Effect of plasma exchange on cytokines measured by multianalyte bead array in thrombotic thrombocytopenic purpura.

The serum cytokine profile in thrombotic thrombocytopenic purpura (TTP) has not been extensively characterized. In this pilot study, a novel technique was utilized to evaluate multiple cytokines in patients with idiopathic TTP during a course of plasma exchange (PE). Single serum samples were obtained from five TTP patients before and after each PE. Random sera were obtained from nine healthy volunteers who served as controls. The samples were evaluated for 13 cytokines (IL-1B, IL-2 , IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IFN-gamma, GM-CSF, and TNF-alpha) using the Luminex bead array (LINCOplex) multianalyte detection system that permits simultaneous detection of multiple cytokines from a single sample. Each patient received 4-6 PEs (Cobe Spectra) with 3.0-4.0 L of fresh frozen plasma as replacement fluid. Four of 5 patients received corticosteroids prior to and during PE. The control group did not receive steroids. Baseline values for IL-8 (182.9 vs. 6.5 pg/mL, P < 0.05) and TNF-alpha (11.4 vs. 0.9 pg/mL, P < 0.001) were significantly higher in TTP patients compared with controls. Other tested cytokines were not significantly different between the two groups. Comparison of cytokine values pre- and post-PE indicate a substantial decrease after each PE. However, cytokines rebounded to abnormal levels by the following day. There was no correlation between cytokines and serum LDH or platelet count. These findings suggest that certain cytokines, particularly IL-8 and TNF-alpha, are altered in TTP, and this may indicate a direct role in TTP pathogenesis, reflect ongoing tissue injury, or perhaps indicate an inadequate attempt to limit tissue injury.