CD2-mediated autocrine growth of herpes virus saimiri-transformed human T lymphocytes.

Abstract

SummaryHerpes virus saimiri (HVS) immortalizes T lymphocytes from a variety of primates and causes acute T cell lymphomas and leukemias in nonnatural primate hosts. Here we have analyzed the requirements for growth of three HVS-transformed human T cell lines. The cells expressed the phenotype of activated T cells: two were CD4 + , and one was CD8 + . All three cells responded to all allogeneic human cell lines tested with enhanced proliferation, production of interleukin 2 (Ib2), and increased expression of the I1:2 receptor. Binding of CD2 to its ligand CD58 was the critical event mediating stimulation because: (a) monoclonal antibodies (mAbs) to CD2 and to CD58, but not to a variety of other surface structures, blocked induced and spontaneous proliferation and Ib2 production; (b) only anti-CD2 mAbs were stimulatory if crosslinked; (c) a nonstimulatory cell was rendered stimulatory by CD58 transfection; and (d) the cells responded specifically to CD58 on sheep red blood cells. Growth of the cells required activation because cyclosporin A and FK506 blocked stimulator cell-induced II:2 production and proliferation as well as the spontaneous growth of the lines. Antibodies to the I1:2 receptor reduced proliferation of the cells and blocked 11:2 utilization. Taken together, these results show that HVS-transformed T cells proliferate in response to CD2-mediated contact with stimulator cells or with each other in an I1:2-dependent fashion. They suggest that HVS transforms human T cells to an activationdependent autocrine growth. Herpes virus saimiri (HVS) is the prototype of the lymphotropic 3~-2 herpes viruses (rhadinoviruses). Natural hosts of the virus are the squirrel monkeys (Saimiri sciureus).By cocultivation with permissive monolayer cells, HVS can be isolated from PBL >80% of the population, and at least one in 106 T cells will yield virus (reviewed in reference 1). The virus persists in T cells for their lifetime. HVS is not pathogenic for squirrel monkeys, even after immunosuppression. In contrast to this benign behavior in its natural host, HVS has a high oncogenic potential in numerous other New World primates (1). It causes acute lymphoproliferative syndromes, leukemias, and lymphomas. After infection, the animals die within a few weeks from rapidly progressing neoplasias. Cell lines can be established from infected animals that initially produce virus in "~1-10% of the cells, but after prolonged cultivation the ability to produce virus is lost (2), HVS is able to transform T lymphoeytes of nonhuman primates as well as human PBL and thymocytes to continuous growth (2, 3). The molecular basis of T cell stimulation and transformation is unknown.In this study we show that transformation with HVS induces human T cells to respond to cell-cell contact with each other and with other cells leading to I1:2-dependent autocrine growth. The critical stimulating signal in this contact is given by binding of the CD2 molecule to its natural ligand. These HVS-transformed T cells are the first example of an activation-de...

A herpesvirus saimiri-based gene therapy vector with potential for use in cancer immunotherapy

“…16,17 Infection of human blood lymphocytes and thymocytes with strains of subgroup C, in contrast to the other subgroups, yields continuously proliferating T-cell lines. 18,19 Earlier publications have demonstrated that a selectable HVS has the ability to persist in a variety of human cell lines for long periods of time, apparently without the production of infectious progeny. 20,21 In this report, we describe our findings using a nontransforming wild-type (wt) virus carrying the enhanced green fluorescent protein (EGFP) and neomycin resistance (neo r ) marker genes.…”

Induction of a Novel Cellular Homolog of Interleukin-10, AK155, by Transformation of T Lymphocytes with Herpesvirus Saimiri

“…In contrast to multiple reports on preserved functions, little is known about cellular features which are clearly changed after transformation. The most pronounced difference is a specific type of hyperreactivity to CD2 stimulation via cell-bound CD58 or cross-linked CD2 antibodies (33). Moreover, unusually high levels of gamma interferon are produced after stimulation, which shifts transformed T helper 2 cells to the T helper 0 phenotype (6).…”

Rhadinovirus vector-derived human telomerase reverse transcriptase expression in primary T cells

“…In the CD2 hyperreactivity test, 19,33 5 Â 10 4 transformed T cells were incubated alone or in the presence of an antibody and/or 5 Â 10 4 stimulator cells in 200 ml of complete RPMI 1640 medium in flat-bottom wells. The rat monoclonal antibody 39C1.5 (anti-CD2, Beckman Coulter, Krefeld, Germany), recognizing the human T11.1 CD2 epitope, was used in stimulation and blocking assays at 1 mg ml À1 .…”

“…These virus mutants carry the hTERT expression cassette at the right end of the L-DNA and with or without the stpC/tip gene (orf1) at the left L-DNA end. As HVS-transduced T cells exhibit a few specific properties such as CD2 hyperreactivity, 33 elevated IL-26 34 and Lyn expression, 19,35 we analyzed the influence of the stpC/ tip deletion (Dorf1) on these properties and concluded that hTERT could not substitute them in this phenotype, although hTERT was functionally expressed after transduction. The interaction of StpC with Ras and tumor necrosis factor-associated factors leading to nuclear factorkB activation, in addition to the association of Tip with signal transducers activators of transcription and tipassociated protein, are crucial for the facilitated growth transformation of human T lymphocytes.…”