OBJECTIVETo investigate the efficacy and safety as well as the effects of lower dose of rituximab on B-lymphocytes, serum immunoglobulin, and platelet glycoprotein-specific antibodies in patients with chronic refractory immune thrombocytopenic purpura (ITP).

METHODSTwenty chronic refractory ITP patients, median age 47 (20 to 60) years old, received intravenous rituximab at the dose of 100mg once weekly for 4 consecutive weeks. Laboratory studies included complete blood cell count, regular monitoring of liver and kidney functions, blood coagulation and serum concentrations of IgG, IgM and IgA. CD3(+), CD4(+), CD8(+), CD19(+), CD20(+) cell numbers were assayed by flow cytometry prior to and following rituximab. Platelet glycoprotein antibodies were detected by ELISA. The detection of indicators were compared by paired T test, with P < 0.05 as statistically significant.

RESULTSThere was significant difference of the average platelet count between prior- \[(13 ± 5) × 10(9)/L\] and post-treatment \[(124 ± 106) × 10(9)/L\] with lower dose rituximab (P < 0.01). Reaching PLT peak period was of (24 ± 7) d with median time of 18 d. The responses were of 11(55%) CR, 4 (20%) R and 5 (25%) NR, respectively, with median response duration of 8 months (5 - 23 months). There were no significant changes of peripheral blood white blood cell count, hemoglobin, serum immunoglobulin, as well as CD3(+), CD4(+), CD8(+) lymphocyte counts during prior- and post-treatment. CD19(+)/CD20(+) cells were almost depleted in all patients \[(125.65 ± 14.12) × 10(6)/L vs (50.53 ± 29.11) × 10(6)/L, P < 0.01)\]. Expectedly, three cases of positive detection of platelet antibodies were negative after 4 weeks of lower dose of rituximab; one patient experienced infusion-related reaction.

CONCLUSIONTreatment with lower dose rituximab may be an effective and safe approach in patient with chronic refractory ITP. However, the optimal therapeutic schedule, long-term efficacy and adverse events need further investigation.