Polymorphism and expression of macrophage migration inhibitory factor does not contribute to glucocorticoid resistance in idiopathic thrombocytopenic purpura.

Glucocorticoids (GCs) are considered the important drugs used in treatment of idiopathic thrombocytopenic purpura (ITP). However, about 10-30% patients with ITP develop GC resistance after standard treatment with GC. The macrophage migration inhibitory factor (MIF) has been shown to act as a counter-regulator of the anti-inflammatory and immunosuppressive effects of GCs on immune cells. In addition, MIF-173G/C polymorphism was associated with higher MIF expression both in vitro and in vivo. In this case-control study, we investigated the association of GC resistance with MIF polymorphism and expression. MIF mRNA expression was analyzed by semiquantitative real-time RT-PCR in GC-sensitive and GC-resistant ITP patients. MIF protein expression in serum was performed by ELISA. Genotyping for the MIF -173G/C polymorphism was analyzed by a Polymerase chain reaction Tm-shift genotyping method. We found no association of GC resistance and MIF mRNA and protein expression. According to sex, age, initial blood platelet count, and disease course, the patients were further subdivided into 8 groups, no statistical difference was found. In addition, we compared the distribution of the MIF -173G/C genotype and allele frequencies between the GC-sensitive ITP patients and the GC-resistant and found no statistical difference. The present study suggested that MIF polymorphism and expression does not contribute to GC resistance in ITP.