Primary Antibodies

Primary antibodies validated for western blot, IHC, immunofluorescence and ELISA

St John's Laboratory offers more than 60,000 primary antibodies covering the full range of research targets, applications and species. Our catalogue includes rabbit and mouse monoclonals, goat and rabbit polyclonals, recombinant antibodies, and KO-validated formats — available as trial sizes, standard vials, concentrates and bulk quantities.

Browse primary antibodies

60,000+

Primary antibodies in catalogue

17+

Validated species

1yr

Guarantee on all antibodies

By type By application By validation Choosing the right antibody

Antibody format

Monoclonal, polyclonal and recombinant formats

Select a format based on your application requirements. Monoclonals offer high specificity to a single epitope; polyclonals provide broader signal amplification across multiple epitopes; recombinant antibodies deliver consistent lot-to-lot reproducibility without animal use.

Monoclonal antibodies

Mouse and rabbit monoclonals targeting a single epitope. Suitable for quantitative applications including flow cytometry, ELISA and western blot where specificity and reproducibility are essential.

Polyclonal antibodies

Rabbit, goat and sheep polyclonals raised against multiple epitopes. Higher sensitivity in IHC and IF where signal amplification is a priority.

Recombinant antibodies

In vitro-produced monoclonals from synthetic genes. No animal or hybridoma dependency. Consistent sequence and specificity across batches — recommended for publication-quality data.

Conjugated primary antibodies

HRP-, FITC- and fluorophore-conjugated formats for direct detection without a secondary antibody. Reduces background in multiplex IF and flow cytometry workflows.

Application

Antibodies by validated application

Every antibody in our catalogue lists only confirmed validated applications. Always refer to the individual datasheet for recommended dilutions and lot-specific validation data before use.

Western blot (WB)

The largest validated application in our range. Antibodies are tested at confirmed dilutions across multiple cell line and tissue lysates, with representative blot images included in the datasheet.

Immunohistochemistry (IHC)

Validated for formalin-fixed paraffin-embedded (FFPE) and fresh-frozen tissue. Our IHC-Guaranteed range offers performance assurance backed by an explicit validation standard.

Immunofluorescence (IF)

Antibodies confirmed for use in fixed-cell and live-cell imaging workflows, with representative IF images available in datasheets. Compatible with most fluorescent secondary antibody platforms.

Flow cytometry (FC)

Validated for surface and intracellular staining in suspension cell populations. Both unconjugated formats for use with secondary antibodies and directly conjugated primaries are available.

Validation level

Selecting by validation standard

Antibody performance varies by lot, target and tissue type. Filter by validation level to match your experimental requirements for specificity and reproducibility.

KO-validated antibodies

Tested in knockout cell line models where the target gene is fully inactivated. Absence of signal in KO samples confirms target specificity. Recommended for high-impact studies and publications requiring rigorous antibody validation.

IHC-Guaranteed antibodies

Each antibody in this collection has been validated in IHC with confirmed tissue staining results. If it does not perform as specified, contact our technical team for resolution or replacement.

Trial size antibodies

20 µl trial vials for over 13,000 antibodies in our Antibody Validation Project (AVP). Test the antibody in your system before committing to a full size. Return your results for a refund on the trial cost.

PTM-specific antibodies

Phospho, acetyl and methyl antibodies that detect proteins at specific post-translational modification states. Essential for studying kinase pathways, epigenetic regulation and cell signalling events.

Monoclonal or polyclonal?

Monoclonal antibodies bind a single epitope, giving consistent, reproducible signal — the preferred choice for quantitative assays, ELISA, and flow cytometry where cross-reactivity must be minimised. Polyclonal antibodies recognise multiple epitopes on the same target, producing stronger signal amplification — often more effective for low-abundance targets in IHC and IF. If your target is denatured under SDS-PAGE conditions, polyclonals are generally more tolerant of epitope disruption.

Key factors when selecting a primary antibody

Confirm the validated application matches your experimental method
Check species reactivity against your sample source
Review datasheet images from your target application before ordering
For reproducibility-critical studies, choose recombinant or KO-validated formats
Match host species to your secondary antibody to avoid cross-reactivity
Consult individual datasheets for confirmed working dilutions

Related categories

Also in our catalogue

Secondary antibodies

Over 50 secondary antibody formats with HRP, FITC, biotin and gold conjugation options.

CD marker antibodies

Antibodies against CD4, CD8, CD19, CD34, CD44, CD117 and other cell surface markers.

ELISA kits

Sandwich and competitive ELISA kits for quantitative protein detection in serum, plasma and cell lysates.

Nanobodies

Single-domain antibody fragments for imaging, proximity labelling and difficult-to-access epitopes.

Our Commitment to You

✓

1 year guarantee
on all antibodies

✉

Free shipping
on eligible orders

Technical support
Mon–Fri 9 am – 6 pm

Full datasheets
with validation images

Peer-reviewed
citations available

CD Marker Antibodies

CD marker antibodies validated for flow cytometry, IHC and immunofluorescence

CD (cluster of differentiation) antigens are cell surface proteins used to identify and classify immune cell populations, stem cells and tumour markers. St John's Laboratory supplies antibodies against a broad range of CD markers, validated for flow cytometry, IHC, western blot and immunofluorescence in human and mouse systems.

Browse CD marker antibodies

100+

CD marker targets covered

Validated applications per target

1yr

Guarantee on all antibodies

Immune cell markers Stem cell markers Choosing a CD marker antibody

Immunology

T cell, B cell and myeloid lineage markers

CD markers are essential tools for identifying and characterising immune cell subpopulations in peripheral blood, lymph nodes and tissue sections. The antibodies below cover the most commonly used lineage markers in immunology and inflammation research.

Anti-CD4 antibodies

CD4 is expressed on helper T cells, regulatory T cells and monocytes. Used extensively in flow cytometry immunophenotyping and IHC for lymphoma classification and HIV research. Validated for WB, IHC, IF and FC in human and mouse samples.

Anti-CD8 antibodies

CD8 identifies cytotoxic T lymphocytes. A primary marker in tumour-infiltrating lymphocyte (TIL) analysis, transplant immunology and viral infection studies. Validated for FC, IHC and WB.

Anti-CD19 antibodies

CD19 is expressed throughout B cell development from pro-B cells to plasma cells. Key marker for B cell immunophenotyping, leukaemia classification and CAR-T cell target identification. Validated for FC, WB and IHC.

Anti-CD14 antibodies

CD14 marks monocytes and macrophages. Used to distinguish monocyte subsets in peripheral blood and to study innate immune activation in infection and inflammatory disease models.

Stem cell biology

Haematopoietic and progenitor cell identification

Stem cell markers define progenitor populations in bone marrow, peripheral blood and tissue. These antibodies are validated in both flow cytometry panels and IHC of FFPE tissue for lineage tracing and cell characterisation.

Anti-CD34 antibodies

CD34 is expressed on haematopoietic progenitor cells, endothelial cells and mast cell precursors. Widely used in bone marrow biopsy analysis, angiogenesis research and leukaemia diagnosis workflows. Validated for IHC and FC.

Anti-CD117 (c-Kit) antibodies

CD117 encodes the c-Kit receptor tyrosine kinase. Expressed on haematopoietic stem cells, mast cells and gastrointestinal stromal tumour (GIST) cells. Used in stem cell characterisation and oncology IHC panels. Validated for WB, IHC and FC.

Anti-CD44 antibodies

CD44 marks cancer stem cell populations and plays a role in cell adhesion, migration and hyaluronic acid binding. Used in tumour biology, metastasis research and stem cell isolation. Validated for WB, IHC, IF and FC.

Anti-CD79 antibodies

CD79a and CD79b are components of the B cell antigen receptor complex. Used in B cell lymphoma classification, particularly diffuse large B cell lymphoma (DLBCL). Validated for IHC and WB in human samples.

Which application is best for CD marker detection?

Flow cytometry is the standard method for quantitative immunophenotyping, allowing simultaneous detection of multiple CD markers in live or fixed cell populations. IHC is preferred when spatial localisation within tissue sections is required — for example, TIL quantification in tumour biopsies or bone marrow biopsy analysis. Western blot is useful for confirming total protein expression but does not preserve spatial context. Refer to each datasheet to confirm validated applications for your specific marker and sample type.

Selecting the right CD marker antibody

Confirm species reactivity — most CD markers are validated in human; check datasheet for mouse cross-reactivity
For flow cytometry, check whether an unconjugated or directly conjugated format is available
For IHC, look for FFPE-validated antibodies with antigen retrieval conditions listed
Where quantitative data is critical, prefer recombinant or KO-validated formats
Always consult the individual datasheet for recommended dilutions before use

Related categories

Also relevant to your research

Flow cytometry antibodies

Full range of FC-validated primary antibodies beyond CD markers.

IHC-Guaranteed antibodies

Performance-guaranteed antibodies for tissue section staining.

Primary antibodies

The full primary antibody catalogue across all targets and applications.

ELISA kits

Quantitative cytokine and protein detection kits for immunology research.

Our Commitment to You

✓

1 year guarantee
on all antibodies

✉

Free shipping
on eligible orders

Technical support
Mon–Fri 9 am – 6 pm

Full datasheets
with validation images

Peer-reviewed
citations available

ELISA Kits

ELISA kits for quantitative detection of cytokines, growth factors and signalling proteins

Our ELISA kits use validated capture and detection antibody pairs to quantify specific target proteins in serum, plasma, cell culture supernatant, cell lysates and tissue homogenates. Available as sandwich and competitive formats, each kit is supplied with all required reagents and a validated standard curve for reliable quantitation.

Browse ELISA kits

Kit formats: sandwich and competitive

96-well

Standard plate format

1yr

Guarantee on all kits

Sandwich ELISA kits Competitive ELISA kits Choosing the right kit

Most common format

Sandwich ELISA kits for high-sensitivity antigen quantification

Sandwich ELISA kits use two antibodies — a capture antibody pre-coated on the plate and a detection antibody in solution — to bind the target antigen from both sides. This dual-antibody format delivers high sensitivity and specificity, making it the standard method for cytokine, growth factor and protein biomarker quantification in biological fluids.

Sandwich ELISA kits

Ready-to-use 96-well kits with pre-coated plates, detection antibody, standard protein, HRP-conjugated secondary, TMB substrate and stop solution. Compatible with serum, plasma, cell lysate and tissue homogenate samples.

Species-specific formats

Kits are available for human, mouse and rat samples. Species-matched capture and detection antibodies minimise non-specific binding in single-species experiments. Confirm species compatibility on individual product pages before ordering.

Cytokine and chemokine detection

ELISA kits covering IL-1, IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma and other inflammatory mediators. Standard curves are validated across the physiological range relevant to cell culture supernatant and serum samples.

Growth factor quantification

Kits for VEGF, EGF, FGF, TGF-beta and related growth factors used in angiogenesis, wound healing and cancer biology studies. Refer to individual datasheets for sample type compatibility and detection range.

Alternative format

Competitive ELISA kits for small molecule and hapten detection

Competitive ELISA kits measure antigen concentration through signal competition rather than capture. A fixed amount of labelled antigen competes with unlabelled antigen in the sample for a limited number of antibody binding sites. As sample antigen concentration increases, signal decreases. This format is suited to small molecules, haptens and antigens that cannot bind two antibodies simultaneously.

Competitive ELISA kits

Used for low-molecular-weight targets including hormones, drugs, vitamins and small peptides. Concentration is calculated from a standard inhibition curve. Refer to individual datasheets for validated sample matrices and quantitation range.

When to use competitive ELISA

Choose competitive format when the target antigen is too small to be bound by two antibodies simultaneously, when only one specific antibody is available, or when measuring analytes present at very high concentrations that exceed the dynamic range of sandwich kits.

Sandwich or competitive ELISA?

Sandwich ELISA is the default choice for most protein detection applications. It offers higher sensitivity, a wider dynamic range and greater specificity than competitive formats, and works well for proteins of 10 kDa and above that can accommodate two antibodies. Competitive ELISA is required for small molecules, haptens and antigens under approximately 5 kDa, or where only a single specific antibody exists. If you are unsure which format to use, contact our technical support team with your target and sample type.

Getting reliable ELISA results

Run samples in duplicate or triplicate to confirm reproducibility
Dilute samples to fall within the linear range of the standard curve
Use fresh standards prepared on the day of the assay
Equilibrate all reagents to room temperature before use
Ensure plate washing steps are thorough — inadequate washing is the most common source of high background
Always include a negative control in each run

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