Characterization of amoxicillin and clavulanic acid specific T‐cell clones from patients with immediate drug hypersensitivity

Background Betalactam (BL) antibiotics are the most common cause of drug hypersensitivity. Amoxicillin (AX), which is often prescribed alongside clavulanic acid (Clav), is the most common elicitor. The aim of this study was to determine whether AX and Clav‐responsive T‐cells are detectable in patients with immediate hypersensitivity to AX‐Clav, to assess whether these T‐cells display the same specificity as that detected in skin and provocation testing, and to explore T‐cell activation pathways. Methods Drug‐specific T‐cell clones were generated from immediate hypersensitive patients´ blood by serial dilution and repetitive mitogen stimulation. Antigen specificity was assessed by measurement of proliferation and cytokine release. CD4+/CD8+ phenotype and chemokine receptor expression were analyzed by flow cytometry. Results 110 AX‐specific and 96 Clav‐specific T‐cell clones were generated from seven patients with positive skin test to either AX or Clav. Proliferation of AX‐ and Clav‐specific clones was dose‐dependent, and no cross‐reactivity was observed. AX‐ and Clav‐specific clones required antigen‐presenting cells to proliferate, and drugs were presented to CD4+ and CD8+ T‐cells by MHC class‐II and I, respectively. A higher secretion of IL‐13 and IL‐5 was detected in presence of the culprit drug compared with the alternative drug. Clones expressed CD69, CCR4, CXCR3, and CCR10. Conclusions Our study details the antigen specificity and phenotype of T‐cell clones generated from patients with AX‐Clav‐induced immediate hypersensitivity diagnosed by positive skin test. AX‐ and Clav‐specific clones were generated from patients irrespective of whether AX or Clav was the culprit, although differences in cytokine secretion were observed. AX‐ and Clav‐specific T‐cell clones can be generated from the same patient with immediate hypersensitivity, irrespective of whether AX or Clav is the culprit drug in the combination AX‐Clav. No cross‐reactivity between AX and Clav is detected. Differences in cytokine secretion are observed between T‐cell clones generated against the culprit or the alternative drug in the combination AX‐Clav.Abbreviations: AX, amoxicillin; Clav, clavulanic acid.