ACUTE VASCULAR (HUMORAL) REJECTION IN NON-OKT3-TREATED CARDIAC TRANSPLANTS

To determine the incidence and morphologic features of acute vascular rejection (AVR) in cardiac transplant patients who have not received O KT3 induction therapy, we performed immunofluorescence (IF) staining f or Clq and C3c and 341 endomyocardial biopsies from 135 patients. Each AVR biopsy, defined by positive IF, was further evaluated for C4c, C5 , IgG, IgM, and IgA. Light and electron microscopy were also performed . The clinical features of each case were reviewed. A total of 29 biop sies from 6 recently transplanted patients (1993) and 10 biopsies from 4 long-term transplants (pre-1993) had IF evidence of AVR. All patien ts with AVR had linear vascular deposits of various complement compone nts and immunoglobulins. Of the 6 recently transplanted patients, 4 we re multiparous females. The male had a single episode of AVR. IF patte rns were variable between and within patients. Clq and C3c were the mo st consistently detected complement components. IgM was the most frequ ently detected antibody. Of the 10 cases of AVR, 6 occurred within the first month post-transplant. Myocyte necrosis was present in all case s with cardiac dysfunction. Patients with early onset AVR had more rec urrences and one fatality. There was one fatality in the long-term tra nsplant group. Concomitant grades 0 to 4+ cellular rejection did not c orrelate with results of IF or clinical severity. The incidence of AVR in non-OKT3-treated patients is 7%. Of the early onset patients, 66% are multiparous female, indicating the possible importance of prior se nsitization. IF patterns are not predictive of outcome. AVR may be asy mptomatic, but early onset predicts a difficult clinical course and is detected only by IF screening.