Effects of interleukin-2 on pulmonary and systemic transvascular fluid filtration

Interleukin-2 (IL-2) therapy for patients with advanced cancer may be compromised by dose-limiting and life-threatening pulmonary and systemic edema. We studied the effects of bolus IL-2 infusion on lung and soft-tissue transvascular fluid and protein filtration in six sheep with chronic lung and soft-tissue lymphatic cannulation. Changes in lung (QL) and soft-tissue (QS) lymph flow were used as indicators of transvascular fluid filtration. A dose of 100,000 U/kg IL-2 was administered every 8 hours for 3 days. A significant increase (p less than or equal to 0.05) in both QL and QS was observed after each IL-2 infusion, with maximal flow occurring 2 to 3 hours after infusion. After 72 hours of IL-2 infusion, a fourfold maximal increase in QL occurred, which recovered to near-baseline values within 24 hours. Elevations in QL and QS were not associated with increases in pulmonary arterial or pulmonary arterial wedge pressures, but these elevations were associated with significant (p less than or equal to 0.05) increases in cardiac output (7.7 +/- 0.5 to 11.4 +/- 0.4 L/min) and a consistent decrease in systemic vascular resistance. A significant increase in lung lymph/plasma protein ratio (0.49 +/- 0.06 to 0.93 +/- 0.04 for albumin) revealed a marked increase in pulmonary microvascular porosity. This change, however, was not observed in the systemic microcirculation. Serum concentrations of tumor necrosis factor did not increase with the observed changes in pulmonary microvascular porosity. We conclude that IL-2 increases both pulmonary and systemic microvascular fluid flux. In addition, there is a marked increase in pulmonary, but not systemic, protein permeability that is not a consequence of changes mediated by tumor necrosis factor.