Familial differences in endotoxin-induced TNF release in whole blood and peripheral blood mononuclear cells in vitro; relationship to TNF gene polymorphism

Abstract

Healthy volunteers show large interindividual differences in endotoxin-induced TNF release in vitro and certain HLA class II types can be related to phenotypic TNF resporise. To investigate the possibility of a genetic basis for endotoxin responsiveness, we tested TNF release in whole blood and PBMNC after stimulation by endotoxin in 47 relatives of 7 healthy volunteers. All volunteers were HLA-typed and the TNF-gene associated Nco1 and DNA microsatellite polymorphisms were determined. A significant difference in TNF release by PBMNC and the Nco1 genotype could be established, showing a lower response of TNFB*2 homozygotes than TNFB*1 homozygotes (165 vs 265, 413 vs 703 and 462 vs 832 pg/106 PBMNC for 1, 10 and 100 ng/ml of endotoxin respectively; P < 0.05). The highest endotoxin-induced TNF release was observed in TNFB*1/TNFB*2 heterozygotes (340, 911 and 1,149 pg/10 6 PBMNC respectively; P < 0.05 compared to TNFB*1 homozygotes and P < 0.0005 when compared to TNFB*2 homozygotes). TNFa and TNFb microsatellite typing revealed extensive polymorphism, showing a significantly lower TNF release in whole blood in individuals with TNFa2, -a6 and -a10 alleles than in individuals with TNFa4 and -a11 microsatellite haplotypes.