Natural killer (NK) T cells are a lymphocyte subset with a distinct surface phenotype, an invariant T cell receptor (TCR), and reactivity to CD1. Here we show that mouse NK T cells can recognize human CD1d as well as mouse CD1, and human NK T cells also recognize both CD1 homologues. The unprecedented degree of conservation of this T cell recognition system suggests that it is fundamentally important. Mouse or human CD1 molecules can present the glycolipid α-galactosylceramide (α-GalCer) to NK T cells from either species. Human T cells, preselected for invariant Vα24 TCR expression, uniformly recognize α-GalCer presented by either human CD1d or mouse CD1. In addition, culture of human peripheral blood cells with α-GalCer led to the dramatic expansion of NK T cells with an invariant (Vα24+) TCR and the release of large amounts of cytokines. Because invariant Vα14+ and Vα24+ NK T cells have been implicated both in the control of autoimmune disease and the response to tumors, our data suggest that α-GalCer could be a useful agent for modulating human immune responses by activation of the highly conserved NK T cell subset.

Although many T cells carry two in-frame V alpha rearrangements, the products of both V alpha rearrangements have never been shown simultaneously on the surface of normal cells. With the use of monoclonal antibodies to V alpha 2, V alpha 12, and V alpha 24, up to one-third of mature T cells expressed two V alpha chains as part of two functional and independent T cell receptors (TCRs). Thus, the "one cell, one receptor" rule does not apply to a large subset of alpha beta T cells. Cells that belong to this dual TCR subset may be specific for a broader range of antigens than cells with a single receptor, which may be important for autoimmunity and alloreactivity.

The transfer of high-avidity T-cell receptor (TCR) genes isolated from rare tumor-specific lymphocytes into polyclonal T cells is an attractive cancer immunotherapy strategy. However, TCR gene transfer results in competition for surface expression and inappropriate pairing between the exogenous and endogenous TCR chains, resulting in suboptimal activity and potentially harmful unpredicted specificities. We designed zinc-finger nucleases (ZFNs) promoting the disruption of endogenous TCR β and α chain genes. ZFN-treated lymphocytes lacked CD3/TCR surface expression and expanded with IL-7 and IL-15. Upon lentiviral transfer of a TCR for the WT1 tumor antigen, these TCR-edited cells expressed the new TCR at high levels, were easily expanded to near-purity, and proved superior in specific antigen recognition to matched TCR-transferred cells. In contrast to TCR-transferred cells, TCR edited lymphocytes did not mediate off-target reactivity while maintaining anti-tumor activity in vivo, thus demonstrating that complete editing of T-cell specificity generate tumor-specific lymphocytes with improved biosafety profile.

Adenosine deaminase (ADA) deficiency results in severe combined immunodeficiency, the first genetic disorder treated by gene therapy. Two different retroviral vectors were used to transfer ex vivo the human ADA minigene into bone marrow cells and peripheral blood lymphocytes from two patients undergoing exogenous enzyme replacement therapy. After 2 years of treatment, long-term survival of T and B lymphocytes, marrow cells, and granulocytes expressing the transferred ADA gene was demonstrated and resulted in normalization of the immune repertoire and restoration of cellular and humoral immunity. After discontinuation of treatment, T lymphocytes, derived from transduced peripheral blood lymphocytes, were progressively replaced by marrow-derived T cells in both patients. These results indicate successful gene transfer into long-lasting progenitor cells, producing a functional multilineage progeny.

SummaryThe T cell receptor (TCR)-c~//~ CD4-8-(double negative, DN) T cell subset is characterized by an oligoclonal repertoire and a restricted V gene usage. By immunizing mice with a DN T cell clone we generated two monodonal antibodies (mAbs) against Vol24 and V311, which have been reported to be preferentially expressed in DN T cells. Using these antibodies, we could investigate the expression and pairing of these Vc~ and V~ gene products among different T cell subsets. Vo~24 is rarely expressed among CD4 + and especially CD8 + T cells. In these cases it is rearranged to different Jcx segments, carries N nucleotides, and pairs with different V3. Remarkably, Voe24 is frequently expressed among DN T cells and is always present as an invariant rearrangement with JolQ, without N region diversity. This invariant Vc~24 chain is always paired to V311. This unique Ve~24-Jc~Q/V311 TCR was found in expanded DN clones from all the individuals tested. These findings suggest that the frequent occurrence of cells carrying this invariant TCR. is due to peripheral expansion of rare clones after recognition of a nonpolymorphic ligand.