INTRAGRAFT EXPRESSION OF MESSENGER-RNA FOR INTERLEUKIN-6 AND TUMOR-NECROSIS-FACTOR-ALPHA IS A PREDICTOR OF RAT SMALL-INTESTINE TRANSPLANT REJECTION

Detection of rejection after small intestine transplantation (SIT) is difficult, relying largely on histopathology. The purpose of this stud y was to determine if the intragraft expression of messenger RNA (mRNA ) for interleukin-2 receptor (IL-SR), interleukin-6 (LL-6), and tumor necrosis factor-alpha (TNF) correlated with rejection in a unidirectio nal, heterotopic rat SIT model. Graft samples were obtained on postope rative day (POD) 3, 5, 7, 8, 9, 10, 12, and 14. After staining, formal in-fixed samples were blindly evaluated for rejection. Reverse transcr iptase polymerase chain reaction (rtPCR) using primers specific for be ta-actin, IL-BR, IL-6, and TNF was performed on liquid nitrogen-frozen samples. Semiquantitation was accomplished using radionuclide incorpo ration and beta-scintillation counting. Intestinal histopathology in a ll isografts (ISO) and POD 3 allografts (ALLO) was normal. Rejection p rogressed in ALLO from mild on POD 5 to severe by POD 8. rtPCR analysi s revealed constitutive expression of IL-2R mRNA in both ISO and ALLO. TNF and IL-6 demonstrated significant increases in mRNA expression in ALLO compared to ISO beginning on POD 5. In summary, intragraft expre ssion of IL-BR mRNA demonstrated late up-regulation in ALLO which did not correlate with rejection. TNF and IL-6 mRNA expression predicted r at SIT rejection. rtPCR analysis of TNF and IL-6 may serve as a useful diagnostic adjunct for rat SIT rejection. (C) 1994 Academic Press, In c.