Cross-reactivity in drug hypersensitivity reactions to sulfasalazine and sulfamethoxazole.

BACKGROUND: Sulfonamides are generally classified into 2 groups: antibiotics and non-antibiotics. Recent studies showed that patients allergic to sulfonamide antibiotics do not have a specific risk for an allergy to sulfonamide non-antibiotic. However, the anti-inflammatory drug sulfasalazine represents an important exception. Used in rheumatic diseases, it is classified as a non-antibiotic sulfonamide, but is structurally related to antibiotic sulfonamides. Therefore, we aimed to analyze in vitro the cross-reactivity between the antimicrobial sulfamethoxazole and the anti-inflammatory drug sulfasalazine. METHODS: PBMC from 2 patients with severe hypersensitivity syndrome to sulfasalazine, 3 patients with sulfamethoxazole allergy and 5 healthy donors were isolated and incubated with medium only (negative control), 2 concentrations (10, 100 µg/ml) of sulfapyridine, 2 concentrations (100, 200 µg/ml) of sulfamethoxazole, and tetanus toxoid (10 µg/ml) as a positive control. After 6 days of culture, (3)H-thymidine was added and cell proliferation was measured. RESULTS: In all patients tested, the lymphocyte transformation tests were positive for both sulfapyridine and sulfamethoxazole, suggesting a strong cross-reactivity to these drugs. None of the healthy donors reacted to any of the drugs tested. We refrained from provoking our patients with either sulfasalazine or sulfamethoxazole, as they had a clear, typical history, severe symptoms and were positive on in vitro tests to both compounds. CONCLUSIONS: We demonstrate that in the case of sulfamethoxazole and sulfasalazine, cross-reactivity is dependent on chemical features rather than the indication of the drugs. Therefore, patients with hypersensitivity to sulfasalazine or sulfamethoxazole should be specifically advised to avoid both drugs.

SwissTecLive: effectiveness and safety of dimethyl fumarate in the treatment of RRMS in the Swiss clinical practice setting.

BACKGROUND: Delayed-released dimethyl fumarate (DMF) is an oral disease-modifying therapy (DMT) approved for treating patients with multiple sclerosis (MS). This post-marketing study aimed at collecting real-world data on the safety, effectiveness, and tolerability of DMF in patients with relapsing remitting multiple sclerosis (RRMS). METHODS: 1-year post-marketing survey of patients prescribed DMF followed-up quarterly in hospital setting and private neurological practices in Switzerland from January 2015 to January 2018. Data on relapses, Expanded disability status scale (EDSS) score change, safety, tolerability, treatment adherence as judged by the treating neurologist and satisfaction were collected. Patients could refer to a patient support program. RESULTS: Of the 158 patients, 67 (42.4%) were treatment naïve, 91 (57.6%) switched from a prior MS DMT to DMF, 131 (82.9%) were treatment adherent, 108 (68.4%) used the support program, and 45 (28.5%) discontinued the therapy. Insufficient tolerability and insufficient effectiveness were the main reasons for discontinuation. 134 (84.8%) patients remained relapse free, 97 (61.4%) had stable or decreased EDSS score after 12 months. 74 (46.8%) patients reported adverse events; of these, 28 (17.7%) discontinued DMF treatment. Physicians and patients rated treatment satisfaction similarly (median score 8.0 of 10). CONCLUSIONS: The results obtained from this real-world observation are consistent with the efficacy and safety findings reported in pivotal and larger observational trials evaluating DMF treatment. Most side effects were experienced early after therapy initiation reflecting the timing of therapy discontinuation.

Tolerability, treatment satisfaction and quality of life outcomes in stable multiple sclerosis patients switched from injectable therapies to auto injected intramuscular interferon beta 1a: The SFERA study.

BACKGROUND: Interferon beta (IFNB) and Glatiramer acetate, long-term first line disease modifying treatments (DMTs) for multiple sclerosis (MS), have different injection frequencies crucial for injection site related side effects. We aimed at investigating whether switching to intramuscular IFNB-1a injected once/week with the Avonex®Pen™ device improves treatment tolerability and quality of life in stable MS patients. METHODS: Clinically stable MS patients, whom their treating neurologist switched from high frequency injectable DMTs to weekly intramuscular IFNB-1a because of bothersome injection site reactions, were included. Injection site and systemic tolerability were measured by a composite 100 mm visual analogue scale at screening, months 4 and 12. Treatment satisfaction, quality of life, relapses and EDSS progression were also recorded. The primary endpoint was change in injection site tolerability from screening to Month 4. Descriptive statistics and Wilcoxon paired signed-rank tests were applied. RESULTS: The median injection site tolerability and systemic tolerability were significantly improved at months 4 (n = 36) and 12 (n = 33) [change -51.60 (IQR: -60.13, -39.60) mm (p < 0.0001); -26.00 (-54.00, 2.25) mm (p = 0.002)]. Median treatment satisfaction was significantly improved at month 12 [change of 18.00 (2.00, 47.50) mm (p = 0.0003)]. Physical and mental components of the SF-36 did not change significantly, and 30/33 (90.9%) and 33/33 (100%) patients were free from relapses and EDSS progression at month 12. CONCLUSIONS: Weekly intramuscular IFNB-1a may represent an alternative treatment option for clinically stable MS patients suffering from intolerable injection-related side effects under treatment with high frequency injectable DMTs.

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.

In vitro tests of T cell-mediated drug hypersensitivity.

Allergic side-effects of drugs are a major problem of drug therapy. Diagnosis of drug-hypersensitivity reactions in patient is still very difficult as a broad spectrum of different drugs can elicit various immune-mediated diseases with distinct pathomechanisms. In this review, we summarize current in vitro techniques with an emphasis on diagnosis of T cell- mediated drug allergies and discuss recent research finding that may be applied to develop tests allowing for a better diagnosis of drug hypersensitivity in the future.

Long-lasting reactivity and high frequency of drug-specific T cells after severe systemic drug hypersensitivity reactions.

BACKGROUND: Drug-reactive T cells are involved in most drug-induced hypersensitivity reactions. The frequency of such cells in peripheral blood of patients with drug allergy after remission is unclear. OBJECTIVE: We determined the frequency of drug-reactive T cells in the peripheral blood of patients 4 months to 12 years after severe delayed-type drug hypersensitivity reactions, and whether the frequency of these cell differs from the frequency of tetanus toxoid-reactive T cells. METHODS: We analyzed 5 patients with delayed-type drug hypersensitivity reactions, applying 2 methods: quantification of cytokine-secreting T cells by enzyme-linked immunospot (ELISpot), and fluorescent dye 5,6-carboxylfluorescein diacetate succinimidyl ester (CFSE) intensity distribution analysis of drug-reactive T cells. RESULTS: Frequencies found were between 0.02% and 0.4% of CD4(+) T cells reacting to the respective drugs measured by CFSE analysis, and between 0.01% and 0.08% of T cells as determined by ELISpot. Reactivity was seen neither to drugs to which the patients were not sensitized nor in healthy individuals after stimulation with any of the drugs used. CONCLUSION: About 1:250 to 1:10,000 of T cells of patients with drug allergy are reactive to the relevant drugs. This frequency of drug-reactive T cells is higher than the frequency of T cells able to recognize recall antigens like tetanus toxoid in the same subjects. A substantial frequency could be observed as long as 12 years later in 1 patient even after strict drug avoidance. Patients with severe delayed drug hypersensitivity reactions are therefore potentially prone to react again to the incriminated drug even years after strict drug avoidance.

Pharmacological interaction of drugs with immune receptors: the p-i concept.

Drug-induced hypersensitivity reactions have been explained by the hapten concept, according to which a small chemical compound is too small to be recognized by the immune system. Only after covalently binding to an endogenous protein the immune system reacts to this so called hapten-carrier complex, as the larger molecule (protein) is modified, and thus immunogenic for B and T cells. Consequently, a B and T cell immune response might develop to the drug with very heterogeneous clinical manifestations. In recent years, however, evidence has become stronger that not all drugs need to bind covalently to the MHC-peptide complex in order to trigger an immune response. Rather, some drugs may bind directly and reversibly to immune receptors like the major histocompatibility complex (MHC) or the T cell receptor (TCR), thereby stimulating the cells similar to a pharmacological activation of other receptors. This concept has been termed pharmacological interaction with immune receptors the (p-i) concept. While the exact mechanism is still a matter of debate, non-covalent drug presentation clearly leads to the activation of drug-specific T cells as documented for various drugs (lidocaine, sulfamethoxazole (SMX), lamotrigine, carbamazepine, p-phenylendiamine, etc.). In some patients with drug hypersensitivity, such a response may occur within hours even upon the first exposure to the drug. Thus, the reaction to the drug may not be due to a classical, primary response, but rather be mediated by stimulating existing, pre-activated, peptide-specific T cells that are cross specific for the drug. In this way, certain drugs may circumvent the checkpoints for immune activation imposed by the classical antigen processing and presentation mechanisms, which may help to explain the peculiar nature of many drug hypersensitivity reactions.