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C1QC / Complement C1q subcomponent subunit C · IHC design guide
Design Immunohistochemistry for C1QC
Plan paraffin-section C1QC IHC with catalog antibody A05666-1 at 1:100–1:300 (datasheet: IHC 1:100–1:300). Interpret mainly plasma positivity (HPA tissue IHC) alongside C1QC secretion and cell-surface association (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
C1QC 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 | Mainly plasma staining (HPA tissue IHC); secreted/cell surface (UniProt) | |
| Staining pattern | Mainly plasma; medium glandular and stromal staining (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Colon+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 sections (standard IHC practice; not target-specific) | |
| Caveat | Secretion can separate tissue RNA from protein staining (HPA tissue IHC) | |
| Regulation | Lymphoid tissue-enhanced RNA (HPA tissue RNA) | |
| Isoform / epitope | No annotated isoforms; mature chain starts at aa 29 (UniProt) |
Section 1
Recommended C1QC IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published C1QC IHC methods for colon tissue and vascular tissue (PMC9589315; PMC11880100).
| Sample | Paraffin-embedded human lung carcinoma tissue; fixative not specified (datasheet A05666-1) |
| Fixation | Image fixative and duration unreported (datasheet A05666-1); 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 citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane 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 anti-C1QC, 1:100 - 1:300 (datasheet A05666-1) |
| 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 | C1QC-positive staining in glandular cells of colon (HPA tissue IHC: Medium). HPA tissue profile: Mainly plasma positivity. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 HIER at 95–98 °C for 20 min (page antigen-retrieval rule); the colon study also reports citric-acid thermal retrieval (PMC9589315: methods).
Section 2
What Is the Expected C1QC Staining Pattern?
C1QC is secreted and can associate with antigen–antibody complexes on pathogen surfaces; it has no transmembrane segment (UniProt P02747 subcellular location; topology). In tissue sections, expect mainly plasma positivity, with medium staining reported in selected glandular cells and endometrial stromal cells (HPA: tissue IHC). Interpret cell-associated staining cautiously: HPA rates the tissue pattern Supported but reports low consistency between staining and RNA expression (HPA: reliability).
| Chromogen is mainly in plasma-associated spaces, with some staining along nearby tissue structures. | This fits the reported mainly plasma-positive pattern (HPA: tissue IHC) and the secreted location of C1QC (UniProt P02747 subcellular location). Location alone cannot identify the cell that produced the protein; HPA notes that RNA and protein locations can differ for a secreted variant (HPA: reliability description). |
| Medium staining appears in colon, fallopian tube, gallbladder, or prostate glandular cells, or in endometrial stromal cells. | These are reported positive cell and tissue combinations (HPA: tissue IHC). Assess each alongside its local plasma signal and a negative detection control (general IHC practice). Medium staining supports the reported pattern but does not, by itself, establish local C1QC synthesis (HPA: reliability description). |
| Strong, sharply nuclear staining dominates the section. | A dominant nuclear pattern conflicts with the secreted and cell-surface annotations (UniProt P02747 subcellular location). Treat it as suspect and check the negative detection control, counterstain, and antibody-specific staining pattern (general IHC practice). |
| Adipocytes or cardiomyocytes stain strongly, or caudate glial cells show a strong cell-body signal. | Those cell types were reported as not detected in the named tissues (HPA: tissue IHC). Consider cross-reactivity or endogenous detection activity, especially if the signal also appears in a negative detection control (general IHC practice). A result in one specimen is not proof of either cause. |
| Most structures acquire a uniform haze, or no signal appears in a section expected to be positive. | Diffuse haze makes the reported plasma-focused pattern difficult to judge (HPA: tissue IHC); inspect negative controls for background (general IHC practice). For absent signal, first verify the chosen positive tissue and cell type against the HPA record, then check the staining run (HPA: tissue IHC; general IHC practice). |
💡Expected C1QC appearanceCall the result consistent when plasma-associated staining predominates and any reported glandular or endometrial stromal signal is around medium intensity; dominant nuclear staining or strong signal in HPA-negative cell types is suspect (HPA: tissue IHC; UniProt P02747 subcellular location).
| Secretion and surface association | C1QC is annotated as secreted and cell-surface-associated, with no transmembrane segment (UniProt P02747 subcellular location; topology). Interpret extracellular signal as potentially meaningful, while avoiding an inference that the nearest stained cell produced it. |
| Protein processing | The annotated signal peptide spans residues 1–28 and the mature chain spans 29–245 (UniProt P02747 processing). An epitope in the signal peptide and one in the mature chain would warrant different interpretation; this payload does not locate either antibody's epitope. |
| Tissue pattern and confidence | HPA reports mainly plasma positivity and rates tissue IHC Supported, while noting low agreement with RNA expression for this secreted protein (HPA: tissue IHC; reliability). Use the tissue staining record to assess appearance, not RNA location as a strict map of protein. |
| Antibody validation | HPA lists HPA001471 and CAB009828 as IHC Supported; neither has an ICC status in the supplied antibody record (HPA: antibodies). Supported is the reported status here; the payload does not report IHC Enhanced for either antibody. |
| IF/ICC interpretation? | HPA lists C1QC as secreted but provides no main ICC-IF location or cell-line images in this record (HPA: subcellular ICC-IF). There is therefore no image-backed intracellular IF pattern to recommend here; consult the separate IF/ICC guide for that application. |
| Situation | Likely cause | Next action |
|---|---|---|
| No chromogen appears in the selected positive tissue. | The field may lack the reported positive compartment, or the IHC detection run may have failed (HPA: tissue IHC; general IHC practice). | Inspect plasma-containing areas and the named HPA-positive cell type in the same tissue; confirm that the run's positive detection control stained (HPA: tissue IHC; general IHC practice). If both are blank, check reagent preparation, incubation, and detection steps (general IHC practice). |
| The section is broadly brown, including regions expected to be unstained. | Background from detection chemistry or nonspecific antibody binding can obscure the mainly plasma-positive pattern (general IHC practice; HPA: tissue IHC). | Compare a negative detection control and review blocking, washing, antibody concentration, and chromogen development (general IHC practice). Score C1QC only after the compartment pattern is distinguishable (HPA: tissue IHC). |
| Strong staining appears in adipocytes, cardiomyocytes, or caudate glial cells. | These named cell types were not detected in HPA tissue IHC; cross-reactivity or endogenous detection activity is possible (HPA: tissue IHC; general IHC practice). | Verify cell identity on the counterstained section, inspect a negative detection control, and compare with the HPA-positive pattern before assigning the signal to C1QC (HPA: tissue IHC; general IHC practice). |
| Only glandular or stromal cells stain, with little evident plasma signal. | Medium glandular and endometrial stromal staining is reported, but HPA describes the overall pattern as mainly plasma-positive (HPA: tissue IHC). | Review nearby plasma-containing areas and a matching HPA tissue entry. Record the cell type and compartment separately; do not infer local synthesis from cell staining alone because protein and RNA locations may differ (HPA: tissue IHC; reliability description). |
| A bright nuclear pattern is the principal finding. | Nuclear localisation is unsupported by the supplied secreted and cell-surface annotations (UniProt P02747 subcellular location). | Check whether the counterstain was mistaken for chromogen, then compare negative detection controls and the expected plasma-associated distribution (general IHC practice; HPA: tissue IHC). |
| An IF/ICC image shows puncta or an intracellular pattern that seems inconsistent with IHC. | The supplied HPA ICC-IF record has no main location or cell-line images for C1QC; IHC tissue distribution cannot establish an intracellular IF pattern (HPA: subcellular ICC-IF; tissue IHC). | Describe the observed IF compartments without assigning a validated C1QC location from this record; use the separate IF/ICC guide for application-specific evaluation (HPA: subcellular ICC-IF). |
Experiment evidence
IHC & IF images showing C1QC staining
A05666-1 · IHCImmunohistochemistry analysis of paraffin-embedded human lung carcinoma tissue, using C1QC Antibody. The picture on the right is blocked wit
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000159189-C1QC/tissue/cerebral+cortex#imid_531010
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000159189-C1QC/tissue/colon#imid_530936
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000159189-C1QC/tissue/liver#imid_530929
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000159189-C1QC/tissue/kidney#imid_530930
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for C1QC IHC & IF
🧪Run colon first: glandular cells should stain (HPA: Colon glandular cells, Medium). Use cervix glandular cells as the negative comparator (HPA: Cervix glandular cells, Not detected); on the colon slide, assess adjacent non-glandular cells for background without assuming they are C1QC-negative (HPA: only glandular cells listed for Colon).
Positive control tissue: Colon (Glandular cells, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for C1QC; derive a cell-line control from the positive tissue's cell type (Glandular cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary (secondary-only) control and a host- and clonality-matched isotype control; use C1QC knockout material if available, or peptide blocking as shown for the selected catalog antibody (selected SKU tissue-IHC caption: peptide-blocked image). For chromogenic detection, quench endogenous peroxidase and check for endogenous biotin if using avidin–biotin detection (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and retrieval requirement are unreported in the supplied evidence; optimize retrieval empirically (selected SKU tissue-IHC caption: paraffin-embedded tissue, with retrieval and fixative unstated). The caption does not establish fixation, and the evidence does not establish whether frozen sections or IF would be easier (selected SKU tissue-IHC caption: fixative unreported; HPA: no ICC-IF image cell lines). Because C1QC is secreted and can associate with cell surfaces, extracellular staining may complicate attribution to colon glandular cells (UniProt P02747: secreted; cell surface). The selected A05666-1 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image A05666-1).
HPA tissue IHC evidence for C1QC
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Low consistency between antibody staining and RNA expression data. At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). 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 |
|---|---|---|---|---|
| Colon | Glandular cells | Medium | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | Medium | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | Medium | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | Medium | Protein (IHC) | HPA → |
| Prostate | Glandular cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced C1QC IHC Tips
Troubleshoot C1QC staining by checking retrieval, compartment, controls and scoring in paraffin section chromogenic IHC; use the IF guidance for multiplex experiments.
How should I retrieve C1QC in paraffin sections when staining is weak?
Start with citrate buffer at pH 6.0 for heat-induced retrieval at 95–98 °C for 20 minutes (page retrieval setting). Let sections cool in retrieval buffer for about 20 minutes, then wash in PBS before blocking; keep cooling and washing consistent across slides (standard IHC practice). If staining remains weak, compare a slightly longer retrieval time on adjacent sections while retaining the stated citrate buffer and pH, because over-retrieval can damage tissue morphology (standard IHC practice). Include the catalog antibody’s peptide-blocked comparison and a no-primary control when judging whether added staining is specific (catalog caption A05666-1; standard IHC practice).
Could fixation explain weak or uneven C1QC staining?
Target-specific C1QC sensitivity to fixation is unknown from the supplied evidence, and the catalog’s paraffin-section caption does not report a fixative (catalog caption A05666-1). For new specimens, document fixative, fixation duration and section thickness, then process matched sections together so a staining difference can be traced to a controlled variable (standard IHC practice). If fixation varies across samples, first compare morphology and a validated control stain before changing the C1QC antibody conditions (standard IHC practice). Test any fixation adjustment on matched material with identical pH 6.0 citrate retrieval and detection settings; do not infer a C1QC-specific fixation effect from tissue staining patterns (page retrieval setting; standard IHC practice).
Where should a convincing C1QC signal appear in chromogenic IHC?
Assess C1QC as a secreted protein that can associate with cell surfaces, rather than expecting a transmembrane staining pattern (UniProt P02747 subcellular location and topology). Its C1q complex can bind antigen-associated IgG or IgM, so extracellular or surface-associated chromogen may reflect deposited protein rather than synthesis by the adjacent cell (UniProt P02747 function). Compare signal with tissue architecture and the matching peptide-blocked image; loss of staining after peptide competition supports antibody-dependent staining but does not identify its source (catalog caption A05666-1; standard IHC interpretation). Score intracellular, surface-associated and extracellular deposits separately where morphology permits, and check suspicious nuclear-only staining against a no-primary control (standard IHC practice).
How do processing and epitope location affect C1QC IHC interpretation?
C1QC has a 1–28 signal peptide and a 29–245 mature chain, with collagen-like and C1q regions at 31–112 and 115–245, respectively (UniProt P02747 processing and domains). The supplied record lists 0 isoforms, a glycosylation site at residue 75 and hydroxylated residues in the collagen-like region (UniProt P02747 isoforms and modifications). The catalog caption reports peptide blocking but does not disclose an epitope sequence, so do not assign a staining pattern to one domain or modification (catalog caption A05666-1). When troubleshooting, compare matched sections under the same pH 6.0 retrieval conditions and treat peptide competition as a specificity check, not epitope mapping (page retrieval setting; standard IHC practice).
How can IF help identify the source of C1QC staining?
For a separate IF experiment, multiplex C1QC with a validated macrophage marker such as CD68 to test whether signal overlaps a plausible producing cell population (standard IF practice). Distinguish overlap within cells from adjacent extracellular deposits, since C1QC is secreted and can bind cell surfaces (UniProt P02747 subcellular location; standard IF interpretation). Select fluorophores after examining unstained tissue autofluorescence, reserving a brighter, spectrally separated channel for weaker signal and including single-stain controls (standard IF practice). If probing an intracellular epitope, compare mild detergent permeabilisation with an unpermeabilised section; for a surface-accessible epitope, start without detergent, since the catalog caption does not identify the antibody’s epitope (standard IF practice; catalog caption A05666-1).
What controls help distinguish C1QC staining from chromogenic background?
Run a no-primary control through the same peroxidase detection and DAB steps to reveal reagent-dependent background (standard IHC practice). Use a peroxide block, for example 3% hydrogen peroxide for 10 minutes, as a general chromogenic workflow step, then wash thoroughly before antibody incubation (standard IHC practice). Check whether staining concentrates at section edges, folds, necrotic areas or incompletely washed regions, and compare those features with intact tissue on the same slide (standard IHC practice). The catalog’s peptide-blocked paraffin-section image offers an antibody competition comparison, but reduction after blocking cannot by itself establish which cells produced this secreted protein (catalog caption A05666-1; UniProt P02747 subcellular location).
How should I score C1QC when deposits and cells both stain? ⚠ ANSWER MARKED FOR VERIFICATION
Define separate regions for cellular staining and extracellular deposits before scoring, because C1QC is secreted and can associate with cell surfaces (UniProt P02747 subcellular location; standard IHC quantification). For cellular staining, report percentage of positive cells and intensity, or calculate an H-score from 0 to 300 using intensity categories 0–3 (standard IHC quantification). For deposits, measure positive area per mm² of evaluable tissue rather than assigning deposits to nearby cells (standard IHC quantification). Normalise cell counts to the relevant counted cell population and deposit area to intact tissue area, applying the same threshold to stained and control sections (standard IHC quantification).
When is a strong C1QC signal likely to be artefactual?
Treat nuclear-only signal cautiously because the supplied localisation places C1QC outside cells and at cell surfaces, with no transmembrane segment (UniProt P02747 subcellular location and topology). Do not equate a stained cell’s position with C1QC production: secreted C1QC can be present near cells that did not synthesize it (UniProt P02747 subcellular location; standard IHC interpretation). Compare intact central tissue with section edges and necrotic zones, and inspect no-primary slides for endogenous peroxidase or detection background (standard IHC practice). Weigh peptide-blocked staining alongside morphology and controls; HPA reports mainly plasma positivity and limited RNA–protein consistency, so staining alone does not establish the source of C1QC (catalog caption A05666-1; HPA tissue IHC).
Boster reagents
Best C1QC / Complement C1q subcomponent subunit C IHC Antibodies
A05666-1 has a C1QC IHC image from a human lung carcinoma paraffin section (catalog image caption); the catalog lists IHC and IF applications and Human, Mouse and Rat reactivity (catalog applications and reactivity).
Real IHC data
Anti-C1QC/Complement Component C1Qc Antibody
Cat # A05666-1
A05666-1 has a peptide-blocked IHC comparison in paraffin-embedded human lung carcinoma tissue (catalog image caption). The catalog lists IHC, IF and ICC applications and Human, Mouse and Rat reactivity for A05666-1; no IF image is supplied (catalog applications, reactivity and image listings).
Which to pick: Choose A05666-1 for tissue IHC: its own image shows staining of a paraffin-embedded human lung carcinoma section with a peptide-blocked comparison; the fixative is unreported (catalog image caption). For IF/ICC, A05666-1 is catalog-listed for both applications at 1:50 for IF, but no IF image is supplied (catalog applications, IF dilution and image listings). For work across species, A05666-1 is the listed rabbit polyclonal with Human, Mouse and Rat reactivity; the supplied IHC image shows human tissue only (catalog host, dilution_raw, reactivity and image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P02747 (C1QC_HUMAN, Complement C1q subcomponent subunit C).
- Human Protein Atlas. C1QC tissue IHC expression (reliability: Supported).
- Human Protein Atlas. C1QC subcellular location (ICC-IF): Secreted.
- Human Protein Atlas. C1QC antibody validation summary (2 antibodies).
- Complement C1QC as a potential prognostic marker and therapeutic target in colon carcinoma based on single-cell RNA sequencing and immunohistochemical analysis. Bosnian journal of basic medical sciences 2022 — PMC9589315.
- Identification of hub genes in the crosstalk between type 2 diabetic nephropathy and obesity according to bioinformatics analysis. Adipocyte 2024 — PMC11556279.
- Identification of novel biomarkers for atherosclerosis using single-cell RNA sequencing and machine learning. Mammalian genome : official journal of the International Mammalian Genome Society 2025 — PMC11880100.
- High complement protein C1q levels in pulmonary fibrosis and non-small cell lung cancer associated with poor prognosis. BMC cancer 2022 — PMC8790889.
- PubMed PMID:1706597 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:16710414 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for C1QC (Complement C1q subcomponent subunit C). Expected localisation Mainly plasma staining (HPA tissue IHC); secreted/cell surface (UniProt). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A05666-1 at 1:100 - 1:300 (the product's own IHC validation image is shown). Controls (HPA): positive Colon (Glandular cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung carcinoma tissue; fixative not specified (datasheet A05666-1); 2. Fixation: Image fixative and duration unreported (datasheet A05666-1); 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-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-C1QC, 1:100 - 1:300 (datasheet A05666-1); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Secretion can separate tissue RNA from protein staining (HPA tissue IHC); Isoform / epitope: No annotated isoforms; mature chain starts at aa 29 (UniProt); Regulation: Lymphoid tissue-enhanced RNA (HPA tissue RNA). Evidence: UniProt P02747, HPA tissue IHC · Supported, HPA ICC-IF · Secreted, Datasheet A05666-1, PMC9589315, PMC11880100. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/C1QC/immunohistochemistry-ihc-guide.