Immunocytochemical use of internally radiolabelled monoclonal antibodies against tyrosine hydroxylase, substance P and enkephalin.

An improved protocol for the internal radiolabelling of monoclonal antibodies with tritiated lysine is described. Hybridoma cell lines producing monoclonal antibodies against the biosynthetic enzyme tyrosine hydroxylase and the neuropeptides, substance P and enkephalin, were employed in this investigation. Immunocytochemical detection of the endogenous antigens with these internally labelled antibodies was performed and when used in immunocytochemistry, the subsequent data were in complete agreement with previous light and electron microscopic studies. These results indicate that the present internal radiolabelling procedure does not alter the ability of the monoclonal antibody to recognise the endogenous antigen. This study, therefore, supports the use of internally labelled antibodies with compatible immunocytochemistry techniques in double staining procedures.