Increased capillary permeability mediated by a dengue virus-induced lymphokine

Abstract

The mechanism of increased capillary permeability, seen in cases of dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), is not known. Dengue type 2 virus (DV) is known to induce production of a lymphokine, the cytotoxic factor (CF), by the T lymphocytes ofmouse spleen. The data presented here show that intraperitoneal inoculation of CF in mice results in increased capillary permeability in a dose-dependent manner, as shown by leakage of intravenously injected radiolabelled iodine (¹²⁵1) or Evans blue dye. Peak leakage occurred 30 min after inoculation of CF and the vascular integrity was restored by 2 hr. The increase in capillary permeability was abrogated by pretreatment ofmice with anti-CF antibodies, avil (HI receptor blocker) or ranitidine (H₂ receptor blocker). The findings thus show that a DV-induced lymphokine, the CF, increases the capillary permeability via release of histamine.