Jackson Immuno Research Inc.
specializing in secondary antibodies and conjugates

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Whole IgG Affinity-Purified Secondary Antibodies

"I have used a wide variety of secondaries and Jackson ImmunoResearch has consistently been the best. The fluorophores are bright and stable and their selective (x reactivity removed) secondaries have always shown species specificity in multiple labeling."

Janet Duerr, Ohio University

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FabuLight - Fab-Label Primary Antibodies with Fluorophore-Conjugated Fab anti-Fc

FabuLight™ - Fab Anti-Fc Fragment Secondary Antibodies

Label Primary Antibodies In Solution Without Compromising Activity

FabuLight antibodies are Fab fragment secondary antibodies specific to the Fc region of IgG or IgM primary antibodies. They are available conjugated with 9 different fluorophores and biotin, and enable labeling of primary antibodies prior to incubation with cells or tissue. This provides a time saving alternative to sequential incubation flow cytometry and immunohistochemistry procedures, without compromising the active site of the primary antibody.

Possible uses of FabuLights also include labeling cell surface immunoglobulins without cross-linking and activating B cells, and labeling Fc chimeras (fusion proteins).

FabuLights are not provided cross-adsorbed against other species, so blocking steps may be required to avoid labeling endogenous immunoglobulins. For advice on developing protocols, refer to the example below, or the FabuLight white paper.

Save Time and Preserve Cells by Reducing Incubation and Washing Steps:

Incubation with FabuLight-labeled primary antibodies requires fewer washes than sequential incubation with primary antibodies and labeled secondary antibodies, thereby reducing damage to cells in flow cytometry protocols. Incubation steps in protocols requiring multiple primary antibodies from the same host animal are also reduced.

No Interference With the Primary Antibody Active Site:

FabuLight binds to the Fc portion of the primary antibody (either anti IgG, Fcγ specific or anti-IgM, μ chain specific), leaving the antigen-binding region active.

No Precipitation:

The resulting complex of primary antibody with FabuLight does not precipitate or aggregate, because the dye-conjugated Fab anti-Fc secondary antibody fragments are monovalent. FabuLight-primary antibody complexes offer good tissue penetration and low non-specific binding.

Browse FabuLight - Affinity-Purified Fab Anti-Fc Fragment Specific Antibodies

Download White Paper - FabuLight - Fab labeling primary antibodies with fluorophore-conjugated Fab anti-Fc

Using FabuLight

Optimal protocols for each application must be established empirically. Label the less abundant target antigen first for optimal results. Complexing at a 3:1 molar ratio of FabuLight:Primary Antibody (equal weight ratios) provides a good degree of labeling of the primary antibody without excessive amounts of unbound Fab. Titrating Fab-labeled complexes vs. their target antigens will minimize the amount of free Fab anti-Fc, thereby minimizing potential cross-talk in a multiple labeling application.

Example - Using FabuLight to Label Two Antigens on Tissue

Importance of Sequential Labeling and Titrating Primary vs. Target Antigen

Technical Tips

  • FabuLight antibodies have not been adsorbed to remove cross-reactivities to other species, so it may be necessary to block endogenous IgG prior to incubation with an unlabeled Fab anti-IgG (H+L) prior to application of a Fab-labeled complex.
  • Fab-Labeled complexes do not provide as bright a signal as sequential incubation with a primary antibody followed incubation with a labeled secondary antibody.
  • To avoid displacement of the Fab-primary antibody by a subsequent labeled secondary antibody, a light cross-linking with glutaraldehyde may be necessary, provided that it does not affect antigenicity of subsequent target proteins.
  • For all multiple labeling applications, we recommend incubating FabuLights sequentially to minimize cross-reactivity.