Background: Type 1 Diabetes (T1D) is a T cell-mediated autoimmune disorder caused by the destruction of insulinsecreting cells. B7-H3 (CD276) plays a vital role in T cell response. However, B7-H3 expression and its clinical significance in T1D remain unclear. The aim of this study was to investigate the correlations between the expression of B7-H3 and clinical parameters in T1D patients. The possible role of B7-H3 gene variants with T1D was also discussed. Methods: Four B7-H3 single nucleotide polymorphisms (SNPs) were genotyped in 121 T1D patients and 120 healthy controls by polymerase chain reaction (PCR) direct sequencing. Expression of membrane B7-H3 (mB7-H3) in peripheral blood lymphocytes was determined by flow cytometry. Levels of soluble B7-H3 (sB7-H3) in serum were analyzed by enzyme linked immunosorbent assay (ELISA). Results: The B7-H3 haplotype T-A-C-T was less frequently observed in T1D patients compared to the controls (OR: 0.31, 95% CI: 0.16-0.61). B7-H3 expression on monocytes showed significant upregulation in T1D patients and was positively correlated with several clinical features including ALT, fast C-peptide 120 min, HbAlc, IFN-γ, IL-6 and TNF-α (P < 0.05). The concentration of sB7-H3 in serum increased in T1D patients (P < 0.0001). We also observed that B7-H3-T-A-C-T was associated with the decreased release of sB7-H3 but not the membrane form. Conclusions: B7-H3 may act as a potential biomarker related to the pathogenesis of T1D. The B7-H3-T-A-C-T polymorphism variant is associated with the low risk of T1D as well as less release of sB7-H3.

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