Mechanisms that limit proliferative potential of drug-specific LTT in drug-induced severe cutaneous adverse reaction patients

摘要

Background / ObjectivePrior use of “lymphocyte transformation test” (LTT) suggestedthat it was less often positive in Stevens-Johnsonsyndrome (SJS), Toxic Epidermal Necrolysis (TEN), thanin other cutaneous reactions, with possible dependence onsampling date. We explored the possible role of inhibitoryco-receptors in LTT, using well-defined groups of patientswho reacted to carbamazepine (CBZ), or lamotrigine(LTG), sulfamethoxazole (SMX) and allopurinol (ALL).MethodThirty one cases of SJS/TEN, and controls patients withDRESS (21) or exposed without reaction (EWR; (20)) wereprovided by the RegiSCAR group. Peripheral mononuclearcells (PBMC) were tested by qRT-PCR for the expressionof the inhibitory co-receptors and their respective ligands:PD-1/PDL1, CTLA4/B7.1. LTT was performed withPBMCs by measuring H3-thymidine incorporation after 6days incubation with CBZ/LTG/ALL (10μg/ml), SMX(50μg/ml) or medium, in the presence or not of blockingantibodies. Stimulation index ≥ 2.5 was considered positive.Mann-Whitney U test was used for comparison of geneexpression level. A p value ≤0.05 was considered statisticallysignificant.ResultsPositive LTT was observed in 3/23 (13%) SJS/TEN and in2/18 (11%) DRESS tested during the acute phase, and 7/22(32%) SJS/TEN and 4/12 (33%) DRESS tested after recovery(late). LTT were all negative in EWR. As compared totheir expression in PBMC of EWR, i) overexpression ofCTLA4 and of B7.1 was found in acute and late SJS/TEN,respectively; ii) overexpression of PD-1 and PDL1 wasfound in acute DRESS. Combined addition of anti-CTLA4and anti-PDL1 mAbs to LTT cultures of SJS/TEN (2 CBZand 2 SMX) and DRESS (4 CBZ) increased drug-inducedproliferation index, even turning some negative LTT intopositive LTT (4 out of 8; 50%).ConclusionWe confirm that reactive T cells are rarely detected inacute phase of SCAR, and to a lesser extent after recovery.We show for the first time that CTLA4- and PD-1pathways are active in SJS/TEN and DRESS, respectively,and may contribute to the negative reactivity of LTT.The use of anti-CTLA4 and anti-PDL1 mAbs could helpto sensitize drug-specific LTT.