HLA ANTIGENS AS MARKERS FOR ALLELIC VARIANTS OF TUMOR NECROSIS FACTOR-A. FAMILY STUDIES.
O. Rosina, O. Gudzowaty, DS. Bernstein and D. Skerrett. Department of Medicine, Division of Hematology, Tissue Typing Laboratory, Mount Sinai Medical Center and Department of Pathology, Columbia University, NY.
TNF-?, one of the large group of immunoregulatory cytokines, is implicated in graft rejection and graft vs. host disease. TNF-? genes located within MHC complex are part of the HLA system.The genetic variations in the promoter region of TNF-? have been found to correlate with the level of TNF-? production. High and low producers have polymorphic substitutions at position -308 in the promoter region. TNF-? alleles segregate with different HLA antigens. We investigated the linkage of HLA and TNF-? haplotypes in marrow transplant recipients and donors.
Frozen DNA from BMT patients, family members and unrelated donors were typed for TNF-? high/ low expression genotypes by PCR-based typing using cytokine genotyping tray (One Lambda Inc). All samples were typed for HLA class I antigens by molecular low resolution typing (serological equivalent) and class II by high resolution typing (allele level). HLA haplotypes were assigned by family studies, and TNF-? high and low expression genotypes were analyzed for each HLA haplotype.
Fifty-two donor/recipient pairs were studied.The frequency of TNF-? high expression A genotype (nucleotide sequence at position-308) was 16%; low expression G haplotype (alternative sequence at the same position) was 84%. We observed the linked segregation of HLA haplotype: A1, B8, Cw7, DRB1*03 and TNF-? A haplotype in a homozygous patient. In addition, we found linked segregation of HLA-B51, Cw14, DRB1*0803 and TNF-? A haplotype in two patients. The linkage was confirmed by family studies. The rest of the HLA and TNF-? haplotypes were found only as a single event. The observed linkage between HLA antigens and TNF-? high expression haplotype can be used as a genetic marker for TNF-? expression in transplant patients when family studies are not available.