C4d Antibody

Overview

This antibody is specific to Complement 4d (C4d) and it reacts with the secreted as well as cell-bound protein. C4d is a degradation product of the activated complement factor C4b. Complement 4b is typically activated by binding of antibodies to specific target molecules. Following activation and degradation of the C4 molecule, thio-ester groups are exposed, which allow transient, covalent binding of the degradation product C4d to endothelial cell surfaces and extracellular matrix components of vascular basement membranes near the sites of C4 activation. The presence of C4d in peritubular capillaries is a key indicator for acute humoral (i.e. antibody-mediated) rejection of kidney, heart, pancreas and lung allografts. As an established marker of antibody-mediated acute renal allograft rejection and its proclivity for endothelium, this component can be detected in peritubular capillaries in chronic renal allograft rejection as well as hyperacute rejection, acute vascular rejection, acute cellular rejection, and borderline rejection. C4d has been shown to be a significant predictor of transplant kidney graft survival. C4d antibody, combined with antibody to C3d, can be utilized as a tool for diagnosis of allograft rejection that may warrant a prompt and aggressive anti-rejection treatment.

This anti-C4d antibody is supplied as CF488 Conjugate (Mouse, Monoclonal (mouse origin), clone C4D204, Mouse IgG1, kappa, Unconjugated) and is designed to support common target-detection workflows after the on-page specifications.

Key elements and design rationale

• Target: C4d
• Format: CF488 Conjugate
• Localization: Intracytoplasmic vacuoles of endothelial cells; Secreted
• Species reactivity: Human
• Applications (listed): IHC-P
• Conjugate: Unconjugated
• Clone and antibody class: Monoclonal (mouse origin), clone C4D204, Mouse IgG1, kappa

Because antibody performance can depend on epitope context, sample preparation, and biological state, interpret signals using appropriate controls and orthogonal evidence when possible.

Biological background

C4d is referenced in public gene/protein resources (e.g., UniProt and NCBI Gene), which provide curated names/synonyms, protein features, and pathway context. When designing assays, consider potential isoforms, post-translational modifications, and cell-type specific expression that may influence observed signal.

Research relevance and current trends

• Profiling C4d expression across model systems, perturbations, and time points to support mechanistic hypotheses.
• Combining antibody-based detection with multi-omics or imaging readouts to link C4d signal with phenotype.
• Using well-matched controls (isotype controls, genetic perturbations, or independent reagents) to strengthen interpretation of target-associated signal.

Common research applications

• IHC-P

Use the listed applications as a starting point and tailor experimental design to your sample type and readout requirements.

Notes for experimental interpretation

• Specificity considerations: closely related family members, isoforms, or PTMs can affect apparent specificity; confirm with independent approaches when critical.
• Controls: include negative controls and, when feasible, genetic or pharmacologic perturbations to support target attribution in your system.
• Species and sample context: differences in sequence, expression, fixation, or extraction conditions can change signal behavior across models.

Customization & Add-ons: Can’t find the antibody you need—or require a custom format for your assay? We can help you source the best match or support custom antibody solutions for diverse research needs, including species and isotype selection, conjugations and labeling (e.g., HRP/AP, biotin, fluorophores), purification grade options (Protein A/G, affinity purified), formulation preferences (buffer selection, carrier-free, glycerol-free), custom concentrations and aliquoting, low-endotoxin options for cell-based work, and application-focused QC/validation support (project dependent). Click Talk to a Scientist to submit a request, email us at support@biohippo.com, or explore our Research Services for additional support—our team will follow up with feasibility details and next steps.