L’activation des cellules NKCD56dim par l’engagement ou non du récepteur FγRIIIA/CD16A entraîne la perte d’expression membranaire de celui-ci par un mécanisme dépendant au moins en partie de la metalloprotéase ADAM17. Celle-ci clive le récepteur entre l’Alanine 195 et la Valine 196 et agit exclusivement en cis. La modulation d’expression du FγRIIIA/CD16A est un marqueur d’activation des cellules NK plus fortement corrélé à la dégranulation qu’à la production d’IFN-γ. L’engagement du récepteur FγRIIIA/CD16A ou le co-engagement des récepteurs activateurs des NKCD56dim induisent de manière non corrélée la dégranulation et la production d’IFN-γ. Cette dichotomie fonctionnelle varie selon les donneurs et dépend de l’expression des récepteurs inhibiteurs spécifiques des molécules du CMH-I. La production d’IFN-γ est ainsi associée à l’expression des KIRs (Killer like-Immunoglobuline Receptor) mais pas à celle du NKG2A. Une meilleure compréhension des réponses effectrices dépendantes du FγRIIIA/CD16A est importante pour améliorer l’efficacité thérapeutique des anticorps monoclonaux à visée anti-tumorale. / FγRIIIA/CD16A-dependent or independent activation of CD56dim NK cells induces down-modulation of this receptor. The mechanism partially involves the ADAM17 metalloprotease, which cleaves the FγRIIIA/CD16A between Alanine 195 and Valine 196 and acts exclusively in cis. FγRIIIA/CD16A downmodulation is a marker of NK cell activation more strongly correlated with degranulation than to IFN-γ- production. FγRIIIA/CD16A engagement or activating receptors co-engagement on CD56dim NK cell induces degranulation and IFN-γ-production, which are not correlated. This functional dichotomy depends on the donor and on the CMH-I-specific inhibitory receptor expression. IFN-γ-production is thus associated with KIRs (Killer like-Immunoglobuline Receptor) but not with NKG2A expression. Understanding the FγRIIIA/CD16Adependent functional responses is essential to improve the efficacy of monoclonal antibodies used in cancer therapy.

La pharmacocinétique (PK) des anticorps monoclonaux (mAbs) est sujette à d’importantes variations interindividuelles. Le récepteur néonatal au Fc des IgG (FcRn) et le statut immun à l’encontre de ces mAbs sont des déterminants de cette PK. La bioconjugaison des mAbs à des cytotoxiques entraîne une altération de leur PK. Nous montrons que le taux de couplage modifie l’affinité de ces espèces pour le FcRn à pH6. La proportion d’agrégats au sein des solutions d’anticorps armés augmente avec le taux de couplage et pourrait entraîner une altération de leur PK. Par ailleurs, cette agrégation est impliquée dans l’immunogénicité des mAbs, et nous avons donc cherché à identifier des acides aminés impliqués dans l’agrégation de mAbs indiqués en clinique. Il apparait que la nature biochimique de résidus des paratopes pourrait augmenter cette agrégation. Les anti-TNF- présentent très peu d'agrégats et figurent pourtant parmi les plus immunogènes chez l’Homme. Nous avons donc exploré le rôle des complexes immuns dans leur immunogénicité chez la souris. Il apparait que la présence du FcRn n’est pas à l’origine de l’immunisation contre ces mAbs, contrairement à celle des complexes immuns. Ces résultats donnent des pistes pour la production de mAbs plus efficients et mieux tolérés. / The pharmacokinetic (PK) profile of monoclonal antibodies (mAbs) shows interindividudal variability. The neonatal Fc receptor (FcRn) and the immounogenicity of these mAbs are determinative factors of mAb PK. Generation of antibody-drug-conjugates alters their PK profile. We show that the the affinity for FcRn at pH6 increases with the drug-to-mAb ratio, as does the amount of aggregates inside the mAb-drug-conjugate. The amount of aggregates could be responsible for an avidity effect towards FcRn. These aggregates are known to cause immunogenicity, so we studied biochemical determinants inside the aminoacid sequence of marketed mAbs. We show that the biochemical nature of some aminoacids inside the paratope has an impact on the amount of aggregation. Anti-TNF- mAbs show very little aggregation but are very immunogenic in humans. We studied the role of the formation of immune complexes in the immunization against anti-TNF- mAbs in mice, and showed that immune complexes, but not FcRn are essential in the immunization process against anti- TNF- mAbs. These results give leads towards the generation of more efficient, better tolerated mAbs.

Submitted by Priscila Nascimento (pnascimento@icict.fiocruz.br) on 2012-11-09T16:36:26Z No. of bitstreams: 1 carlos-humberto-marques.pdf: 2761227 bytes, checksum: cf168e11c904e07038251644b2018901 (MD5) / Made available in DSpace on 2012-11-09T16:36:26Z (GMT). No. of bitstreams: 1 carlos-humberto-marques.pdf: 2761227 bytes, checksum: cf168e11c904e07038251644b2018901 (MD5) Previous issue date: 2005-05 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Imunobiológicos. Rio de Janeiro, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil. / Os anticorpos monoclonais possuem diversasaplicações em transplantes, na composição de conjuntosde reativos para diagnóstico, grande variedade de doenças auto-imunes e, principalmente, na terapia do câncer. A tecnologia de produção de anticorpos monoclonais recombinantes revolucionou a geração de imunoglobulinas, possibilitando a obtenção de anticorpos humanizados dirigidos a uma grande variedade de antígenos específicos. A baixa seletividade das metodologias atuais para diagnóstico e terapia de neoplasiasconstitui um dos principais empecilhospara a prática oncológica. Nesse particular, a utilização de imunoglobulinas submetidas à engenharia genética já é uma realidade e significa um avanço estratégico, abrangendo cerca de 25% do mercado biofarmacêutico global de proteínas terapêuticas. Este trabalho aponta os aspectos fundamentais à concretização da metodologia de humanização de anticorpos por transplante das regiões determinantes de complementaridade – CDR, com ênfase em uma proposta de produção do anticorpo anti – CD20 contrao Linfoma Não-Hodgkin. A introdução do Instituto de Tecnologia emImunobiológicos - Bio-Manguinhos nesse promissor e importante mercado de biofármacos através da implantação da metodologia de humanização do anticorpo monoclonal murino anti-CD20 é objeto desta dissertação. Viabilizar sua produção torna-se extremamente importante, tanto para a identificação precisa e precoce da enfermidade, quanto para atender um segmento do mercado brasileiro ainda desprovido de tratamento abrangente e eficaz. A apresentação do estudo dos anticorpos, sua estrutura e características, o estudo dosdiferentes sistemas de expressão, cultivo, purificação,bem como a proposta de reestruturação e redimensionamento do Laboratório de Tecnologia de Anticorpos Monoclonais, parcerias, colaborações, recursos humanos necessários e aspectos de mercado, são aqui considerados. / Monoclonal antibodies (Mabs) have several applications in transplants, reagents for diagnosis, a great variety ofauto-immune diseases and mainly, in cancer therapy. Mabs production employing recombinant echnologymade a revolution in immunoglobulinsgeneration, enabling the production of humanized antibodiesthat recognize specific antigens. The low selectivity of the current techniquesfor neoplasm diagnosis and therapy is one of the major impediments for oncology practice. In this regard, the use of eneticallyengineered immunoglobulins has become a reality and meansa strategic development comprising around 25% of the global biopharmaceutical market. This work shows the most important aspects in Mabs humanization through complementary determining regions (CDR) graft methodology, emphasizing a proposal ofanti-CD20 Mab production against non-Hodgkin lymphoma. Introducing the Instituto de Tecnologia emImunobiológicos – Bio-Manguinhos in this important and promising biopharmaceutical market through the establishment of humanization methodology is the main object of this dissertation. Making humanized Mabs production feasible is veryimportant not only for the earlyand precise identification of illnesses, but also to meet a demand of the Brazilian market that still lacks comprehensive and efficient treatment. The study of Mabs, their structureand properties, expression systems, cultivation, purification, new dimensions and structure of the laboratory, partnerships, cooperation,human resources and market analysis are considered herein.