Human Isotype Controls

• SEO Title Tag (≤60 chars):Human Isotype Control Antibodies (IgG1, IgG4, Fc-Silent) | ichor.bio
• Meta Description (≤155 chars): Research-grade human isotype controls — IgG1–4, Fc-silent (LALA, LALAPG, N297A, S228P), ADCs & Fab formats. Low-endotoxin, bulk mg to g supply.
• Target Keyword Strategy: Human isotype control, Fc-silent isotype control, LALA isotype control, LALAPG control, aglycosylated N297A isotype control, IgG4 S228P isotype control, ADC isotype control.
• H1 Heading:Human Isotype Control Antibodies

Isotype controls establish the baseline reference for antibody experiments — matching your primary target antibody’s host species, immunoglobulin subclass, and Fc architecture to distinguish specific target binding from Fc-receptor (FcγR) binding, complement activation, or non-specific matrix interactions.

ichor.bio supplies one of the industry's deepest selections of recombinant human isotype controls. Our portfolio encompasses wild-type IgG1, IgG2, IgG3, and IgG4 subclasses, monovalent Fab fragments, Fc-only regions, VHH single-domain antibodies, and payload-conjugated ADC controls. Crucially, we offer an extensive suite of Fc-engineered variants — including effector-silent backbones (LALA, LALAPG, N297A, D265A), hinge-stabilized IgG4 formats (S228P, SPLE, SPLEPG), bispecific heterodimerization pairs (DuoBody® F405L/K409R), and Fc-enhanced variants (SDIE). All antibodies are recombinantly produced, low-endotoxin or ultra-low-endotoxin (<1.0 EU/mg or <0.01 EU/mg), carrier-free, and available in scalable milligram-to-gram quantities for in vitro, ex vivo, and in vivo research.

●        Modifications: None (Native human IgG1 constant region sequence).

●        Why Created:Serves as the gold-standard negative control for native human IgG1 therapeutic antibodies. Retains high-affinity binding to FcγRI (CD64), moderate binding to FcγRII (CD32) and   FcγRIII (CD16), C1q binding for complement-dependent cytotoxicity (CDC), and FcRn binding for normal IgG half-life.

●        Therapeutic mAbs with this Backbone:Rituximab, Trastuzumab, Cetuximab, Adalimumab, Infliximab, Elotuzumab, Daratumumab.

●        Modifications:None (Native human IgG2 constant region sequence).

●        Why Created: Human IgG2 naturally exhibits minimal binding to FcγR receptors (except FcγRIIa H131 variant) and weak C1q activation. Created to match therapeutic antibodies designed to   neutralize soluble ligands or receptors without inducing host immune destruction.

●        Therapeutic mAbs with this Backbone:Denosumab (Prolia/Xgeva), Panitumumab (Vectibix), Evolocumab (Repatha).

●        Modifications: None (Native human IgG3 constant region sequence with extended hinge).

●        Why Created: Human IgG3 possesses an extended polyproline hinge region delivering superior flexibility, making it the most potent activator of complement (CDC) and   FcγR-mediated effector functions among human subclasses. Used to control for high-potency effector studies.

●        Modifications: None (Unmodified native human IgG4 constant region).

●        Why Created: Wild-type IgG4 possesses reduced FcγR engagement and minimal C1q activation. However, wild-type IgG4 undergoes dynamic intra-chain disulphide        reduction leading to in vivo Fab-arm exchange (swapping heavy-light chain dimers with endogenous circulating IgG4). Serves as an unmutated control for structural comparisons.

●        Modifications: Leucine-to-Alanine substitutions at positions 234 and 235 in the CH2 domain ($\text{Leu234Ala} / \text{Leu235Ala}$).

●        Why Created: Disruption of the lower hinge region severely impairs binding to FcγRI, FcγRIIa, FcγRIIIa, and C1q, silencing Antibody-Dependent Cellular Cytotoxicity (ADCC) and Complement-Dependent Cytotoxicity (CDC) while maintaining FcRn recycling and serum half-life.

●        Therapeutic mAbs with LALA: Durvalumab (Imfinzi), Teplizumab (Tzield), Faricimab (Vabysmo), Guselkumab (Tremfya).

●        Modifications: Triple mutation combining LALA with Proline-to-Glycine substitution at position 329 ($\text{Leu234Ala} / \text{Leu235Ala} / \text{Pro329Gly}$).

●        Why Created: While LALA significantly attenuates FcγR interaction, residual binding to FcγRIIa/IIIa can persist. Pro329 disrupts the proline sandwich required for FcγR binding, delivering near-complete ("ultra-silent") abolishment of FcγR engagement and complement C1q binding. Ideal for T-cell bispecific engagers.

●        Therapeutic mAbs with LALAPG: Glofitamab (Columvi), Mosunetuzumab (Lunsumio), Cevostamab, Cibisatamab.

●        Modifications: Mutation of the conserved N-linked glycosylation site at Asparagine-297 ($\text{Asn297Ala}$, $\text{Asn297Gln}$, or $\text{Asn297Ser}$).

●        Why Created: N-linked glycans attached at Asn297 maintain the structural open conformation of the CH2 domains. Mutating Asn297 completely eliminates glycan attachment, collapsing the Fc cavity and preventing binding to all FcγRs and C1q without altering the primary protein backbone outside of position 297.

●        Therapeutic mAbs with N297 Mutations: Atezolizumab (Tecentriq — N297A), Otelixizumab.

●        Modifications: Aspartate-to-Alanine substitution at position 265 ($\text{Asp265Ala}$), single or combined with $\text{Asn297Ala}$.

●        Why Created: Asp265 forms key contact points with FcγR receptor chains. Mutating Asp265 to Ala abolishes FcγR and C1q binding. Combining D265A with N297A provides dual-layered structural and aglycosylated effector silencing.

●        Modifications: Glutamate-233 to Alanine and Leucine-235 to Alanine ($\text{Glu233Ala} / \text{Leu235Ala}$).

●        Why Created: Designed to eliminate FcγRI binding and reduce FcγRII/III engagement in lower-hinge engineered constructs.

●        Modifications: Quadruple mutation combining lysine replacement with Leu234Phe, Leu235Glu, and Pro331Ser.

●        Why Created: Engineered lower-hinge and CH2 mutations designed to silence effector mechanisms while optimizing biophysical stability and reducing potential immunogenicity in humanized therapeutics.

●        Modifications: Serine-to-Proline point mutation at position 228 in the core hinge region ($\text{Ser228Pro}$, changing sequence from CPSC to CPPC).

●        Why Created: Wild-type IgG4 hinge inter-heavy chain disulphide bonds are in equilibrium with intra-chain bonds, allowing Fab-arm exchange in vivo. S228P stabilizes the inter-chain disulphide bonds, preventing Fab-arm exchange and locking the molecule into a stable, bivalent structure.

●        Therapeutic mAbs with IgG4 S228P: Pembrolizumab (Keytruda), Nivolumab (Opdivo), Cemiplimab (Libtayo), Dostarlimab (Jemperli), Dupilumab (Dupixent).

●        Modifications: Hinge-stabilizing S228P combined with Leucine-235-to-Glutamate substitution ($\text{Ser228Pro} / \text{Leu235Glu}$).

●        Why Created: Native IgG4 retains residual affinity for FcγRI. The L235E mutation eliminates residual FcγRI binding, creating a stable, effector-silent IgG4 backbone.

●        Therapeutic mAbs with SPLE: Tislelizumab (BGB-A317), Toripalimab (Loqtzi).

●        Modifications: Triple mutation combining hinge stabilization (S228P), FcγRI elimination (L235E), and Pro329Gly FcγR sandwich disruption.

●        Why Created: Provides ultra-silent IgG4 background activity, preventing both Fab-arm exchange and any interaction with FcγRI, FcγRII, or FcγRIII on macrophages or myeloid cells.

●        Modifications: S228P core hinge stabilization combined with Phenylalanine-234 to Alanine and Leucine-235 to Alanine ($\text{Phe234Ala} / \text{Leu235Ala}$).

●        Why Created: Applies the FALA silencing mechanism to stabilized IgG4, abolishing residual low-affinity FcγR interactions.

●        Modifications: Serine-239 to Aspartate, Ile332 to Glutamate ($\pm \text{Ala330Leu}$).

●        Why Created: Fc Enhancement. These mutations selectively increase binding affinity to FcγRIIIa (CD16a) on natural killer (NK) cells and macrophages by up to 100-fold, dramatically boosting ADCC and ADCP potency.

●        Therapeutic mAbs with SDIE: Margetuximab (Margenza), Inebilizumab (Uplizna).

●        Modifications: Proline-331 to Serine and Glutamate-430 to Glycine.

●        Why Created: E430G enhances cell-surface antibody hexamerization upon target antigen binding. This ordered hexamer formation provides an ideal platform for high-avidity C1q binding, driving massive complement activation (CDC).

●        Therapeutic Platform: HexaBody® platform constructs.

●        Modifications: Point mutations in the CH3 domain ($\text{Phe405Leu}$ or $\text{Lys409Arg}$).

●        Why Created: Enables controlled Fab-arm exchange (cFAE) in vitro. Combining an F405L homodimer with a K409R homodimer under mild reducing conditions yields a bispecific heterodimer with >95% efficiency (DuoBody® technology).

●        Therapeutic mAbs: Amivantamab (Rybrevant), Epcoritamab (Epkinly), Talquetamab (Talvey), Teclistamab (Tecvayli).

●        Modifications: Glutamate-356 to Aspartate and Methionine-358 to Leucine ($\text{Glu356Asp} / \text{Met358Leu}$).

●        Why Created: Reverts the isoallotype sequence to match specific human IgG1 allotypes (e.g., G1m1 / G1m3 non-markers), eliminating potential immunogenicity when testing patient-matched or allotype-specific therapeutics.

●        Modifications: Lysine-447 to Alanine substitution ($\text{Lys447Ala}$) or C-terminal lysine truncation.

●        Why Created: Native recombinantly expressed IgG heavy chains undergo variable enzymatic cleavage of C-terminal lysine by host carboxypeptidases, leading to charge heterogeneity. K447A eliminates charge variants, resulting in a highly uniform charge profile across manufacturing lots.

●        Modifications: Enzymatic or recombinant removal of the entire Fc domain (retaining VH-CH1 and VL-CL).

●        Why Created: Serves as a strictly monovalent antigen-binding control. Completely eliminates FcγR engagement, complement activation, and FcRn binding, isolating background signal caused solely by non-specific variable region (V-domain) interactions.

●        Modifications: Recombinant expression of the hinge-CH2-CH3 domains without Fab regions.

●        Why Created: Serves as a control for Fc-receptor interactions, FcRn transport, or Fc-fusion proteins (e.g., Etanercept, Aflibercept) in the absence of antigen-binding domains.

●        Formats:

○        Human IgG1 - Deruxtecan (DAR4 & DAR8)

○        Human IgG1 - MMAE / VcMMAE (DAR4)

○        Human IgG1 LALAPG - Deruxtecan / MMAE (DAR4 & DAR8)

●        Why Created: ADCs present distinct background mechanisms including payload internalization, non-specific cell uptake via pinocytosis, bystander killing, and payload cleavage. Non-targeting ADC isotype controls conjugated at specified Drug-to-Antibody Ratios (DAR4 or DAR8) isolate true target-mediated ADC cytotoxicity from non-specific payload exposure.

●        Therapeutic ADCs Matched: Enhertu (Trastuzumab deruxtecan — DAR8), Adcetris (Brentuximab vedotin — MMAE DAR4), Polivy (Polatuzumab vedotin), Padcev (Enfortumab vedotin).

●        Modifications: Camelid single-domain antibody (nanobody) variable domain attached to Human IgG1 Fc or a Polyhistidine tag.

●        Why Created: Controls for heavy-chain-only nanobody therapeutics and diagnostics, matching physical footprint, target accessibility, and human Fc effector functionality.

●        Therapeutic Examples: Caplacizumab (Cablivi), Envafolimab.