Detection of Merkel cell polyomavirus in chronic lymphocytic leukemia T-cells

Chronic lymphocytic leukemia/small cell lymphoma (CLL/SLL) is the most common B-cell leukemia/lymphoma, effecting >15,000 patients/year. There has been a proposed limited antigenic etiology, at least in some cases, of CLL/SLL based upon immunoglobulin heavy chain stereotypy found across unrelated cases, suggesting viral source may provide such antigenic stimulation. With an established epidemiological link between CLL/SLL and Merkel cell carcinoma (MCC), there has been some interest in investigating a possible leukemogenic role of Merkel cell polyomavirus (MCPyV), which is found in 80% of MCC cases. Recent studies have shown that MCPyV is present in lymphocytes in a small percentage of CLL/SLL cases, but the specific tropism for lymphocytes has not been well-established. In this study, we used quantitative PCR to investigate the presence of MCPyV in fluorescence activated cell sorted purified B- and T-cells from 23 CLL/SLL cases. Three of 23 cases (13%) had detectable MCPyV in T-cells, and none of the cases had detectable MCPyV in B-cells. These findings suggest that MCPyV may have tropism for T-cells in addition to previously reported neoplastic B-cells.