RESUMO
Objective: To understand the relationship between chloroquine resistance and the virulence of Plasmodium berghei. Met hods: Dynamic changes of histopathologic features of livers, spleens, brains, hearts, lungs and kidneys of mice infected with the chloroquine-sensitive (N) and the chloroquine-resistant (RC) strains of P. berghei were compared. Results: In mice infected with the N strain, deposition of heavy hemoz oin in livers and spleens, congestive edema in lungs, and congestion and embolis m in the brain capillaries were observed. The histopathologic features revealed ac ute inflammatory reaction. In mice infected with the RC strain, histopathologic variations of livers and spleens were associated with changes of parasitemia. In terstitial pneumonia was displayed in lungs. There were chronic histopathologic changes of the organs in the mice infected with RC strain. Conclusion: The mice infected by the N strain with potent virulence die due to adher ence of the erythrocytes to microvascular endothelia and embolism of the microva scula, especially in their brain. Immune responses of the mice infected by the R C strain with poor virulence may be a delayed-type hypersensitive inflammation a ssociated with CD4+Th1 at an early stage of the infection, but may become anti body-dependent immune response assisted with CD4+Th2, which play a key role in elimination of the malaria parasites at later stage of the infection.
RESUMO
Objective: To understand the relationship between chloroquine resistance and the virulence of Plasmodium berghei. Met hods: Dynamic changes of histopathologic features of livers, spleens, brains, hearts, lungs and kidneys of mice infected with the chloroquine-sensitive (N) and the chloroquine-resistant (RC) strains of P. berghei were compared. Results: In mice infected with the N strain, deposition of heavy hemoz oin in livers and spleens, congestive edema in lungs, and congestion and embolis m in the brain capillaries were observed. The histopathologic features revealed ac ute inflammatory reaction. In mice infected with the RC strain, histopathologic variations of livers and spleens were associated with changes of parasitemia. In terstitial pneumonia was displayed in lungs. There were chronic histopathologic changes of the organs in the mice infected with RC strain. Conclusion: The mice infected by the N strain with potent virulence die due to adher ence of the erythrocytes to microvascular endothelia and embolism of the microva scula, especially in their brain. Immune responses of the mice infected by the R C strain with poor virulence may be a delayed-type hypersensitive inflammation a ssociated with CD4+Th1 at an early stage of the infection, but may become anti body-dependent immune response assisted with CD4+Th2, which play a key role in elimination of the malaria parasites at later stage of the infection.