Human Immune Responses to Dengue Viruses.

Severe complications are commonly observed in individuals undergoing a secondary dengue infection with a different dengue virus serotype than experienced as the primary infection. Thus, it is important to understand the mechanism(s) of immunologic sensitization which appear to result in more severe subsequent dengue infections. We are developing techniques for detecting viral-specific and non-specific lytic destruction of cells infected with dengue virus. A persistently infected human lymphoblastoid cell line has been developed and used as the target cell system for detecting antibody-dependent cell mediated cytotoxicity (ADCC), and to detect complement-dependent antibody-mediated lysis of dengue virus infected cells. These assays presently, use dengue-type 2 virus infected Raji cells as target cells. Peripheral blood mononuclear cells (PBMC) from humans without antibodies to dengue 2 virus lysed dengue 2 virus-infected Raji cells to a significantly greater degree than uninfected Raji cells. Addition of mouse antidengue antibody increased the lysis of dengue-infected Raji cells by PBMC. Dengue 2 immune human sera also increased lysis of dengue-infected Raji cells by PMBC. These results indicate that both PBMC-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) can cause significant lysis of dengue-infected Raji cells.