A GENOMIC POLYMORPHISM WITHIN THE TUMOR-NECROSIS-FACTOR LOCUS INFLUENCES PLASMA TUMOR-NECROSIS-FACTOR-ALPHA CONCENTRATIONS AND OUTCOME OF PATIENTS WITH SEVERE SEPSIS

Objectives: To determine the allele frequency and genotype distributio n of a bi-allelic tumor necrosis factor (TNF) gene polymorphism and pl asma TNF-alpha concentrations in postoperative intensive care unit (IC U) patients suffering from severe sepsis. Design: Prospective, consecu tive entry study of patients with severe sepsis in a postoperative ICU . Setting: University hospital. Patients: Forty patients with diagnosi s of severe sepsis, admitted to the ICU between June 1993 and December 1994. Interventions: None. Measurements and Main Results: A 782 basep airs fragment of genomic DNA, including the polymorphic site of the re striction enzyme Ncol within the TNF locus, was amplified by means of polymerase chain reaction, The genotype of each patient was determined after Ncol digestion of the amplified product and subsequent agarose gel electrophoresis. Reading the size of the resulting DNA bands from the agarose gel demonstrated the genotype, as defined by the two allel es TNFB1 and TNFB2, Serial blood samples were drawn every sixth hour d uring the first 48 hrs and every 12th hour thereafter, for less than o r equal to 96 hrs after diagnosis, TNF-alpha plasma concentrations wer e detected by an enzyme-linked immunosorbent assay, Assessment of orga n dysfunction was performed by calculating a Multiple Organ Failure sc ore. The overall allele frequency (TNFB1 0.35; TNFB2 0.65) and genotyp e distribution (TNFB1 homozygotes 10%; TNFB1/TNFB2 heterozygotes 48%; TNFB2 homozygotes 42%) in 40 patients with severe sepsis were comparab le with those values found in normal individuals. Development of multi ple organ failure occurred in 33 (82.5%) of 40 patients, whereas 23 (5 7.5%) of 40 patients did not survive, In contrast to the overall allel e frequency, nonsurvivors showed a significantly higher prevalence of the allele TNFB2 (p < .005), Patients homozygous for the allele TNFB2 demonstrated a higher mortality rate than heterozygous (TNFB1/TNFB2) p atients (p = .0022), In addition, patients with TNFB2 homozygotes disp layed higher circulating INF-alpha concentrations as well as higher Mu ltiple Organ Failure scores compared with heterozygous (TNFB1/TNFB2) p atients. Conclusions: The bi-allelic Ncol polymorphism within the TNF locus is a genomic marker for patients with increased TNF-alpha respon se and poor prognosis in severe sepsis, The amount of TNF released in situations of severe infection and sepsis appears to be influenced gen etically, TNFB2 homozygous individuals displaying increased circulatin g TNF plasma concentrations combined with high mortality rate may be i ncluded in future studies testing anti-TNF strategies in severe sepsis .