Immuno-Biological Laboratories Co., Ltd.

Gastrointestinal stromal tumors (GISTs) are malignant subepithelial tumors, known for their poor prognosis due to distant metastasis. Because GIST is covered by a normal mucosal layer, effective tissue biopsy under conventional endoscopy is difficult, thereby leading to delayed diagnosis and a dismal prognosis. We performed molecular imaging of GIST targeting c-KIT using fluorescence-labeled anti-c-KIT antibody/fragments and fluorescent endoscopy.

Mouse anti-human c-KIT monoclonal antibody, its F(ab')₂ and Fab fragments were labeled with AF680. Two GIST cell lines (GIST-T1, GIST-882M) were used for experiments. Antibodies were intravenously administered to mice xenografted with GIST-T1 or GIST-882M, and each tumor was observed using IVIS Spectrum and self-developed simple fluorescent endoscopy.

The GIST-T1 cell live imaging revealed strong signals on cell membranes after 1 min incubation, and thereafter, they aggregated and internalized inside the cells within 130 min in all antibody/fragment groups. In vivo mouse experiments, AF680-labeled IgG slowly accumulated in tumors peaking at 24 h after injection. However, AF680-labeled F(ab')₂ and Fab rapidly accumulated in tumors peaking at 1-2 h, and completely cleared from the body within 24 h. Fab showed the strongest fluorescence intensity in tumors. Fluorescence endoscopy could clearly detect GIST xenograft tumors 1-2 h after AF680-labeled F(ab')₂ and Fab injection.

AF680-labeled antibody/fragments showed clear and specific fluorescence signals in GIST xenografts in mice. Particularly, AF680-labeled Fab showed the strongest signal intensity at 1-2 h post-administration and rapid clearance, suggestive of the safety. This approach may enable molecular imaging diagnosis of GIST by endoscopy in outpatient settings in the future.

To support in vivo and in vitro studies of intravascular triglyceride metabolism in mice, we created rat monoclonal antibodies (mAbs) against mouse LPL. Two mAbs, mAbs 23A1 and 31A5, were used to develop a sandwich ELISA for mouse LPL. The detection of mouse LPL by the ELISA was linear in concentrations ranging from 0.31 ng/ml to 20 ng/ml. The sensitivity of the ELISA made it possible to quantify LPL in serum and in both pre-heparin and post-heparin plasma samples (including in grossly lipemic samples). LPL mass and activity levels in the post-heparin plasma were lower in Gpihbp1^-/- mice than in wild-type mice. In both groups of mice, LPL mass and activity levels were positively correlated. Our mAb-based sandwich ELISA for mouse LPL will be useful for any investigator who uses mouse models to study LPL-mediated intravascular lipolysis.

Background: The cerebrospinal fluid (CSF) levels of tau phosphorylated at threonine 217 (p217tau) or 181 (p181tau), and neurofilament light chain (NfL) are definite biomarkers of tauopathy and neurodegeneration in Alzheimer’s disease (AD). Objective: To validate their utility in excluding other neurological diseases and age-related changes in clinical settings. Methods: We developed monoclonal antibodies against p217tau and NfL, established novel ELISAs, and analyzed 170 CSF samples from patients with AD or other neurological diseases. Results: In AD, p217tau is a more specific and abundant CSF component than p181tau. However, CSF NfL levels increase age-dependently and to a greater extent in central and peripheral nervous diseases than in AD. Conclusions: CSF p217tau correlates better with AD neurodegeneration than other tau-related biomarkers and the major phosphorylated tau species. The clinical usage of NfL as a neurodegeneration biomarker in AD requires exclusion of various central and peripheral neurological diseases.