The effect of Escherichia coli endotoxin on plasma histaminase activity in the domestic fowl and the involvement of caeruloplasmin.

The injection of four-to nine-week-old fowls with Escherichia coli O111:B4 endotoxin (0-1 and 1-0 mg/kg) produced a two to eight fold rise in the histaminase activity of the plasma 24 h afterwards. In some cases this increase was still detectable after 48 h. This activity was strongly correlated with the p-phenylenediamine oxidase activity of caeruloplasmin. Electrophoretic studies with 7-5 per cent polyacrylamide gels indicated that fowl caeruloplasmin also was histaminase and putrescinase activity and that the release of this protein from the liver by endotoxin is largely responsible for the increase in the activity of the plasma. In untreated fowls this activity was lower than published values for several mammals and does not explain the relative resistance of the fowl to the acute effects of endotoxins and large doses of histamine.