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Angiotensin II (AII), a product of rennin-angiotensin system, exerts an important role on the function of immune system cells. In this study, the effect of AII on the phagocytic activity of mouse peritoneal macrophages was assessed. Mice peritoneal macrophages were cultured for 48 h and the influence of different concentrations of AII (10(-14) to 10(-7) M) and/or losartan, 10(-16) to 10(-6) M), an AT1 angiotensin receptor antagonist, on phagocytic activity and superoxide anion production was determined. Dimethylthiazoldiphenyltetrazolium bromide reduction and the nucleic acid content were used to assess the cvtotoxicity of losartan. A stimulatory effect on phagocytic activity (P < 0.05) was observed with 10(-13) M and 10(-12 M) AII concentrations. The addition of losartan (up to10(-14) M) to the cell cultures blocked (P < 0.001) the phagocytosis indicating the involvement of AT1 receptors. In contrast, superoxide anion production was not affected by AII or losartan. The existence of AT1 and AT2 receptors in peritoneal macrophages was demonstrated by immunofluorescence microscopy. These results support the hypothesis that AII receptors can modulate murine macrophage activity and phagocytosis, and suggest that AII may have a therapeutic role as an immunomodulatory agent in modifying the host resistance to infection.

A study of the local and migratory effects of free silicone gel taken from a mammary prosthesis is reported. Thirty eight Wistar rats were injected in their subcutaneous space with 1 cm3 of silicone gel. The animals were sacrificed on day: 3, 7, 15, 30, 60, 180, 240, 360, 420, 450. The visceral organs (heart, kidneys, lungs, stomach, gonads, liver, pancreas, spleen, intestine), as well as the tissue adjacent to the region of injection, were histologically analyzed. There was no detectable silicone and no damage to the visceral organs based on routine histopathological analysis. The greatest fibrosis was observed at the extremities of the disk formed by the silicone in the subcutaneous space.

Wistar rats were used to study the effects, if any, of membrane thickness and implant volume of a silicone gel prosthesis on the development of fibrous capsule contraction. A total of 30 miniprosthesis with three different membrane thicknesses and two different volumes were implanted in the subcutaneous space of five animals. One hundred eighty days later the fibrous capsule was resected and histologically analyzed. Different grades of thickness were observed. The statistical analysis of the data indicates that the thickness of the prosthesis' membrane and the implant's volume did not impact significantly on the grade of fibrosis.