Abstract
Inverse anaphylaxis was produced in guinea pigs by the injection of anti-guinea pig-rabbit serum or anti-sheep hemolysin (the Forssman antigen being common in guinea pigs and sheep). A decrease of whole blood histamine was noted, this being parallel with a decrease of circulating leukocytes and thrombocytes. At the same time plasma histamine levels rose. Leukocytes disappeared in the pulmonary circulation. Pulmonary histamine levels decreased, then rose.