Clinical significance of in vitro donor-specific hyporesponsiveness in renal allograft recipients as demonstrated by the MLR.

A longitudinal study was carried out on 19 recipients of cadaveric renal allografts, monitoring their anti-donor and anti-third party responses in the mixed lymphocyte reaction (MLR) at the time of transplantation and at 3, 6, and 12 months post-transplant. Two patterns of responses were identified: in the first (n = 11), patients showed, or later developed, donor-specific hyporesponsiveness, and in the second (n = 8), patients had persistent antidonor and anti-third party responses. After 1 year, the serum creatinine, number of episodes of acute rejection and biopsy findings were compared in both groups. In the first group, the mean serum creatinine was 136.4 mmol/l, the total number of acute rejection episodes was three and in nine of the ten available biopsies, there were minimal cellular infiltrates and normal appearance of the glomeruli, tubules and blood vessels. In the second group, the mean serum creatinine was 163 mmol/l, the total number of acute rejection episodes was 12 and in five of the seven biopsies available, evidence of ongoing rejection was obtained. The difference in mean serum creatinine was not statistically significant (P > 0.05), but the difference in the numbers of acute rejection episodes was (P < 0.05). It is concluded that in some renal allograft recipients, a state of donor-specific hyporesponsiveness develops, and this state may be associated with better graft outcome at 1 year. These data may be useful in selecting patients for reduced immunosuppressive therapy.