Prevalence of KIR2DL2/DS2 and KIR2DL3 and presence of B19V in patients with thyroid disorders

The functions of human natural killer cells are controlled by diverse families of antigen receptors. Prominent among these are the killer cell immunoglobulin-like receptors (KIR), controlled by a family of genes clustered in one of the most variable regions of the human genome — on chromosome 19q13.4. This study aimed to investigate the possible interplay between KIR allotype, B19 infection, and thyroid disorders. Thyroid gland tissue of 30 patients with autoimmune thyroid gland diseases (AITD), 30 patients with non-autoimmune thyroid gland diseases (non-AITD) and 30 deceased subjects whose histories did not show any of autoimmune or thyroid diseases (control group) were enrolled in the study. The presence of B19V, KIR2DL2/DS2, and KIR2DL3 was detected using PCRs (nPCR, PCR). The results showed that 28% of samples of thyroid tissue from patients with AITD and 67% with non-AITD were positive for the presence of B19V, in contrast only 5% control tissue samples harbored B19V DNA. B19V-positive AITD patients had higher frequency of KIR2DL2/DS2 homozygosity and lower frequency of homozygous KIR2DL3 genotype compared to B19V negative cases (33% vs 21% and 17% vs 46%, respectively). Although our data showed that B19V positive patients with AITD had a higher frequency of homozygosity for KIR2DL2/DS2, further studies with larger groups of patients are necessary to confirm the relationship between KIR, B19V and susceptibility to thyroid disease.