Association of T Cell Costimulatory and Downregulatory Gene Polymorphisms and Susceptibility to Multiple Myeloma.

Multiple myeloma (MM) is a B-lineage malignancy characterized by an accumulation of isotype-switched, immunoglobulin-producing monoclonal plasma cells. Additionaly phenotype and functional abnormalities of T cell are observed. The implication of T cells in the development of plasmocytoma has been shown in murine model. The study was undertaken to evaluate the association between polymorphisms of the genes encoding major T cell costimulatory (CD28, ICOS) and downregulatory (CTLA-4) molecules and susceptibility to MM in a Polish population. One hundred patients with MM and 202 healthy subjects were studied. Genomic DNA was isolated from whole frozen blood using the NucleoSpin^R Blood kit. Allele identification was achieved by PCR amplification. The amplified product for SNP loci was purified and minisequenced using the commercial kit SNapShot (PE Applied Biosystems). The dinucleotide repeat polymorphism was studied by PCR and fluorescence based technique. The products were analyzed on the ABI PRISM 310 Genetic Analyzer (ABI PRISM 310 capillary electrophoresis system).

We found an association of 49G in exon 1 and (AT)₈₂ alleles in 3′untranslated region in the CTLA-4 gene with MM [p=0.018, OR=1.57, 95% CI=1.08–2.29 and p=0.0013, OR=1.85, 95% CI=1.27–2.72, respectively] while no association between T/C substitution in intron 3 of the CD28 gene, the dinucleotide (GT)n repeat polymorphism in intron 4 in ICOS gene and C/T base exchange in the promoter (position −318) in the CTLA-4 gene and MM was observed. Our results indicate that the A/G substitution in exon 1 and microsatelite polymorphism in the 3′untranslated region in the CTLA-4 gene might be a susceptibility locus for MM.

The present study is the largest and comprehensive to date to evaluate the association between genetic polymorphisms of genes encoding T cell costimulatory and downregulatory molecules and susceptibility to MM.