IVDT_In Vitro Diagnostics Technology

IVD Technology, Spring 2013

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ASSAY DEVELOPMENT monoclonal antibodies. Our recent Kd measurement data for 1000 RabMAbs (not shown) has substantiated this. Identical or similar epitopes sometimes may be found on apparently unrelated molecules. As a result, antibodies directed against one antigen may react unexpectedly with an unrelated antigen. Tus, the specifcity of an antibody is extremely important to avoid a false positive or signal-to-noise ratio problem in diagnosis. With rabbit's larger antibody repertoire and stringent antibody screening, a highly specifc RabMAb can be developed, which has been well-demonstrated in the IHC diagnostic application. In comparison with mouse monoclonal antibodies to the same targets, RabMAbs detect with higher sensitivity and specifcity, giving cleaner staining patterns with lower or no background on parafn-embedded tissue.11 In addition, each immunized rabbit spleen contains as much as 50 times more lymphocytes than a mouse spleen. Rabbit lymph nodes, bone marrow, and other lymphatic organs also provide numerous sources of B cells for generating a larger hybridoma pool for the selection of higher afnity and specifc hybridoma clones. Tere are various techniques to enhance the detection sensitivity for immunoassays; however, the signal-to-noise ratio (specifcity) typically does not improve. We believe a better quality antibody is the best solution to address the dual issues of sensitivity and specifcity. Novel epitope recognition. Rabbit antibodies have been shown to recognize epitopes that are not recognized by mouse antibodies. Tis phenomenon may be caused by reduced immunodominance in the rabbit, which allows the recognition of low abundant proteins or epitopes that usually are not visible to the mouse immune system.9 It has also been shown that rabbits have higher success rates than mice in generating antibodies against these small epitopes, such as protein modifcation or cleavage sites, or conformational epitopes. Te ability to develop rabbit monoclonal antibodies against novel epitopes ofers a new opportunity for immunodiagnostics since many disease targets are in low abundance or form complexes with other proteins. RabMAb to estrogen receptor (ER), SP-1 clone, an FDA approved antibody for pathological assessment of breast cancer prognosis and treatment, is one such example. Because of the novel epitope recognized by this antibody, the sensitivity and specifcity for the pathological assessment are improved signifcantly.12 Another example is RabMAb to ERG, clone EP110 or EPR3864, which demonstrates exquisite concordance between ERG protein expression and the presence of ERG gene rearrangements in prostate cancer because of its ability to recognize a rare epitope.13 Easy to recognize small molecules or haptens. It is observed that rabbits develop antibodies to small molecules more easily than mice—the nonpep- Stabilize Biomolecule Activity Without Protein StabilZyme® Protein-Free Stabilizer Day 0 Day 12 Day 28 Day 49 Day 81 Percent Retained Activity 100 80 60 40 20 0 StabilZyme® HRP NEW StabilZyme® Protein-Free Competitor Stabilizer MOPS (Neg Control) Visit us at Immunology/AAI, Biomarker World Congress and ASM. New SurModics StabilZyme® Protein-Free Stabilizer eliminates unwanted interference and cross-reactivity. StabilZyme stabilizer is designed for conjugated proteins, antibody-coated particles and unmodifed proteins when a protein-free formulation is required. Rely on SurModics for stabilization success. Figure: Percent retained activity is determined by dividing the 37°C accelerated sample by the 4°C control. Arrhenius accelerated stability projections for StabilZyme Protein-Free Stabilizer demonstrate approximately 86% retained activity for greater than 2 years. SA AvaMPLES ilab le orders@surmodics.com | 952-500-7200 | www.surmodics.com Visit us at MD&M East, Booth #3526 ivd tech n o lo gy.com magenta cyan yellow black I VD T EC H N O LO G Y | S PR I NG 2 0 1 3 2 5 ES236233_IV1305_025.pgs 04.23.2013 23:42 UBM

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