Analysis of the polymorphism of the tumour necrosis factor (TNF) gene and promoter and of circulating TNF-alpha levels in heart-transplant patients suffering or not suffering from severe rejection

Plasma TNF-alpha levels are generally higher in heart-graft patients who ex perience a rejection episode than in those who do not. Because the TNF gene and its promoter are polymorphic, we studied the relationships between gen etic variability at the TNF locus, the occurrence of graft rejection and TN F-alpha plasma levels in 62 heart-transplant patients in order to investiga te inter-individual differences in plasma TNF-alpha levels after allogeneic stimulation. TNF-alpha was immunoenzymatically measured in blood specimens collected on the same day as endomyocardial biopsy. After PCR amplificatio n of DNA, NcoI and AspHI polymorphisms were characterized by their restrict ion profiles, TNFa microsatellites by electrophoretic separation on acrylam ide and the promoter region by sequencing. Plasma levels and molecular gene tic results were compared to the grade of heart graft rejection established according to pathological criteria. In our study, allograft rejection was associated neither with NcoI or AseHI polymorphism nor with nucleotide chan ges in the TNF-A promoter. We observed low TNF-alpha levels in n1/n1 homozy gous patients and in subjects with G-->A at position - 308 of the promoter sequence. Concerning the polymorphism of the TNFa microsatellite, our resul ts might suggest an association with graft rejection but we have to be very careful in drawing conclusions because of the small size of the sample.