Immortalization of human T cells expressing T-cell receptor gamma delta by herpesvirus saimiri.

Herpesvirus saimiri (HVS) has recently been shown to immortalize human CD4+ and CD8+ T cells expressing T-cell receptor alpha beta (TCR-alpha beta) with the maintenance of their original phenotypes and functional properties. However, the immortalization of human T cells expressing TCR-gamma delta by HVS has not been successful. Here we report that HVS can also infect and immortalize human T cells expressing TCR-gamma delta. Two human TCR-gamma delta+ T-cell clones, which continuously proliferated in interleukin-2-containing culture medium without any exogenous stimulation or addition of feeder cells for more than 8 months, were established by HVS infection. Morphologically, the HVS-transformed TCR-gamma delta+ T-cell clones were granular lymphocytes which exhibited wide-range HLA-unrestricted cytotoxicity as untransformed TCR-gamma delta+ T cells. Their phenotypes and cytotoxic activities were not altered during long-term culture. The immortalization of human TCR-gamma delta+ T cells by HVS infection would be useful for functional analysis of this lymphocyte population, which is believed to play an important role in protection against various infectious diseases.