Evidence for the participation of mast cells in the innate resistance of mice to Schistosoma mansoni: effects on in vivo treatment with the ionophore 48-80

1. Evidence is presented for the participation of mast cells in the resistance of mice to infection by Schistosoma mansoni. 2. Intravenous injection of 1 microng/g body of the ionophore 48-80, a potent mast cell degranulator, significantly reduced (42-62%) the histamine content of the ear tisse of normal mice and either inceased or decreased resistance to parasite penetration and infection depending on whether the injection of the ionophore was i min or 2 days before cervarial penetration. 3. When 48-80 was injected 5 min before the benning of cercarial penetration, the number of parasites recovered from ear tissue 2 days later or from the portal system 30 days later was significantly reduced (39-71% and 27-40%, respectively) in relation to untreated controls. This resistance caused by 48-80 was blocked when mice were simultaneously treated with cyproheptadine, an antagonist of vasoactive amines. 4. In contrast, when 48-80 was administered 2 days before the beginning of cercarial penetration, the number of parasites retrieved from ear tissue 2 days later or from the portal system 30 days later was 32-64% and 28-30% larger, respectively, in relation to untreated controls. 5. These findings indicate that the local inflammatory reaction mediated by mast cells is important in the resistance of mice to infection with S. mansoni

Aural myiasis caused by wohlfahrtia magnifica

A case recorded of aural myiasis caused by Wohlfahrtia magnifica