Thesis (M.Sc. (Tropical Medicine))--Mahidol University, 1982.

Thesis (Ph. D.)--University of Missouri--Columbia, 1997. / "December 1997." Typescript. Vita. Includes bibliographical references (leaves 100-109). Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 96-139) Also available in print.

Thesis (Ph. D.)--University of Missouri--Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves: 100-109). Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 232-263). Also available in print.

Thesis (Ph.D.)--University of California, San Francisco, 2004. / Bibliography: leaves 85-92. Also available online.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 232-263). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 61-64). Also available in print.

Human Natural Killer (NK) cells are regulated by a variety of germ-line encoded activating and inhibitory receptors. Broadly, activating receptors detect ligands that are expressed or up-regulated on cancerous or infected cells, while inhibitory receptors bind self-molecules to induce tolerance against healthy cells. Highly homologous pairs of activating and inhibitory receptors are also expressed on NK cells, including Killer Ig-like Receptors KIR2DL1 and KIR2DS1, which bind the same ligands, class I MHC proteins from the C2 group. Here, two super-resolution microscopy techniques, stimulated emission depletion (STED) and ground state depletion microscopy followed by individual molecule return (GSDIM) were used to examine the nanometre-scale organization of KIR2DL1 and KIR2DS1, as well as molecules engaged in their signalling. Both receptors were observed to constitutively assemble in nanometre-scale clusters at the surface of NK cells but displayed differential patterns of clustering - the activating receptor KIR2DS1 formed nanoclusters 2.3-fold larger than its inhibitory counterpart KIR2DL1. Site-directed mutagenesis established that the size of nanoclusters was controlled by transmembrane amino-acid 233, a lysine in KIR2DS1. Mutated variant of KIR2DS1 in which lysine 233 was substituted with alanine formed significantly smaller clusters than the wild-type KIR2DS1. Reciprocally, substitution of isoleucine found at position 233 in KIR2DL1 sequence with lysine resulted in the receptor assembling into larger clusters. Super-resolution microscopy also revealed two ways in which KIR nanoclusters impact signalling. First, KIR2DS1 and DAP12 nanoclusters were juxtaposed in the resting-cell state but coalesced upon receptor ligation. Second, quantitative super-resolution microscopy revealed that membrane-proximal clusters of the kinase ZAP-70 or phosphatase SHP-1, as well as their phosphorylated active forms, were more often found in contact with larger KIR nanoclusters. Together, this work has established that size of KIR nanoclusters depends on the transmembrane sequence and impacts downstream signalling.

Orientadores: Ronei Luciano Mamoni, Maria Heloisa Souza Lima Blotta / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-16T10:37:38Z (GMT). No. of bitstreams: 1 Longhi_LarissaNaraAlegrini_M.pdf: 6631958 bytes, checksum: 45b4fc2e64262b037302e0269ebd8f71 (MD5) Previous issue date: 2010 / Resumo: Tradicionalmente o papel das células NK na resposta imunológica tem sido associado com a resistência à infecção viral e tumores, porém estudos recentes apontam para a participação destas células na resposta imunológica contra outras doenças infecciosas. O objetivo deste estudo foi avaliar a possível participação de células NK (CD56+CD3-) na resposta imunológica ao fungo Paracoccidioides brasiliensis. Foram utilizadas células CD56+ isoladas por meio imunomagnético provenientes de pacientes com paracoccidioidomicose e de indivíduos controle. As células CD56+ foram avaliadas quanto à capacidade citotóxica direta contra leveduras de P. brasiliensis (cepa virulenta - Pb18 e avirulenta - Pb265) e contra células-alvo (monócitos) infectadas com leveduras de ambas as cepas. Também foi avaliada a expressão dos constituintes dos grânulos citotóxicos (granzima A, B, perforina e granulisina), receptores de ativação (NKG2D) e de inibição (KIR2DL2/L3/S2 e KIR3DL1), marcadores de ativação (CD69 e CD25), assim como a produção de citocinas (IFN-g e TNF-a) por meio de PCR em tempo real e por citometria de fluxo. A participação da IL-15 na ativação das células NK foi avaliada pela adição da citocina recombinante em alguns experimentos. Para avaliar a participação dos grânulos na atividade citotóxica direta e contra células-alvo em alguns experimentos as células foram tratadas com inibidores específicos (SrCl, concanamicina A ou EGTA). Os resultados demonstraram que células de pacientes apresentam resposta citotóxica (direta e contra células-alvo) inferior àquela observada nos indivíduos controle. A citotoxicidade direta foi dependente de grânulos, mas independente de perforina, enquanto que a citotoxicidade contra células-alvo foi dependente de perforina. A expressão de granulisina (RNAm e proteína) foi maior nas células de indivíduos controle. Além disso, observamos que células CD56+ apresentam a capacidade de secretar essa proteína após o estímulo com leveduras de P. brasiliensis. Também observamos que as células CD56+ de doadores normais são ativadas (aumentam a expressão de CD69 e CD25) quando estimuladas com o fungo, enquanto as células NK de pacientes não mostraram esse aumento, a não ser quando estimuladas com IL-15. Estes resultados demonstraram que as células CD56+ podem participar ativamente da resposta imunológica contra o P. brasiliensis, podendo contribuir tanto para a morte direta do fungo como de células infectadas, e que a granulisina pode desempenhar um papel preponderante no controle da infecção pelo P. brasiliensis. Outro fato importante observado foi que as células CD56+ quando estimuladas por células leveduriformes de P. brasiliensis produzem e secretam IFN-g, uma citocina com atuação importante na ativação de outras células do sistema imunológico como macrófagos e linfócitos, e dessa forma pode contribuir para o desenvolvimento da resposta imunológica adquirida subseqüente à infecção. / Abstract: Besides their role in viral infection and tumor resistance, recent studies have showed that NK cells also participate in the immune response against other infectious diseases. The aim of this study was to evaluate the possible role for NK cells (CD56+) in the immune response against the fungi Paracoccidioides brasiliensis. CD56+ cells from patients with paracoccidioidomycosis and healthy individuals were isolated by immmunomagnetic columms and antibodies. We evaluated the capacity of the direct killing of P. brasiliensis yeast cells (Pb18 virulent strain and Pb285 avirulent strain), as well as, the ability to kill infected target cells (monocytes infected with either virulent or avirulent strains). The CD56+ cells also were assessed in order to evaluate the expression of citotoxic granules (granzyme A, B, perforin and granulysin) and the expression of the activation receptor NKG2D, the inhibition receptors KIR2DL2/L3/S2 and KIR3DL1 and the activation molecules CD69 and CD25. We also determine the capability of production and release of cytokines (IFN-g and TNF-a) using Real Time PCR, flow cytometry and ELISA. The role of IL-15 was analyzed by the addition of recombinant cytokine in some experiments. To determine if the cytotoxic activity was dependent of granules, cell cultures were supplemented with specific inhibitors which prevent granule release. The results showed that cells from patients present a lower citotoxic response when compared to healthy individuals. The direct citotoxicity seems to be granule-dependent but independent on perforin, whereas the citotoxicity against target cells showed to be perforin dependent. It was observed an augmented expression of granulysin (mRNA and protein) in cells from controls, and that CD56+ cells are able to produce and release granulysin after stimulation with P. brasiliensis yeast cells. Furthermore, the analyses of CD56+ cells from controls showed elevated expression of CD25 and CD69 after the stimulus with yeast cells, while cells from patients are only activated in the presence of IL-15. These results demonstrated that CD56+ cells can participate actively of the immune response against the P. brasiliensis infection either by destroying directly yeast cells or by the recognition and killing of infected cells. Granulysin is the possible mediator of the cytotoxic effect observed in this study, once this protein is produced and released by CD56+ cells. Another important data is the finding that CD56+ cells are able to produce IFN-g after the stimulus, which could influence the subsequent acquired immunological response by stimulating others cells as macrophages and lymphocytes. / Mestrado / Ciencias Biomedicas / Mestre em Ciências Médicas