CDA / Cytidine deaminase · IHC design guide

Design Immunohistochemistry for CDA

Plan chromogenic CDA IHC in paraffin sections using the catalog antibody’s documented conditions (datasheet A01578-1). Use bone marrow hematopoietic cells as a reference for observed staining, while assessing signal by cell population (HPA tissue IHC).

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

Immunohistochemistry protocol sheet for CDA (IHC for CDA): expected localisation Tissue compartment not established (HPA tissue IHC), antibody A01578-1, validated IHC image, and IHC protocol steps — Printable **CDA** IHC protocol sheet — expected localisation Tissue compartment not established (HPA tissue IHC), antibody A01578-1, controls and protocol steps. Open the full CDA IHC guide →

Navigate to: Protocols Staining pattern Controls Antibodies

CDA 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	Tissue compartment not established (HPA tissue IHC)
	Staining pattern	A subset of immune cells stains; compartment unreported (HPA tissue IHC)
	Antigen retrieval	Citrate pH 6 HIER, heat-mediated (datasheet A01578-1)
	Positive control ⓘ	Bone marrow
	Negative control ⓘ	Adipose tissue+4 more · see all

Important caveats

Reasons your staining may differ from the expected pattern.

	Fixation	Keep fixation consistent between sections (standard IHC practice; not target-specific)
	Caveat	Granulocyte abundance may shift apparent signal (UniProt)
	Regulation	Expression varies by cell type (UniProt)
	Isoform / epitope	One 1–146 chain; no isoforms annotated (UniProt)

Section 1

Recommended CDA IHC & IF Protocols

Compare the catalog antibody’s IHC protocol (datasheet: A01578-1) with published CDA staining of lung cancer tissue (PMC9440127; PMC8056724).

Recommended immunohistochemistry (IHC-P) protocol parameters
Sample	Paraffin-embedded human intestinal cancer tissue; fixative not specified (datasheet A01578-1)
Fixation	Image fixative and duration unreported (datasheet A01578-1); verify before use.
Sectioning	4–5 µm sections on charged slides (standard)
Deparaffinisation	Xylene, graded ethanol series to water (standard)
Antigen retrieval	Heat retrieval: Citrate pH 6, 20 min (datasheet A01578-1)
Peroxidase block	3% H2O2, 10 min, room temperature (standard)
Blocking	10% goat serum (datasheet A01578-1)
Primary antibody	Rabbit anti-CDA, 1μg/ml (datasheet A01578-1)
Primary incubation	Overnight at 4 °C (datasheet A01578-1)
Detection	Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01578-1)
Counterstain	Hematoxylin, blue, dehydrate and mount (standard)
Expected result	CDA-positive staining in hematopoietic cells of bone marrow (HPA tissue IHC: Medium). HPA tissue profile: Expression in a subset of immune cells. No signal in the no-primary control.

💡Decision noteStart with citrate pH 6 heat retrieval for the catalog antibody (datasheet: A01578-1). The emitted article excerpts do not specify a validated retrieval condition (PMC9440127; PMC8056724).

Section 2

What Is the Expected CDA Staining Pattern?

CDA staining should appear in a subset of immune cells, with medium staining reported in bone marrow hematopoietic cells (HPA tissue IHC: Enhanced reliability). Nucleoplasmic localization is reported in cultured cells (HPA ICC-IF: Approved), so nuclear enrichment is a reasonable pattern to examine in sections, but its transfer to IHC is unconfirmed. CDA has no transmembrane segment (UniProt P32320 topology).

What am I looking at on my slide?
A subset of bone marrow hematopoietic cells stains at medium intensity.	This matches the clearest supplied tissue result (HPA tissue IHC: Medium in bone marrow hematopoietic cells). A mixed population is expected from the reported subset-of-immune-cells profile (HPA tissue IHC); uniform staining of every cell would need scrutiny.
Staining is nucleoplasmic in some positive cells.	This agrees with the approved cultured-cell localization (HPA ICC-IF: nucleoplasm). The compartment was measured by ICC-IF, so assess an IHC nuclear pattern alongside cell identity and controls rather than treating it as independently validated in paraffin sections.
Strong membrane staining dominates, with little staining in the expected cells.	A membrane pattern conflicts with the supplied nucleoplasmic ICC-IF result (HPA ICC-IF) and CDA lacks a transmembrane segment (UniProt P32320 topology). Check controls and detection background before interpreting it as CDA.
Cells reported as unstained show a strong chromogenic signal.	Strong adipocyte staining, for example, conflicts with the reported absence in adipose tissue (HPA tissue IHC: Not detected in adipocytes). Cross-reactivity or endogenous detection activity is possible; compare a negative reagent control and the tissue context.
No staining appears in bone marrow hematopoietic cells.	This misses the supplied medium-level positive reference (HPA tissue IHC: bone marrow). Check tissue preservation and the IHC workflow with controls; a blank section alone cannot distinguish technical failure from sample-specific low expression.

💡Expected CDA appearanceCall positive when a subset of bone marrow hematopoietic cells shows medium staining (HPA tissue IHC), with possible nucleoplasmic enrichment (HPA ICC-IF); widespread strong adipocyte or dominant membrane staining is discordant (HPA tissue IHC; UniProt P32320 topology).

How each factor affects the staining
Tissue and cell selection	Bone marrow hematopoietic cells provide the clearest supplied positive comparison (HPA tissue IHC: Medium). Esophageal squamous cells, hepatocytes, splenic red-pulp cells and lymph-node non-germinal-center cells are reported only at low levels (HPA tissue IHC); a faint result there is less decisive.
Cell population within a section	HPA describes expression in a subset of immune cells (HPA tissue IHC). UniProt reports high expression in granulocytes and very low expression in fibroblasts, chondrocytes, monocytes, and T- and B-cell lines (UniProt P32320 tissue specificity). Those records do not assign every stained cell in a section.
Compartment evidence and modality	Nucleoplasm is an approved ICC-IF location (HPA ICC-IF), while UniProt provides no subcellular annotation (UniProt P32320). Use nucleoplasmic staining as a supported comparison, with the modality difference stated, rather than as a required IHC scoring rule.
Antibody and tissue evidence	The listed antibody HPA064202 has Enhanced IHC and Approved ICC validation (HPA antibodies). HPA also reports only medium consistency between antibody staining and RNA expression, with staining in unannotated cells or structures (HPA tissue IHC: Enhanced reliability); inspect the pattern before assigning cell identity.
Protein structure and processing	CDA is a 146-residue chain with no signal peptide, propeptide, transmembrane segment, glycosylation site or listed modified residue (UniProt P32320). These facts do not identify the antibody epitope or establish an antigen retrieval setting or fixation sensitivity.
IF/ICC Q: Should its localization guide section scoring?	A: Use the approved nucleoplasmic ICC-IF result as a comparison (HPA ICC-IF: Approved). It does not itself validate nucleoplasmic localization in paraffin IHC, and no IF/ICC protocol option is supplied here.

Why is my staining missing, weak or wrong?
Situation	Likely cause	Next action
Bone marrow positive control is blank.	The expected medium signal is absent (HPA tissue IHC: bone marrow hematopoietic cells); the section or staining run may have failed.	Check a known working control, reagent sequence and detection setup. Review retrieval conditions as general IHC practice; CDA-specific retrieval and fixation sensitivity are unreported in the supplied sources.
Only very faint staining appears in liver or esophagus.	Low protein staining is reported in hepatocytes and esophageal squamous cells (HPA tissue IHC: Low); faint signal there is not by itself a failed run.	Compare with bone marrow hematopoietic cells, reported at medium intensity (HPA tissue IHC). Score the relevant cell population rather than treating whole-section intensity as the result.
Adipocytes or respiratory epithelial cells stain strongly.	These cells are reported as not detected in the listed adipose tissue and bronchus sections (HPA tissue IHC); nonspecific binding or endogenous chromogenic activity is possible.	Inspect a matched negative reagent control and compare staining across compartments and cell types (general IHC practice). Treat persistent signal in those cells as discordant with the supplied HPA pattern.
Brown signal is widespread across cells and extracellular areas.	Diffuse chromogen can obscure the reported subset-of-immune-cells pattern (HPA tissue IHC); background from detection or staining conditions is possible (general IHC practice).	Review blocking, washes, antibody concentration and detection exposure using appropriate controls (general IHC practice). Reassess whether discrete hematopoietic cells remain distinguishable.
A crisp membrane rim is the dominant pattern.	That compartment differs from the nucleoplasmic ICC-IF observation (HPA ICC-IF), and CDA has no transmembrane segment (UniProt P32320 topology). The IHC compartment itself has not been independently established here.	Check the negative reagent control and compare with the expected cell distribution (general IHC practice; HPA tissue IHC). Avoid calling a membrane-only pattern CDA from these sources.
Staining intensity varies between sections.	The supplied tissue record includes medium, low and undetected cell populations (HPA tissue IHC); section composition may change the apparent result. Target-specific fixation sensitivity is unreported.	Compare the same annotated cell type across sections, verify run controls and document retrieval and detection conditions (general IHC practice). Do not attribute variation specifically to CDA epitope masking without evidence.

Source: UniProt P32320 Human Protein Atlas tissue Human Protein Atlas subcellular

Experiment evidence

IHC & IF images showing CDA staining

IHC analysis of CDA using anti-CDA antibody (A01578-1). CDA was detected in paraffin-embedded section of human intestinal cancer tissue. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CDA Antibody (A01578-1) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC)(Catalog # SA1022) with DAB as the chromogen.

A01578-1 · IHCIHC analysis of CDA using anti-CDA antibody (A01578-1). CDA was detected in paraffin-embedded section of human intestinal cancer tissue. Hea

IHC analysis of CDA using anti-CDA antibody (A01578-1). CDA was detected in paraffin-embedded section of human lung cancer tissue. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CDA Antibody (A01578-1) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC)(Catalog # SA1022) with DAB as the chromogen.

A01578-1 · IHCIHC analysis of CDA using anti-CDA antibody (A01578-1). CDA was detected in paraffin-embedded section of human lung cancer tissue. Heat medi

HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000158825-CDA/tissue/cerebral+cortex#imid_17774487

HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000158825-CDA/tissue/colon#imid_17774413

HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000158825-CDA/tissue/liver#imid_17774398

HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000158825-CDA/tissue/kidney#imid_17774415

HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA064202; green = CDA, blue = nucleus, red = microtubules.

← swipe / scroll for more images →

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

Sample controls for CDA IHC & IF

🧪Run bone marrow first and score staining in hematopoietic cells (HPA: Medium in bone marrow hematopoietic cells). Use adipose tissue adipocytes as the negative comparison (HPA: Not detected in adipocytes); on the marrow slide, assess nonhematopoietic stromal cells as candidate internal negatives and expect little or no staining relative to hematopoietic cells, while confirming their identity by morphology (standard IHC practice).

Positive control tissue: Bone marrow (Hematopoietic cells, HPA Medium)

Negative control tissue: Adipose tissue (HPA Not detected)

ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CDA in A-431, SiHa, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).

Technical controls: Include a no-primary, secondary-only control; a concentration-matched rabbit IgG isotype control matching the primary antibody’s clonality where known; and CDA knockout material as a biological negative (caption: rabbit anti-CDA antibody; standard IHC practice). In bone marrow, quench endogenous peroxidase and check for endogenous biotin background when using the caption’s biotin-based DAB detection (caption: biotinylated secondary, SABC and DAB; standard IHC practice).

⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A01578-1 tissue-IHC caption does not state a fixative (caption: fixative not stated). The paraffin-section example uses heat retrieval in citrate buffer at pH 6 for 20 minutes; this provides a starting condition but does not establish that retrieval is required (caption: retrieval conditions). Whether frozen sections or IF are easier is unreported; HPA has ICC-IF images with approved nucleoplasmic localization, while marrow endogenous peroxidase can complicate chromogenic interpretation (HPA: nucleoplasm approved; standard IHC practice).

HPA tissue IHC evidence for CDA

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Antibody staining in cells/structures not annotated, view images.). 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
Bone marrow	Hematopoietic cells	Medium	Protein (IHC)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Adipose tissue	Adipocytes	Not detected	Protein (IHC)	HPA →
Adrenal gland	Glandular cells	Not detected	Protein (IHC)	HPA →
Appendix	Glandular cells	Not detected	Protein (IHC)	HPA →
Breast	Adipocytes	Not detected	Protein (IHC)	HPA →
Bronchus	Respiratory epithelial cells	Not detected	Protein (IHC)	HPA →

Section 3

Advanced CDA IHC Tips

Troubleshoot CDA staining in paraffin sections by checking retrieval, cell identity, compartment, and controls before comparing staining intensity.

Which retrieval conditions should I try first for weak CDA staining in paraffin sections?

Start with heat mediated retrieval in citrate buffer at pH 6 for 20 minutes (datasheet A01578-1). That exact treatment preceded CDA detection in a paraffin section, although the caption does not report the fixative (datasheet A01578-1). Keep heating time, cooling, and section thickness consistent across the test series, then compare the proportion of stained cells and background under matched detection conditions (standard IHC practice). If staining remains weak, test a different retrieval buffer or heating duration on adjacent sections, retaining the citrate condition as the reference and including a no primary control (standard IHC practice).

How should I handle fixation when CDA staining varies between paraffin blocks?

CDA specific sensitivity to fixation is unknown from the supplied evidence; the selected paraffin section caption does not state its fixative (datasheet A01578-1). Record the actual fixative and fixation duration for each block, and avoid attributing staining differences to fixation before comparing matched tissue and processing conditions (standard IHC practice). Use the reported pH 6 citrate retrieval for 20 minutes as a starting condition when evaluating the catalog antibody (datasheet A01578-1). Compare serial sections with identical antibody incubation and detection, and use morphology plus a no primary control to separate processing effects from background (standard IHC practice).

Should CDA staining be nuclear, cytoplasmic, or restricted to particular cells?

HPA reports an approved nucleoplasmic location for CDA, while UniProt supplies no subcellular location annotation and reports no transmembrane segment (HPA subcellular; UniProt P32320 topology). In tissue IHC, assess nuclear staining alongside cell identity rather than treating every brown nucleus as CDA positive (HPA tissue IHC: expression in a subset of immune cells; standard IHC practice). Bone marrow hematopoietic cells showed medium staining, and UniProt reports high expression in granulocytes (HPA tissue IHC; UniProt P32320 tissue specificity). If staining is predominantly extracellular or confined to damaged tissue, check morphology, retrieval, and detection controls before assigning it to CDA (standard IHC practice).

How can I investigate staining that disagrees with the expected CDA epitope?

The supplied record lists one 1–146 CDA chain, 0 isoforms, 0 glycosylation sites, and no signal peptide or transmembrane segment (UniProt P32320). Those annotations do not establish where the catalog antibody binds or whether fixation and retrieval preserve its epitope (UniProt P32320; datasheet A01578-1). Compare the staining pattern with an independently validated antibody recognizing a documented, distinct epitope, if available, and review any epitope information supplied for the reagent (standard IHC practice). Keep retrieval and detection conditions matched, then judge agreement by cell type and compartment rather than overall color intensity alone (standard IHC practice; HPA subcellular).

How should I assess CDA by IF while using this IHC guide?

For IF or ICC, pair CDA with a validated marker that identifies the expected granulocyte population or another cell population under study, and verify marker specificity in that specimen (UniProt P32320 tissue specificity; standard IF practice). Choose fluorophores after checking tissue autofluorescence in unstained controls, placing a potentially weak CDA signal in a spectrally cleaner channel (standard IF practice). Because HPA places CDA in the nucleoplasm and UniProt reports no transmembrane segment, test permeabilisation sufficient for nuclear epitope access after fixation (HPA subcellular; UniProt P32320 topology; standard IF practice). Optimise IF fixation independently; the catalog caption documents paraffin IHC and does not report a fixative or establish IF performance (datasheet A01578-1).

What should I check when DAB background obscures sparse CDA positive cells?

Run a no primary control through the same secondary antibody, streptavidin–biotin detection, and DAB development to locate detection background (datasheet A01578-1; standard IHC practice). Include a peroxidase block before chromogenic detection, and check whether endogenous biotin contributes signal when using the reported streptavidin–biotin workflow (datasheet A01578-1; standard IHC practice). The caption used 10% goat serum blocking and 1 μg/ml primary antibody overnight at 4°C; reproduce those conditions before changing one variable at a time (datasheet A01578-1). Review section edges and damaged areas separately, since their staining can obscure the subset of immune cells reported to express CDA (HPA tissue IHC; standard IHC practice).

How should I score CDA staining when only some cells are positive? ⚠ ANSWER MARKED FOR VERIFICATION

Define the cell population and compartment before scoring, because HPA reports expression in a subset of immune cells and an approved nucleoplasmic location (HPA tissue IHC; HPA subcellular). For a defined population, report the percentage of positive cells or an H-score combining intensity and proportion, with thresholds fixed before comparing specimens (standard IHC practice). For spatial analysis, count positive cells per mm² of viable tissue and state whether the denominator is all cells or the relevant cell population (standard IHC practice). Normalise comparisons to the same tissue area or eligible cell count, and exclude necrosis and technical edge staining using consistent rules (standard IHC practice).

How can I distinguish convincing CDA staining from artefact in a positive section?

A convincing result should align with identifiable cells and a reproducible compartment: HPA reports nucleoplasmic CDA and expression in a subset of immune cells (HPA subcellular; HPA tissue IHC). Bone marrow hematopoietic cells showed medium staining, while UniProt reports high expression in granulocytes, providing cell context for comparison without making every immune cell positive (HPA tissue IHC; UniProt P32320 tissue specificity). Treat staining limited to section edges, necrotic areas, or the no primary control as possible artefact; also check residual endogenous peroxidase or biotin signal in the chromogenic workflow (standard IHC practice; datasheet A01578-1). Interpret unexpected cell types or diffuse extracellular staining cautiously and seek agreement across morphology, controls, and an independent antibody where available (standard IHC practice).

Boster reagents

Best CDA / Cytidine deaminase IHC Antibodies

The catalog antibody has real CDA IHC data from paraffin sections of human cancer tissues and mouse intestine (A01578-1 image captions); rat reactivity is listed without a rat IHC image (catalog: reactivity).

Real IHC data

Anti-CDA Antibody ®

Cat # A01578-1

View product →

A01578-1 is the only SKU and is listed for IHC in human, mouse, and rat samples (catalog: applications and reactivity). Its IHC images show human intestinal, lung, and mammary cancer tissues and mouse intestine in paraffin sections (A01578-1 image captions).

Which to pick: Choose A01578-1 for paraffin-section tissue IHC: its images document that preparation, while the fixative is unreported (A01578-1 image captions). It is a polyclonal rabbit antibody listed as reactive with human, mouse, and rat; the rat evidence is catalog reactivity, with no rat IHC image supplied (catalog: host, dilution_raw, reactivity; A01578-1 image captions). No IF/ICC-validated SKU or IF image is supplied, so there is no supported IF/ICC pick here (catalog: applications and if_image_alts).

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

References

UniProt Consortium. UniProt entry P32320 (CDD_HUMAN, Cytidine deaminase).
Human Protein Atlas. CDA tissue IHC expression (reliability: Enhanced).
Human Protein Atlas. CDA subcellular location (ICC-IF): Localized to the nucleoplasm..
Human Protein Atlas. CDA antibody validation summary (1 antibodies).
DNA methylome and single-cell transcriptome analyses reveal CDA as a potential druggable target for ALK inhibitor-resistant lung cancer therapy. Experimental & molecular medicine 2022 — PMC9440127.
Scheduling nab-paclitaxel combined with gemcitabine as first-line treatment for metastatic pancreatic adenocarcinoma. British journal of cancer 2020 — PMC7283477.
Chemotherapy-induced CDA expression renders resistant non-small cell lung cancer cells sensitive to 5'-deoxy-5-fluorocytidine (5'-DFCR). Journal of experimental & clinical cancer research : CR 2021 — PMC8056724.
hENT1 Predicts Benefit from Gemcitabine in Pancreatic Cancer but Only with Low CDA mRNA. Cancers 2021 — PMC8616255.
PubMed PMID:7923172 — UniProt-cited evidence.
PubMed PMID:9878810 — UniProt-cited evidence.
PubMed PMID:9596658 — UniProt-cited evidence.