Human Herpes Virus 8 Viral Load in Multicentric Castleman's Disease
J Arce, C Huang, M Levin, Q Pan, H Ratech. Montefiore Med Ctr/Albert Einstein Coll Med, Bronx
Background: Multicentric Castleman's disease (MCD) is frequently associated with human herpes virus 8 (HHV8), especially in patients co-infected with human immunodeficiency virus (HIV). On the other hand, some individuals with MCD do not have detectable HHV8. To our knowledge, this is the first study to use a quantitative polymerase chain reaction (Q-PCR) assay in order to identify HHV8 in lymph nodes.
Design: HHV8 viral load (VL) was measured in lymph node biopsies from 46 HIV+ patients and 101 HIV- individuals using a Q-PCR assay originally developed for plasma (J Clin Microbiol 39:4269, 2001). We normalized HHV8 VL values to a mammalian house-keeping gene, HCK. For HHV8-positive controls, we tested Kaposi sarcoma (KS) in skin (N=5) and primary effusion lymphoma (PEL; N=1). In addition, we immunohistochemically stained lymph node tissue sections for HHV8 latent nuclear antigen (LNA-1).
Results: The lower limit for sensitivity of the HHV8 Q-PCR assay was 70 viral copies per reaction. The HHV8 VL data is expressed as viral copy number per cell. Among the HHV8-positive control samples, the VL for KS in skin ranged from 5.3E+01 to 6.9E+02. A single case of PEL had the highest VL equal to 1.2E+04. HHV8 was detected by Q-PCR in 10/147 lymph nodes: 4.4E+02 ± 6.4E+02 (mean ± sd); range, 0.5E+00 to 2.1E+03. Q-PCR HHV8 and immunostaining results for LNA-1 agreed, except in patient no. 10, who did not have MCD (Table 1). All LNA-1-positive lymph nodes had an HHV8 VL of at least 2.6E+01. The HHV8 VL in lymph nodes was not influenced by the presence of KS in another anatomic site or by highly active antiretroviral therapy (HAART).