Double-negative (CD4^- CD8^-) T cells with an α/β T cell receptor: Non-MHC-restricted cytolytic activity and lymphokine production

T cell lines with a novel phenotype (CD3⁺ TCR-α/β⁺ CD4^- CD8^-) were developed from the peripheral blood of a patient with a combined immunodeficiency and tissue injury resembling graft-vs-host disease. One of these IL-2-dependent T cell lines demonstrated non-MHC-restricted cytolytic function against tumor targets, syngeneic and allogeneic fibroblasts, and PHA blasts from allogeneic donors. The other cell line only became cytotoxic in the presence of lectin or anti-CD3 antibody. The two cell lines also differed in their expression of the T-200 gene products CD45RO (gp180) and CD45RA (gp220). Both cell lines produced tumor necrosis factor-α and -β and IFN-γ activity when activated with mitogens or PMA and IL-1. The in vitro functions of these T-cell lines suggest a potential role for α/β double-negative T lymphocytes in tissue injury resembling graft-vs-host disease.