Effect of dengue virus-induced cytotoxin on capillary permeability

Capillary permeability is increased in cases of dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) but its genesis is not known. Dengue type 2 virus (DV) induces production of a cytokine (CF2) by mouse macrophages. The present study was undertaken to investigate the effect of CF2 on capillary permeability. It was observed that intraperitoneal inoculation of CF2 in mice increased the capillary permeability in a dose-dependent manner, as shown by leakage of intravenously injected radioactive iodine (125I) or Evan's blue dye in the peritoneal cavity. Peak leakage occurred at 30 min and the vascular integrity was restored by 1-2 h. The increase in capillary permeability was abrogated by pretreatment of mice with avil (H1 receptor blocker) but not by ranitidine (H2 receptor blocker). The findings thus show that DV-induced CF2 increases the capillary permeability via release of histamine.