Human herpesvirus 8 (HHV-8) has been associated with classical, endemic (African), and AIDS-related Kaposi's sarcoma (KS), body cavity-based primary effusion lymphomas, and multicentric Castleman's disease (MCD). This antibody recognizes HHV-8 interleukin-6 (IL-6) is a cytokine that promotes the growth of KS and myeloma cells and is found at elevated levels in MCD lesions and patient sera.