O desenvolvimento de imunidade naturalmente adquirida na malária é lento e depende de fatores como o número de malárias prévias, intervalo entre cada malária, exposição a variantes antigênicas múltiplas e idade do indivíduo. Mecanismos imunes efetores dependentes de anticorpos são importantes no desenvolvimento dessa imunidade. Vários estudos têm mostrado que as subclasses IgG1 e IgG3 anti-P. falciparum, conhecidas por sua ação citofílica, são anticorpos protetores, enquanto anticorpos não citofílicos como IgG4 reconhecendo os mesmos epítopos seriam bloqueadores dos mecanismos protetores. Dados recentes sugerem que sob determinadas condições, IgG2 também pode ter ação citoíflica e participar da proteção na malária. Neste trabalho, nós estudamos pela primeira vez, a evolução das subclasses de IgG contra formas eritrocitárias de P. falciparum de pacientes com malária falciparum não complicada internados em hospital por até 42 dias, sob tratamento com mefloquina. As subclasses de IgG foram avaliadas por ELISA em 48 pacientes (7 amostras de soro de cada um colhidas nos tempos 0h, 48h, 7, 14, 28, 35 e 42 dias), quanto à quantidade (concentração, ug/ml; índices de reatividade, IR; ou em freqüência, %) e quanto à avidez dos anticorpos (índice de avidez, IA). Amostras de soro de 14 pacientes (tempos: 0, 48h, 7, 21 e 28 dias) também foram avaliadas quanto à especificidade e a avidez de reconhecimento das diferentes bandas protéicas do antígeno de P. falciparum por Immunoblotting. As subclasses IgG1, IgG2, IgG3 e IgG4 anti-P. falciparum, na maioria de alta avidez, estavam presentes no início do tratamento, respectivamente, em 100%, 39,5%, 80,6% e 28,4% dos pacientes e com concentrações médias de 20, 2; 3,8; 1,5 e 0,05 ?g/mL. As concentrações máximas das subclasses de IgG foram alcançadas no 7o dia, e os IAs máximos de IgG1 e IgG3 foram alcançados no 7o dia, e os de IgG2 no 14o dia e os de IgG4 no 2o dia. A concentração inicial dos anticorpos IgG3 anti-P. falciparum apresentou correlação negativa com o tempo de clareamento parasitário (TCP) e a relação das somas dos anticorpos IgG1, IgG2 e IgG3 pelos níveis de IgG4 se correlacionaram negativamente com a parasitemia inicial. No Immunoblotting, foram identificadas frações protéicas que podem estar relacionadas com o reconhecimento imune protetor, por serem reconhecidas pelas subclasses IgG1, IgG2 e IgG3 e não reconhecidas ou reconhecidas tardiamente por IgG4: 125, 96, 86, 75, 55 e 47 kDa. A resposta predominante das subclasses IgG1, IgG2 e IgG3 observada nestes pacientes, todos com malária não complicada, pode indicar que esses anticorpos estão cooperando para o controle de formas graves da doença e refletirem um certo grau de desenvolvimento de imunidade adquirida / The development of naturally acquired immunity to malaria is slow and depends of several factors as number of previous malaria, interval between each malaria attack, exposure to parasite multiple antigen variant and ageassociated maturation of the immune system. Antibody-dependent effector immune mechanisms are believed to be important to the protective immunity. A number of studies have showed that anti-P. falciparum IgG1 and IG3, named cytophilic antibodies, are protective, whereas the noncytophilic, IgG4, that recognize the same epitopes may block the protective mechanisms. Recent data have suggested that in certain situations, IgG2 can also act as cytophilic and to cooperate in protection. In this work, we have studied, for the first time, the evolution of the IgG subclasses against P. falciparum blood stages in uncomplicated falciparum malaria patients taken into hospital upon mefloquine treatment and followed up 42 days. These antibodies were determined by ELISA in 48 patients (7 serum samples from each patient collected in different times: 0h, 48h, 7, 14, 28, 35 and 42 days). The results were expressed in concentration (ug/ml), index of reactivity (IR) or frequency (%) and the avidity were expressed as index of avidity (IA). Serum samples 14 patients (time of collection: 0, 48h, 7, 21 and 42 days) were also evaluated by Immunoblotting as their specificity and avidity against different proteins of the P. falciparum blood stages The subclasses Anti-P. falciparum IgG1, IgG2, IgG3 and IgG4, high avidity predominantly, were present since the beginning of the treatment, respectively, in 100%, 39,5%, 80,6% and 28,4% of the patients with the following concentrations: 20, 2; 3,8; 1,5 and 0,05 ?g/mL. The highest concentrations were reached at day 7, and IgG1 and the highest IgG3 IAs were reached at day 7, and the highest IgG2 IAs at day 14 and the highest IgG4 IAs at day 2. The initial concentration of anti-P. falciparum IgG3 showed a negative correlation with the parasitemia clearance time (PCT) and the ratio between the sum of IgG1, IgG2 and IgG3 levels to IgG4 levels was negatively correlated with the initial parasitemia. Six protein fractions were identified by the Immunoblotting that can be related to protective immune recognition, because they were recognized by IgG1, IgG2 and IgG3 antibodies and not or only later recognized by IgG4 antibodies: 125, 96, 86, 75, 55 and 47 kDa. The predominant IgG1, IgG2 and IgG3 responses observed in these uncomplicated malaria patients may suggest that these antibodies are cooperating to the control of severe disease and reflecting a certain development of protective immunity

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 4 uppsatser.

Thesis (Ph.D. (Tropical Medicine))--Mahidol University, 1999.

Thesis (M.Sc. (Tropical Medicine))--Mahidol University, 2003.

Thesis (Ph. D.)--Cornell University, January, 2009. / Vita. Includes bibliographical references (leaves 126-137).

Introduction Malaria retinopathy is a set of visible changes in the retina which are specific to falciparum malaria. Studies to date have been mostly limited to comatose African children. Retinal changes in adults with severe malaria and severely unwell patients without malaria have been less well studied and the specificity, pathogenesis, diagnostic and prognostic value of malarial retinopathy in adults are not known. Methods A series of observational studies of retinopathy in Bangladesh, India and Malaysia were done from 2008-2012. The aims were to describe the spectrum of retinal changes in falciparum and knowlesi malaria in adults, determine their specificity for severe falciparum malaria, quantify the impact of malaria retinopathy on visual function, understand its pathogenesis and assess the potential contribution of retinopathy to confirming diagnosis of malarial coma, predicting prognosis and understanding pathogenesis of cerebral malaria. Results 495 patients were enrolled and underwent retinal photography (305 with P. falciparum malaria (112 cerebral, 68 noncerebral severe, 125 uncomplicated), 44 P. knowlesi, 43 sepsis, 41 encephalopathy and 62 healthy). Retinal whitening and white-centred haemorrhages were common and specific to severe falciparum malaria. Retinopathy was most common and severe in cerebral (88%) and fatal (91%) falciparum malaria. Moderate-severe retinopathy was 95% specific for cerebral malaria in comatose patients, and its severity correlated with depth of coma. Vessel whitening was not seen and papilloedema was rare. In noncerebral severe falciparum malaria, retinopathy predicted increased likelihood of later development of coma and death. Retinal findings in Bangladeshi children were similar to those in adults. Optic nerve sheath diameter was mildly increased and brain swelling minimal on MRI. Severity of retinopathy correlated with plasma lactate, serum bicarbonate, sequestered parasite load and red cell stiffness suggesting a central role for microvascular obstruction in the pathogenesis. Severity of retinal whitening correlated with decreased visual acuity. Conclusions Retinal changes seen in severe P. falciparum malaria in Asian adults is similar, but not identical, to that seen in African children. They have potential to help with diagnosis and prognosis of Asian adults with severe falciparum malaria. Microvascular obstruction is prominent in the pathogenesis of retinopathy and coma in adults whereas raised intracranial pressure is not.

O desenvolvimento de imunidade naturalmente adquirida na malária é lento e depende de fatores como o número de malárias prévias, intervalo entre cada malária, exposição a variantes antigênicas múltiplas e idade do indivíduo. Mecanismos imunes efetores dependentes de anticorpos são importantes no desenvolvimento dessa imunidade. Vários estudos têm mostrado que as subclasses IgG1 e IgG3 anti-P. falciparum, conhecidas por sua ação citofílica, são anticorpos protetores, enquanto anticorpos não citofílicos como IgG4 reconhecendo os mesmos epítopos seriam bloqueadores dos mecanismos protetores. Dados recentes sugerem que sob determinadas condições, IgG2 também pode ter ação citoíflica e participar da proteção na malária. Neste trabalho, nós estudamos pela primeira vez, a evolução das subclasses de IgG contra formas eritrocitárias de P. falciparum de pacientes com malária falciparum não complicada internados em hospital por até 42 dias, sob tratamento com mefloquina. As subclasses de IgG foram avaliadas por ELISA em 48 pacientes (7 amostras de soro de cada um colhidas nos tempos 0h, 48h, 7, 14, 28, 35 e 42 dias), quanto à quantidade (concentração, ug/ml; índices de reatividade, IR; ou em freqüência, %) e quanto à avidez dos anticorpos (índice de avidez, IA). Amostras de soro de 14 pacientes (tempos: 0, 48h, 7, 21 e 28 dias) também foram avaliadas quanto à especificidade e a avidez de reconhecimento das diferentes bandas protéicas do antígeno de P. falciparum por Immunoblotting. As subclasses IgG1, IgG2, IgG3 e IgG4 anti-P. falciparum, na maioria de alta avidez, estavam presentes no início do tratamento, respectivamente, em 100%, 39,5%, 80,6% e 28,4% dos pacientes e com concentrações médias de 20, 2; 3,8; 1,5 e 0,05 ?g/mL. As concentrações máximas das subclasses de IgG foram alcançadas no 7o dia, e os IAs máximos de IgG1 e IgG3 foram alcançados no 7o dia, e os de IgG2 no 14o dia e os de IgG4 no 2o dia. A concentração inicial dos anticorpos IgG3 anti-P. falciparum apresentou correlação negativa com o tempo de clareamento parasitário (TCP) e a relação das somas dos anticorpos IgG1, IgG2 e IgG3 pelos níveis de IgG4 se correlacionaram negativamente com a parasitemia inicial. No Immunoblotting, foram identificadas frações protéicas que podem estar relacionadas com o reconhecimento imune protetor, por serem reconhecidas pelas subclasses IgG1, IgG2 e IgG3 e não reconhecidas ou reconhecidas tardiamente por IgG4: 125, 96, 86, 75, 55 e 47 kDa. A resposta predominante das subclasses IgG1, IgG2 e IgG3 observada nestes pacientes, todos com malária não complicada, pode indicar que esses anticorpos estão cooperando para o controle de formas graves da doença e refletirem um certo grau de desenvolvimento de imunidade adquirida / The development of naturally acquired immunity to malaria is slow and depends of several factors as number of previous malaria, interval between each malaria attack, exposure to parasite multiple antigen variant and ageassociated maturation of the immune system. Antibody-dependent effector immune mechanisms are believed to be important to the protective immunity. A number of studies have showed that anti-P. falciparum IgG1 and IG3, named cytophilic antibodies, are protective, whereas the noncytophilic, IgG4, that recognize the same epitopes may block the protective mechanisms. Recent data have suggested that in certain situations, IgG2 can also act as cytophilic and to cooperate in protection. In this work, we have studied, for the first time, the evolution of the IgG subclasses against P. falciparum blood stages in uncomplicated falciparum malaria patients taken into hospital upon mefloquine treatment and followed up 42 days. These antibodies were determined by ELISA in 48 patients (7 serum samples from each patient collected in different times: 0h, 48h, 7, 14, 28, 35 and 42 days). The results were expressed in concentration (ug/ml), index of reactivity (IR) or frequency (%) and the avidity were expressed as index of avidity (IA). Serum samples 14 patients (time of collection: 0, 48h, 7, 21 and 42 days) were also evaluated by Immunoblotting as their specificity and avidity against different proteins of the P. falciparum blood stages The subclasses Anti-P. falciparum IgG1, IgG2, IgG3 and IgG4, high avidity predominantly, were present since the beginning of the treatment, respectively, in 100%, 39,5%, 80,6% and 28,4% of the patients with the following concentrations: 20, 2; 3,8; 1,5 and 0,05 ?g/mL. The highest concentrations were reached at day 7, and IgG1 and the highest IgG3 IAs were reached at day 7, and the highest IgG2 IAs at day 14 and the highest IgG4 IAs at day 2. The initial concentration of anti-P. falciparum IgG3 showed a negative correlation with the parasitemia clearance time (PCT) and the ratio between the sum of IgG1, IgG2 and IgG3 levels to IgG4 levels was negatively correlated with the initial parasitemia. Six protein fractions were identified by the Immunoblotting that can be related to protective immune recognition, because they were recognized by IgG1, IgG2 and IgG3 antibodies and not or only later recognized by IgG4 antibodies: 125, 96, 86, 75, 55 and 47 kDa. The predominant IgG1, IgG2 and IgG3 responses observed in these uncomplicated malaria patients may suggest that these antibodies are cooperating to the control of severe disease and reflecting a certain development of protective immunity

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Stockholms universitet, 2008. / Härtill 5 uppsatser.