The 16-kDa Hepatokine Nobody Taught You in Grad School: Why LECT2 Is the Missing Link Between Liver, Cartilage, and Tumor Immunity — And How ABP59109 Finally Gives You a Clean Polyclonal Read

If your lab works on NASH, hepatocellular carcinoma, or osteoarthritis, you've almost certainly seen LECT2 light up on a proteomics heatmap or an RNA-seq volcano — and then watched everyone politely ignore it because "it's only 16 kDa, it's secreted, and we don't have a good antibody." That's a mistake. LECT2 (Leukocyte Cell-Derived Chemotaxin 2, UniProt: O14960, Gene ID: 3945) is a ~38 kDa pre-prosecretory polypeptide whose mature, secreted form clocks in at ~15–17 kDa, circulates at surprisingly high levels for a cytokine-like mediator (low µg/mL range in human serum), and punches far above its molecular weight. It was originally cloned from THP-1 macrophages as a neutrophil chemoattractant, but it's since been reclassified as a multifunctional hepatokine/osteokine that binds DC-SIGN (CD209) on dendritic cells and macrophages, modulates M1/M2 polarization, disrupts collagen II networks in articular cartilage, and — most provocatively — acts as a context-dependent tumor suppressor or prometastatic factor in HCC depending on the microenvironment. The LECT2 Polyclonal Antibody (ABP59109) from Abbkine is the reagent that stops the "ignore it" strategy: a rabbit-derived, affinity-purified IgG validated for Western blot, IHC on paraffin (IHC-P), immunofluorescence (IF/ICC), and ELISA, so you can detect this slippery small-secreted protein where it lives — in conditioned media, serum/plasma, liver sections, and cartilage explants — without wondering if your 16 kDa band is a ghost.

LECT2 in One Paragraph: A Tiny Secreted Protein With Outsized Biological Gravity

LECT2 is synthesized with an N-terminal signal peptide (directing it into the ER) and undergoes proteolytic maturation to the mature 133-aa secretory product (15–17 kDa) that is acidic (pI ~5.0) and structurally folded around a highly conserved M23B peptidase-like domain (though it lacks the catalytic residues — it's a homolog, not an active protease). Its canonical receptor is CD209 (DC-SIGN / ICAM-3 receptor), a C-type lectin that triggers ERK1/2 and NF-κB signaling in target myeloid cells. But LECT2's biology sprawls:

Tissue/Context What LECT2 Does There

Liver (hepatocytes → circulation) Major production site; serum LECT2 rises in NASH, liver fibrosis, and HCC; proposed as both a diagnostic biomarker and a metabolic hepatokine linking dietary protein/fat intake to systemic inflammation

Cartilage / joint Binds collagen II, disrupts collagen network integrity, promotes MMP-13 expression, and is upregulated in osteoarthritis (OA) synovial fluid/cartilage — a compelling alternative to the "purely IL-1/TNF" OA narrative

Tumor microenvironment (HCC) Can suppress early HCC growth (anti-angiogenic, NK-cell supportive) but may also promote metastasis at late stages — context is everything

Immune polarization Through DC-SIGN, shifts DC/T-cell crosstalk; modulates M1→M2-like transitions in tumor-associated macrophages

Bone / osteoblasts Classified as an osteokine; influences osteoblast differentiation and mineralization

Why a Polyclonal — And Why LECT2 Is a Tricky Target for Any Antibody

Two things make LECT2 harder than your average cytokine:

1. It's small (~16 kDa mature) and acidic, which means it runs near the gel front where buffer artifacts and secondary bleed-through live — and it can smear if your sample prep leaves it partially aggregated or sticking to plastic/tube walls.
2. It's secreted, so the biologically relevant readout is often how much is in the medium, serum, or tissue ECM — not just whether the hepatocyte lane has a band.

A well-designed polyclonal earns its keep here because:
• Multi-epitope recognition (raised against a synthetic peptide from the mature LECT2 sequence) improves capture reliability across denatured (WB) and fixed (IHC/IF) formats, where a single monoclonal epitope can get masked.

• It gives you one reagent for WB (mature ~16 kDa), IHC-P (cytoplasmic/histiocytic pattern in liver/sinusoidal areas), and ELISA capture — important when you need to go from a tissue section to a plate-readout without switching antibody systems.

Product Profile: ABP59109 — LECT2 / Leukocyte Cell-Derived Chemotaxin 2 Polyclonal Antibody

Feature Detail (typical for Abbkine affinity-purified rabbit pAbs)

Target Human LECT2 (UniProt O14960, Gene ID 3945)

Host / Isotype Rabbit IgG, polyclonal, affinity-purified (peptide-specific)

Immunogen Synthetic peptide derived from human LECT2 (mature region)

MW (observed) ~15–17 kDa mature band (precursor ~38 kDa if you catch it before secretion)

Reactivity Human (cross-reactivity for mouse/rat should be verified on the datasheet — LECT2 is moderately conserved across mammals)

Applications WB (1:500–2,000), IHC-P (1:100–300, antigen retrieval recommended), IF/ICC (1:200–1,000), ELISA (1:10,000–20,000)

Format Liquid in PBS, pH 7.4, 50% glycerol, 0.5% BSA, 0.09% sodium azide

Storage -20°C (avoid freeze–thaw; aliquot working volumes)

(Confirm lot-specific recommended dilutions and any additional validated species/reactivities on the Abbkine page for ABP59109.)

Using ABP59109 Without Falling Into the Classic LECT2 Traps

1. Western Blot: The 16 kDa Band Needs Respect

• Run a 15–18% Tris-glycine gel (or a 4–12% Bis-Tris with good low-MW transfer) — LECT2 sits right near the dye front, so don't let it run off.

• Use PVDF (better low-kDa retention) and confirm transfer with a gentamicin/amphipathic marker if paranoid.

• Positive control: conditioned medium from THP-1 macrophages (PMA-differentiated, LPS-stimulated) or HepG2/Huh7 cells — you should see a crisp ~15–17 kDa band that concentrates in TCA-precipitated supernatant.

• Serum/plasma: LECT2 is a circulating hepatokine — if you blot serum directly, watch for albumin/transferrin front-region smear; a TCA precipitate or centrifugal filter concentrator (10 kDa cutoff) cleans the background beautifully.

2. IHC-P on FFPE (Liver, OA Cartilage, Tumor)

• LECT2 stains cytoplasmic / pericellular, often strongest in hepatocytes and sinusoidal-lining macrophages in liver sections.

• Use heat-induced antigen retrieval — pH 9.0 EDTA typically outperforms pH 6.0 citrate for the mature peptide epitopes.

• Negative control: secondary-only and, if possible, absorb the antibody with excess recombinant LECT2 to confirm specificity (or use an isotype control).

3. IF/ICC: Secreted Pool vs. Intracellular Store

• In cultured hepatocytes or THP-1-derived macrophages, LECT2 signal can be perinuclear/Golgi (ER export) and also visible in the extracellular space if fixed without washing away the medium too aggressively. A brief PFA fix while a thin medium film remains preserves the local secretory halo for IF.

Where Detecting LECT2 Actually Advances the Paper

1. NASH → Fibrosis → HCC Continuum

Liver is the dominant source of circulating LECT2, and serum/hepatic LECT2 levels correlate with fibrosis stage, ballooning, and inflammatory activity in multiple cohort studies. Using ABP59109, you can:
• Quantify intracellular LECT2 in liver lysates/homogenates (normalize to mg total protein, BCA)

• Do IHC scoring across NASH-model vs. control livers (zonal pattern — perivenular vs. pan-acinar — matters)

• Pair with α-SMA, COL1A1, F4/80, and CK7/CK19 panels for a complete portrait

2. Osteoarthritis & Cartilage Degradation

LECT2 is found in OA synovial fluid at elevated levels and localizes to damaged cartilage zones where it binds collagen II. An IHC/IF assay with ABP59109 lets you map LECT2 to surface fibrillation fronts and co-label with MMP-13, ADAMTS-5, and IL-1β/TNF — moving the story from "something is inflamed" to "this specific 16-kDa hepatokine/osteokine is eating the matrix."

3. Hepatocellular Carcinoma (Tumor vs. Adjacent)

The LECT2–CD209 axis can modulate DC maturation and NK-cell interactions in the TME. IHC on TMA (tissue microarray) with ABP59109 gives you a quick H-score or % positive readout across dozens of cases, correlatable to AFP, GPC3, Ki-67, CD34 MVD, and — crucially — patient outcome.

4. Metabolic Syndrome & Systemic Inflammation

As a hepatokine, circulating LECT2 is an emerging candidate biomarker (often discussed alongside FGF21, fetuin-A, and ANGPTL4) for insulin resistance and fatty liver. If you're doing diet-induced obesity (HFD), bariatric surgery, or GLP-1 agonist studies, tracking LECT2 in serial serum by sandwich ELISA (paired with this pAb as capture) or at minimum by pAb WB of concentrated serum gives you a metabolic-variable anchor.

5. CRISPR/AAV & Macrophage Polarization Models

Knocking LECT2 in/out in hepatocytes or THP-1 macrophages? Don't just say "mRNA went down." Show % LECT2 protein remaining ± SEM from a conditioned-medium TCA pellet or lysate, normalized to total protein — and link it to the functional readout (chemotaxis, DC-SIGN signaling, MMP-13 in co-culture).

Quick Lab Hygiene for a 16-kDa Secreted Protein

• Low-binding tubes for serum/supernatant concentration steps (lectins/proteins this small love plastic adsorption — you can lose 30%+ to the tube wall if you're sloppy).

• Protease inhibitors in collection buffers (LECT2 isn't a protease, but co-purifying proteases can clip it into confusing fragments that smear your 15–17 kDa band).

• Warm kit reagents to RT ≥ 30 min before opening; avoid freeze–thaw of the antibody stock (aliquot 10–20 µL if you run it often).

The Bottom Line

LECT2 is one of those proteins that sits at a bizarre but powerful intersection — a 16-kDa secreted hepatokine that binds a C-type lectin receptor, remodels cartilage, talks to macrophages and DCs, and shows up on NASH and HCC radars as both biomarker and effector. Measuring it properly means respecting its size, acidity, and secretory nature: not just "does the blot have a 16 kDa smear," but a clean, specific, reproducible detection you can take to a reviewer. The LECT2 Polyclonal Antibody (ABP59109) from Abbkine is built for that job — affinity-purified rabbit IgG, peptide-derived immunogen, validated for WB (15–17 kDa), IHC-P, IF/ICC, and ELISA, so your NASH, OA, or HCC story has a LECT2 readout that's actually defensible.

Product Reference: ABP59109 – LECT2 Polyclonal Antibody
Learn more and order: https://www.abbkine.com/product/lect2-polyclonal-antibody-abp59109/
(For Research Use Only; not for diagnostic procedures in humans.)