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 micrograms/g body weight of the ionophore 48-80, a potent mast cell degranulator, significantly reduced (42-62%) the histamine content of the ear tissue of normal mice and either increased or decreased resistance to parasite penetration and infection depending on whether the injection of the ionophore was 5 min or 2 days before cercarial penetration. 3. When 48-80 was injected 5 min before the beginning 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.
Gerken
S E
SE
Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
Mota-Santos
T A
TA
Vaz
N M
NM
D000818:Animals; D007113:Immunity, Innate / Q000187:drug effects; D008297:Male; D008407:Mast Cells / Q000276:immunology*; D051379:Mice; D011292:Premedication; D012550:Schistosoma mansoni / Q000302:isolation & purification; D012555:Schistosomiasis mansoni / Q000276:immunology*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology*
D003189:p-Methoxy-N-methylphenethylamine