Allergic reactions to drugs: involvement of T cells

One-month daily and three-month weekly rifapentine plus isoniazid are comparable in completion rate and safety for latent tuberculosis infection in non-HIV Population: a randomized controlled trial

OBJECTIVES

The weekly rifapentine plus isoniazid for 3 months (3HP) improves completion rate of latent tuberculosis infection treatment, but flu-like symptoms are common. The novel 1HP regimen, involving daily rifapentine plus isoniazid for 28 days, has demonstrated low toxicity in HIV-infected populations. We aimed to investigate whether 1HP has a lower incidence rate of systemic drug reaction (SDR) compared with 3HP during treatment in non-HIV populations.

METHODS

This randomized, multicentre trial compared the completion rate and risks of SDRs of 1HP and 3HP in aged ≥13 years non-HIV subjects with latent tuberculosis infection between September 2019 and September 2023 (ClinicalTrials.gov: NCT04094012). We also investigated associations between SDRs and plasma levels of drugs and their metabolites.

RESULTS

A total of 251 and 239 individuals were randomly assigned to 1HP and 3HP groups, respectively, with completion rates of 82.9% (208/251) and 84.5% (202/239), respectively. Among them, 12.7% (32/251) and 10.9% (26/239) of 1HP and 3HP groups experienced SDRs, respectively (p 0.522), predominantly urticaria in 1HP group (59.4% [19/32]) and flu-like syndrome in 3HP group (80.8% [21/26]). Among participants experiencing SDRs, 43.8% (14/32) and 34.6% (9/26) in 1HP and 3HP groups, respectively, completed treatment (p 0.470). Cutaneous reactions were more common in 1HP than 3HP group (32.7% [82/251] vs. 13.0% [31/239], p < 0.001). In 1HP group, urticaria was associated with a higher plasma desacetyl-rifapentine level (ug/mL) at both 2 (median [interquartile range]: 36.06 [17.46-50.79] vs. 22.94 [14.67-31.65], p 0.018) and 6 hours (26.13 [15.80-53.06] vs. 29.83 [18.13-34.01], p 0.047) after dosing.

DISCUSSION

In non-HIV population, the incidence rate of SDR under 1HP is not lower than 3HP. Notably, urticaria, rather than flu-like syndrome, was the predominant SDR associated 1HP. The findings of this study underscore the feasibility of 1HP regimen in non-HIV populations with a high-completion rate exceeding 80%.

The Application of Knowledge-Based Clinical Decision Support Systems to Detect Antibiotic Allergy

Prevention of drug allergies is important for patient safety. The objective of this study was to evaluate the outcomes of antibiotic allergy-checking clinical decision support system (CDSS), K-CDSTM. A retrospective chart review study was performed in 29 hospitals and antibiotic allergy alerts data were collected from May to August 2022. A total of 15,535 allergy alert cases from 1586 patients were reviewed. The most frequently prescribed antibiotics were cephalosporins (48.5%), and there were more alerts of potential cross-reactivity between beta-lactam antibiotics than between antibiotics with the same ingredients or of the same class. Regarding allergy symptoms, dermatological disorders were the most common (38.8%), followed by gastrointestinal disorders (28.4%). The 714 cases (4.5%) of immune system disorders included 222 cases of anaphylaxis and 61 cases of severe cutaneous adverse reactions. Alerts for severe symptoms were reported in 6.4% of all cases. This study confirmed that K-CDS can effectively detect antibiotic allergies and prevent the prescription of potentially allergy-causing antibiotics among patients with a history of antibiotic allergies. If K-CDS is expanded to medical institutions nationwide in the future, it can prevent an increase in allergy recurrence related to drug prescriptions through cloud-based allergy detection CDSSs.

Drug hapten-specific T-cell activation: Current status and unanswered questions

Drug haptens are formed from the irreversible, covalent binding of drugs to nucleophilic moieties on proteins, which can warrant adverse reactions in the body including severe delayed-type, T-cell mediated, drug hypersensitivity reactions (DHRs). While three main pathways exist for the activation of T-cells in DHRs, namely the hapten model, the pharmacological interaction model and the altered peptide repertoire model, the exact antigenic determinants responsible have not yet been defined. In recent years, progress has been made using advanced mass spectrometry-based proteomic methods to identify protein carriers and characterise the structure of drug-haptenated proteins. Since genome-wide association studies discovered a link between human leukocyte antigens (HLA) and an individual's susceptibility to DHRs, much effort has been made to define the drug-associated HLA ligands driving T-cell activation, including the elution of natural HLA peptides from HLA molecules and the generation of HLA-binding peptides. In this review, we discuss our current methodology used to design and synthesise drug-modified HLA ligands to investigate their immunogenicity using T-cell models, and thus their implication in drug hypersensitivity.

Hemophagocytic lymphohistiocytosis is associated with Bartonella henselae infection in a patient with multiple susceptibility genes

BACKGROUND

Adult-onset hemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition, which is often triggered by certain types of infection, cancer and numerous autoimmune diseases; however, of the numerous infectious triggers associated with HLH, the consequences of Bartonella henselae infection have been rarely reported.

CASE PRESENTATION

A 48-year-old female presented with a 20-day history of intermittent fever accompanied by systemic rash, fatigue, anorexia and weight loss later she developed shock and unconsciousness. Blood tests showed a reduction of leukocyte, anemia and thrombocytopenia, and pathological results of a bone marrow biopsy confirmed hemophagocytic activity. Metagenomic next-generation sequencing (mNGS) analysis of the lymph node detected the presence of B. henselae. Whole exome sequencing revealed two gene variants, STXBP2 and IRF5, in this adult patient with secondary HLH. Then, she received minocycline and rifampin combination anti-infective therapy. Intravenous immunoglobulin for 5 days followed by a high dose of methylprednisolone were also administered. The patient was successfully discharged from the intensive care unit and remained in good condition after 2 months of follow-up.

CONCLUSIONS

mNGS served crucial roles in obtaining an etiological diagnosis, which suggested that screening for B. henselae should be considered in patients with HLH, especially those with a cat at home. In addition, the genetic defects were discovered to not only be present in primary HLH, but also in secondary HLH, even in the elderly.

Antibacterial Peptides in Dermatology-Strategies for Evaluation of Allergic Potential

During recent decades, the market for peptide-based drugs, including antimicrobial peptides, has vastly extended and evolved. These drugs can be useful in treatment of various types of disorders, e.g., cancer, autoimmune diseases, infections, and non-healing wounds. Although peptides are less immunogenic than other biologic therapeutics, they can still induce immune responses and cause allergies. It is important to evaluate the immunogenic and allergic potential of peptides before they are forwarded to the expensive stages of clinical trials. The process of the evaluation of immunogenicity and cytotoxicity is complicated, as in vitro models and bioinformatics tools cannot fully simulate situations in the clinic. Nevertheless, several potentially promising tests for the preclinical evaluation of peptide drugs have been implemented (e.g., cytotoxicity assays, the basophil activation test, and lymphocyte activation assays). In this review, we focus on strategies for evaluation of the allergic potential of peptide-based therapeutics.

Prevention of Allergic Reactions in Anesthetized Patients

Hypersensitivity reactions during perioperative period are increasing and may be potentially life-threatening. Therefore, major emphasis is given to prevention. We perform a review to examine which measures should be taken to prevent reactions to products used in elective and emergency surgery. Any patient with a history of previous anaphylaxis or severe reaction during anaesthesia should be referred to allergist for detection of the offending compound. However, the identification of the triggering agent is not always feasible because of the low accuracy of diagnostic tests. In these cases and when emergency surgery is required, it should be considered to replace all drugs administered before the onset of the reaction with alternatives. Furthermore, any cross-reacting agent and latex, especially in patients belonging to populations at-risk for latex allergy should be avoided. In susceptible patients, premedication with antihistamines and corticosteroids might reduce the severity of reaction to drugs or contrast material while it is unclear whether pre-treatment decreases incidence of anaphylactic reactions. There is no evidence that premedication prevents allergic reactions to latex. Overall, physicians should not rely on the efficacy of premedication.

Clinicopathologic correlation of oral lichen planus and oral lichenoid lesions: a preliminary study

Oral lichen planus (OLP) and oral lichenoid lesions (OLL) are clinically and histologically similar lesions but their treatment planning and prognosis are different. The review of the literature indicates numerous criteria to distinguish these two lesions; however there is a lot of inconsistency. Thus, the aim of this study was to determine the correlation of histopathology and clinical OLP and OLL diagnosis and to clarify which histopathologic criteria could best distinguish these two diagnoses. A retrospective study showed that clinically diagnosed 92 OLPs and 14 OLLs have been confirmed histopathologically in 52.2% and 42.9% of cases, respectively. In addition, histopathology showed statistically significant more eosinophils (P<0.0005), plasma cells (P<0.0005), and granulocytes (P<0.05) in OLL than OLP. To establish histopathological diagnosis of OLP and OLL it should be mandatory to define the type of cells in mononuclear infiltrate, which can be associated more accurately with clinical feature and patient history. Therefore, currently accepted diagnostic criteria for OLP and OLL should be modified and validated on a larger number of patients taking into account particular distinguishing histopathological features.

Chemokine expression in diverse nonimmediate drug hypersensitivity reactions: focus on thymus activation-regulated chemokine, cutaneous T-cell-attracting chemokine, and interleukin-10

BACKGROUND

Skin infiltration of different types of T lymphocytes is responsible for inflammatory profiles of nonimmediate drug hypersensitivity reactions (niDHRs). Important chemokines attracting skin-specific homing T cells include thymus activation-regulated chemokine (TARC) and cutaneous T-cell-attracting chemokine (CTACK). Interleukin-10 (IL-10) is a potent chemokine attracting CD8(+) T cells.

OBJECTIVE

To investigate serum levels of TARC, CTACK, and IL-10 in patients with niDHRs and evaluate the correlation among these 3 chemokines.

METHODS

Forty patients, including 19 patients with Stevens-Johnson syndrome and toxic epidermal necrolysis and 21 patients with maculopapular exanthema, and 21 healthy donors were recruited into the study. Clinical data of patients were obtained. Serum TARC, CTACK, and IL-10 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Serum levels of TARC, CTACK, and IL-10 were significantly elevated in patients with niDHRs compared with those in normal controls (P < .05, P < .001, P < .001, respectively). The CTACK and IL-10 levels were significantly higher (P < .05, P < .001) in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis than in normal controls. Patients with maculopapular exanthema exhibited higher levels of TARC, CTACK, and IL-10 compared with normal controls (P < .001, P < .001, P < .05). Serum CTACK levels were positively correlated with TARC levels in all 40 patients (rs = 0.3422, P < .05). Serum CTACK levels positively correlated with detachment of body surface area in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis (rs = 0.510, P < .05).

CONCLUSION

These results support a role for TARC, CTACK, and IL-10 in the pathogenesis of niDHRs for their chemotactic ability to attract different T-cell subtypes and different functional severities in niDHRs.

Structural basis of metal hypersensitivity

Metal hypersensitivity is a common immune disorder. Human immune systems mount the allergic attacks on metal ions through skin contacts, lung inhalation and metal-containing artificial body implants. The consequences can be simple annoyances to life-threatening systemic illness. Allergic hyper-reactivities to nickel (Ni) and beryllium (Be) are the best-studied human metal hypersensitivities. Ni-contact dermatitis affects 10 % of the human population, whereas Be compounds are the culprits of chronic Be disease (CBD). αβ T cells (T cells) play a crucial role in these hypersensitivity reactions. Metal ions work as haptens and bind to the surface of major histocompatibility complex (MHC) and peptide complex. This modifies the binding surface of MHC and triggers the immune response of T cells. Metal-specific αβ T cell receptors (TCRs) are usually MHC restricted, especially MHC class II (MHCII) restricted. Numerous models have been proposed, yet the mechanisms and molecular basis of metal hypersensitivity remain elusive. Recently, we determined the crystal structures of the Ni and Be presenting human MHCII molecules, HLA-DR52c (DRA*0101, DRB3*0301) and HLA-DP2 (DPA1*0103, DPB1*0201). These structures revealed unusual features of MHCII molecules and shed light on how metal ions are recognized by T cells.

Perioperative Allergy: Risk Factors

Perioperative anaphylactic as well as anaphylactoid reactions can be elicited by drugs, diagnostic agents, antiseptics, disinfectants and latex. In some individuals, allergic reactions occur in the absence of any evident risk factor. Previous history of specific safe exposure to a product does not permit to exclude the risk of having a reaction. We have systematically reviewed characteristics in the patient's history or clinical parameters that affect the risk of developing reactions during anesthesia. Evidence shows that patients with previous unexplained reaction during anesthesia are at risk for perioperative allergic reactions. An allergic reaction to an agent is associated with previous reaction to a product that is related with the culprit agent. Multiple surgery procedures, professional exposure to latex and allergy to fruit are associated with an increased frequency of latex allergy. It has been shown that in some instances, allergic perioperative reactions may be more common in atopic patients and in female.

Hypersensitivity reactions to HIV therapy

Many drugs used for the treatment of HIV disease (including the associated opportunistic infections) can cause drug hypersensitivity reactions, which vary in severity, clinical manifestations and frequency. These reactions are not only seen with the older compounds, but also with the newer more recently introduced drugs. The pathogenesis is unclear in most cases, but there is increasing evidence to support that many of these are mediated through a combination of immunologic and genetic factors through the major histocompatibility complex (MHC). Genetic predisposition to the occurrence of these allergic reactions has been shown for some of the drugs, notably abacavir hypersensitivity which is strongly associated with the class I MHC allele, HLA-B*5701. Testing before the prescription of abacavir has been shown to be of clinical utility, has resulted in a change in the drug label, is now recommended in clinical guidelines and is practiced in most Western countries. For most other drugs, however, there are no good methods of prevention, and clinical monitoring with appropriate (usually supportive and symptomatic) treatment is required. There is a need to undertake further research in this area to increase our understanding of the mechanisms, which may lead to better preventive strategies through the development of predictive genetic biomarkers or through guiding the design of drugs less likely to cause these types of adverse drug reactions.

Recent advances in liposomal dry powder formulations: preparation and evaluation

Liposomal drug dry powder formulations have shown many promising features for pulmonary drug administration, such as selective localization of drug within the lung, controlled drug release, reduced local and systemic toxicities, propellant-free nature, patient compliance, high dose carrying capacity, stability and patent protection. Critical review of the recent developments will provide a balanced view on benefits of liposomal encapsulation while developing dry powder formulations and will help researchers to update themselves and focus their research in more relevant areas. In liposomal dry powder formulations (LDPF), drug encapsulated liposomes are homogenized, dispersed into the carrier and converted into dry powder form by using freeze drying, spray drying and spray freeze drying. Alternatively, LDPF can also be formulated by supercritical fluid technologies. On inhalation with a suitable inhalation device, drug encapsulated liposomes get rehydrated in the lung and release the drug over a period of time. The prepared LDPF are evaluated in vitro and in vivo for lung deposition behavior and drug disposition in the lung using a suitable inhaler device. The most commonly used liposomes are composed of lung surfactants and synthetic lipids. Delivery of anticancer agents for lung cancer, corticosteroids for asthma, immunosuppressants for avoiding lung transplantation rejection, antifungal drugs for lung fungal infections, antibiotics for local pulmonary infections and cystic fibrosis and opioid analgesics for pain management using liposome technology are a few examples. Many liposomal formulations have reached the stage of clinical trials for the treatment of pulmonary distress, cystic fibrosis, lung fungal infection and lung cancer. These formulations have given very promising results in both in vitro and in vivo studies. However, modifications to new therapies for respiratory diseases and systemic delivery will provide new challenges in conducting well-designed inhalation toxicology studies to support these products, especially for chronic diseases.

Specificities of B cell reactions to drugs

Betalactams conjugate to protein carriers induced T and B cell effector responses. From these, IgE dependent reactions are the most common and better defined. These antibodies recognize a number of structures that can cross react or selective recognition may occur. The great variability in the chemical structure, specifically at the position R of penicillin and R1 of cephallosporins has made that the recognition of these structures may have clinical relevance in the evaluation of patients allergic to betalactams.

Clinical, radiologic, and induced sputum features of chronic obstructive pulmonary disease in nonsmokers: a descriptive study

Epidemiologic studies show that 5-12% of subjects with chronic obstructive pulmonary disease (COPD) are nonsmokers. Little is known about the pathophysiology of the fixed airflow obstruction in these subjects. We have prospectively identified 25 patients with COPD who had never smoked or had a less than 5 pack years smoking history and present the clinical, radiologic, and induced sputum features. Our population represented 5.7% of total referrals with fixed airflow obstruction over 2 years. Patients had a mean age of 70 years, were predominantly female (86%), and had a mean duration of respiratory symptoms of 7 years. The mean FEV(1) was 58%, and the FEV(1)/FVC was 55%. Features on high-resolution computed tomographic scanning were nonspecific and were considered typical of a wider population with COPD. An induced sputum differential inflammatory cell count suggested the presence of two distinct groups. Nine had significant sputum eosinophilia (mean, 8.1%; normal, less than 1.9%), and the remaining 13 had a normal sputum eosinophil and tended to have a raised sputum neutrophil count (mean, 70.1%; normal, less than 65%). Organ-specific autoimmune disease was present in 7 of the 22 patients (32%) and was particularly prevalent in those without sputum eosinophilia (6 of 13). In conclusion, COPD in nonsmokers predominantly affects females and has at least two pathologic subgroups, one of which may be associated with organ-specific autoimmune disease. Further investigation of this group may disclose novel mechanisms of fixed airflow obstruction.

Late-onset allergy-like reactions to X-ray contrast media

PURPOSE OF REVIEW

The purpose of the present review is to describe recent insight into the pathomechanism of the late-onset allergy-like reactions which affect 2-3% of contrast medium-exposed patients, and to give advice regarding prophylactic measures to avoid recurrence of such reactions.

RECENT FINDINGS

It is well recognized that the majority of contrast media-induced late-onset reactions are cutaneous reactions of the maculopapular, urticarial and angioedema types, with occasional occurrence of more serious, bullous eruptions. Recent findings strongly indicate that these reactions are T cell-mediated. The current evidences for this concept are the described clinical symptoms; the high incidence of reactions in interleukin-2-treated patients; the positive results from skin, provocation and lymphocyte transformation testing of affected patients; and the histopathology of skin eruptions and positive skin test sites.

SUMMARY

On the basis of this new knowledge, several prophylactic measures are proposed to avoid repeat reactions in patients with previous late-onset contrast medium reactions. All persons receiving contrast media should be informed that transient skin reactions may develop up to 7 days after contrast medium exposure. Those who experience such reactions should be advised to see an allergist for diagnosis of the reaction. Skin testing with a panel of different contrast media appears to be useful for confirming the presence of an allergic reaction and for identifying alternative contrast media that can be safely used. For undiagnosed persons, a contrast medium that is structurally different from the product that precipitated the reaction should be chosen if re-exposure to contrast media is required. Pretreatment with corticosteroids may also be tried, although its protective effect has not been systematically studied.

Severe erythroderma as a complication of continuous epoprostenol therapy

Epoprostenol is a vasodilator that is produced by vascular endothelial cells and is currently the "gold standard" therapy for patients with severe primary pulmonary hypertension or pulmonary hypertension secondary to collagen vascular disease. Hypersensitivity to the drug has not been reported. We report a case of a patient with pulmonary hypertension and undifferentiated connective tissue disease who, after 2 months of treatment with epoprostenol, presented with rapidly progressive erythema, scaling, nausea and vomiting, and fever. Test results from a skin biopsy specimen were consistent with a drug reaction. The patient' condition improved after rapid tapering of her epoprostenol and administration of corticosteroids. Epoprostenol may be associated rarely with severe erythroderma.