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FCGR2A / Low affinity immunoglobulin gamma Fc region receptor II-a · IHC design guide
Design Immunohistochemistry for FCGR2A
Plan paraffin-section FCGR2A IHC using the catalog antibody at 0.5–1 µg/mL (datasheet A01450-1). Expect cytoplasmic staining in macrophages and hematopoietic cells, while interpreting signal in light of the HPA warning that staining may represent proteins from more than one gene (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FCGR2A 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 signal; cell membrane protein (HPA tissue IHC; UniProt) | |
| Staining pattern | Cytoplasmic hematopoietic cells, macrophages and lymphoid subsets (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A01450-1) | |
| Positive control | Endometrium+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across samples (standard IHC practice; not target-specific) | |
| Caveat | Staining may reflect proteins from more than one gene (HPA tissue IHC) | |
| Regulation | Immune-cell mix may shift tissue signal (HPA tissue IHC) | |
| Isoform / epitope | 2 isoforms; check extracellular versus cytoplasmic epitope (UniProt) |
Section 1
Recommended FCGR2A IHC & IF Protocols
The catalog antibody uses citrate pH 6 retrieval (datasheet A01450-1). Three published breast cancer IHC protocols add sample and detection details, with dilution where reported (PMC2987696; PMC2976659; PMC2935495).
| Sample | Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A01450-1) |
| Fixation | Image fixative and duration unreported (datasheet A01450-1); 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 A01450-1) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01450-1) |
| Primary antibody | Rabbit anti-FCGR2A, 1μg/ml (datasheet A01450-1) |
| Primary incubation | Overnight at 4 °C (datasheet A01450-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01450-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FCGR2A-positive staining in ciliated epithelial cells of endometrium (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in hematopoietic cells, macrophages and subsets of lymphoid cells. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated citrate pH 6 retrieval (datasheet A01450-1). The three cited excerpts do not report retrieval conditions (PMC2987696; PMC2976659; PMC2935495).
Section 2
What Is the Expected FCGR2A Staining Pattern?
FCGR2A is a cell membrane receptor with an extracellular region spanning residues 34–217 and a transmembrane segment at 218–240 (UniProt P12318 topology). In tissue IHC, expect staining in macrophages and other hematopoietic cells; HPA also describes cytoplasmic staining in these populations (HPA tissue IHC: Supported). Interpret that pattern cautiously because the HPA tissue assessment warns that its antibodies can target proteins from more than one gene (HPA tissue IHC reliability).
| Lung macrophages stain strongly, while nearby respiratory epithelial cells are unstained. | This matches a useful cell-level contrast: lung macrophages are High (HPA tissue IHC), and bronchial respiratory epithelial cells are Not detected (HPA tissue IHC). Judge the positive cells by their identity and distribution, then check whether the staining pattern is consistent across the section. |
| Positive cells show a membrane outline, with some cytoplasmic staining. | Membrane staining fits receptor topology (UniProt P12318 topology). Cytoplasmic staining also appears in HPA tissue IHC, which describes expression in hematopoietic cells, macrophages and subsets of lymphoid cells (HPA tissue IHC profile). Cytoplasmic signal alone therefore does not establish an artefact; compare it with cell-level controls. |
| Signal is confined to nuclei or appears in a compartment unrelated to the expected cellular pattern. | A purely nuclear pattern is unsupported by the reported membrane location (UniProt P12318 subcellular location) and HPA tissue IHC profile. Treat it as a suspect result, check the negative control and tissue morphology, and reassess antibody and detection specificity before calling cells positive. |
| Strong staining appears broadly in cells expected to be unstained, or colour covers the section diffusely. | Broad signal in bronchial respiratory epithelium conflicts with its Not detected HPA result (HPA tissue IHC). Possible technical contributors include nonspecific antibody binding, Fc-mediated reagent binding or endogenous chromogenic activity; diffuse colour can also obscure genuine positive macrophages. Compare appropriate control sections before assigning cell-level positivity. |
| No signal is visible in lung macrophages or other selected positive cells. | Lung macrophages are a High reference population (HPA tissue IHC). Absence there makes the run difficult to interpret. First confirm that macrophages are present in the section, then review the catalog antibody's IHC-P instructions, detection reagents and control staining; do not infer FCGR2A absence from one failed run. |
💡Expected FCGR2A appearanceCall a result positive when identifiable lung macrophages show strong cell-associated staining, potentially including membrane and cytoplasmic signal (HPA tissue IHC: High in lung macrophages; HPA tissue IHC profile; UniProt P12318 topology); broad staining of bronchial respiratory epithelium is suspect (HPA tissue IHC: Not detected).
| Which compartment should guide IHC interpretation? | FCGR2A has an extracellular region at 34–217 and one transmembrane segment at 218–240 (UniProt P12318 topology). HPA nevertheless reports cytoplasmic tissue staining (HPA tissue IHC profile). Use the stained cell population alongside compartment; topology alone cannot prescribe the exact appearance of a chromogenic paraffin section. |
| Which cells offer the clearest tissue contrast? | Lung macrophages are High, bone marrow hematopoietic cells are Medium, and bronchial respiratory epithelial cells are Not detected (HPA tissue IHC). These are cell-specific observations, so a positive immune-cell population does not imply that every cell in the tissue should stain. |
| How much specificity does the HPA pattern establish? | The tissue assessment is Supported, with medium consistency between staining and RNA, and warns of antibodies targeting more than one gene (HPA tissue IHC reliability). HPA010718 and HPA014730 each have Supported IHC status (HPA antibody validation). A matching pattern supports interpretation but cannot, by itself, prove FCGR2A-specific binding. |
| Do the reported isoforms determine the expected staining? | UniProt lists 2 isoforms (UniProt P12318 isoforms). The supplied evidence gives no antibody epitope or isoform coverage, so it cannot establish whether an IHC result represents either isoform individually. Do not explain a missing tissue signal by isoform choice without separate antibody-specific evidence. |
| What should an IF/ICC image show? | HPA reports a mainly plasma membrane location, with an additional uncertain Golgi location; its ICC-IF summary cautions that the antibodies can target proteins from multiple genes (HPA subcellular ICC-IF). That observation can inform localisation, but it does not validate an IHC-P staining pattern or supply an IF/ICC protocol. |
| Situation | Likely cause | Next action |
|---|---|---|
| The expected lung macrophage control is blank. | The run may have failed, or the examined area may lack identifiable macrophages; their reported level is High (HPA tissue IHC). | Check cell identity and section quality, then follow the catalog antibody's IHC-P instructions and verify that the detection control worked. Reassess the result only after a known-positive cell population stains. |
| Respiratory epithelium stains as strongly as nearby immune cells. | Bronchial respiratory epithelial cells are Not detected in HPA tissue IHC; widespread signal could reflect nonspecific binding or detection background rather than the expected cell distribution. | Compare a matched negative control and the positive macrophages. Review blocking, antibody concentration and detection steps as general IHC checks before assigning epithelial positivity. |
| A nuclear-only signal dominates the section. | This localisation lacks support from the membrane assignment (UniProt P12318 subcellular location) and the HPA tissue IHC profile. | Inspect the negative control and morphology, and repeat with the IHC-validated antibody's documented conditions if needed. Treat the nuclear signal as unconfirmed until the expected cell-level pattern is demonstrated. |
| Diffuse chromogen makes individual cells hard to score. | Background from detection reagents, incomplete washing or endogenous enzyme activity can obscure cell-associated staining in chromogenic IHC. | Review wash and detection steps, and use a control lacking primary antibody to assess reagent background. Apply an appropriate endogenous-activity block if the detection chemistry requires one. |
| Immune-rich areas stain broadly, with weak separation between cells. | FCGR2A binds the Fc region of IgG (UniProt P12318 function), so Fc-mediated binding of assay reagents is a plausible contributor; HPA also cautions about cross-gene antibody recognition (HPA tissue IHC reliability). | Check a matched negative control and consider a suitable Fc-blocking step as general IHC practice. Score only identifiable cells with a convincing pattern, using the positive tissue reference for comparison. |
| A low-level tissue or an IF/ICC image disagrees with the IHC result. | Placental trophoblastic cells are Low in tissue IHC (HPA tissue IHC), while the HPA ICC-IF summary describes mainly plasma membrane signal with an uncertain additional Golgi location (HPA subcellular ICC-IF). These observations have different contexts. | Confirm the cell type, assay and antibody validation status before comparing results. Use the tissue IHC evidence to judge the chromogenic section; keep the IF/ICC observation as a localisation reference. |
Experiment evidence
IHC & IF images showing FCGR2A staining
A01450-1 · IHCIHC analysis of FCGR2A using anti-FCGR2A antibody (A01450-1). FCGR2A was detected in paraffin-embedded section of human lung cancer tissue.
A01450-1 · IHCIHC analysis of FCGR2A using anti-FCGR2A antibody (A01450-1). FCGR2A was detected in paraffin-embedded section of mouse spleen tissue. Heat
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000143226-FCGR2A/tissue/cerebral+cortex#imid_2942004
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000143226-FCGR2A/tissue/colon#imid_2941938
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000143226-FCGR2A/tissue/liver#imid_2941931
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000143226-FCGR2A/tissue/kidney#imid_2941932
HPA · ICC-IF HELHuman Protein Atlas immunofluorescence, HEL, antibody HPA010776; green = FCGR2A, blue = nucleus, red = microtubules.
HPA · ICC-IF HELHuman Protein Atlas immunofluorescence, HEL, antibody HPA010776; green = FCGR2A, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FCGR2A IHC & IF
🧪Run lung first and require staining in macrophages (HPA: High in lung macrophages). Run adipose tissue as the negative and assess adipocytes, which should lack detectable staining (HPA: Not detected in adipocytes); on the lung slide, use neighboring nonmacrophage cells with little or no specific membrane staining as internal negative comparators (UniProt P12318: cell membrane).
Positive control tissue: Endometrium (Ciliated epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FCGR2A in HEL, THP-1, U2OS, with annotated localisation: Plasma membrane (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control (selected IHC caption: rabbit primary antibody), plus identically processed FCGR2A-knockout material as a biological negative. In lung, control for macrophage Fc binding and endogenous peroxidase; check endogenous biotin when using the caption’s biotin-based DAB detection (UniProt P12318: IgG-binding receptor; selected IHC caption: biotinylated secondary, SABC and DAB).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A01450-1 paraffin-section caption does not state the fixative (selected IHC caption). The caption demonstrates heat retrieval in citrate buffer at pH 6 for 20 minutes in human lung cancer tissue, but does not establish that retrieval is required in every specimen (selected IHC caption). The supplied evidence does not establish whether frozen sections or IF are easier; in lung IHC, macrophage Fc binding and endogenous peroxidase can complicate interpretation (UniProt P12318: IgG-binding receptor; selected IHC caption: DAB detection).
HPA tissue IHC evidence for FCGR2A
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Medium consistency between antibody staining and RNA expression data. Caution, targets protein from more than one gene. 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 |
|---|---|---|---|---|
| Endometrium | Ciliated epithelial cells | High | Protein (IHC) | HPA → |
| Lung | Macrophages | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Medium | Protein (IHC) | HPA → |
| Spleen | Cells in red pulp | Medium | Protein (IHC) | HPA → |
| Tonsil | Non-germinal center 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 → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FCGR2A IHC Tips
Troubleshoot FCGR2A chromogenic IHC by checking retrieval, cell identity, membrane localisation and assay controls together (UniProt P12318; HPA tissue IHC).
What retrieval should I try first when FCGR2A staining is weak in paraffin sections?
Start with heat-mediated citrate pH 6 antigen retrieval for FCGR2A IHC-P (datasheet A01450-1). The matched paraffin-section image used 20 minutes of retrieval, then a 10% goat-serum block and 1 μg/ml primary antibody overnight at 4°C (caption A01450-1). If staining is weak, check heating, section integrity and a positive cell population before changing retrieval; lung macrophages are a useful reference (standard IHC practice; HPA: High in lung macrophages). Then compare an alternative retrieval condition on adjacent sections while keeping antibody and detection conditions matched, and watch for tissue damage or increased background (standard IHC practice).
Can I adjust fixation to improve FCGR2A staining in paraffin sections?
FCGR2A-specific sensitivity to fixation is unknown from the supplied evidence, so an apparent staining difference cannot be assigned to a particular fixative or fixation duration (caption A01450-1: fixative unreported). The selected image documents a paraffin-embedded section, but does not state how that tissue was fixed (caption A01450-1). Record the fixative, time to fixation and fixation duration for each specimen, and compare similarly processed sections when troubleshooting (standard IHC practice). Check morphology and an established positive cell population alongside the test section; altered processing can affect antigen accessibility and tissue preservation in IHC generally (standard IHC practice).
Should FCGR2A appear on cell membranes or throughout the cytoplasm?
Expect membrane-associated staining because FCGR2A spans residues 218–240, with an extracellular region at 34–217 and a cytoplasmic tail at 241–317 (UniProt P12318 topology). Plasma-membrane localisation is supported, while additional Golgi localisation is uncertain and based on antibodies that may detect proteins from multiple genes (HPA subcellular). Tissue IHC also reports cytoplasmic staining in hematopoietic cells, macrophages and subsets of lymphoid cells (HPA tissue IHC). Assess staining within identified cells and compare membrane accentuation with diffuse cytoplasmic signal, since chromogenic deposits can obscure precise compartment boundaries (standard IHC practice).
How can epitope position change my interpretation of FCGR2A IHC?
FCGR2A has 2 listed isoforms, but the payload does not map this antibody’s epitope onto either isoform (UniProt P12318 isoforms; caption A01450-1). Its extracellular segment spans residues 34–217, and its cytoplasmic segment spans 241–317; extracellular residues 97 and 178 are glycosylation sites (UniProt P12318 topology and glycosylation). The tail also contains reported phosphotyrosines at 288 and 304, so epitope accessibility or modification is a question to investigate only after the binding region is known (UniProt P12318 modified residues; standard IHC practice). Request epitope or isoform-reactivity information, then interpret discordant staining alongside cell identity and an independent antibody or method where available (standard IHC practice).
How could IF help check a disputed FCGR2A IHC pattern?
Use IF as an orthogonal localisation check on appropriately controlled material, while retaining chromogenic paraffin-section IHC as this page’s primary readout (standard IHC/IF practice). Multiplex FCGR2A with a validated macrophage marker when examining lung, since lung macrophages have high reported staining (HPA: High in lung macrophages; standard IF practice). Choose spectrally separated fluorophores and assess tissue autofluorescence with an unstained control before assigning a weak signal to FCGR2A (standard IF practice). Permeabilisation should follow the verified epitope location: an extracellular epitope may be assessed without it, whereas a cytoplasmic-tail epitope requires membrane access (UniProt P12318 topology; standard IF practice).
What controls help distinguish FCGR2A signal from chromogenic background?
The selected demonstration used a 10% goat-serum block, biotinylated secondary antibody, streptavidin–biotin detection and DAB (caption A01450-1). Include a no-primary control and inspect staining after the same detection steps to locate secondary-reagent or endogenous-enzyme background (standard IHC practice). Apply an appropriate peroxidase block for DAB detection, and assess endogenous biotin interference when using a biotin-based system (standard IHC practice; caption A01450-1: detection system). Compare cellular staining with macrophage-rich areas and epithelial areas: lung macrophages are reported high, whereas bronchial respiratory epithelial cells are reported undetected (HPA tissue IHC).
How should I quantify FCGR2A staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the compartment and cell population before scoring, because FCGR2A is a membrane receptor and tissue staining includes macrophages and other hematopoietic cells (UniProt P12318 topology; HPA tissue IHC). For comparable regions, report the percentage of positive cells and an intensity-based H-score, with the scored cell type specified (standard IHC practice). If the question concerns infiltrating cells, report positive-cell density per mm² and normalise to evaluable tissue area; for a cell-specific fraction, normalise to all cells of that defined type (standard IHC practice). Keep section processing, thresholds and image acquisition consistent, and exclude folds, necrosis and damaged edges from the analysis (standard IHC practice).
When is a positive FCGR2A IHC result convincing?
A convincing result places staining in identifiable FCGR2A-associated cells and is compatible with its membrane location; lung macrophages are a documented high-staining population (UniProt P12318 topology; HPA: High in lung macrophages). Treat isolated diffuse staining in an unexpected cell type cautiously, particularly because the HPA tissue antibody can detect proteins from more than one gene (HPA tissue IHC reliability). Compare suspect areas with a no-primary control and inspect section edges, necrosis and endogenous peroxidase signal before calling them positive (standard IHC practice). Report the cell type and staining pattern alongside intensity, and seek an independent specificity check when the biological conclusion depends on a surprising distribution (standard IHC practice).
Boster reagents
Best FCGR2A / Low affinity immunoglobulin gamma Fc region receptor II-a IHC Antibodies
A01450-1 has IHC images from human lung cancer, mammary cancer and placenta sections, and mouse spleen sections (catalog IHC captions). The catalog lists rat reactivity without a rat IHC image (catalog reactivity; catalog IHC captions).
Real IHC data
Anti-FCGR2A Antibody ®
Cat # A01450-1
A01450-1 is the SKU with a rendered IHC card; its figure shows a paraffin section of human lung cancer (A01450-1 figure caption). Its additional IHC captions show human mammary cancer and placenta sections and a mouse spleen section (A01450-1 IHC captions).
Which to pick: Choose A01450-1 for paraffin-section IHC: its caption documents citrate retrieval at pH 6 for 20 minutes and primary antibody at 1 µg/mL; the fixative is unreported (A01450-1 figure caption). No catalog SKU lists IF/ICC or provides an IF image, so neither has documented IF/ICC validation here (catalog applications and IF image fields). For cross-species work, A01450-1 lists human, mouse and rat reactivity, while M01450 lists human only; the A01450-1 IHC captions show human and mouse sections, with no rat IHC image (catalog reactivity; A01450-1 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P12318 (FCG2A_HUMAN, Low affinity immunoglobulin gamma Fc region receptor II-a).
- Human Protein Atlas. FCGR2A tissue IHC expression (reliability: Supported).
- Human Protein Atlas. FCGR2A subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the Golgi apparatus. Caution: Based on antibodies targeting proteins from multiple genes..
- Human Protein Atlas. FCGR2A antibody validation summary (3 antibodies).
- The macrophage colony-stimulating factor 1 response signature in breast carcinoma. Clinical cancer research : an official journal of the American Association for Cancer Research 2009 — PMC2987696.
- FCGR2A contributes to M2 macrophages polarization in HCC through IL-4/JAK/STAT6 axis. Translational oncology 2025 — PMC12177172.
- Analysis of stromal signatures in the tumor microenvironment of ductal carcinoma in situ. Breast cancer research and treatment 2010 — PMC2976659.
- Variations in stromal signatures in breast and colorectal cancer metastases. The Journal of pathology 2010 — PMC2935495.
- PubMed PMID:2824655 — UniProt-cited evidence.
- PubMed PMID:2529342 — UniProt-cited evidence.
- PubMed PMID:16710414 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FCGR2A (Low affinity immunoglobulin gamma Fc region receptor II-a). Expected localisation Cytoplasmic tissue signal; cell membrane protein (HPA tissue IHC; UniProt). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A01450-1). Validated IHC antibody: A01450-1 at 1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Endometrium (Ciliated epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A01450-1); 2. Fixation: Image fixative and duration unreported (datasheet A01450-1); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: Citrate pH 6 , 20 min (datasheet A01450-1); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01450-1); 8. Primary antibody: Rabbit anti-FCGR2A, 1μg/ml (datasheet A01450-1); 9. Primary incubation: Overnight at 4 °C (datasheet A01450-1). Watch for: Fixation: Keep fixation consistent across samples (standard IHC practice; not target-specific); Caveat: Staining may reflect proteins from more than one gene (HPA tissue IHC); Isoform / epitope: 2 isoforms; check extracellular versus cytoplasmic epitope (UniProt); Regulation: Immune-cell mix may shift tissue signal (HPA tissue IHC). Evidence: UniProt P12318, HPA tissue IHC · Supported, HPA ICC-IF · Mainly localized to the plasma membrane. In addition localized to…, Datasheet A01450-1, PMC2987696, PMC2976659. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FCGR2A/immunohistochemistry-ihc-guide.