Indoleamine, 2-3 dioxygenase activity could be an early marker of graft rejection in heart transplantation.

BACKGROUND: The indoleamine, 2-3 dioxygenase (IDO) is an inducible intracellular enzyme with immunosuppressive effects mainly on lymphocyte populations. It has been postulated that indirect determination of IDO serum activity may be a marker of renal graft rejection, but its potential usefulness in heart transplantation (HT) is unknown. METHODS: This longitudinal study included 98 HT patients (83% males) who survived ≥1 year. Mean age was 54.14 ± 11.57 years. Serum IDO activity was analyzed one month after HT by means of high performance liquid chromatography and correlated with the cumulative incidence of acute rejection (AR) during one-year follow-up. AR was defined as biopsy-proven ≥ ISHLT grade 2R rejection or empirically treated non-biopsy-proven rejection. The study sample was divided into two groups: AR group (n = 51), including patients who experienced at least one AR episode during the first year after HT; No-AR group (N = 47), including the remaining patients. RESULTS: Mean serum IDO activity one month after HT was significantly higher (P = .021) in the AR group (3.32 ± 1.56) than in the no-AR group (2.62 ± 1.35). No significant association between serum IDO activity and gender (male: 3.1 ± 1.56, women: 2.43 ± 0.99, P = .092), recipient age (r = -.07, P = .943) or donor age (r = 0.108, P = 0.293) was observed. By means of binary logistic regression, an odds ratio of 1.4 [CI 95%: 1.033-1.876, P = .03] per unit increase of act-IDO was estimated, with no significant modification upon forced adjustment for age and sex. Mean glomerular filtration rate 1 month after HT was 67.01 ± 28.51 mL/min/m(2). No significant correlation between this parameter and serum IDO activity was observed (r = .160, P = .117). CONCLUSIONS: Our study suggests that serum IDO activity one month after HT might be associated with a higher risk of AR during one-year follow-up. This association seems to be independent of recipient gender, age or renal function.

Apoptosis in fresh and cryopreserved cardiac valves of pig samples.

To analyse the influence of cold ischemic time (CIT) (2-24 h) and of cryopreservation (liquid phase) on the viability of the valvular fibroblasts and in the presence of apoptosis. Cardiac valves from 10 pigs were evaluated by anatomo-pathological study of the wall, muscle and leaflet. At the same time, the presence of cellular death due to apoptosis was investigated in two ways; directly on tissue by Apodetec system and by two-colour flow cytometry assay analyzing a suspension of fibroblast from valve leaflets using Anexina V and propidium iodure (PI). We established three groups of samples to compare different experimental conditions: 2 h of ischemia (group 1), 24 h of ischemia (group 2), and a programme of cryopreservation (-1 degrees C/min) after 2 h of ischemia, followed by storage in liquid nitrogen during a week and thawing was performed (group 3). The analysis of viabilities showed slight differences between all three groups. The results indicated CIT of 24 h undergoing more structural affectation than CIT of 2 h. Flow cytometry analysis did not show important differences between groups; however cryopreserved samples (group 3) slightly less viability and a higher percentage of death by apoptosis than group 1 and 2 using flow cytometry. Apoptosis was confirmed on tissue from all valves but mainly in samples of group 2 and group 3. In summary, the viability of the valves in the case of ischemic times of 2 h, 24 h or after cryopreservation/thawing differs slightly. The death of the cells is mainly mediated by necrosis and not by apoptosis.

Severe cardiac allograft dysfunction without endomyocardial biopsy signs of cellular rejection: incidence and management.

Acute dysfunction of cardiac allograft without evidence of cellular rejection is a potentially fatal complication of heart transplantation that suggests a humoral origin. In clinical practice, humoral rejection (HR) is suspected when there is evidence of severe allograft dysfunction but endomyocardial biopsy (EMB) shows no evidence of cellular rejection. Between April 1991 and August 2003, 12 patients (2.74%) among 438 heart transplants displayed this condition. Time post-heart transplant (HT) was 21.3 +/- 24.7 months (range 2 to 72 months). Immunofluorescence studies using classic markers were negative. All patients were treated with methylprednisolone "bolus" and plasmapheresis until clinical recovery, after which their immunosuppressive regimens were modified. Eleven of the 12 patients recovered satisfactory allograft function. In this series the incidence of suspected HR was low. Unlike other studies, we observed HR not only soon but also even years after HT. Plasmapheresis seems to be an effective treatment.