Steroid-free lymphocyte depletion protocols. The potential for partial tolerance?

Induction of tolerance has been a longstanding goal in transplantation. Recent preliminary studies using a steroid-free lymphocyte depletion strategy have been met with great excitement and an equal degree of skepticism. Current studies in this area suggest that immunosuppression can be reduced substantially but acute rejection develops at a rate approximately twice that of standard triple drug protocols. None of the lymphocyte-depleting protocols has resulted in full tolerance as evidenced by patients attaining a maintenance drug-free state. Workers in the field have suggested that a degree of tolerance is achieved and they have coined a growing number of terms to describe this state: prope tolerance, metastable tolerance, and partial tolerance. To date, patient follow-up has been relatively short leaving many unanswered questions about graft survival, chronic allograft nephropathy, and the minimally effective maintenance immunosuppression. Despite these limitations, steroid-free lymphocyte depletion may offer an exciting new treatment paradigm.