A genetic marker of high TNF-alpha production in heart transplant recipients.

The cytokine TNF-alpha has been implicated in the pathogenesis of both acute and chronic transplant rejection. Levels of the cytokine are known to vary in a normal population, leading to speculation that high responders may be at greater risk of rejection. Particular TNF region polymorphic markers have been associated with increased TNF-alpha levels and a biallelic polymorphism has been identified at position -308 of the TNF-alpha promoter that may contribute significantly to the interindividual variation in healthy persons. We describe here a new association between a polymorphic locus in the TNF gene region and increased production of TNF-alpha in heart transplant recipients. We studied two microsatellite markers that flank the TNFA gene, as well as a biallelic polymorphism at position -308 of the TNFA promoter, and found that the microsatellite allele TNFd3 was significantly associated with the capacity of leukocytes to produce TNF-alpha in vitro. No association was demonstrated for the promoter region polymorphism. Patients were receiving cyclosporine (CsA) and prednisolone (pred) at the time of sampling, which are known to interrupt 5' regulation of TNFA transcription in T cells and macrophages and may therefore negate the influence of the -308 polymorphism. Because of this we suggest that TNFd3 may be a marker for a 3' repressor region polymorphism that is of importance in immunosuppressed individuals.