PTPN22 gene regulates natural killer cell proliferation during in vitro expansion

The protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene is expressed in hematopoietic tissue and peripheral blood mononuclear cells including natural killer (NK) cells. The rs2476601 single nucleotide polymorphism (SNP) in the PTPN22 gene is an important susceptibility marker for autoimmunity but its role in NK cell biology is not yet clear. The aim of the current study was to evaluate in a cohort of healthy individuals, whether allelic variants of the rs2476601 SNP are associated with NK cell expansion in vitro. The CT genotype of the rs2476601 SNP was significantly (P = 0.0013) associated with reduced NK cell CD3(-) CD56(+) fraction in culture. The current study shows that the T variant of the rs2476601 SNP could alter NK vs T-cell balance in vitro and suggests that the PTPN22 gene might have an important immune regulatory role in NK cell function which needs further investigation.