Cross-reactivity with drugs at the T cell level

Refractory drug-induced systemic small-vessel vasculitis with two varied extracutaneous manifestations: a case report and review of the literature

BACKGROUND

Clopidogrel and ticagrelor are rarely reported to cause vasculitis via drug hypersensitivity reaction, largely mediated by T cells and immunoglobulin E (IgE). Despite therapeutic advances, the etiology of refractory vasculitides remains incompletely understood. Recently, (non)immunological mechanisms bypassing T cells and IgE have been proposed to explain resistance to standard immunosuppressants. Herein, we report a case of refractory drug-induced systemic small-vessel vasculitis with varied extracutaneous manifestations and incorporate multiple sources of data to provide detailed accounts of complex (non)immunological phenomena involved in this case. Study objectives are to provide an insight about rare presentations of commonly used drugs, upgrade the pathophysiological concepts of drug-induced vasculitis, raise need for further investigation to define causes and risk factors for refractory vasculitis, and discuss most of the current knowledge suggesting novel therapeutic approaches to treat this vasculitis. To our knowledge, this is the first case of the two flares of systemic small-vessel vasculitis in a single patient in response to clopidogrel and ticagrelor exposure, respectively. However, this report is limited by attribution/observer bias.

CASE PRESENTATION

We herein report a 24-year-old Caucasian male student with a medical history of mild seasonal allergic rhinoconjunctivitis, tension-type headaches, posttraumatic arterial stenosis, and previous exposure to ibuprofen, acetylsalicylic acid, and mRNA coronavirus disease 2019 (COVID-19) vaccine who suffered largely from acute urticaria and dyspnea after 20 days of acetylsalicylic acid and clopidogrel introduction. A skin punch biopsy confirmed leukocytoclastic vasculitis. Serologic antibody testing, complement analysis, microbiologic testing, and cancer biomarkers revealed no abnormalities. Regarding the patient's medical history, both acetylsalicylic acid and clopidogrel were exchanged for ticagrelor. Furthermore, the addition of naproxen, cyclosporine, bilastine, prednisolone, and montelukast resulted in complete recovery. After 7 days, diarrhea and hematuria occurred. Urinalysis and computed tomography showed reversible proteinuria with gross hematuria and hypodense changes in kidney medulla, respectively, associated with discontinuation of ticagrelor and naproxen. In addition, the patient recovered completely without any immunosuppression up-titration.

CONCLUSIONS

This case highlights the role of clopidogrel and ticagrelor as possible triggering agents for systemic small-vessel vasculitis and offers an insight into novel therapeutic strategies for refractory vasculitides. Further research is needed to build on the findings of a current report.

Understanding Idiosyncratic Toxicity: Lessons Learned from Drug-Induced Liver Injury

Idiosyncratic adverse drug reactions (IADRs) encompass a diverse group of toxicities that can vary by drug and patient. The complex and unpredictable nature of IADRs combined with the fact that they are rare makes them particularly difficult to predict, diagnose, and treat. Common clinical characteristics, the identification of human leukocyte antigen risk alleles, and drug-induced proliferation of lymphocytes isolated from patients support a role for the adaptive immune system in the pathogenesis of IADRs. Significant evidence also suggests a requirement for direct, drug-induced stress, neoantigen formation, and stimulation of an innate response, which can be influenced by properties intrinsic to both the drug and the patient. This Perspective will provide an overview of the clinical profile, mechanisms, and risk factors underlying IADRs as well as new approaches to study these reactions, focusing on idiosyncratic drug-induced liver injury.

A joint allergist/cardiologist classification for thienopyridines hypersensitivity reactions based on their symptomatic patterns and its impact on the management strategies

The role and importance of thienopyridines such as ticlopidine, clopidogrel, and prasugrel is well-established for several indications, ranging from prevention of acute coronary syndromes to percutaneous coronary interventions, where the dual antiplatelet therapy represents the gold standard to avoid denovo coronary stenosis. However, there is a significant cohort of patients with coronary artery disease who may manifest hypersensitivity reactions to thienopyridines. The examination of the various case reports from medical literature leads to identify mainly four clinical patterns of hypersensitivity to thienopyridines which involves more frequently cutaneous, hematologic, and articular tissues, therefore the kind and predominance of clinical symptoms may determine a different clinical approach to overcome or neutralize thienopyridines hypersensitivity.

Allergic reactions to clopidogrel and cross-reactivity to other agents

Clopidogrel is a widely used antiplatelet agent, particularly after coronary stent implantation. About 1% of patients have allergic or hematologic adverse reactions to clopidogrel. This has important therapeutic implications, as premature discontinuation of clopidogrel is the strongest risk factor for stent thrombosis. Clopidogrel allergy most commonly manifests as a rash. It is important to distinguish this from other causes of rash occurring in patients who have had a recent coronary stent. Although antihistamines and short-term oral corticosteroids are effective in treating most clopidogrel hypersensitivity reactions, some persistent reactions may require discontinuation of clopidogrel. When discontinuation of clopidogrel is required, substitution with an alternative thienopyridine such as ticlopidine traditionally has been performed. However, a recent study suggests that there may be as high as a 27% risk of recurrence of non-life-threatening allergic reactions in such patients, which are usually similar to the allergic reactions that occurred with clopidogrel. No data are available regarding the frequency of cross-reactivity to prasugrel and ticagrelor; these may be potential therapeutic options in some patients.

Clindamycin-induced acute cholestatic hepatitis

We report a case of acute hepatotoxicity in a 42-year-old woman after administration of clindamycin for a dental infection. After 6 d of treatment, she had fatigue, nausea, vomiting, anorexia, pruritus and jaundice. Her laboratory analysis showed alanine aminotransferase (ALT), 1795 IU/L (normal range 0-40); aspartate aminotransferase (AST), 1337 IU/L (normal range 5-34); alkaline phosphatase (ALP), 339 IU/L (normal range 40-150); γ-glutamyl transpeptidase (GGT), 148 IU/L (normal range 9-64 IU/L); total bilirubin, 4.1 mg/dL; direct bilirubin, 2.9 mg/dL and prothrombin time (PT), 13.5 s, with international normalized ratio (INR), 1.04. She was hospitalized, with immediate drug discontinuation. Her liver biopsy specimen showed mixed-type (both hepatocellular and cholestatic) hepatic injury, compatible with a diagnosis of drug-induced hepatitis. An objective causality assessment using the Naranjo probability scale suggested that clindamycin was the probable cause of the acute hepatitis. In susceptible individuals, clindamycin use may lead to acute mixed-type liver toxicity. Complete recovery may be possible if the drug is discontinued before severe liver injury is established.

Cross-reactivity patterns of T cells specific for iodinated contrast media

BACKGROUND

Approximately 3% of patients exposed to iodinated contrast media develop delayed hypersensitivity reactions.

OBJECTIVE

We wanted to better understand the molecular basis of contrast media cross-reactivity.

METHODS

Cross-reactivity was assessed by skin testing and measurement of T-cell activation (CD69 upregulation) and proliferation ((3)H-thymidine uptake, 5,6-carboxyfluorescein diacetate succinimidyl ester staining) of PBMCs, T-cell lines, and T-cell clones of 2 patients with delayed hypersensitivity reactions to iohexol and iomeprol, respectively. Thirteen different contrast media and potassium iodide were compared.

RESULTS

Skin testing and analyses of PBMCs, T-cell lines, and clones showed broad cross-reactivity in both patients. Broad as well as more restricted cross-reactivity patterns were found in iohexol-specific and iomeprol-specific CD4(+) T-cell clones, whereas 1 iomeprol-specific CD8(+) T-cell clone showed no cross-reactivity at all. The reactivity to equimolar concentrations of iohexol and its dimer iodixanol was very similar, suggesting that the dimer was not more stimulatory than its monomer. Consistently low reactivity to iobitridol was found in both patients, but never to iodide. A frequency analysis of contrast medium-specific peripheral T cells gave values between 0.6 % (iomeprol) and 0.05 % (iobitridol).

CONCLUSION

Clinically observed cross-reactivity between different contrast media is a result of the presence of contrast media-specific T cells, some of which show a broad cross-reactivity pattern. Iodide ions, known to be present at low concentration in contrast media solutions, do not seem to be the causative moiety.

CLINICAL IMPLICATIONS

Detailed in vitro analysis might help identify noncross-reactive contrast media.

T cell-mediated hypersensitivity to quinolones: mechanisms and cross-reactivity

BACKGROUND

Quinolones are widely used, broad spectrum antibiotics that can induce immediate- and delayed-type hypersensitivity reactions, presumably either IgE or T cell mediated, in about 2-3% of treated patients.

OBJECTIVE

To better understand how T cells interact with quinolones, we analysed six patients with delayed hypersensitivity reactions to ciprofloxacin (CPFX), norfloxacin (NRFX) or moxifloxacin (MXFX).

METHODS

We confirmed the involvement of T cells in vivo by patch test and in vitro by means of the lymphocyte proliferation test (LTT). The nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones were investigated through the generation and analysis (flow cytometry and proliferation assays) of quinolone-specific T cell clones (TCC).

RESULTS

The LTT confirmed the involvement of T cells because peripheral blood mononuclear cells (PBMC) mounted an enhanced in vitro proliferative response to CPFX and/or NRFX or MXFX in all patients. Patch tests were positive after 24 and 48 h in three out of the six patients. From two patients, CPFX- and MXFX-specific CD4(+)/CD8(+) T cell receptor (TCR) alphabeta(+) TCC were generated to investigate the nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones. The use of eight different quinolones as antigens (Ag) revealed three patterns of cross-reactivity: clones exclusively reacting with the eliciting drug, clones with a limited cross-reactivity and clones showing a broad cross-reactivity. The TCC recognized quinolones directly without need of processing and without covalent association with the major histocompatability complex (MHC)-peptide complex, as glutaraldehyde-fixed Ag-presenting cells (APC) could present the drug and washing quinolone-pulsed APC removed the drug, abrogating the reactivity of quinolone-specific TCC.

CONCLUSION

Our data show that T cells are involved in delayed immune reactions to quinolones and that cross-reactivity among the different quinolones is frequent.

PF4/heparin complexes are T cell-dependent antigens

Heparin-induced thrombocytopenia (HIT) is a life-threatening, thrombotic disorder associated with development of anti-platelet factor 4 (anti-PF4)/heparin autoantibodies. Little is known about the antigenic and cellular requirements that initiate the immune response to these complexes. To begin to delineate mechanisms of autoantibody formation in HIT, we studied the immunizing effects of murine PF4 (mPF4)/heparin in mice with and without thymic function. Euthymic mice were injected with mPF4/heparin complexes, mPF4, heparin, or buffer. Mice injected with mPF4/heparin, but not mPF4 or heparin alone, developed heparin-dependent autoantibodies that shared serologic and functional characteristics of human HIT antibodies, including preferential binding to mPF4/heparin complexes and causing heparin- and FcRgammaIIA-dependent platelet activation. In contrast, athymic mice did not develop HIT-like antibodies. Taken together, these studies establish that PF4/heparin complexes are highly immunogenic and elicit self-reacting anti-PF4/heparin antibodies in a T cell-dependent manner.

Adverse drug interactions and reactions in dermatology: current issues of clinical relevance

This article highlights several adverse drug interactions and reactions relevant to current dermatologic practice. Absorption interactions between drugs and compounds containing polyvalent cations, potential interactions between herbal and conventional medicines, the meaning of sulfa allergy, and adverse cutaneous reactions caused by epidermal growth factor receptor inhibitors are discussed.

Cross-reactivity among drugs: clinical problems

Cross-reactivity among drugs is either mediated by immunologic mechanisms or not. The former kind is usually explained by the presence of common antigenic determinants in the cross-reacting drugs. In the case of compounds provoking non-allergic hypersensitivity reactions, cross-reactivity is explained by a common pharmacological characteristic, such as the inhibitory effect of non-steroidal anti-inflammatory drugs on cyclooxygenase-1 and the capability of muscle relaxants or contrast media to release histamine through a non-immunologic mechanism. The main clinical problem deriving from cross-reactivity among drugs is the compelling need to choose a potentially cross-reactive compound and, therefore, to assess cross-reactivity by diagnostic tests. In choosing alternative compounds, skin testing has been used in evaluating IgE-mediated cross-reactivity between penicillins and cephalosporins, as well as among muscle relaxants. In assessing T cell-mediated cross-reactivity among contrast media, corticosteroids, anticonvulsants and heparins, delayed-reading intradermal tests and patch tests, together with lymphocyte transformation tests, can be performed. Because of the limited sensitivity of in vivo and in vitro testing, the most prudent way of establishing the tolerability of a compound of the same group in patients who especially require one is a graded challenge when other allergologic tests are negative.

Characterization of Human T Cells That Regulate Neutrophilic Skin Inflammation

It is unknown whether neutrophilic inflammations can be regulated by T cells. This question was analyzed by studying acute generalized exanthematous pustulosis (AGEP), which is a severe drug hypersensitivity resulting in intraepidermal or subcorneal sterile pustules. Recently, we found that drug-specific blood and skin T cells from AGEP patients secrete high levels of the potent neutrophil-attracting chemokine IL-8/CXCL8. In this study, we characterize the phenotype and function of CXCL8-producing T cells. Supernatants from CXCL8(+) T cells were strongly chemotactic for neutrophils, CXCR1, and CXCR2 transfectants, but not for transfectants expressing CXCR4, CX3CR1, human chemokine receptor, and RDC1. Neutralization experiments indicated that chemotaxis was mainly mediated by CXCL8, but not by granulocyte chemotactic protein-2/CXCL6, epithelial cell-derived neutrophil attractant-78/CXCL5, or growth-related oncogene-alpha,beta,gamma/CXCL1,2,3. Interestingly, approximately 2.5% of CD4(+) T cells in normal peripheral blood also produced CXCL8. In addition to CXCL8, AGEP T cells produced large amounts of the monocyte/neutrophil-activating cytokine GM-CSF, and the majority released IFN-gamma and the proinflammatory cytokine TNF-alpha. Furthermore, apoptosis in neutrophils treated with conditioned medium from CXCL8(+) T cells could be reduced by 40%. In lesional skin, CXCL8(+) T cells consistently expressed the chemokine receptor CCR6, suggesting a prominent role for CCR6 in early inflammatory T cell recruitment. Finally, our data suggest that CXCL8-producing T cells facilitate skin inflammation by orchestrating neutrophilic infiltration and ensuring neutrophil survival, which leads to sterile pustular eruptions found in AGEP patients. This mechanism may be relevant for other T cell-mediated diseases with a neutrophilic inflammation such as Behçet's disease and pustular psoriasis.

Drug interaction with T-cell receptors: T-cell receptor density determines degree of cross-reactivity

BACKGROUND

Immune-mediated adverse reactions to drugs are often due to T-cell reactivity, and cross-reactivity is an important problem in pharmacotherapy.

OBJECTIVE

We investigated whether chemical inert drugs can stimulate T cells through their T-cell receptor (TCR) and analyzed the cross-reactivities to related compounds.

METHODS

We transfected human TCRs isolated from two drug-reactive T-cell clones (TCCs) by PCR into a TCR-negative mouse T-cell hybridoma. The TCCs were isolated from a patient with drug hypersensitivity to the antibacterial sulfonamide sulfamethoxazole (SMX).

RESULTS

The transfectants reacted to SMX only in the presence of antigen-presenting cells (APCs). Glutaraldehyde-fixed APCs, however, were sufficient to elicit T-cell stimulation, indicating a processing-independent direct interaction of the drug with the TCR and MHC molecule. The transfected hybridomas secreted IL-2 in a drug dose-dependent manner, whereas the degree of reactivity was dependent on the level of TCR expression. One transfectant reacted not only to SMX but also to related sulfonamide compounds. Interestingly, high TCR expression increased cross-reactivity to other structurally related compounds. In addition, SMX-specific TCR cross-reacted only with sulfonamides bearing a sulfanilamide core structure but not with sulfonamides such as celecoxib, furosemide, or glibenclamide.

CONCLUSIONS

These results demonstrate that the T-cell reactivity to drugs is solely determined by the TCR. Moreover, these results show that cross-reactivity of structurally similar compounds correlates with the density of the TCR. Stably transfected T-cell hybridomas may represent a powerful screening tool for cross-reactivity of newly generated sulfonamide-containing compounds such as celecoxib.