Z-MABs have been excellent control antibodies for the assessment of the ”background bindings” of the antigen-specific, isotype matched, antibodies. Binding of the Z-MAB antibody can be detected by the secondary antibody conjugated with enzyme, such as peroxidase or alkaline phosphatase, or fluo molecules such as FITC, Cy3, Cy5, ..etc. With the available biotin-Z-MABs, the background binding can be determined by direct binding of the streptavidin-conjugated HRP without engaging secondary antibodies. The simplified process effectively eliminates the potentially added background signals associated with the secondary antibodies including their potential interactions with cross-species Fc receptors. In addition, the highly stable ABC (avidin-biotin complexes) allows stringent washing conditions and leads to excellent signal to noise ratio.
A CDR-silenced human IgG1 antibody with a wildtype Fc domain, PZHU005 binds to human Fc receptors in the following orders (high to low affinity): FcγRI > FcRn > FcγRIIA [H133] ~ FcγRIIA [R133] > FcγRIIIA [V158] ~ FcγRIIIA [F158] > FcγRIIIB ~ FcγRIIB ~ FcγRIIC.
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What is a Z-MAB®?
Z-MAB® – A next generation control antibody reagent, Z-MAB® stands for Zero-binding monoclonal Antibody.
Z-MAB® is a genetically engineered antibody variant whose antigen-binding capacity has been eliminated. Z-MAB® is suitable to be used as an unbiased control agent for testing specific activities of an antibody of interest.
How are Z-MAB®s created?
Starting with an antibody from a well established antibody drug, we identified the critical amino acid residues in all 6 complementary determining regions (CDRs), engineered selected combinatorial variants and tested for the reduction/loss of their antigen-binding activities. Final candidate Z-MAB®s exhibit excellent CMC and pharmacokinetic properties.
What unmet needs are Z-MAB®s meant to serve?
Choosing a control antibody is probably the most unscientific component for testing the specific activity of an antibody of interest. Control antibodies commercially available thus far include antibodies with no known antigens, e.g. MOPC21; antibodies raised against antigens of evolutionarily distant species, e.g. anti-KLH; antibodies reactive with a known antigen that is distinct from the antigen of interest. If cross-reactivity or high background is observed, most researchers simply move to the next control antibody available until an “ideal” control antibody is found, that is, until the expected result is observed. Z-MAB® has no active antigen-binding activity, and yet retains the overall antibody structure and conformation. It is therefore a bona fide control agent for testing antibodies.
How can Z-MAB®s help antibody-based research and drug development?
Since all isotype Z-MAB®s of the same species (mouse or human) share the same Ig variable regions, one simply selects an isotype-matched Z-MAB® and uses it as a control with peace of mind, no longer blindly sifting through a collection of alleged “control” antibodies to hopefully land with the expected result(s). In addition, Z-MAB®s are particularly useful in animal disease models for antibody drug development where the conventional control antibodies frequently lead to unexpected efficacies.
What Z-MAB®s are available?
Currently, both mouse and human IgG Z-MAB®s are available. In addition to the isotype matched Z-MAB®s, Z-MAB®s with an aglycoyslated Fc domain are available for investigating antibody activities that involve binding to Fc receptor.