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 5

KSHV-induced expression of the proliferation marker Ki67.

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KSHV-induced expression of the proliferation marker Ki67. Tonsil cells w...
Tonsil cells were analyzed for the expression of LANA and the proliferative marker Ki67 72 hpi using MIFC. (A) Representative images of LANA– and LANA+ cells labeled with antibodies directed against LANA and Ki67 following KSHV exposure. (B) Left panel: Histogram showing Ki67 expression in LANA– (gray filled) and LANA+ (black line) cells. Right panel: Mean percentage (±SEM) of cells expressing Ki67 unexposed to KSHV (light gray bar); exposed to KSHV but LANA– (gray bar); or exposed to KSHV and or LANA+ (black bar). (C) Mean percentage (±SEM) of cells expressing Ki67 gated according to relative intracellular viral load into groups with 0, 1–2, 3–4, or ≥5 LANA dots/cell. P value refers to Spearman correlation, which was 0.902. (D) Mean (±SEM) fold change in levels of Ki67 expression was assessed by dividing the Ki67 MFI of each of LANA+ group (gated as in C) by the Ki67 MFI of LANA– cells. Only Ki67+ cells were analyzed. Data represent mean ± SEM from 4 separate tonsil donors. P value refers to Spearman correlation, which was 0.792.