HHV-8 is not a cofactor in the pathogenesis of environmentally induced malignant pleural mesothelioma

After the recognition of human herpes virus 8 (HHV-8) in Kaposi's sarcoma lesions, this new virus has been shown to be associated with various types of malignancy. One of them, body cavity-based lymphoma, is a high grade B-cell lymphoma arising from the body cavities. Similarly, mesothelioma is a tumour that originates from the serosal linings of the pleural, pericardial and peritoneal cavities. One of the striking characteristics of mesothelioma cells is the secretion of interleukin-6 (IL-6). Also, it is known that HHV-8 upregulates the levels of IL-6, and this virally originated IL-6 is a well-established growth factor for HHV-8-associated lesions. Therefore, it was hypothesized that HHV-8 may have a role in the pathogenesis of malignant mesothelioma. Twenty-nine pleural biopsy specimens from environmentally induced malignant mesothelioma patients were investigated for the presence of HHV-8 deoxyribonucleic acid (DNA) using the polymerase chain reaction (PCR). Control pleural samples were collected from 15 biopsy specimens from patients with tuberculosis. From all samples, a segment of the beta-globulin gene was amplified in order to make sure that the DNA was extracted properly and did not contain any inhibitors. The specificity of the PCR amplification was confirmed by means of restriction enzyme analysis using Providencia stuartii I. PCR did not reveal HHV-8 DNA in any of the mesothelioma patients or in the control group. It was possible to amplify a segment of the human beta-globulin gene from all the samples of the patient and control groups. HHV-8 DNA was amplified in the control sample, which was a tissue biopsy specimen from a Kaposi's sarcoma lesion, and it was confirmed that the amplified DNA belonged to HHV-8 by restriction enzyme analysis. Malignant mesothelioma continues to be a public health problem in rural parts of Anatolia, Turkey. The major causal factor of the disease is exposure to asbestos and fibrous zeolite (erionite). It seems that there must be some aetiological factors other than exposure to these minerals as not all patients exposed to asbestos develop the disease and the disease is not always associated with any known exposure. From the present study, it was concluded that human herpes virus 8 does not seem to be associated with environmentally induced malignant mesothelioma in Turkey. Other possible causal factors of malignant mesothelioma should be sought.