Inverted V delta 1/V delta 2 ratio within the T cell receptor (TCR)-gamma delta T cell population in peripheral blood of heart transplant recipients.

We investigated the levels of TCR-gamma delta T cells and their subpopulations V delta 1 and V delta 2 in the peripheral blood lymphocytes (PBL) of 28 heart transplant (HTx) patients. Patients (n = 10) receiving cyclosporin A (CsA) for treatment of a nephrotic syndrome (NS) and 10 healthy individuals served as controls. There was no difference in levels of TCR-gamma delta T cells between the different groups. However, an elevated proportion of V delta 1+ gamma delta T cells was found in the PBL of HTx patients, especially when these cells were present in their graft-infiltrating lymphocyte (GIL) cultures. V delta 1+ gamma delta T cells of HTx patients showed normal expression of CD45RO and lacked the activation markers CD25 and HLA-DR. After expanding in IL-2-containing medium, PBL cultures of HTx patients more often were dominated by V delta 1 cells than PBL cultures of controls, in which V delta 2 cells were predominantly grown. The aberrant composition of the TCR-gamma delta population in HTx patients was not a result of immunosuppressive medication, since the proportion V delta 1+ gamma delta T cells was normal in the PBL of the NS patients receiving a similar dose of CsA. It is postulated that long-term antigenic stimulation by the graft, at low level, might be responsible for the altered composition of the gamma delta pool in the HTx patients. Since no donor HLA-specific gamma delta T cells have been detected, other ligands, such as heat shock proteins, may be involved.