Hydroa vacciniforme (HV) is a disease of Epstein-Barr virus (EBV)+ T cell lymphoproliferative disorders (LPDs), but natural killer (NK) cell markers are positive in some cases. We studied the possibility that EBV+ T cells can coexpress NK cell markers such as CD16 and CD56, mimicking a natural killer T (NKT) cell phenotype. Flow-cytometric analysis was performed for blood samples from 5 patients with systemic HV (sHV)/HV-like LPDs, 5 with classic HV (cHV), and 5 with adult T-cell leukemia (ATL). We further performed T-cell receptor (TCR) repertoire analysis of EBV+ T-cells, and immunostaining of HV-like skin lesions. Of 5 blood samples from sHV patients, T cells were increased in 3 patients (7.2, 13.1 and 7.9% in the lymphocyte fraction, respectively), and T cells were predominant in 2 patients with fatal outcome (94.0 and 97.6%, respectively). The TCR+CD3+ T-cells expressed CD16 and/or CD56, ranging from 7.5 to 42.3%. Large granular lymphocytes (LGLs) of the T-cell type expressed CD16 and/or CD56 more frequently. All 5 patients with cHV had increased percentages of T cells, ranging from 7.1 to 36.0%, in which CD16 and/or 56+ cells ranged from 1.02 to 9.72%. By contrast, CD3+CD4+ ATL cells expressed CD16 and/or CD56 in less than 1.2%. The TCR usage of T-cell dominant sHV was distinct from that of invariant NKT (iNKT) cells with V24-J18/V11 TCR. The TCR of circulating T-cells in 2 sHV patients was composed of V1, characteristic for the epithelial type of T cells. A considerable number of CD56+ cells were observed among CD3+ T-cells in the sHV skin lesion. In conclusions, both EBV+ T- and T-cells in HV patients frequently coexpress NK-cell markers such as CD16 and CD56, but distinct from iNKT cell lineage.

Coexpression of TCR/CD3 complex and natural killer cell markers, CD16 and/or CD56, by Epstein-Barr virus-infected T-cells in hydroa vacciniforme-like lymphoproliferative disorders