Antibody-dependent cellular cytotoxicity mediated by plasma obtained before secondary dengue virus infections: potential involvement in early control of viral replication.

BACKGROUND

Preexisting dengue virus (DV)-specific antibodies from prior heterologous DV infection may have several effects in secondary DV infection. These antibodies may mediate protective effects by means of antibody-dependent cellular cytotoxicity (ADCC), in which virus-specific antibodies bind to the surface of heterologous DV-infected cells and mediate natural killer cell lysis. In the present study, we examined the ability of plasma obtained before secondary DV infection to induce ADCC of DV-infected cells.

METHODS

Plasma samples were obtained before DV2 or DV3 infection in a prospective cohort study of Thai schoolchildren. The ADCC activity in the plasma samples was measured by (51)Cr-release assay, using persistently DV2- or DV3-infected Raji cells as targets.

RESULTS

ADCC activity in plasma obtained before secondary infection directly correlated with neutralizing antibody titers, anti-DV immunoglobulin G1 levels, and a multitypic 50% plaque reduction neutralization test pattern. ADCC activity in pre-secondary DV3 infection plasma samples inversely correlated with plasma viremia levels, but no such correlation was seen in pre-secondary DV2 infection plasma samples. ADCC activity did not correlate with disease severity in subsequent secondary DV2 or DV3 infection but was lowest in plasma from patients with dengue hemorrhagic fever due to secondary DV3 infection.

CONCLUSIONS

ADCC may contribute to the early control of secondary DV3 viremia in vivo.