99mTc direct labeling of anti-CEA monoclonal antibodies: Quality control and preclinical studies

Castiglia, S.G. de; Duran, Adrian; Fiszman, Gabriel L.; Horenstein, Alberto L.

doi:10.1016/0969-8051(94)00097-4

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Labeling mAb 6D1.1 with 99m Tc was always highly efficient, resulting in 97% radiochemical purity as evaluated by ITLC-SG. This result is in absolute accordance with others (22) and reflects an excellent labeling efficiency.…”

Section: Resultssupporting

confidence: 93%

Evaluation of an anti-carcinoembryonic monoclonal antibody suitable for immunoscintigraphy

Moraes¹,

Lima²,

Prado³

et al. 1999

Braz J Med Biol Res

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An anti-carcinoembryonic antigen (CEA) monoclonal antibody (mAb 6D1.1) was evaluated in vitro and in vivo to determine its suitability as a tracer for immunoscintigraphy of colorectal carcinomas. Determination of mAb affinity for CEA showed a constant of association of 0.63 ± 0.11 x 10 9 M -1 . Binding of technetium-99m ( 99m Tc)-6D1.1, labeled by a direct method, to human cultured lineages was highly specific. Binding to only CEA-positive LS-174T cells resulted in a saturable curve inhibited by pre-incubation with unlabeled mAb. No binding at all was observed for the human lineages MeWo (melanoma) or ZR75-30 (breast carcinoma), neither of them expressing CEA cells. Intravenous injection of 99m Tc-6D1.1 into nude mice xenografted with human LS-174T tumors resulted in planar images of excellent quality. Localization of an irrelevant mAb labeled with either 99m Tc or iodine-125 was never observed in tumor masses. Biodistribution studies on excised tumoral tissue showed retention of 28.48% of the injected dose per gram of LS-174T tumor. The tumor-to-blood ratio was 3.46. The same analysis performed on the other three human xenografted tumors studied demonstrated that only the CEA-producing HT-29 (colorectal adenocarcinoma) retained 99m Tc-6D1.1 while the other two (ZR75-30 and MeWo) did not. These data demonstrate that this mAb is an adequate tool for targeting CEA-expressing tumors in experimental models.

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Section: Resultssupporting

confidence: 93%

Evaluation of an anti-carcinoembryonic monoclonal antibody suitable for immunoscintigraphy

Moraes¹,

Lima²,

Prado³

et al. 1999

Braz J Med Biol Res

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“…GERADOS POR REDUÇÃO DE ANTICORPO O comprimento de onda com máxima absorbância foi de 407 nm, no espectro visível de energia, sendo este comprimento de onda utilizado em várias análises e recomendado em vários protocolos na literatura, para quantificação dos grupos -SH (Castiglia et al, 1995). Este valor foi adotado neste trabalho.…”

Section: Análise Da Quantidade De Grupos Sulfidrilas (-Sh)unclassified

“…Para utilizar o método de (Hnatowich et al, 1994). (Rhodes, 1974;Castiglia et al, 1995 % 99mTc-AcM red. % Impurezas: TcO4-e MDP-99mTc % 99m TcO2 (+4) FIGURA 25.…”

Section: Construção Da Curva Padrão De Cisteínaunclassified

Estudo de marcação do anticorpo monoclonal anti-PBP2a com 99mTc

Mororó¹

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Staphylococcus aureus is a major cause of life-threatening infections such as bacteremia and endocarditis. Unfortunately, many strains of this bacterial species have become resistant to certain antibiotics, including methicillin and amoxicillin. These strains are known as methicillin-resistant S. aureus (MRSA). The penicillin binding protein 2a (PBP2a) is the enzyme responsible for conferring resistance β-lactams antibiotics for MRSA, being one promising molecule for therapy with mAb. However, besides the therapy, the methods of diagnosis are also inefficient because the diagnosis currently takes several days to produce a reliable result. Taking into account, the objective of this research was radiolabeling one anti-PBP2a mAb developed by Bio-Manguinhos/FioCruz-RJ, utilizing 99m Tc, for in situ diagnostic of the infectious caused by MRSA. First, anti-PBP2a mAb was reduced utilizing 2-mecaptoethanol (2-ME) for generate sulphydryl groups (-SH) and after to be labeled with 99m Tc. In this work, were utilized two techniques of direct method: Method 1, using tartrate and gentisic acid reagents, acting like transchelant and stabilizer agents, respectively; and Method 2, using one commercial kit of MDP. Besides the radiolabeling, the mAb reduced and mAb labeled with 99m Tc were submitted to immunoreactivity analysis, with SDS-PAGE non-reducing, Immunoblotting, ELISA and neutralization assay in vitro methods. The quantity produced of sulphydryl groups by mAb was satisfactory, approximately 5 per mAb, utilizing 6.500:1 of 2-ME:mAb molar ratio. The better labeling method was Method 2, with labeling yield of 73.5%, and showed a good stability after 2 hours (73.2%). The better formulation was: 0.5 mg of mAb anti-PBP2a, 10 µL of MDP kit, after resuspended with 5 mL of saline, and 75.48 MBq (2.04 mCi) of 99m Tc, reacting by 15 minutes. The labeled mAb maintained the immunoreactivity,

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