Pathophysiologic and clinical features of MDS are related to the phenotype of the dysplastic hematopoietic clone. The immunogenetic background resulting from complex genetic predisposition traits may influence the quality of the immune response and shape the clinical features of MDS, including the severity of cytopenias and speed of malignant evolution. To test this hypothesis we selected the following immunogenetic factors: KIR and KIR-ligand (KIR-L) genotype, as well as cytokine/receptor single nucleotide polymorphisms (SNP). We genotyped a cohort of 90 patients with MDS/sAML (30 RA/RCMD, 30 RARS/ RCMD-RS, 30 RAEB/sAML); 60 healthy donors matched for ethnicity were analyzed as a control. A group of 66 patients with aplastic anemia (AA) was used as a reference. HLA type, KIR, KIR-L haplotypes, and the following SNPs were analyzed: IL-1α (−889 T/C),IL2 (−330 T/G +166 G/T), IL4 (−1098 T/G -590 T/C -33 T/C, IL-1R (−1970 C/T), IL-1RA (mspa 111100 T/C), IL-4RA (+ 190 G/A), IL-1 β (−511 C/T, +3962 T/C), IL-6 (−174 C/G, nt565 G/A), IL-10 (−1082 G/A, -819 C/T), IL-12 (−1188 C/A), TGF-β (+10 C/T, +25 G/C), INF- γ (+874 A/T), TNF- α (−308 G/A, -238 G/A), CTLA-4 (exon 1, +49 A/G), FcgIIIR (+559 G/T) as well as SNPs in the CD45 gene (exon 4 +77 C/G, +138 A/G). In the MDS cohort, no difference in the frequency of KIR genotype constellations was identified. However, a higher frequency of 2DS5 (66% vs. 26%, p=.01) and a decreased frequency of 2DL3 (62% vs. 87% p=.02) was found when patients with hypocellular MDS (N=10) were analyzed separately. No significant difference in KIR-L C1/C2 genotype frequency between the group was found. However, an increased incidence of C2/C2 was found in high grade MDS/sAML (RAEB/sAML 44% vs. 13%, p=.02). In MDS, there was a decreased frequency of stimulatory 2DS1/C2 mismatch consistent with potentially enhanced cytotoxicity (17% vs. 44%, p=.01). No significant difference in the MDS cohort compared to control and when MDS subgroup were compared to each other, was found for the SNPs in IL-4RA, IL-12, IL-1α, IFN-γ, IL-2, IL-1 α, IL-1R, and IL4. However, when we examined the frequency of TGF- β genotypes, the MDS population showed a higher rate of TT codon 10 variant (59% vs. 32% in controls, p=.002) and of GG codon 25 variant (71% vs. 35% in controls, p=.0001), consistent with a “high secretor phenotype”. Of note is that, when AA was examined and compared to controls, a higher frequency of TGF-β high secretor genotype was found (GG codon 25 variant; 61% vs 35% in controls, p=.03). We also found a higher incidence of A/A genotype for CTLA-4 in MDS (47 vs 27, p=.001). This relationship was even more pronounced in hypocellular MDS. Moreover, hypocellular MDS was characterized by a higher prevalence of IL10 -819 T/T and -592 A/A phenotypes (40% vs 12% p=.03), which are functionally associated with a lower secretion. In sum, our findings demonstrate that various immunogenetic factors may be demonstrated in MDS patients, which may likely influence the quality of immune response and shape clinical features of MDS. Certain genotypic constellations (e.g., TGF gene variants) resemble, in particular in hypocellular MDS, a constellation seen in AA.
Disclosure: No relevant conflicts of interest to declare.