Automated sequential chromogenic IHC double staining with two HRP substrates.

Automated IHC double staining using diaminobenzidine and HRP Magenta is illustrated utilizing a new acidic block with sulfuric acid to prevent cross-reactivity. Residual cross-reactivity in double staining is determined to arise from chromogenic-bound antibodies and amplification system during the first part of the double staining.

Improved catalyzed reporter deposition, iCARD.

Novel reporters have been synthesized with extended hydrophilic linkers that in combination with polymerizing cross-linkers result in very efficient reporter deposition. By utilizing antibodies to stain HER2 proteins in a cell line model it is demonstrated that the method is highly specific and sensitive with virtually no background. The detection of HER2 proteins in tissue was used to visualize individual antigens as small dots visible in a microscope.

Detection of gamma-globin mRNA in fetal nucleated red blood cells by PNA fluorescence in situ hybridization.

Objectives: Fetal nucleated red blood cells (NRBC) that enter the peripheral blood of the mother are suitable for non-invasive prenatal diagnosis. The application of peptide nucleic acid (PNA) probes for tyramide amplified flow fluorescence in situ hybridization (FISH) detection of gamma-globin mRNA in fixed fetal NRBC is investigated.

Methods: Hemin-induced K562 cells or nucleated blood cells (NBC) from male cord blood were mixed with NBC from non-pregnant women and analysed using both slide and flow FISH protocols.