Caled for C10H10F2 m/e 168.0745, Found m/e 168.0745; m/e 168 (M+, 24), 151 (16), 150 (86), 149 (25), 140 (42), 135 (14), 133 (14), 127 (22), 122 (100), 109 (90). Product 11: F NMR -101.25 ppm (broad singlet); H NMR 1.75 (m, 4 H), 2.25 (m, 4 H), 6.3 ppm (broad singlet, 2 H); mass spectrum, Caled for C10H10F2 m/e 168.0745, Found m/e 168.0750; m/e 168 (M+, 53), 151 (19), 150 (87), 149 (26), 140 (72), 135 (20), 133 (21), 127 (28), 122 (100), 109 (84).Acknowledgment. We thank Professor J. Slivnik for the xenon difluoride, Professor J. Marsel for providing facilities, and the Boris Kidric Foundation for financial assistance.

We studied the effect of the plant alkaloid castanospermine on the biosynthesis and secretion of human hepatoma glycoproteins. The HepG-2 cells, grown in the presence or absence of the alkaloid, were labelled with [2-3H]mannose and then the labelled glycopeptides were prepared by Pronase digestion. This material was analysed by gel filtration on Bio-Gel P-4 before and after treatment with endo-beta-N-acetylglucosaminidase H. Castanospermine caused an accumulation of high-mannose oligosaccharides, by 70-75% over control. The major accumulated product, which could also be labelled with [3H]galactose and was only partially susceptible to alpha-mannosidase digestion, was identified by h.p.l.c. as a Glc3Man9GlcNAc. Thus the alkaloid inhibits glucosidase I in the human hepatoma cells. Analysis of total glycoproteins secreted by the cells into the medium revealed the presence of only complex oligosaccharides in both control and treated cultures, and the amount of the oligosaccharides labelled with radioactive mannose, galactose or N-acetylmannosamine, secreted by treated cells, was decreased by about 60%. The rate of secretion of total protein labelled with [35S]methionine and precipitated from the medium with trichloroacetic acid was inhibited by up to 40% in the presence of castanospermine. Pulse-chase studies utilizing [35S]methionine labelling were performed to study the effect of the alkaloid on secretion of individual plasma proteins. Immunoprecipitation at different chase times with monospecific antisera showed that castanospermine markedly decreased the secretion rates of alpha 1-antitrypsin, caeruloplasmin and, to a lesser extent, that of antithrombin-III. Secretions of apolipoprotein E, a glycoprotein containing only O-linked oligosaccharide(s), and albumin, a non-glycosylated protein, were not affected by the drug. It is suggested that castanospermine inhibits secretion of at least some glycoproteins containing N-linked oligosaccharides, owing to the inhibition of oligosaccharide processing.

A B S T R A C T These studies describe the IgE-mediated release of a basophil kallikrein-like enzyme that is an arginine esterase and is inhibited by plasma, diisopropylphosphofluoridate, and Trasylol. The substrate specificity for the synthetic amino acid ester substrates p-toluenesulfonyl-L-arginine methyl ester, benzoyl-arginine methyl ester, and acetyl-tyrosine methyl ester is similar for the basophil enzyme and plasma kallikrein. The interaction of arginine esteraseactive fractions from ion-exchange (DEAE-Sephacel) and gel filtration (Sepharose 6B) chromatography, with human plasma kininogen, generates immunoreactive kinin. The basophil arginine esterase and kiningenerating activities co-chromatograph on Sepharose 6B and the quantity of kinin generated is, in general, proportional to the arginine esterase activity of the column fractions, suggesting that these two activities are subserved by the same protease. The ability of this protease to generate kinin equally well from heat-and acid-treated plasma, as from fresh human plasma, suggests that this protease has kallikrein-like activity. These data suggest that kallikrein-like activity can be generated from human basophils as a direct result of a primary IgE-mediated immune reaction, thus providing a potential link between reactions of immediate hypersensitivity and the plasma and(or) tissue kiningenerating systems.

The development of monoclonal antibodies of high affinity and selectivity for tumor antigens has supported the development of radiolabeled antibodies for diagnostic localization and targeted delivery of therapeutic radionuclides. Several radionuclide chelating agent systems have been developed for indium-111 and technetium-99m that have shown good sensitivity and specificity for tumor detection in patients. Feasibility for therapy has been shown in animal models and a few patient studies with iodine-131 and yttrium-90. This review covers selection of radionuclides and chemistry of antibody radiolabeling.

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