Depletion of CD25+ cells during acute toxoplasmosis does not significantly increase mortality in Swiss OF1 mice

The interleukin (IL)-2R alpha chain (CD25) is expressed on regulatory T cells (Treg), which constitute more than 85 percent of the CD25+ T cell population in a naïve mouse. CD25 is also expressed on effector T cells in mice suffering from an acute infection by the obligate intracellular protozoan parasite, Toxoplasma gondii. Lethal toxoplasmosis is accompanied by a significant loss of Treg in mice naturally susceptible to toxoplasmosis. The present study was done to explore the role of Treg cells using an anti-CD25 antibody-mediated depletion in mice naturally resistant to toxoplasmosis. Although a significant decrease in the percentage of Treg cells was observed following anti-CD25 monoclonal antibody injections, the depletion of CD25+ cells during acute toxoplasmosis did not significantly increase the mortality of Swiss OF1 mice and no significant difference was observed in the brain parasitic load between the mice in the depleted-infected and isotype-infected groups. We found no significant difference between the titres of total IgG in the sera of the mice from the two groups in the chronic phase. However, CD25+ cells depletion was followed by significantly higher levels of IL-12 in the serum of depleted mice than in that of mice injected with the isotype control antibody.

Diagnosis of disseminated toxoplasmosis by polymerase chain reaction in bronchoalveolar lavage fluid of a patient with aids / Diagnóstico de toxoplasmose disseminada através de técnica de reação em cadeia da polimerase realizada no lavado bronco-alveolar de paciente com sida

Pulmonary toxoplasmosis is a challenging diagnosis in immunosuppressed patients with nonspecific clinical picture and radiologic findings. We present a case of pneumonia due to Toxoplasma gondii diagnosed by polymerase chain reaction (PCR) in the bronchoalveolar lavage (BAL) fluid of a patient with acquired immunodeficiency syndrome (AIDS). Coinfection with Pneumocystis jirovecii was found in the same specimen. Direct examination and culture for bacteria, mycobacteria and other fungus were negative. Despite the intensive management, respiratory compromise evolved rapidly, with the need for ventilatory support. Acute respiratory distress syndrome developed, and the patient died of multiple organ failure. This case illustrates that a high index of suspicion is necessary for diagnosis of pulmonary toxoplasmosis, a potentially fatal condition. Due to high diagnostic performance, PCR in BAL fluid should be included in the evaluation of immunosuppressed patients with nonspecific pulmonary diseases.

O diagnóstico de toxoplasmose pulmonar em pacientes imunossuprimidos é difícil, devido ao quadro clínico e aos achados radiológicos inespecíficos. Neste artigo, relatamos o caso de uma paciente com síndrome da imunodeficiência adquirida (SIDA), que apresentou pneumonia por Toxoplasma gondii diagnosticada através de reação em cadeia da polimerase (PCR) no lavado bronco-alveolar (LBA). A paciente apresentava co-infecção com Pneumocystis jirovecii. Os demais exames microbiológicos, como bacterioscópico, cultural para bactérias, micobactérias e fungos, foram negativos. Apesar do manejo intensivo, a paciente evoluiu com síndrome do desconforto respiratório agudo e óbito por falência múltipla dos órgãos. Este caso demonstra que um alto índice de suspeita clínica é necessário para o diagnóstico de pneumonia por Toxoplasma gondii. Devido ao seu desempenho diagnóstico, o PCR para Toxoplasma gondii no LBA deve ser incluído na avaliação de pacientes imunossuprimidos com quadros pulmonares inespecíficos.

Age influence in the natural resistance of white rat and mice to the protozoan Toxoplasma gondii

Groups of 1, 5, 10, 15 and 30 day old rats (Sprague Dawley) and Wistar mice were infected per os with different inocula of Toxoplasma gondii oocysts from an avirulent strain. Infection pattern was followed by determination of survival time, tissue lesions, parasite presence and serology. Although all the animals survived the total experimental period (30 day), there were important differences between both rodents regarding to Toxoplasma natural resistance. Brain cysts, as well as tachyzoites in other organs were regularly present in mice but not in rats. On the other hand, most of the organs from mice presented characteristic T. gondii lesions, while in rats a normal tissues were observed, with the exception of an acute reaction found in the brain of a 15d old animal

Prevalencia da Encefalite por Toxoplasma em pacientes com SIDA no Hospital de Clinicas de Porto Alegre / Prevalence of toxoplasmic encephalitis in patients eith AIDS in Hospital de Clinicas de Porto Alegre

Com o objetivo de determinar a prevalencia da encefalite por toxoplasma (ET) em pacientes com SIDA, em nosso meio, bem como descrever o perfil sorologico antitoxoplasma desta populacao, revisaram-se 313 prontuarios de pacientes portadores do virus da imunodeficiencia humana (VIH) internados entre maio/85 e dezembro/89. A prevalencia presuntiva (por achados tomograficos) foi de 8,9% (28 casos). Em 192 pacientes foram dosados anticorpos antitoxoplasma (IgG) no sangue; destes 65,6% foram reagentes. Vinte e sete pacientes com ET tinham dosagem de anticorpos antitoxoplasma no sangue, sendo 26 reagentes. Quinze pacientes com ET tinham dosagem de anticorpos antitoxoplasma no sangue, sendo 26 reagentes. Quinze pacientes com ET tinham dosagem de anticorpos antitoxoplasma no liquor sendo 14 reagentes. Concluimos que a prevalencia da ET, em pacientes com SIDA, em nosso meio, e semelhante a descrita na literatura, e que maiores esforcos se devem empregar para a obtencao de material (por biopsia ou necropsia)a fim de firmar o diagnostico definitivo