Cytokine and Chemokine Responses in Human Herpesvirus 8 Infection of Monocyte Derived Dendritic Cells and B Lymphocytes

Human herpesvirus-8 induces a wide range of inflammatory immune mediators known to contribute to its associated cancer, Kaposi’s Sarcoma (KS). Soluble immune mediators, such as cytokines, chemokines and growth factors produced during HHV-8 infection have been associated with tumor-cell proliferation, angiogenesis and vascular permeability. We sought to determine immune mediator production by two antigen presenting cells (APC) that are susceptible to HHV-8 infection, i.e., monocyte derived Dendritic cells (MDDC) and B lymphocytes. \ud Dendritic cells abundantly express the HHV-8 receptor, type II C-type lectin, DC-specific ICAM-3 grabbing nonintegrin (DC-SIGN) resulting in viral entry, whereas only a small percentage of activated B cells express DC-SIGN in vitro. Despite this, HHV-8 infection of MDDC results in an abortive replicative cycle, whereas full-lytic cycle replication occurs in the B cells. I hypothesized that immune mediators produced by HHV-8 infected APC are unique between cell types and that HHV-8 infects a subset of B cells and initiates cytokine and chemokine production that contributes to HHV-8 replication, viral dissemination and initiation of KS and HHV-8 lymphomas.\ud I used a cytometric bead array to determine cytokine and chemokine production in B cells and MDDC, as well as qRT-PCR, TCID50 assay and flow cytometry to determine HHV-8 replication in B cells. I identified significant differences in the quality and quantity of cytokine and chemokine profiles of HHV-8 infected APC. MDDC produced significant levels of MCP-1, MIP-1α, MIP-1β, RANTES, IP-10 and IL-10, while B cells produced significant levels of MIP-1α, MIP-1β, IL-6, TNF-α and IL-8. HHV-8 lytic replication in B cells resulted in polyfunctional immune mediator activity that may contribute to viral replication and proliferation of target cell populations in HHV-8 related cancers. The importance of this work was demonstrated by the detection of B cell-produced cytokines and chemokines in HHV-8/HIV co-infected individuals who developed KS. This is the first extensive, multiparameter, longitudinal study of HHV-8 infection of B cells and immune mediators in development of KS. This study provides novel targets for vaccine development and treatment options for KS, which could have great implications on Public Health