum can be used in place of or in addition to animal IgG. The species of animal serum must be the same as theantibody reagent in the assay.

10

Specificity

Cat Number

Host / Source

FormatCanine Plasma, Pooled/Mixed Gender, Unfiltered, Non-Sterile (Heparin)

N01262C

CaninePlasmaMouse Serum, Filtered

N14010M

Mouse

Neat

Porcine Serum, Sterile Filtered

N64250P

Pig

Neat

Rabbit Serum, Sterile Filtered and Heat InactivatedN01267R

RabbitNeat

Blockers Practical Guide

Chicken Immunoglobulins
Chicken Igs should be used in sandwich or competitive ELISAs or lateral flow assays that use a chicken antibody. Any
human anti-chicken antibodies in the patient sample that could potentially interfere with the assay signal can bind to thechicken IgY, preventing non-specific binding that could interfere with assay results.
Specificity

Cat Number

Host / Source

FormatIgY, Chicken

A01366C

Chicken Eggs

Purified

IgY, Chicken

A01460C

Chicken Serum

Purified

Goat Immunoglobulins
Goat Igs should be used in sandwich or competitive ELISAs or lateral flow assays that use a goat antibody. Any humananti-goat antibodies in the patient sample that could potentially interfere with the assay signal can bind to the goat Ig,
preventing non-specific binding that could interfere with the assay results.
Specificity

Cat Number

Host / Source

FormatIgG, Goat-Differential ppt

A66200H

Goat Serum

Purified

Human Immunoglobulins
Human Igs can be used in flow cytometry, IHC, sandwich or competitive ELISAs or lateral flow assays to block non-specificbinding. The selected antibody should match the primary/capture antibody’s host species, isotype (including heavy chain(IgA, IgG, IgD, IgE, or IgM) and light chain (kappa or lambda class) and if relevant, conjugation.
Specificity

Cat Number

Host / Source

FormatIgE, lambda

A01720H

Human Myeloma

Purified

IgE, kappa and lambda

A75671H

Human Myeloma

Purified

IgA1, kappa

A50166H

Human Myeloma

Purified

IgA1, lambda

A50165H

Human Myeloma

Purified

IgA

A50167H

Human Plasma

Purified

IgG

A50170H

Human Plasma

PurifiedIgG (Fc)

A50175H

Human Plasma

Purified

IgM >95% Pure

A50168H

Human Plasma

Purified

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11

Product List
Mouse Immunoglobulins
Mouse Igs should be used in sandwich or competitive ELISAs or lateral flow assays that use a mouse antibody. Any humananti-mouse antibodies (HAMA) present in the patient sample that could potentially interfere with the assay signal can bind tomouse Ig, preventing non-specific binding that could interfere with the assay results.
Specificity

Cat Number

Host / Source

FormatIgG2a, kappa, Mouse

A01696M

Mouse Myeloma

Purified

IgG, Mouse Protein A (9-13mg/ml) Dialyzed Azide Free

A66186M-NA

Mouse Serum

Purified

IgG, Mouse-Caprylic Acid Cut

A66187M

Mouse Serum

Purified

IgG, Mouse-Protein A (9-13 mg/mL)

A66186M

Mouse Serum

Purified

IgG, Mouse-Protein A (22-28 mg/mL)

A66181M

Mouse Serum

Purified

IgG, Mouse Protein A (45-55mg/mL) No Azide

A66189M

Mouse Serum

Purified

IgG, Mouse-Protein A (50-55 mg/mL)

A66185M

Mouse Serum

Purified

IgG, Mouse-Protein A (50-55mg/ml)

A66185M-LY

Mouse Serum

Purified
Lyopholized

Rabbit Immunoglobulins
Rabbit Igs should be used in sandwich or competitive ELISAs or lateral flow assays that use a rabbit antibody. Any humananti-rabbit antibodies in the patient sample that could potentially interfere with the assay signal can bind to rabbit Ig, preventing
non-specific binding that could interfere with the assay results.
Specificity

Cat Number

Host / Source

FormatIgG, Rabbit-Differential ppt

A66100H

Rabbit Serum

Purified

IgG, Rabbit-Differential ppt

A66105R

Rabbit Serum

PurifiedRat Immunoglobulins
Rat IgG should be used in sandwich or competitive ELISAs or lateral flow assays that use a rat antibody. Any human anti-rat
antibodies in the patient sample that could potentially interfere with the assay signal can bind to rat IgG, preventing non-specificbinding that could interfere with the assay results.
Specificity

Cat Number

Host / Source

FormatIgG, Rat, ≥ 60 mg/mL

A41182R

Rat Serum

Purified

IgG, Rat

A64391R

Rat Serum

Purified

Sheep Immunoglobulins
Sheep Igs should be used in sandwich or competitive ELISAs or lateral flow assays that use a sheep antibody. Any humananti-sheep antibodies in the patient sample that could potentially interfere with the assay signal can bind to sheep Ig, preventing
non-specific binding that could interfere with the assay results.

12

Specificity

Cat Number

Host / Source

FormatIgG Sheep, >=70mg/mL

A66400S

Sheep Serum

Purified

Blockers Practical Guide

Solid Phase Blockers
Solid phase blocking agents are designed to saturate unoccupied binding sites on the solid phase to prevent non-specificbinding. Typically blocking buffers are able to block both hydrophobic and hydrophilic sites on the solid phase. In addition,
they can serve as stabilizing agents and prevent denaturation as proteins react at the surface of the solid phase.
Specificity

Cat Number

Host / Source

FormatBlocking Buffer for ELISA

J82100Bn/an/a

Blocking Buffer for Lateral Flow Assays, PBS based

J82300B

n/a

LiquidCoating Stabilizer & Blocking Buffer

J16430Dn/aLiquidConjugate Stabilizer Diluent, HRP

J16200Dn/aLiquid

BSA, Standard Powder

A64801B

BovinePurified

Gamma Globulin, Bovine

A51300B

Bovine Serum

Purified

Bovine Serum Albumin (BSA)

C5BP01-188

ChickenAff.Pur.

IgG Absorbents
IgG absorbents are designed for the removal of human IgG and Ig / rheumatoid factor (RF) complexes from serum andplasma prior to testing for specific IgM antibodies in ELISA or other immunoassays. Removal of IgG interference has been
demonstrated to significantly increase the sensitivity of IgM detection.
Specificity

Cat Number

Host / Source

FormatIgM Assay Diluent

8120

Goat

PurifiedIgG (Fc)

L15406G

Goat

Monospecific

IgG (Fc)

G5G16-048

Goat

Aff. Pur.

IgG (Fc)

L62540G

Goat

Purified

TRU Block™ - HAMA & RF Blocker
In double mouse monoclonal sandwich assays, an active blocker against human anti-mouse antibodies (HAMA) andrheumatoid factor (RF) should be used to prevent non-specific interference leading to false assay results. TRU Block is a
proprietary active blocker that can significantly reduce assay interference and improve assay results. It can be used at alower concentration than passive blocking reagents such as mouse IgG.
Specificity

Cat Number

Host / Source

FormatTRU Block™, Ready Heterophilic Antibody Interference, Active Blocker

8001

Confidential

Purified

TRU Block™ 2, Heterophilic Antibody Interference, Active Blocker

A66802H

Mouse & Confidential

Purified

TRU Block™ 3, Heterophilic Antibody Interference, Active Blocker

A66803H

Mouse & Confidential

Purified

TRU Block™, Heterophilic Antibody Interference, Active Blocker

A66800H

Mouse & Confidential

Purified

TRU Block™ Ultra, Heterophilic Antibody Interference, Active Blocker

8000

Confidential

Purified

TRU Block™ Ultra, Heterophilic Antibody Interference, Active Blocker (no Azide)

8002

Confidential

Purified

HAMA & RF Reagents
HAMA (human anti-mouse antibodies) or rheumatoid factor positive patient samples that can be used to test theeffectiveness of a blocking agent in any type of assay.
Specificity

Cat Number

Host / Source

FormatRheumatoid Factor (RF) Control Serum

A01270H

Human Plasma

Neat

Rheumatoid Factor (RF) Control Serum

A12916H

Human Plasma

Neat

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13

Product List
Secondary Antibodies
Secondary antibodies are used for indirect detection and they can provide an increase in sensitivity through signal amplification,and greater flexibility for labeling and detection. The secondary antibody should not be from the same host species as theprimary antibody, but it should have the species specificity for the primary antibody. For example, if the primary antibody issourced from rabbits, the secondary antibody should be anti-rabbit but it should be raised in a host species other than rabbit(e.g. goat anti-rabbit secondary).

Mouse Immunoglobulins

Polyclonal Goat Anti-Human

Specificity

Cat Number

FormatIsotype

Specificity

Cat Number Format

IgA (Fc), Human

Z01253M

Purified

IgG2b

IgG (H+L)

W01262FL

FITC

IgA (Fc), Human

Z01253P

HRP

IgG2b

IgA

L66605G

MonospecificIgA (Secretory Component),
Human

Z42750M

Purified

IgG1

IgE (epsilon)

L62507G

Purified

IgA, Human

Z01250M

Purified

IgG1

IgG (Fc) (min x w/Hu Bov Hrs Ms)

W99036P

HRP

IgE (Fc), Human

Z86104M

Purified

IgG2a

IgG (Fc), Goat

MAGG16-264

Purified

IgG2b,kIgG (Fc), Human

Z01247M

Purified

IgG

IgG (Fc), Human

Z54101M

Purified

IgG1

IgG (Fc), Human

Z86101P

HRP

IgG

IgG (Fc), Human

Z86213M

Purified

IgG

IgG (Fc), Rabbit

MARG16-125

Purified

IgG2b,kIgG, Human

Z01236M

Purified

IgG1,kIgG, Sheep

P86502M

Purified

IgG1

IgG1 (Fc), Human

Z86102M

Purified

IgG1

IgG2 (Fc) gamma-2, Human

Z86002M

Purified

IgG2

IgG4 (Fc), Human

Z86140M

Purified

IgG1

IgM (Fab-region), Human

Z86215M

Purified

IgG2b

IgM (Fc), Human

Z86113M

Purified

IgG1

IgM (Heavy Chains), Human Z86110M

Purified

IgG1

IgM (Heavy Chains), Human Z86114M

Purified

IgG1

IgM, Human

Z01235M

Purified

IgG1,kIgM, Human

Z45190M

Purified

IgG1

Polyclonal Rabbit

14

Specificity

Cat Number

FormatIgG (Fc), Canine

W99114C

Aff.Pur.

IgG (Fc), Human

W99165C

Aff.Pur.

IgG (H&L), Mouse

W01256R

Aff.Pur.

IgG (H&L), Sheep

R5SG10-048

Aff.Pur.

IgG (H&L), Sheep

W99245P

HRP

IgM, Mouse

W99020C

Aff.Pur.

Blockers Practical Guide

IgG (Fc) (min x w/Hu Bov Hrs Ms Rab) W01252G

Aff.Pur.

IgG (Fc)

G5G16-0482

HRP

IgG (Fc)

W66040G

Aff.Pur.

IgG (Fc)

W99008A

Alk.Phos.

IgG (H&L)

W01260AF

Alexa Fluor 488

IgM (Fcu)

L66607G

Monospecific

IgM (Fcu)

W99154A

Alk.PhosIgM (Fcu)

W99154G

Aff.Pur.

IgM (mu) (min x w/Bov Gt Ms Rab)

W01251G

Aff.Pur.

IgM (mu) (min w/IgA and IgG)

W01259G

Aff.Pur.

IgM (mu)

G5G54-048

Aff.Pur.

IgM (mu)

G5G54-0482

HRP

IgM (mu)

L04354G

Monospecific

IgM (mu)

L62650G

Purified

IgM (mu)

W01258G

Aff.Pur.

IgM (mu)

W66210G

Aff.Pur.

IgM (mu)

W66310G

Aff.Pur.

Kappa Light Chain (Free & Bound)

L15805G

Purified

Kappa Light Chain (Free & Bound)L62805G

MonospecificLambda Light Chain (Free & Bound)

K04365G

Purified

Lambda Light Chain (Free & Bound)

L15905G

Purified

Lambda Light Chain (Free & Bound)L62905G

MonospecificPolyclonal Goat Anti-Mouse
Specificity

Cat Number

FormatIgE (epsilon chain)

W03700G

HRP

IgG (Fc)

G5MG16-048

Aff.Pur.

IgG (Fc)

W41202GHRP

IgG (gamma)

G5MG20-0482

Aff.Pur.

IgG (H&L) (min x w/Hu Bov Hrs)

W99062G

Aff.Pur.

IgG (H&L)

G5MG10-048

Aff.Pur.

IgG (H&L)

G5MG10-0482

PurifiedIgG (H&L)

G5MG10-0484

Aff.Pur.

IgG (H&L)

W41250G

TRITC

IgG (H&L)

W41502G

FITC

IgG (H&L, Goat)

G5MG10-766

Aff.Pur

IgG1

W03910G

HRP

Polyclonal Goat Anti-RabbitSpecificity

Cat Number

FormatIgG (Fc)

G5G16-766

Aff.Pur.

IgG (H&L)

G5RG10-048

Aff.Pur.

IgG (H&L)

G5RG10-0482

HRP

IgG (H&L)

G5RG14-0483

FITC

IgG (H&L)

S5RG10-0481

Alk.Phos.

IgG (H&L)

W41604G

Aff.Pur.

Polyclonal Goat Anti-Bovine
Specificity

Cat Number

FormatIgG (H&L)

W01254G

Aff.Pur.

IgG (H&L)

W99101G

Aff.Pur.

Polyclonal Goat Anti-Canine
Specificity

Cat Number

FormatIgG (Fc)

W99114C

Aff.Pur.

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15

Meridian Life Science, Inc.
5171 Wilfong Road | Memphis, TN 38134
901.382.8716 • 800.327.6299
www.MeridianLifeScience.com

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