Supplementary Material for: Enhancement of Drug-Specific Lymphocyte Proliferation Using CD25<sup>hi</sup>-Depleted CD3<sup>+</sup> Effector Cells

2014-02-13T00:00:00Z (GMT) by Srinoulprasert Y. Pichler W.J.
<b><i>Background:</i></b> The lymphocyte transformation test (LTT) is used for in vitro diagnosis of drug hypersensitivity reactions. While its specificity is over 90%, sensitivity is limited and depends on the type of reaction, drug and possibly time interval between the event and analysis. Removal of regulatory T cells (Treg/CD25<sup>hi</sup>) from in vitro stimulated cell cultures was previously reported to be a promising method to increase the sensitivity of proliferation tests. <b><i>Objective:</i></b> The aim of this investigation is to evaluate the effect of removal of regulatory T cells on the sensitivity of the LTT. <b><i>Methods:</i></b> Patients with well-documented drug hypersensitivity were recruited. Peripheral blood mononuclear cells, isolated CD3<sup>+</sup> and CD3<sup>+</sup> T cells depleted of the CD25<sup>hi</sup> fraction were used as effector cells in the LTT. Irrelevant drugs were also included to determine specificity. <sup>3</sup>H-thymidine incorporation was utilized as the detection system and results were expressed as a stimulation index (SI). <b><i>Results:</i></b> SIs of 7/11 LTTs were reduced after a mean time interval of 10.5 months (LTT 1 vs. LTT 2). Removal of the CD25<sup>hi</sup> fraction, which was FOXP3<sup>+</sup> and had a suppressive effect on drug-induced proliferation, resulted in an increased response to the relevant drugs. Sensitivity was increased from 25 to 82.35% with dramatically enhanced SI (2.05 to 6.02). Specificity was not affected. <b><i>Conclusion:</i></b> Removal of Treg/CD25<sup>hi</sup> cells can increase the frequency and strengths of drug-specific proliferation without affecting specificity. This approach might be useful in certain drug hypersensitivity reactions with borderline responses or long time interval since the hypersensitivity reaction.