KSHV infects a subset of human tonsillar B cells, driving proliferation and plasmablast differentiation
Lynn M. Hassman, … , Thomas J. Ellison, Dean H. Kedes
Lynn M. Hassman, … , Thomas J. Ellison, Dean H. Kedes
Published January 18, 2011
Citation Information: J Clin Invest. 2011;121(2):752-768. https://doi.org/10.1172/JCI44185.
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Research Article

KSHV infects a subset of human tonsillar B cells, driving proliferation and plasmablast differentiation

Abstract

Kaposi sarcoma–associated herpesvirus (KSHV; also known as HHV8) is the causative agent of two B cell tumors, multicentric Castleman disease (MCD) and primary effusion lymphoma (PEL). However, little is known about the nature of the specific B cell subtype(s) most susceptible to infection. Identifying these cells would provide direct insight into KSHV transmission and virus-induced transformation. To identify this subset and to determine whether infection alters its cellular phenotype, we exposed human tonsillar cells to KSHV and characterized infected cells using high-throughput multispectral imaging flow cytometry (MIFC). Stable expression of the virally encoded latency-associated nuclear antigen (LANA), a marker of latent KSHV infection, was observed predominantly in cells expressing the l light chain of the B cell receptor. These LANA+ B cells proliferated and exhibited similarities to the cells characteristic of MCD (IgMl-expressing plasmablasts), including blasting morphology with elevated expression of Ki67, variable expression of CD27, and high levels of IgM and IL-6 receptor. Furthermore, the proportion of infected cells showing a blasting phenotype increased upon addition of exogenous IL-6. Our data lead us to propose that oral transmission of KSHV involves the latent infection of a subset of tonsillar IgMl-expressing B cells, which then proliferate as they acquire the plasmablast phenotype characteristic of MCD.

Authors

Lynn M. Hassman, Thomas J. Ellison, Dean H. Kedes

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Figure 2

Expression and maintenance of LANA within human tonsillar B cells.

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Expression and maintenance of LANA within human tonsillar B cells. MIFC ...
MIFC was used to identify cells expressing characteristic nuclear LANA dots following KSHV infection of tonsillar B cells isolated from 6 donors. (A) Representative images of B cells from cultures unexposed (left panel) or exposed (right panel) to KSHV. (B) Isolated B cells were cultured in the absence or presence of KSHV, and the percentage of LANA dot–positive cells was determined at 60–84 hpi for individual donors represented by individual symbols. Horizontal bars represent the mean value for all donors. (C) Cells from a separate tonsil were cultured without (gray line) or with (black line) KSHV for the indicated times before MIFC analysis of B cells gated within the software. For analyses at 7 dpi only, cells were kept in the presence of CD40L-3T3 cells to maintain viability. N, DAPI-stained nucleus; BF, bright-field.