[Pulmonary hypertensive responses to erythrocytes components in sensitized rabbits]

Antigen erythrocytes cause a transient pulmonary hypertension in sensitized rabbits. We investigated the main responsible component in the antigen erythrocytes. Eleven rabbits were immunized intravenously with human O-N type erythrocytes every ten days until the agglutinin titer = 1:8,000 was obtained. Another ten rabbits without immunization served as a control group. Human erythrocytes were osmolitically hemolyzed and then separated into hemoglobin and membrane components by centrifugation. In sensitized rabbits, a bolus injection of human hemoglobin 0.7 ml.kg-1 caused increases in pulmonary arterial and airway pressures within 3-4 min. Increase in pulmonary arterial pressure after injection of hemoglobin component was significantly higher than that after injection of membrane component in sensitized rabbits. However, in nonsensitized rabbits both components were ineffective. Leukocytes counts decreased by 73-62% in sensitized rabbit, while they decreased by 16-37% in nonsensitized rabbits 5 min after injection of hemoglobin or membrane component. Platelets decreased by 54-61% in sensitized rabbits, while they decreased by 24-9% in nonsensitized rabbits 5 min after injection of hemoglobin or membrane component. We conclude that hemoglobin is the responsible component in the antigen erythrocytes and chemical mediators, such as thromboxane and platelet activating factor, may not be released from platelets and leukocytes.