BCL2 / Apoptosis regulator Bcl-2 · IHC design guide

Design Immunohistochemistry for BCL2

Plan paraffin-section BCL2 IHC around cytoplasmic staining in lymphoid non-germinal center cells (HPA tissue IHC). This guide helps select cell-type controls and interpret staining alongside BCL2’s membrane localisation (UniProt).

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use

Immunohistochemistry protocol sheet for BCL2 (IHC for BCL2): expected localisation Cytoplasmic tissue staining (HPA tissue IHC); mitochondrial outer, ER and nuclear membranes expected (UniProt), antibody M00040-1, validated IHC image, and IHC protocol steps — Printable **BCL2** IHC protocol sheet — expected localisation Cytoplasmic tissue staining (HPA tissue IHC); mitochondrial outer, ER and nuclear membranes expected (UniProt), antibody M00040-1, controls and protocol steps. Open the full BCL2 IHC guide →

Navigate to: Protocols Staining pattern Controls Antibodies

BCL2 Immunohistochemistry Experimental Design Guide

Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.

Must know before staining

	Expected localisation	Cytoplasmic tissue staining (HPA tissue IHC); mitochondrial outer, ER and nuclear membranes expected (UniProt)
	Staining pattern	Cytoplasmic in lymphoid non-germinal center cells (HPA tissue IHC)
	Antigen retrieval	Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen)
	Positive control ⓘ	Appendix+4 more · see all
	Negative control ⓘ	Adrenal gland+4 more · see all

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Keep fixation conditions consistent across sections (standard IHC practice; not target-specific)
	Caveat	Lymphoid cell mix can change the apparent positive fraction (HPA tissue IHC)
	Regulation	Expression varies by tissue and cell type (HPA tissue IHC)
	Isoform / epitope	2 isoforms, Alpha and Beta; epitope coverage is unknown (UniProt)

Section 1

Recommended BCL2 IHC & IF Protocols

The catalog antibody’s IHC-P protocol is accompanied by published BCL2 staining methods for breast lesions and follicular lymphoma tissue (PMC9592210; PMC5930855).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded tissue sections; fixative not specified (datasheet M00040-1; sample unspecified)
Fixation	Image fixative and duration unreported (datasheet M00040-1); verify before use.
Sectioning	4–5 µm sections on charged slides (standard)
Deparaffinisation	Xylene, graded ethanol series to water (standard)
Antigen retrieval	Heat-induced epitope retrieval in Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear antigen)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% normal serum of the secondary host, 30 min, room temperature (standard)
Primary antibody	Rabbit monoclonal (clone HF-2) anti-BCL2, 1:50-1:100 (datasheet M00040-1)
Primary incubation	Overnight at 4 °C (standard)
Detection	HRP-polymer secondary, DAB chromogen 5–10 min (standard)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	BCL2-positive staining in non-germinal center cells of appendix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in several different tissue types, including thyroid gland and lymphoid organs. No signal in the no-primary control.

💡Decision noteStart with Tris-EDTA pH 9.0 HIER at 95–98 °C for 20 min (page retrieval); sodium citrate is a published alternative (PMC9592210).

Section 2

What Is the Expected BCL2 Staining Pattern?

BCL2 should appear mainly as cytoplasmic staining in appropriate cells on paraffin sections (HPA: tissue IHC profile). Its membrane-associated distribution includes mitochondria, endoplasmic reticulum and nuclear membranes (UniProt P10415: locations; transmembrane segment 212–233). High staining is reported in lymph node non-germinal center cells and bone marrow hematopoietic cells (HPA: tissue IHC). HPA rates its tissue profile Enhanced, with medium consistency between antibody staining and RNA expression (HPA: reliability).

What am I looking at on my slide?
Cytoplasmic staining in lymph node non-germinal center cells, with little staining in nearby unstained cells (HPA: tissue IHC).	This matches an HPA high-staining cell population. Score the relevant cells rather than the whole section: mixed tissues can contain both stained and unstained populations (HPA: lymph node IHC; general IHC practice).
Predominantly nuclear or extracellular staining, without a convincing cytoplasmic component.	This does not match the HPA tissue profile or the principal mitochondrial localization seen by ICC-IF (HPA: tissue IHC and subcellular). Review morphology, counterstain and detection controls before interpreting it as BCL2 (general IHC practice).
Strong staining in a cell type listed as not detected, such as heart cardiomyocytes (HPA: tissue IHC).	Treat this as unexpected for that cell population, not proof of a new expression pattern. Check antibody specificity and endogenous detection activity with appropriate controls (HPA: heart muscle IHC; general IHC practice).
Uniform haze across cells, connective tissue and empty spaces.	A diffuse field obscures cell boundaries and is unsuitable for cell-specific scoring (general IHC practice). Assess blocking, washing and detection background; HPA's cytoplasmic profile does not validate a uniform haze (HPA: tissue IHC).
No signal in lymph node non-germinal center cells used as a positive control (HPA: high IHC staining).	The run has not demonstrated detection in an expected positive population. Check section quality and the IHC workflow before calling the test specimen negative; HPA does not establish a BCL2-specific fixation failure (HPA: lymph node IHC; general IHC practice).

💡Expected BCL2 appearanceCall a convincing positive when high cytoplasmic staining is present in the expected lymph node non-germinal center cells; isolated nuclear, extracellular or uniform background staining is suspect (HPA: lymph node IHC and tissue profile; general IHC practice).

How each factor affects the staining
Compartment and resolution	UniProt places BCL2 at the mitochondrial outer, endoplasmic reticulum and nuclear membranes; HPA describes tissue IHC as cytoplasmic. Do not require individual organelles to be resolved in chromogenic sections (UniProt P10415: locations and topology; HPA: tissue IHC; general IHC practice).
Cell population used for controls	HPA reports high staining in appendix and lymph node non-germinal center cells, and no detection in heart cardiomyocytes. Compare the named cell populations, not entire organs; a negative population is a comparison control, not proof that every cell in that tissue lacks BCL2 (HPA: tissue IHC).
Strength of antibody evidence	CAB000003 has Enhanced IHC validation, while the HPA tissue profile has Enhanced reliability with medium staining/RNA consistency. These labels describe evidence quality; neither guarantees that every specimen or cell will stain strongly (HPA: antibody validation and tissue reliability).
Antigen retrieval and fixation	Record and follow the catalog antibody's validated IHC-P conditions, including retrieval where specified (general IHC practice). Neither HPA tissue staining nor UniProt topology establishes a BCL2-specific fixation or retrieval effect; none is reported in the supplied evidence (HPA: tissue IHC; UniProt P10415: topology).
Isoforms and epitope	UniProt lists Alpha and Beta isoforms, but the supplied record gives no antibody epitope or isoform-specific IHC result. Do not assign a staining difference to an isoform without separate validation (UniProt P10415: isoforms; general IHC practice).
IF/ICC cross-check — Q&A	Q: Must IF look identical to chromogenic IHC? A: HPA reports enhanced mitochondrial localization by ICC-IF, while tissue IHC is described as cytoplasmic. Interpret each image at its own resolution; this is a localization comparison, not an IF protocol (HPA: subcellular and tissue IHC).

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Known-positive lymph node cells are blank (HPA: high in non-germinal center cells).	The control has not confirmed a working IHC run; section quality, reagent delivery or assay conditions may be responsible (general IHC practice).	Verify the named cells are present, then review the catalog IHC-P conditions, detection reagents and a concurrent positive control before scoring study sections (general IHC practice).
All tissue compartments look similarly brown.	Nonspecific detection or background may hide the cell-specific cytoplasmic pattern reported by HPA (HPA: tissue IHC; general IHC practice).	Examine a no-primary control, washing and blocking; judge staining only where cell borders and the expected population remain interpretable (general IHC practice).
Heart cardiomyocytes stain strongly (HPA: not detected in this cell type).	The result conflicts with HPA's observation and could reflect cross-reactivity or endogenous detection activity; it is not diagnostic of either cause (HPA: heart muscle IHC; general IHC practice).	Check no-primary and detection controls, then compare the same run with a named HPA-positive population before assigning BCL2 specificity (HPA: tissue IHC; general IHC practice).
Signal appears confined to nuclei or outside cells.	That distribution does not fit HPA's cytoplasmic tissue profile. UniProt's nuclear-membrane location does not, by itself, validate nuclear-only chromogenic staining (HPA: tissue IHC; UniProt P10415: locations).	Inspect morphology and counterstain, exclude precipitate or edge artifact, and compare with a positive-control section showing the expected cytoplasmic pattern (general IHC practice; HPA: tissue IHC).
Some cells in a positive tissue are unstained.	HPA assigns levels to specified cell populations, such as non-germinal center cells in lymph node; an organ-wide score can misrepresent that observation (HPA: tissue IHC).	Identify the relevant population on the counterstained section and record its staining intensity and fraction separately from surrounding cells (HPA: tissue IHC; general IHC practice).
A retrieval change alters staining between runs.	The supplied UniProt and HPA records do not establish BCL2-specific retrieval or fixation sensitivity; changed assay conditions can complicate comparison (UniProt P10415; HPA: tissue IHC; general IHC practice).	Compare sections with the same positive control and documented catalog IHC-P conditions; report the observed difference without attributing it to BCL2 epitope masking (general IHC practice).

Source: UniProt P10415 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing BCL2 staining

M00040-1 · IHCImmunohistochemical analysis of paraffin-embedded Human non-Hodgkin's lymphoma, using the Antibody at 1:50 dilution.

M00040-1 · IHCImmunohistochemical analysis of paraffin-embedded Human squamous cell carcinoma , using the Antibody at 1:50 dilution.

M00040-1 · IFImmunofluorescent analysis of Jurkat cells, using Bcl-2 Antibody .

M00040-2 · IHCImmunohistochemical analysis of paraffin-embedded Human lung adenocarcinoma, using the Antibody at 1:100 dilution.

M00040-2 · IHCImmunohistochemical analysis of paraffin-embedded Human thyroid cancer, using the Antibody at 1:300 dilution.

M00040-2 · IFImmunofluorescent analysis using the Antibody at 1:150 dilution.

M00040-4 · IHCHuman spleen was stained with anti-Bcl-2 rabbit antibody

M00040-4 · IHCRat spleen was stained with anti-Bcl-2 rabbit antibody

IF analysis of BCL2 and Tubulin alpha using anti-BCL2 antibody (A00040-2) and anti-Tubulin alpha antibody (M03989-3). BCL2 and Tubulin alpha were detected in immunocytochemical section of U20S cells. Enzyme antigen retrieval was performed using IHC enzyme antigen retrieval reagent (AR0022) for 15 mins. The cells were blocked with 10% goat serum. And then incubated with 5μg/mL rabbit anti-BCL2 antibody (A00040-2) and mouse anti-Tubulin alpha Antibody (M03989-3) overnight at 4°C. Cy3 Conjugated Goat Anti-Rabbit IgG (BA1032) and DyLight®488 Conjugated Goat Anti-Mouse IgG (BA1126) were used as secondary antibody at 1:100 dilution and incubated for 30 minutes at 37°C. Visualize using a fluorescence microscope and filter sets appropriate for the label used.

A00040-2 · IFIF analysis of BCL2 and Tubulin alpha using anti-BCL2 antibody (A00040-2) and anti-Tubulin alpha antibody (M03989-3). BCL2 and Tubulin alpha

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000171791-BCL2/tissue/cerebral+cortex#imid_19182987

HPA · Thyroid glandHuman Protein Atlas IHC, Thyroid gland. Source: https://www.proteinatlas.org/ENSG00000171791-BCL2/tissue/thyroid+gland#imid_19182939

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000171791-BCL2/tissue/colon#imid_19182897

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000171791-BCL2/tissue/liver#imid_19182898

HPA · ICC-IF SiHaHuman Protein Atlas immunofluorescence, SiHa, antibody CAB080071; green = BCL2, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

Real IHC / IF data behind the staining-pattern expectations in this section.

Sample controls for BCL2 IHC & IF

🧪Run appendix first: non-germinal center cells should stain (HPA: High in appendix non-germinal center cells). Use adrenal gland glandular cells as the negative tissue (HPA: Not detected); unstained neighboring cells on the appendix slide provide a background reference, but their BCL2-negative status is unverified.

Positive control tissue: Appendix (Non-germinal center cells, HPA High)

Negative control tissue: Adrenal gland (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show BCL2 in SiHa, U2OS, with annotated localisation: Mitochondria (enhanced) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only control and an irrelevant immunoglobulin control matched to the primary antibody’s host species and isotype or clonality. Use BCL2 knockout material as a biological specificity control where available; block endogenous peroxidase for chromogenic detection, particularly when evaluating hematopoietic cells.

⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence, and the selected paraffin-section caption does not state its fixative (M00040-1 tissue-IHC caption). Antigen retrieval requirements must be established for the chosen antibody; the evidence does not establish whether frozen sections or IF are easier. In appendix, distinguish cellular staining from chromogenic background due to endogenous peroxidase in blood-derived cells.

HPA tissue IHC evidence for BCL2

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.

Positive expression · recommended positive controls

Tissue	Cell type	Level	Evidence	Source
Appendix	Non-germinal center cells	High	Protein (IHC)	HPA →
Bone marrow	Hematopoietic cells	High	Protein (IHC)	HPA →
Bronchus	Respiratory epithelial cells	High	Protein (IHC)	HPA →
Endometrium	Cells in endometrial stroma	High	Protein (IHC)	HPA →
Epididymis	Glandular cells	High	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Adrenal gland	Glandular cells	Not detected	Protein (IHC)	HPA →
Caudate	Glial cells	Not detected	Protein (IHC)	HPA →
Cerebellum	Cells in granular layer	Not detected	Protein (IHC)	HPA →
Cerebral cortex	Endothelial cells	Not detected	Protein (IHC)	HPA →
Heart muscle	Cardiomyocytes	Not detected	Protein (IHC)	HPA →

Section 3

Advanced BCL2 IHC Tips

Troubleshoot BCL2 staining in paraffin sections by checking retrieval, compartment, cell identity and controls before comparing chromogenic signal across samples.

How should I troubleshoot weak BCL2 staining after antigen retrieval?

Use Tris-EDTA pH 9.0 HIER at 95–98 °C for 20 min (page retrieval specification). Let sections cool in retrieval buffer, then compare the affected slide with a concurrently processed positive control; the catalog antibody has a paraffin-section image of human non-Hodgkin’s lymphoma at 1:50 (M00040-1 caption). If staining remains weak, compare a citrate buffer at pH 6.0 as a fallback while holding detection conditions constant (standard IHC practice). Judge improvement by expected cytoplasmic or membrane-associated staining, since BCL2 is reported at the mitochondrial outer membrane, nuclear membrane and endoplasmic-reticulum membrane (UniProt P10415 localisation).

Could fixation explain weak or patchy BCL2 staining?

The selected image documents staining of a paraffin-embedded section, but its caption does not report a fixative or fixation duration (M00040-1 caption). BCL2-specific sensitivity to fixation is therefore unknown from the supplied evidence; compare sections with documented processing histories before assigning weak signal to fixation (M00040-1 caption; standard IHC practice). Check whether morphology and staining vary together across the section, and repeat retrieval and staining with a consistently processed positive control (standard IHC practice). Record fixative, fixation time, tissue thickness and processing conditions for each comparison, because uncontrolled differences make an apparent BCL2 effect difficult to interpret (standard IHC practice).

Where should BCL2 signal appear in a chromogenic section?

Expect predominantly cytoplasmic or membrane-associated staining in positive cells, consistent with BCL2 at the mitochondrial outer membrane, nuclear membrane and endoplasmic-reticulum membrane (UniProt P10415 localisation). The Human Protein Atlas describes cytoplasmic tissue staining and enhanced mitochondrial localisation by ICC/IF (HPA tissue IHC; HPA subcellular). Review staining at high magnification against cell boundaries and nuclei; diffuse nuclear-only DAB should prompt a check of counterstain, retrieval and controls (standard IHC practice; UniProt P10415 localisation). Use cell identity as a second check: non-germinal-center cells in lymph node show high expression in the supplied tissue profile, while abundance can vary by cell population (HPA tissue IHC).

Could isoform choice or epitope masking change the IHC result?

BCL2 has Alpha and Beta isoforms, but the supplied caption does not identify the catalog antibody’s epitope or establish which isoforms it detects (UniProt P10415 isoforms; M00040-1 caption). Its transmembrane segment spans residues 212–233, so epitope position would affect how a membrane-associated target is exposed during staining (UniProt P10415 topology; standard IHC practice). Phosphorylation is annotated at residues 69, 70 and 87; do not infer that these modifications alter this antibody’s staining without an epitope map and direct validation (UniProt P10415 modified residues). If results differ between antibodies, compare their documented epitopes and staining in matched sections before attributing the difference to an isoform (standard IHC practice).

How can I adapt the BCL2 question to multiplex IF?

Treat IF as a separate validation: the supplied image establishes paraffin-section chromogenic staining at 1:50, without documenting IF performance or fixative (M00040-1 caption). In lymphoid tissue, multiplex BCL2 with a cell-identity marker such as CD45, then assess signal within the expected non-germinal-center population rather than across all cells (HPA: high in lymph-node non-germinal-center cells; standard IF practice). Choose a far-red fluorophore when tissue autofluorescence obscures shorter wavelengths, and include single-color and no-primary controls (standard IF practice). For a cytosol-facing epitope, start with mild permeabilisation; if its mapped position requires access across a membrane, optimise permeabilisation separately and confirm mitochondrial-pattern staining (UniProt P10415 topology; HPA subcellular; standard IF practice).

What should I check when BCL2 DAB staining looks widespread?

Compare the section with a no-primary control and inspect whether DAB deposits follow cell structures or collect at tissue edges and damaged areas (standard IHC practice). Include a peroxidase-blocking step before chromogenic detection and verify that washes remove unbound reagents; these are general workflow controls, not evidence about BCL2 itself (standard IHC practice). If background rises with the catalog antibody, titrate around the caption’s 1:50 condition while keeping retrieval, detection and exposure to DAB consistent (M00040-1 caption; standard IHC practice). Evaluate suspected background against the reported cytoplasmic tissue profile and the identities of cells in the section, since staining is not expected to be uniform across every cell type (HPA tissue IHC).

How should I score BCL2 across heterogeneous tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION

Define the cell population and region of interest before scoring, then report the percentage of positive cells and an intensity-based H-score using the same thresholds across sections (standard IHC practice). If the question concerns scattered positive cells, report positive-cell density per mm² of viable tissue as well, and document excluded necrotic or folded areas (standard IHC practice). Normalise cell counts to the number of evaluable cells in the chosen population, or density to measured viable area, rather than total slide area (standard IHC practice). Keep retrieval, antibody dilution and DAB development matched; the catalog image’s 1:50 dilution provides a documented starting condition, not a universal scoring threshold (M00040-1 caption; standard IHC practice).

How can I distinguish true BCL2 staining from an artefact?

A credible positive result places signal in the expected cytoplasmic or membrane-associated compartment and in a plausible cell population, such as non-germinal-center cells in lymph node (UniProt P10415 localisation; HPA tissue IHC). Question isolated nuclear-only signal, abrupt edge staining or deposits over necrotic regions, and compare them with intact internal areas (UniProt P10415 localisation; standard IHC practice). Check a no-primary control for endogenous enzyme or detection background before calling faint DAB positive (standard IHC practice). Use a concurrently stained positive control and interpret negative cells in context: the supplied atlas profile reports both high-expression populations and populations with no detected staining (HPA tissue IHC; standard IHC practice).

Boster reagents

Best BCL2 / Apoptosis regulator Bcl-2 IHC Antibodies

IHC images cover human paraffin sections and human and rat spleen (catalog image captions); IF imaging covers U20S cells (A00040-2 image caption). Mouse reactivity is listed for M00040-2 and M00040-4 (catalog).

Real IHC data Immunohistochemical analysis of paraffin-embedded Human non-Hodgkin's lymphoma, using the Antibody at 1:50 dilution.

Anti-Bcl-2 Rabbit Monoclonal Antibody

Cat # M00040-1

View product →

Real IHC data Immunohistochemical analysis of paraffin-embedded Human lung adenocarcinoma, using the Antibody at 1:100 dilution.

Anti-Bcl-2 Rabbit Monoclonal Antibody

Cat # M00040-2

View product →

Real IHC data Human spleen was stained with anti-Bcl-2 rabbit antibody

Anti-Bcl-2 Rabbit Monoclonal Antibody

Cat # M00040-4

View product →

Real IF data

Anti-Bcl-2/BCL2 Antibody ®

Cat # A00040-2

View product →

M00040-1 shows human paraffin-embedded non-Hodgkin’s lymphoma, and M00040-2 shows human paraffin-embedded lung adenocarcinoma (catalog image captions). M00040-4 shows human and rat spleen IHC, while A00040-2 shows IF/ICC in U20S cells (catalog image captions).

Which to pick: For human paraffin-section IHC, choose rabbit monoclonal M00040-1 or M00040-2 (catalog applications and antibody descriptions; each SKU’s IHC image caption: paraffin-embedded human tissue); neither caption reports the fixative (catalog image captions). For IF/ICC, choose A00040-2, which lists both applications and shows U20S cell staining (catalog applications; A00040-2 image caption). For human, mouse or rat reactivity, choose recombinant rabbit monoclonal M00040-4 (catalog description and reactivity); its human and rat spleen IHC captions report neither tissue processing nor fixative (M00040-4 image captions).

Each figure is that product's own IHC / IF validation image from its datasheet.

References

UniProt Consortium. UniProt entry P10415 (BCL2_HUMAN, Apoptosis regulator Bcl-2).
Human Protein Atlas. BCL2 tissue IHC expression (reliability: Enhanced).
Human Protein Atlas. BCL2 subcellular location (ICC-IF): Localized to the mitochondria..
Human Protein Atlas. BCL2 antibody validation summary (3 antibodies).
Patterns of Immunohistochemical Expression of P53, BCL2, PTEN, and HER2/neu Tumor Markers in Specific Breast Cancer Lesions. Evidence-based complementary and alternative medicine : eCAM 2022 — PMC9592210.
Double-hit lymphomas: clinical, morphological, immunohistochemical and cytogenetic study in a series of Brazilian patients with high-grade non-Hodgkin lymphoma. Diagnostic pathology 2017 — PMC5219810.
The t(14;18) translocation is absent from endothelial and follicular dendritic cells of follicular lymphoma (FL) and shows heterogeneous presence in preserved FL mantle zones. Diagnostic pathology 2018 — PMC5930855.
Clinical and Pathological Features of Double-Hit and Triple-Hit High-Grade B-Cell Lymphomas: A Retrospective Study from Three Portuguese Tertiary Centers. International journal of hematology-oncology and stem cell research 2022 — PMC9547779.
PubMed PMID:3523487 — UniProt-cited evidence.
PubMed PMID:1508712 — UniProt-cited evidence.
PubMed PMID:2875799 — UniProt-cited evidence.