Modulation of antibody response to sheep red blood cells by cyclophosphamide in Calomys callosus (Rodentia)

1. Calomys callosus, a wild rodent reservoir of Trypanosoma cruz, notably resistent to laboratory infection with this parasite, is currently under study as a new experimetnal model for Chagas' disease. 2. To investigate the humoral response of C. callosus, rodents were injected with sheep red blood dells (SRBC) and the resulting antibody titers measured 0,5,9,14,20,27 and 37 days later by direct agglutination test. 3. Modulation of the antibody response by cyclophosphamide (Cy) was also studied, showing that the administration of 400 or 200 mg Cy/Kg body weight one day prior to SRBC inoculation significantly lower than those of controls on the 5th day after SRBC inoculation; subsequent differences were not statistically significant. 4. When SRBC were injected 5 or 10 days after Cy administration, the same effect was observed, indicating that the time of antigen inoculation is important in antibody modulation. A second dose of 200 mg Cy/Kg on day 5 resulted in significant antibody suppression up to the 37 th day. The administration of 20mg Cy/Kg resulted in a slight antibody enhancement seen on the 5 th day after SEBC inoculation given on day O. 5. These data demonstrate that cyclophosphamide modulates the T-dependent antibody response in C. callosus in a manner similar to the mouse model

Trypanosoma cruzi interaction with macrophages: differences between tissue culture and blodstream forms.

Macrofagos obtidos do peritoneo de camundongos apos estimulo, com peptona, foram cultivados em laminulas, infectados com tripomastigotas das cepas F y Y de T. cruzi, obtidos de cultivo de tecidos ou do sangue de camundongos infectados. Os parasitas, obtidos de cultivo de tecidos, tanto da cepa Y como os da cepa F, sao interiorizados por macrofagos em proporcao muito mais elevada do que os sanguicolas.Parasitas de cultivo de tecidos incubados com soro de camundongos normais, ou soro hiperimune especifico em diluicao subaglutinante, comportam-se esencialmente como parasitas nao opsonizados. Foram observadas diferencas a nivel ultraestrutural na fase inicial de interacao entre macrofagos e tripomastigotas das duas origens. Apos 30 minutos, tripomastigotas de cultivo de tecidos localizam-se em agrupamentos na area de contato com os macrofagos. Enquanto os tripomastigotas sanguicolas estao na maioria das vezes no interior de vacuolos fagociticos largos, apos 3 horas de interacao os tripomastigotas de cultura situam-se em um unico vacuolo estreito. Tanto as formas de cultivo de tecidos quanto os tripomastigotas sanguicolas de cepa Y multiplicam-se em macrofagos; os tripomastigotas sanguicolas da cepa F sao destruidos no interior da celula hospedeira, enquanto os tripomastigotas de cultivo de tecidos desta cepa sao capazes de multiplicar-se

Macrophage-trypanosome infection. Dead and live cell scoring.

Descreve-se uma tecnica, usando azul de tripano e posterior fixacao, que permite visualizacao perfeita de T. cruzi no interior de macrofagos e ao mesmo tempo a distincao entre celulas hospedeiras vivas e mortas