Primary-secondary antibody incompatibility preventing detection (Immunohistochemistry (No Staining))

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Accepted Answer

No signal detected despite proper primary antibody binding. Secondary antibody fails to recognize or bind to the primary antibody, breaking the detection chain. Common causes: 1) Secondary antibody not raised against primary antibody host species 2) Isotype mismatch between primary and secondary antibodies 3) Secondary antibody conjugate incompatible with detection system 4) Wrong secondary antibody selected for primary antibody class (IgG, IgM, etc.) Solutions: 1) Ensure secondary antibody is raised against primary antibody species (e.g. anti-rabbit for rabbit primary) 2) Verify isotype compatibility between primary and secondary antibodies 3) Confirm secondary antibody conjugate matches detection method (HRP for DAB, fluorophore for IF) 4) Check that secondary antibody recognizes primary antibody class (IgG, IgM, etc.) 5) Run positive control with validated antibody pair to confirm detection system