acute transplant rejection
A transplant rejection that is caused by an immune response directed against the graft and occurs between 1 week and several months after transplantation. Acute rejection is diagnosed on histological analysis of a graft biopsy. Acute rejection is thought to result from two immunological mechanisms that may act alone or in combination: (1) a T-cell-dependent process that corresponds to acute cellular rejection, and (2) a B-cell-dependent process that generates the acute humoral rejection.