Cardiopulmonary effects of recombinant interleukin-2 infusion in sheep

The systemic administration of recombinant interleukin-2 (rIL-2) with or without lymphokine-activated killer (LAK) cells, a new treatment for patients with advanced cancer, is associated with a presumed "third-space" syndrome. To further define the extent and time course of this toxicity, we established a chronic sheep model and monitored changes in systemic and central vascular pressures, cardiac function, and gas exchange during a 72-h continuous intravenous infusion of rIL-2 at a total dose of 5 (group 3) or 9 x 10(5) U/kg (group 4). At 72 h, caudal mediastinal lymph flow, histology, and extravascular lung water-to-dry lung weight ratio (EVLW/DLW) were obtained. During the rIL-2 infusion there was a dose-dependent significant decrease in systemic blood pressure and arterial Po2 and an increase in core temperature. In group 4, pulmonary arterial pressure increased from a base line of 13 ± 5 to 21 ± 6 mmHg (P less than 0.05). Lung lymph flow was significantly increased in groups 3 and 4 compared with animals receiving 0.9% NaCl or excipient infusions (groups 1 and 2). EVLW/DLW values were elevated in groups 3 and 4 (P less than 0.01). In animals receiving rIL-2, histological evaluation revealed a dose-dependent infiltration of lung tissue by lymphoblastoid cells that stained esterase negative. We conclude that rIL-2 infusion in doses comparable to those given to humans results in alterations in systemic and central hemodynamics, gas exchange, high-protein lung lymph flow, and infiltration of lymphoblastoid cells into the lung parenchyma.