TNF-alpha is a master regulator of drug-specific T-cell activation.

Background

The activation of T-lymphocytes is implicated in delayed-onset drug hypersensitivity. However, currently defined cellular and genetic risk factors are not sufficient for the development of comprehensive predictive tools, translatable across conventional drug classes, new modalities and diverse reaction phenotypes.

Objectives

In this study, we aimed to assess the frequency of interactions between drugs, HLA proteins, and T-cell receptors within human populations and the role of TNFα as a critical regulator.

Methods

To study the frequency and functionality of T-cell responses, a novel in vitro culture system was employed to mimic the inflammatory microenvironment, achieved through 6-day culture of PBMC from drug-naïve and drug tolerant individuals with a panel of drug(metabolites) commonly associated with hypersensitivity, and TNFα. T-cell proliferation was measured through [³H]-thymidine incorporation and cytokine analysis was performed using the ELISpot assay.

Results

T-cell responses to antibiotics were frequently detectable in drug tolerant and drug naïve individuals following the addition of TNFα. 90% and 60% of drug naïve individuals produced a detectable T-cell response to vancomycin and piperacillin, respectively. Similarly, T-cell responses to dapsone, sulfamethoxazole and/or reactive nitroso metabolites were present at high frequencies (>65%). Drug immunogenicity was inhibited by the introduction of TNFα antagonists and HLA blocking antibodies. Assays performed using PBMC components (CD3+, CD4+, CD8+, CD45RO+ and CD45RA+) show that drugs readily prime and activate naïve T-cells, with CD4+CD45RA+ T-cells preferentially activated.

Conclusion

We challenge the central dogma that tolerant individuals do not express the correct immunological receptors to mount a drug-specific T-cell response and that the cellular machinery for response elicitation is not limited to hypersensitive patients.