RETINOBLASTOMA SUSCEPTIBILITY GENE-PRODUCT RETRIEVAL IN FORMALIN-FIXED, PARAFFIN-EMBEDDED TISSUE - A HEATING METHOD FOR ENHANCING IMMUNOHISTOCHEMICAL STAINING

We examined immunohistochemical methods to visualize the retinoblastom a susceptibility gene product (RB) in formalin-fixed, paraffin-embedde d sections of the U2-OS and Saos-2 human osteosarcoma cell lines. Immu nocytochemical studies showed clear staining with an anti-RB antibody in 88% of the smeared U2-OS cells and in none of the smeared Saos-2 ce lls. Antigen retrieval methods evaluated included microwave-oven and a utoclave pretreatment of paraffin-embedded sections immersed in Dulbec co's phosphate buffered saline (pH 7.4) prior to incubation with the p rimary antibody. Strong and discrete staining of U2-OS cell nuclei for RB was seen after autoclave treatment, stronger than that seen follow ing microwave-oven heating. Moreover, neither microwave-oven nor autoc lave pretreatment produced positive staining in the nuclei of Saos-2 c ells. Therefore, tissues previously considered unsuitable for immunohi stochemical analysis of the RB can be studied after autoclave treatmen t.