T-CELL CLONAL CHANGE AFTER ALLO-KIDNEY TRANSPLANTATION IN HUMANS

Whether T cells circulating peripherally express changes at a clonal l evel after renal transplantation is uncertain. To clarify this issue, we analyzed T-cell clonality of peripheral blood lymphocytes (PBLs) in 12 renal transplant recipients by a novel polymerase chain reaction-s ingle-strand conformation polymorphism (PCR-SSCP) method that can disc riminate T-cell clones with different T-cell receptor (TCR) VP motifs. The PCR-SSCP study showed that after transplantation, only a few dist inct T-cell clonotypes accumulated in the absence of clinical episodes , irrespective of the compatibility of HLA antigens. In contrast, vari ous T-cell clones appeared in cases of acute rejection (AR) and infect ion. These subsided immediately after the AR was resolved; however, th ey remained long after the resolution of the infection. In a case of A R followed by an infectious episode, distinct T-cell clones appeared c oncomitantly with each episode. Several of them disappeared or remaine d thereafter. In one case, significant numbers of accumulating bands w ere observed by in-vitro stimulation by mixed lymphocyte reaction (MLR ); several were identical to those found in vivo. However, some of tho se that did not appear in vitro were apparent in vivo. In conclusion, the appearance of T-cell clonotypes at a peripheral level indicates th e existence of immunologically activated T-cell clones, which were sig nificantly affected by immunosuppressive therapy. It was also determin ed that the T-cell immune system is much more complicated in vivo than in vitro.