Inability of Rat Anaphylatoxin to Induce Histamine Release in Rats

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Abstract
The role of rat anaphylatoxin in histamine release and increased vascular permeability during the first 30 min period in zymosan-air-pouch inflammation, an experimental model of inflammation induced by zymosan in an air-pouch prepared on the back of rats, was investigated. Complement depletion by cobra venom factor did not affect the histamine release nor the increased vascular permeability in the inflammation of this type. In spite of apparent anaphylatoxin activity, zymosan activated serum (ZAS) failed to cause any significant release of histamine when infused in the air-pouch on the back. Anaphylatoxin purified from rat serum activated with zymosan in the presence of an inhibitor (.epsilon.-aminocaproic acid) of anaphylatoxin inactivator gave a single band in both polyacrylamide gel electrophoresis (PAGE) and [sodium dodecyl sulfate] SDS-PAGE. The MW estimated by SDS-PAGE was .apprx. 7000. The purified rat anaphylatoxin failed to induce histamine release nor increased vascular permeability even at 50 .mu.g/ml, although it caused contraction of guinea pig ileum at 0.8 .mu.g/ml. Apparently, rat anaphylatoxin does not participate in histamine release and increased vascular permeability in the zymosan-air-pouch inflammation.