Intragraft cytokine expression in heart transplants with mild or no histological rejection

The study of pro-inflammatory cytokines produced in situ in heart allografts may help to understand the mechanisms of rejection and open new possibilities to control graft rejection. Methods: A total of 23 endomyocardial biopsies obtained from 16 transplanted patients treated with triple-drug therapy (azathioprine, prednisone, and cyclosporine) were studied, mRNA expression for tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-10, IL-12, IL-15, transforming growth factor (TGF)-β, and β-actin was determined by reverse transcription polymerase chain reaction (RT-PCR) and Southern blotting. Semiquantitative analysis was done by establishing the ratio between densitometric integrated value of each cytokine with the β-actin and correlated with the histopathologic findings. Results: Three groups of biopsies were determined according to the International Society for Heart and Lung Transplantation criteria: grade 0 (control group, n = 12), grade 1A (sub-clinical rejection, n = 6) and quilty effect' (n = 5). An increased expression of mRNA for TNF-a and IL-6 (p = 0.0091 and 0.0075, respectively) was found associated with rejection grade 1A episodes, mRNA for IL-1β was nonspecifically expressed in all the study groups, while IL-10 mRNA was not detected in any of the biopsies studied, mRNA for IL-12 and IL-15 was not associated with rejection. Interestingly, TGF-β was not detected in any of the biopsies with the 'quilty pattern'. Conclusion: The association of TNF-a and IL-6 mRNA in situ expression with mild histologically probed rejection episodes may be used in the monitoring of heart transplants.