Isotype Controls

Quick Search: Select by Host Species and Subclass

Mouse IgG1 Mouse IgG2a Mouse IgG2b Mouse IgG3 Mouse IgM Human IgG1 Human IgG2 Human IgG3 Human IgG4 Human IgA Human IgM Rat IgG1 Rat IgG2a Rat IgG2b Rabbit IgG Goat IgG Sheep IgG Hamster IgG Chicken IgY

1. Definition

Isotype controls are non‑immune antibodies matched to the primary antibody’s host species, isotype, and conjugation but lacking specificity for the target antigen. They are used as negative controls to quantify nonspecific, including Fc‑receptor–mediated, binding, which is particularly important in FcR‑rich myeloid populations.

2. Critical Selection Parameters

Parameter	Technical Rationale
Ig Subclass	Different subclasses (e.g., IgG1 vs IgG2a) have distinct Fcγ‑receptor affinities and background profiles; best practice is to use an isotype control with the same subclass.
Concentration	Nonspecific binding is governed by mass‑action; the control antibody should be matched to the primary by µg/mL, not just by dilution factor.
Fluorochrome	The fluorochrome and F/P ratio affect charge and nonspecific “stickiness”; the isotype control should use the same dye and a similar F/P ratio.
Host Species	Matching host species ensures the secondary antibody recognizes control and primary identically; an exact species match is recommended.

3. Browse Available Isotypes

Host Species	Available Isotypes / Subclasses	Search Catalog
Human	IgG1, IgG2, IgG3, IgG4, IgA, IgM, IgE	View Human Reagents
Mouse	IgG1, IgG2a, IgG2b, IgG3, IgM, IgA	View Mouse Reagents
Rabbit	IgG, IgA, IgM	View Rabbit Reagents
Rat	IgG1, IgG2a, IgG2b, IgG2c, IgM	View Rat Reagents
Hamster	IgG (Armenian & Syrian)	View Hamster Reagents
Chicken	IgY	View Chicken Reagents

Validation Standards

"Acceptable negative controls should use pre‑immune or isotype‑specific sera; omission of the primary antibody alone is considered inadequate."

Technical Note

In flow cytometry, isotypes evaluate FcR-binding but are not sufficient for defining gating boundaries; FMO (Fluorescence Minus One) controls are mandatory for assessing spectral spillover.

Mouse IgG2a Isotype Control PerCP Antibody Rat IgG2a Isotype Control FITC Antibody 

Complementary Assay Reagents

Fc Blocking Solutions Secondary Antibodies Flow Staining Buffers Viability Dyes Fixation/Permeabilization