Background The role of humoral immunity in acute rejection in solid organ t
ransplantation remains controversial, although it is known that the presenc
e of antidonor antibodies may precipitate graft rejection. We investigated
the clinical relevance of antidonor humoral immunity for living donor liver
transplantation (LDLT) by means of now cytometry crossmatch (FCXM).
Methods. T cell FCXM using fresh donor peripheral lymphocytes was performed
before and up to 1 month after LDLT in 58 patients. Ten patients received
ABO-incompatible grafts. IgM and IgG antidonor antibodies were analyzed in
relation to clinical acute rejection as defined by liver function tests wit
h or without histological evidence.
Results. Pretransplantation FCXM was positive for five patients (8.6%), res
ulting in two cases of positive posttransplantation FCXM and two rejection
episodes. Twelve patients (20.7%) showed positive posttransplantation FCXM.
The incidence of acute rejection within 1 month was 100% in FCXM-positive
patients and 17.4% in FCXM-negative patients (P<0.001). Thirteen (76.5%) of
17 rejection episodes in ABO-compatible cases were associated with concomi
tant antidonor IgM antibody. IgG antibody was also identified in six of the
se episodes. Antidonor antibodies disappeared after rejection treatments in
all cases, but with some delay in clinical improvement. On the other hand,
no antidonor antibodies were detected in any of the four rejection episode
s in ABO-incompatible cases.
Conclusions. Early acute rejection in LDLT is significantly associated with
antidonor T cell antibody formation in ABO-compatible cases. This suggests
a definite role for donor-specific humoral immunity in acute rejection. Re
jection episodes without antidonor antibodies may suggest graft injury by p
ure cellular immunity, or possibly the presence of humoral immunity trigger
ed by antigene not present on donor T cells.