NONENZYMATIC RETRIEVAL OF ANTIGEN PERMITS STAINING OF FOLLICLE CENTERCELLS BY THE RABBIT POLYCLONAL ANTIBODY TO PROTEIN GENE-PRODUCT-9.5

The rabbit polyclonal antibody to protein gene product 9.5 (PGP9.5) wi ll detect the L1 isoenzyme of ubiquitin carboxy-terminal hydrolase (UC H), which is a marker for neurones and neuroendocrine tissue. We re-ev aluated this antibody using the technique of non-enzymatic antigen ret rieval (boiling sections in citrate buffer, heated by microwave oven) followed by streptavidin-biotin-peroxidase staining. Due to the fortui tous choice of appendix as positive control material containing small nerves, we found strong, repeatable cytoplasmic and nuclear staining o f lymphoid follicle centre cells in addition to neural tissue. This ef fect could be repeated on other lymphoid tissues and was not dependent on microwave heating, but did require boiling in an ionic buffer solu tion. Staining was also observed with a fresh batch of antibody and wi th four of the live different batches of antibody which were supplied to us. This pattern was not obtained in fresh tissue, in fixed materia l following trypsinization, or by increasing the primary antibody conc entration. We suggest that the boiling of sections in citrate buffer i s exposing an epitope for the anti-PGP9.5 antibody which is inaccessib le in the native or fixed state and therefore we would recommend retes ting of antibody specificity following non-enzymatic retrieval of anti gen.