Detection of viral interleukin-6 in Kaposi sarcoma–associated herpesvirus–linked disorders

Expression of a viral interleukin-6 (vIL-6) has been detected in certain Kaposi sarcoma (KS)–associated herpesvirus positive (KSHV+) lesions. The release of vIL-6 systemically and its contribution to the pathogenesis of HIV-related malignancies was studied. Serum vIL-6 was detected in 13 (38.2%) of 34 HIV+ patients with KS, in 6 (85.7%) of 7 HIV+patients with primary effusion lymphoma (PEL) and/or multicentric Castleman disease (MCD), and in 18 (60.0%) of 30 HIV+, mostly homosexual, individuals without KS, MCD, or PEL. By contrast, serum vIL-6 was detected in only 3 (23.1%) of 13 patients with classic KS, 1 (2.5%) of 40 blood donors from the United States, and 4 (19.0%) of 21 blood donors from Italy. Circulating vIL-6 levels were associated with HIV+ status (P < .0001). However, within the HIV+ cohort, serum vIL-6 levels were not associated with the occurrence of KSHV-associated malignancies (P = .43).