RESUMO
This study dealt with the in vivo determination and distribution of Fc gamma receptors on macrophage, and the fibronectin expression by macrophage, in liver granuloma, in the acute [8 weeks] and chronic [20 weeks] stages of Schistosoma mansoni infection in mice. The application of electron microscopic immunoperoxidase technique delineated the location and distribution of Fc gamma receptors on macrophage surface membrane in both acute and chronic immunomodulated granuloma. In the acute granuloma, it revealed an increased density of Fc gamma receptors on macrophage surface denoting its activation. Whereas in chronic granuloma the Fc gamma receptors on macrophage were demonstrated to be less dense. This diminished expression can be taken as a monitor of immunomodulation and is attributed to diminished expression of the receptors on the macrophage surface itself and not only to decrease in number of cells. Immunoelectron labelling of tissue fibronectin displayed intracellular deposition in macrophage, endothelial cells and fibroblast cells in the 8 weeks granuloma. It decreased in the immunomodulated granuloma in correlation with Fc gamma receptors. Thus understanding of the complex interactions between Fc gamma receptors, fibronectin and macrophage may be helpful in attempts to manipulate fibrous tissue deposition in granulomatous lesions