Study on the relations between HLA-DRB1alleles and ITP children

Wang HM¹, Yan WY², Shen BJ¹, Zhu N², Qi HY²

¹ Affiliated Hospital of Shan Dong Medical University, Jinan, China

² Shandong Umbilical Cord Blood Stem Cell Center

Objective: In order to study the relations between HLA-DRB1alleles and ITP children.

Methods: PCR-SSO was used to identify DRB1 alleles of 42 ITP children, 36 ITP children from them were identified anti-GPIIb/IIIa and anti-GPIb/Ix autoantibody by modified monoclonal antibody specific immobilization of platelet antigens (MAIPA).

Results: (1) Compared with health controls, DRB1*17 was significantly increased (relative risk=2.76, P<0.05, etiologic factor=0.1064) and DRB1*1202 was significantly decreased (relative risk=0.20, P<0.05, prophylactic factor=0.7616) in ITP children. (2) When HLA-DRB1 alleles were compared between patients with a good or poor response to steroids and IVIgG therapy, HLA-DRB1*11 was significantly decreased (c²=6.091, P<0.025) in patients with a poor response, furthermore, the most of HLA-DRB1*11-positive patients were old female children. (3) Twenty-seven patients (27/36, 75%) had anti-GPIIb/IIIa and seventeen (17/36, 47.22%) had anti-GPIb/Ix autoantibodies, the positivity of both anti-GPIIb/IIIa (P=0.217) and anti-GPIb/Ix (P=0.103) autoantibodies was associated with HLA-DRB1*02; however, antibody positivity between refractory and non-refractory ITP children showed no significant differences.

Conclusion: (1) ITP appears to be associated with DRB1*17, while DRB1*1202 appears to be protective to ITP. (2) There is a possibility that HLA-DRB1*11 play an important role in resistance to steroid and IgG therapy. (3) It seems likely that the production of anti-platelet autoantibodies correlated with DRB1*02, but that were not correlated with the therapy response. In conclusion, our findings indicate that genetic factors influence the clinical course of ITP, but this study should be considered preliminary and further studies of this issue are needed.

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