BAFF (
B-cell activating factor belonging to the TNF family) is an essential component of B-cell homeostasis, and is required for the normal survival and development of B cells. To further explore the role of this
cytokine in the pathogenesis of
idiopathic thrombocytopenic purpura (
ITP), BAFF/BAFF-R (one of receptors of BAFF) expression levels were determined and the correlation between the clinical parameters and the BAFF expression levels was analyzed. A total of 57 patients with
ITP were enrolled and 25 age and sex-matched healthy volunteers served as controls. Serum was obtained from 41 patients with
ITP and 22 healthy volunteers and was analyzed with a commercial human soluble BAFF (sBAFF) ELISA kit. BAFF and BAFF-R
mRNA expression of peripheral blood (PB) (n = 42) and splenocytes (SP) (n = 8) mononuclear cells (MNC) were determined by real-time quantitative PCR. The SPMNC of normal controls came from three
hereditary spherocytosis patients who underwent
splenectomy. The untreated patients with
ITP had higher serum BAFF levels (Median 1430 pg/ml, Range: 534-5787 pg/ml) than those of normal controls (Median 1120 pg/ml, Range: 640-2376 pg/ml, p = 0.006) and treated
ITP group (Median 662 pg/ml, Range 267-1265 pg/ml, p = 0.000). On the other hand, serum BAFF levels of treated patients with
ITP were lower than those of normal controls (p = 0.001). There was a weak correlation (the Pearson correlation coefficient is - 0.242) between platelet count and BAFF (p = 0.064). However, BAFF levels did not correlate with platelet associated
immunoglobulin or
immunoglobulin levels. Moreover, the serum BAFF levels were not statistically different between acute and chronic
ITP (p = 0.841). PBMNC of
ITP had higher BAFF but not BAFF-R
mRNA expression than that of normal controls. BAFF
mRNA expression of SPMNC had a positive correlation with BAFF-R in
ITP patients but not in PBMNC of normal controls and untreated
ITP patients. The BAFF-R
mRNA expression of SPMNC was shown to be 15.29 times higher than that of PBMNC in
ITP. BAFF might contribute to autoimmunity and disease development in
ITP. However, BAFF serum level must be carefully considered as a
surrogate marker of disease activity in
ITP.