Localization of the genes for tumor necrosis factor and lymphotoxin between the HLA class I and III regions by field inversion gel electrophoresis

Abstract

The human major histocompatibility (HLA) complex is located on the short arm of chromosome 6 in the 6p21. 31-6p21.33 region (Spring et al. 1985, Ziegler et al. 1985a). The physical length of the entire HLA complex is unknown so far, but our estimate based on the separation of DNA fragments containing HLA genes by pulsed-field gel electrophoresis (Schwartz and Cantor 1984, Carle andOlson 1984) indicates that it encompasses at least 2500 kb pairs (Ragoussis et al. 1986). This estimate has recently been confirmed (Lawrance et al. 1987). Apart from the highly polymorphic class I and II loci, the HLA complex contains the genes for several complement components and 21-steroid hydroxylase (class III region) (Lamm and Olaisen 1985). In addition, the loci for tumor necrosis factor (TNFA) as well as lymphotoxin (TNFB) are also near or even within the HLA region (Nedwin et al. 1985). Spies and co-workers (1986) demonstrated that the TNF genes map either centromeric to HLA-DP or telomeric to the class I1 region, although apparently not in the vicinity of any known class I or III genes. The recent demonstration that the TNF loci are situated 70 kb upstream of the H-2D gene in the BALB/c mouse between the class III and class I regions (Mfiller et al. 1987a, b) suggested an analogous location in man, because the genetic organization of the major histocompatibility complexes (MHC) of both species is very similar. To clarify the position of the TNFA and TNFB genes on the HLA map, we have assigned TNFA to large DNA restriction fragments separated by field inversion gel electrophoresis (FIGE) (Carle et al. 1986), which hybridize with either class 1II-or class Ispecific probes as well. These results prove that the TNFA locus is localized between the HLA class III region and the HLA-B locus.To avoid interpretative difficulties which might arise from haplotype-specific restriction fragment length polymorphisms, mutant human cell lines with monosomy 6 or HLA hemizygosity were employed. All mutants were derived from BJAB-B95.8.6 lymphoma cells with the HLA haplotypes A1, Cw4,B35 and A2, C-,B13 (Spring et al. 1985). Mutant BM 19.7 is a monosomy 6 mutant cell line retaining the A2 haplotype (Ziegler et al. 1985b). BM 28.7 also exhibits monosomy 6, but with loss of the chromosome bearing the A2 haplotype (Ragoussis et al. 1986). In the interstitial deletion mutant BM 2.2.3, the class I region of the A2 haplotype has been deleted, but the class II and III regions of this haplotype are still present, as is the chromosome 6 carrying the A1 haplotype (Ziegler et al. 1985a).Large genomic DNA fragments were generated with various restriction enzymes, separated by FIGE, and analyzed by hybridization to Southern blots (Southern 1975) under stringent conditions. In the Bss HII digests (Fig. 1), a 370 kb DNA fragment was detected which hybridized both to the HLA-B locus-specific probe that had been derived 29 kb 5' of the HLA-B gene (Fig. lb) and to the TNFA probe (Fig. lc), indicating linkage of TNFA with the HLA-B locus. The class III loci ...

DNA polymorphism of HLA class II genes in primary biliary cirrhosis

“…The TNFa gene codes for TNF and is situated between the H L A class III region and the H L A -B locus (Ragoussis et al 1988). This may be of importance i n t h e etiology of PBC because the production of TNF is correlated to the HLA-DR type (Bendtzen et al 1988) and possibly also to the TNF~ gene variant (Fugger et al 1989a).…”

Cytokines in Inflammatory Bowel Disease

“…TNF TNF-a and p are 17-kDa polypeptides whose genes are located in the major histocompatibility complex (MHC) region in experimental animals and man (85)(86). Linkage disequilibrium with polymorphic TNF-a genes and certain HLA-DR types has been demonstrated (87)(88)(89).…”

The cytokine network in the pathogenesis of systemic lupus erythematosus and possible therapeutic implications

“…The TNF genes are unique in that they are the only known cytokines located within the major histocompatibility complex, both in mice and human [21,97,113]. A striking association between different MHC alleles, especially class II alleles, and various autoimmune diseases has been well established [61].…”