Hydroa Vacciniforme Is Associated with Increased Numbers of Epstein–Barr Virus–Infected γδT Cells

Hydroa vacciniforme (HV) is a rare photosensitivity disorder of childhood associated with Epstein–Barr virus (EBV)+ T-cell infiltration. We have summarized clinical manifestations of HV, and analyzed EBV+ T-cell subsets as well as EBV DNA load in lymphocyte fractions, in comparison with hypersensitivity to mosquito bites (HMB), an EBV-associated T/natural killer (NK) lymphoproliferative disorder. We found that 31 of 33 (93.9%) HV lesions were composed of EBV+ T cells and reactive EBV− cytotoxic T cells, without significant CD56+ cell infiltration, whereas many CD56+ cells were present in 8 of 9 (88.9%) HMB lesions. Of 13 (20.6%) HMB patients with or without HV, 12 (92.3%) showed increased percentages (>32%) of NK cells in the peripheral blood, whereas in the 16 patients with HV alone, 14 (87.5%) showed no increase. Of the 11 HV patients, 10 (90.9%) had increased percentages (>5%) of circulating γδT cells, with a mean value of 15.7 ± 2.9%, and the γδT-cell fractions contained larger amounts of EBV DNA than non-γδT-cell fractions. A triple-labeling method revealed that all three HV patients examined had increased percentages of EBER+, T-cell receptor (TCR)γδ+, and TCRαβ− cells. Our observations indicate that HV is associated with increased numbers of EBV+ γδT cells, whereas HMB is associated with EBV+ NK cells.