Experimental paracoccidioidomycosis in high and low antibody responder mice of Selection IV-A.
High (H) and low (L) responder mice were selected for their ability to produce antibodies against sheep and human erythrocytes (Selection IV-A). In this selection, the difference in antibody responsiveness between H and L lines (HIV-A and LIV-A mice, respectively) was shown to depend mainly on macrophage function. The more rapid catabolism of antigens by macrophages in L mice has been suggested as the main cause of the low antibody production. Due to this high macrophage activity, L animals have been described as more resistant than H animals to intracellular pathogens. These animals were utilized as an experimental model of paracoccidioidomycosis. HIV-A and LIV-A mice were infected with Paracoccidioides brasiliensis by the intravenous route. As expected, H mice were more susceptible to P. brasiliensis with a shorter survival time and higher levels of specific antibodies when compared to L mice. Contrasting with the survival time, the lungs, spleen and liver from H mice showed typical nodular granulomas containing epithelioid and giant cells and few fungi. On the other hand, in LIV-A mice, the lesions of these organs were characterized by looser granulomas with irregular borders and the presence of a large number of fungi. However, the adrenal gland showed different lesion patterns. In H mice these lesions were extensive and characterized by loose granulomas with numerous fungi, while in LIV-A mice the lesions were small and limited to the cortex. Moreover the HIV-A mice presented higher levels of serum corticosterone when compared to LIV-A ones. The higher susceptibility of H mice could be attributed to the extensive lesions of the adrenal glands. These results suggest the use of the H line from the IV-A Selection as an experimental model for further studies of adrenal involvement in paracoccidioidomycosis.
Soares
A M
AM
Department of Microbiology and Immunology, Biosciences Institute, UNESP, SP, Brazil. microimunologia@ibb.unesp.br
Rezkallah-Iwasso
M T
MT
Oliveira
S L
SL
Peraçoli
M T
MT
Montenegro
M R
MR
Musatti
C C
CC
D000311:Adrenal Glands / Q000473:pathology; D000818:Animals; D000908:Antibodies, Fungal / Q000097:blood; D000918:Antibody Specificity; D003345:Corticosterone / Q000097:blood; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D008099:Liver / Q000473:pathology; D008168:Lung / Q000473:pathology; D008297:Male; D051379:Mice; D010229:Paracoccidioidomycosis / Q000276:immunology* / Q000401:mortality / Q000473:pathology
D000908:Antibodies, Fungal; D003345:Corticosterone