The details of pathological research determine the success or failure of TCR trials

1. What is TCR?
   Tissue Cross-Reactivity is an in vitro test that detects the binding of antibody drugs to epitopes on tissues. The purpose is to confirm the binding of the tested antibody to the epitope of the pharmacodynamic target tissue, and to detect whether the antibody binds to the tissue antigen of the non-target site, so as to provide a reference for determining the relevant animal species for non-clinical safety testing and predicting toxic target organs.

2. Why do TCR
   Antibody drugs have immune properties. In addition to binding to antigens, if the same or similar epitopes exist in normal human tissues, they will also bind to other tissues and cells outside the target organs to cause serious adverse reactions.

Therefore, TCR testing is an important part of the preclinical safety evaluation of antibody drugs. It is very important for the development of antibody drugs and is also a requirement of domestic and foreign regulatory agencies.

1. What is the core technology of the TCR test?
   Immunohistochemistry technology (IHC, immunohistochemistry). Using frozen or fixed tissue specimens, sectioning, and staining the tissues in situ by antigen-antibody reaction and histochemical color reaction in the tissue cells with specific antibodies labeled with chromogenic reagents, and qualitatively, localizing, and quantitatively determining the corresponding antigens A technology.

2. Where do the human organs and tissues needed for the experiment come from?
   Donate human tissues, surgical tissues, placental tissues, cell lines, and commercial human tissue chips.

3. How to deal with fresh tissue correctly?
   To freeze fresh tissue, chemical fixation is not recommended.

Pay attention to rapid freezing when freezing, try to avoid slow freezing or repeated freezing and thawing, ice crystals will form in the tissue, damage the tissue, and also bring observation obstacles to the subsequent experiments.

1. How to judge whether my pathological section is sealed?
   Stain the tissue with anti-transferrin receptor antibody. If the blood cells in the tissue section are faint yellow-brown, then the section is sealed.

2. When to choose the one-step method (direct method) for histochemical staining?
   The one-step method is to couple the biotin label with the primary antibody, and only need one step of immunohistochemical reaction to complete the staining method. This method avoids the non-specific staining of the secondary antibody and reduces interference. However, due to the combination of the primary antibody and biotin, it is likely to destroy the spatial structure of the primary antibody, especially the antibody antigen binding site, resulting in false negatives or false positives.

3. What are the frequently encountered problems in TCR test?
   False positive/false negative

Take off

Non-specific staining

Edge effect

“Yin Yang Face”

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