PURIFICATION AND PATHOGENICITY OF THE CYTOTOXIC FACTOR FROM THE CASESOF DENGUE HEMORRHAGIC-FEVER

Pathogenesis of dengue haemorrhagic fever/dengue shock syndrome (DHF/D SS) is not yet clear in spite of extensive efforts. Here we report the discovery of a cytotoxic cytokine (hCF) in the sera of the patients w ith DHF/DSS which is capable of increasing vascular permeability in mi ce. The presence of hCF was detected in the sera of the cases of DHF b y dot blot test. hCF was purified from the sera of 34 dot blot-positiv e patients of DHF by ion-exchange chromatography followed by high perf ormance liquid chromatography. The eluted hCF was cytotoxic to normal mouse spleen cells, had a molecular weight of 43 kD and an isoelectric point of pH 4.5-5. It reacted in dot blot and Western blot tests with anti-mouse cytotoxic factor (mCF) and anti-hCF-antisera. The effect o f hCF on the capillary permeability and the blood-brain barrier of mic e was investigated using leakage of Evans blue dye-bound plasma protei ns. It was observed that inoculation of the hCF in mice increased the capillary permeability and damaged the blood-brain barrier in a dose-d ependent manner. This is the first evidence of the presence of cytotox ic factor (hCF), a homologue of mCF, in the sera of the cases of DHF/D SS which can cause reversible damage to capillaries.