The localization of radioantibodies in human brain tumors. II. Radioautography.

needed to determine whether rabbit anti-human glioma antibodies would localize in human brain tumors (2) 1251 radioautography was also required. As shown by Fitch et al. (3) and later by Appeigren et at. (1), a vast im provement in radioautographic resolution over that with ‘@‘I can be obtained with 125J To demonstrate the presence of radiolabeled compounds that are dissolved in tissue fluids or, at most, loosely bound, the technic of Ullberg (6), in which tissues are frozen, thinly sectioned in the frozen state, and layered with radioautographic stripping film provides the most meaningful information. In the case of labeled com pounds that are firmly bound or trapped in tissues, the tissues may be fixed according to routine histologic prac tice, sectioned, mounted on slides, deparaffinated, washed thoroughly, and dipped in warm radioautographic emul sion. Kyogoku et at. (4) used this latter technic to demonstrate the disposition of ‘25I-labeled anti-hepatoma and anti-liver antibodies in rat hepatomas and liver, and Wood (7), to show tumor thrombi formed in the presence of ‘251-labeled fibrinogen and plasmin. In both instances the exquisite radioautographs appear to be attributable to tissue-fixed proteins rather than to unbound proteins in the plasma space, the latter having presumably been removed by thorough washing. The present radioautographic study on the localization of radioantibodies in the gliomas of 11 patients was also confined to the description of tissue-fixed protein after thorough washing of the tissue sections to remove un bound radioglobulin. The radioautographs were, there S The following abbreviation is used : RISA, radioactive iodi nated serum albumin. fore, more indicative of radioantibody localization in tissues than would have been the case if unwashed frozen sections layered with stripping film had been used. Radioautographs of other tumors, obtained after primary craniotomy, were also made in cases where RISA-131I or 125I or neohydrin-@°3Hg had been administered prior to surgery for purposes of regional external scintillation scanning. These additional radioautographs made it possible to study more extensively the phenomenon of non specific binding of labeled compounds in tissue sections. MATERIALS AND METHODS Tissue removed from the area of previous tumor resec tion, several days after antibody infusion, was separated grossly into recurrent tumor and normal adjacent brain. The tissue was fixed in 10 % formalin for 2 days, dehy drated, embedded in paraffin, cut into tissue slices 8 @ in thickness, and mounted upon glass slides, 3 by 1 inch. Each slide …