The in vitro amplification of β-lactam-specific memory t cells improves the diagnostic performance of IGE detection and lymphocyte transformation test

b-Lactams (b-Ls) represent the most frequent cause of adverse drug reactions (ADRs) due to immunological mechanisms. The diagnostic platform is actually based on in vivo assays, whereas in vitro assays do not seem to appropriately answer the requirements of clinical practice and they are mainly field of research or still matter of debate. Both specific IgE determination and lymphocyte transformation test (LTT) exhibit modest (if not low) sensitivity whereas flow-cytometric basophil activation test is still under investigation and limited to immediate reactions. Although short-term T-cell lines (TCLs) have only been used so far to characterize the immunological mechanisms of ADRs, taking advantage from a large number of selected patients with history of b-Lactam sensitization we demonstrate here that hapten-specific TCLs can be induced from the peripheral blood of high proportions of ADR+ patients independently of circulating IgE and LTT, type (immediate vs delayed) or extension (local vs systemic) of the reaction. We also show that wide cross-reactivity between b-L-haptens is exhibited by short-term T-cell lines and detection of specificity can be performed independently of processing-dependent presentation. On the basis of these results, IgE detection, LTT and haptenspecific TCL induction altogether exhibit high specificity (95.5%) and sensitivity (80.5%) thus significantly improving the diagnostic performance of singularly available in vitro tests in b-Lactam sensitization.