Production and characterization of a monoclonal antibody to dog hepatic lipase

Two-step purification of mouse kidney ornithine decarboxylase

We developed a simple two-step purification procedure for ornithine decarboxylase (ODC, EC 4.1.1.17), consisting of DEAE-Cellulofine chromatography and affinity chromatography on a HO-101 monoclonal anti-rat liver ODC antibody-Affi-Gel 10 column. By this method, ODC was purified 1700-fold to homogeneity with about 80% yield from the kidney of ICR mice treated with testosterone enanthate. The final specific activity range between 1.0 x 10(6)-1.4 x 10(6) nmol/h.mg protein. On SDS-polyacrylamide gel electrophoretic analysis, the final preparations gave a major protein band of Mr 54,000 and a minor band of Mr 51,000. Although relative staining intensity of the two bands varied depending on preparations, both bands could be stained by immunoblotting and labeled by a preincubation with [14C]difluoromethylornithine (DFMO). On Oudin double diffusion immunoanalysis, a single fused precipitin line was formed between purified anti-mouse kidney ODC IgG and both the purified enzyme and crude mouse kidney extract. In contradiction with earlier reports, no significant difference was observed between mouse kidney ODC and rat liver ODC in either final specific activity or specific binding of labeled DFMO.

Lipoprotein lipase in liver. Release by heparin and immunocytochemical localization

We have previously demonstrated that infusion of Intralipid to rats causes a pronounced increase of the lipoprotein lipase activity in the liver. In this paper we study where in the liver this lipoprotein lipase is located. When isolated livers from Intralipid-treated rats were perfused with heparin, substantial amounts of lipoprotein lipase were released into the perfusate. The identity of the lipase activity was demonstrated by specific inhibition with antisera to lipoprotein lipase, and to hepatic lipase, respectively, and by separation of the two lipase activities by chromatography on heparin-Sepharose. We have also studied the localization of both enzymes by an immunostaining procedure based on post-embedding incubation of ultrathin tissue sections with specific antibodies which were then visualized using protein A-colloidal gold complexes. There was no marked difference in localization for the two enzymes which were both seen at the luminal side of endothelial cells, at the interdigitations of the space of Disse and inside both hepatocytes and endothelial cells. Thus, lipoprotein lipase is present in the liver in positions similar to where the functional pool of hepatic lipase is located and analogous to where lipoprotein lipase is found in extrahepatic tissues. These results raise the possibility that the enzyme has a functional role in the liver.

Monoclonal antibodies against salt-resistant rat liver lipase. Cross-reactivity with lipases from rat adrenals and ovaries

To obtain monoclonal antibodies against rat salt-resistant liver lipase, mice were immunized with enzyme purified from heparin-containing rat liver perfusates. Hybridomas were screened for antibody production by means of an enzyme-linked immunosorbent assay (ELISA) and an immunoprecipitation assay. Five hybridoma cell lines secreting antibodies against rat liver lipase indicated as A, B, C, D and E, have been obtained. All antibodies possess gamma one (gamma 1) heavy chains and kappa (kappa) light chains. The antibodies precipitate salt-resistant lipase from rat post-heparin plasma, are positive in ELISA, inhibit liver lipase activity and bind monospecifically with the enzyme as shown by immunoblotting. The monoclonal antibodies showed no significant reactivity with human liver lipase. The salt-resistant lipases of rat adrenals and ovaries are also precipitated by the monoclonal antibodies directed against the liver enzyme. Therefore, the heparin-releasable lipases of the liver, adrenals and ovaries possess identical epitopes.