[Expression and gene polymorphisms of B cell activating factor in patients with idiopathic thrombocytopenic purpura].

Objective: To analyze the polymorphisms of B cell activating factor (BAFF) gene and the plasma levels of BAFF in patients with idiopathic thrombocytopenic purpura (ITP), and to investigate their roles in the pathogenesis of ITP.

Methods: Alleles specific polymerase chain reaction (AS-PCR) and agarose gel electrophoresis were used to identify polymorphisms -871C/T of BAFF promotor in 133 ITP patients and 117 healthy controls. The plasma levels of BAFF were assayed by ELISA.

Results: In ITP group, the frequency of C/C, C/T and T/T was 33.1%, 42.1% and 24.8%, respectively, the corresponding frequency in control group was 55.6%, 33.3% and 11.1%, respectively. The allele frequency of T in ITP and control groups was 45.9% and 27.4%, respectively. There was a significant difference in the BAFF -871C/T genotypic frequency between the ITP and control groups (P < 0.05). BAFF antigen in untreated ITP, treated patients and controls was 875.86 pg/ml, 502.59 pg/ml and 736.88 pg/ml, respectively, being also a significant difference among the three groups (P < 0.05). BAFF antigen in homozygous T/T was higher than that in homozygous C/C and heterozygous C/T, but the difference was not statistically significant (P > 0.05).

Conclusions: Over expression of BAFF may be a risk factor for ITP patients. There is a correlation of the BAFF promotor polymorphism -871C/T with ITP, but the polymorphism does not affect the expression of BAFF.