Haptoglobin (HPT/HP) ELISA Kit — Research-Use-Only Quantification of Haptoglobin in Serum, Plasma, and Other Validated Matrices

Overview

The Haptoglobin (HPT/HP) ELISA Kit provides a calibrated, plate-based immunoassay to quantify haptoglobin—a hemoglobin-binding plasma glycoprotein encoded by the HP gene—in human research samples. Haptoglobin’s biochemical role in hemoglobin scavenging and iron conservation is well documented across authoritative sources such as NCBI Gene and NLM (NCBI Gene: HP, NLM MeSH). Biochemical background on globin–heme interactions and plasma transport can be found through NIH and NIDDK resources (NIH, NIDDK—NIH). For foundational immunoassay principles, see NCBI Bookshelf and university method guides (NCBI Bookshelf—Immunoassays, UCSF IT—Research Guides, U-Michigan Research Guides).

Analyte Biology & Rationale (HP/HPT)

Haptoglobin is a liver-expressed glycoprotein that complexes with free hemoglobin to reduce oxidative damage and facilitate clearance via the CD163 pathway (general macrophage scavenger literature: NLM, NIH OER). Background on protein glycosylation and plasma proteomics can be referenced from NCBI and university proteomics portals (NCBI Protein, UT Austin—Proteomics, UW Madison Biochemistry). Gene–protein resources are consolidated at Genome.gov and NLM (Genome.gov, NLM—Chemistry Resources).

Assay Principle (Sandwich ELISA)

This sandwich ELISA employs:

1. Capture antibody pre-coated on a 96-well microplate.

2. Haptoglobin standards and diluted samples are incubated to allow antigen binding.

3. Biotinylated detection antibody binds captured HP, followed by streptavidin-HRP.

4. TMB substrate is added; HRP converts TMB to a measurable chromophore.

5. Stop solution yields a stable end-point read at 450 nm with 570–630 nm reference.

General ELISA chemistry references: NIH ODS Lab Methods, NCBI Bookshelf—Assay Design, UCSF Core Facilities.

Kit Components (Typical)

• Pre-coated 96-well plate (anti-HP capture)

• HP calibrator/standards (lyophilized or liquid) traceable to internal reference

• Detection antibody (biotin-conjugated)

• Streptavidin-HRP concentrate

• Sample diluent, wash buffer (10×/20×), substrate (TMB), stop solution

• Seals, plate layout template, IFU

For laboratory quality and method validation frameworks: NIST—Metrology Basics, NIH Reproducibility, ORIGINAL NIH Training.

Recommended Sample Types & Pre-Analytics

Validated matrices (typical RUO): human serum, EDTA/citrate/heparin plasma; other matrices require user validation.
Key pre-analytical controls:

• Follow institutional biosafety practices (CDC Biosafety).

• Standardize venipuncture and processing; minimize hemolysis (see general lab handling: NIH OER).

• Aliquot to avoid freeze-thaw cycles; store per IFU.

• Use polypropylene tubes and low-bind plastics for protein work (general lab guides: MIT OpenCourseWare—Labs, Columbia Research Support).

Calibration Curve & Reportable Range

• Prepare a 7–8 point standard curve (e.g., 0 to high ng/mL or μg/mL range per kit IFU) using serial dilutions.

• Fit data with 4-PL or 5-PL regression (absorbance vs. concentration).

• Verify back-calculated standards and include low/high QC controls each run.

• For statistical modeling and curve-fitting theory: NIST/SEMATECH e-Handbook, UCLA IDRE Stats.

Assay Performance (Typical RUO Expectations)

• Sensitivity / LOD/LOQ: Determined by blank distribution and low-level standard precision (see NIST).

• Precision: intra-assay and inter-assay %CV from replicate QC pools.

• Linearity/Recovery: evaluate serial dilutions in matrix, spike-and-recovery for epitope accessibility.

• Specificity: minimal cross-reactivity to homologous proteins tested (document per IFU).

• Hook effect: assess high-dose samples; re-test at higher dilution when indicated.

Quality-system concepts for university labs: Stanford EH&S, Yale EHS.

Interferences & Matrix Effects

• Hemolysis can introduce free hemoglobin, potentially affecting antigen–antibody interactions; standardize draw/processing (CDC Lab Resources).

• Lipemia, icterus, and biotin at supraphysiologic levels may influence optical density or binding; confirm with spike-recovery and dilutional linearity.

• Use manufacturer-recommended sample diluents and dilution factors; consult institutional method development guidelines (U-Penn Research Integrity).

Step-by-Step Workflow (Abbreviated)

1. Bring all reagents to room temperature; prepare standards/QC.

2. Load standards, controls, samples (in recommended duplicates).

3. Incubate per IFU; avoid edge effects using plate sealing and consistent timing.

4. Wash thoroughly (≥ 3–5×); verify washer performance (see NIST).

5. Add detection reagents, incubate, wash, then TMB and stop.

6. Read at 450 nm with reference filter; export data to validated analysis template.

7. Review QC rules (e.g., Westgard-style logic adapted for research) and re-run if out-of-control.

For general bench best practices, see Harvard EHS and NIH Training.

Data Analysis & Acceptance

• Apply 4-PL/5-PL model and inspect residuals.

• Confirm R², AIC/BIC if available, and back-calculation within acceptance limits.

• Flag samples outside reportable range; re-test at suitable dilutions.

• Archive raw data with SOP versioning and lot traceability (ORI—Research Integrity).

Troubleshooting (Common Research Scenarios)

• Low signal: insufficient incubation, degraded HRP, incorrect substrate; verify storage/expiry (NLM—Shelf Life/Storage).

• High background: incomplete washing, contaminated buffers; validate washer performance (UCSF Cores).

• Poor precision: pipetting variability—calibrate pipettes regularly (NIST Weights & Measures).

Storage & Stability

• Store components as indicated (commonly 2–8 °C for liquids; −20 °C for lyophilized).

• Avoid repeated freeze–thaw; prepare aliquots.

• Record lot, receive date, open date, and expiry in lab LIMS (NIH Data Management).

Compliance, Safety, and RUO Use

• Follow institutional biosafety policies and PPE requirements (CDC Biosafety, Yale EHS).

• RUO only: performance characteristics established for research; not validated for diagnostic use (FDA—RUO Guidance Overview).

Suggested Keywords & On-Page SEO (Non-YMYL, Research-Focused)

• Primary: Haptoglobin ELISA Kit, HP ELISA, HPT ELISA, Haptoglobin quantification, Sandwich ELISA for haptoglobin

• Secondary: research use only immunoassay, plasma protein ELISA, hemoglobin-binding protein assay, colorimetric 450 nm ELISA, 4-PL standard curve

• Support: RUO haptoglobin standard, ELISA sensitivity LOD LOQ, spike-recovery, dilutional linearity, intra-assay %CV

Internal-link ideas (replace with your URLs):

• “ELISA buffers & diluents” category page

• “Microplate readers (450 nm)” category page

• “Pipettes & tips” category page

• “Protein standards & controls” category page