Lymphocyte stimulation test with drug-photomodified cells in patients with quinolone photosensitivity

Update on Quinolone Allergy

PURPOSE OF REVIEW

Quinolones are a group of synthetic antibiotics widely use as first-line treatment for many infections. There has been an increase in the incidence of hypersensitivity reactions to quinolones in recent years, likely due to increased prescription. The purpose of this review is to summarize the clinical pictures, the methods used for diagnosing and the management of allergic reactions to quinolones.

RECENT FINDINGS

Allergic reactions to quinolones can be immediate or delayed, being anaphylaxis and maculopapular exanthema respectively the most frequent clinical entities. A precise diagnosis is particularly difficult since clinical history is often unreliable, skin tests can induce false-positive results, and commercial in vitro test are not well validated. Therefore, drug provocation testing is considered the gold standard to establish diagnosis, which is not a risk-free procedure. Cross-reactivity between quinolones is difficult to predict due to the small number of patients included in the few published studies. Moreover, hypersensitivity to quinolones has also been associated with beta-lactam and neuromuscular blocking agent allergies, although further studies are needed to understand the underlying mechanisms. Avoidance of the culprit quinolone is indicated in patients with a diagnosis of hypersensitivity to these drugs. When quinolone treatment is the only therapeutic option available, desensitization is necessary. This review summarizes the complex diagnostic approach and management of allergic reactions to quinolones.

Quinolone hypersensitivity

PURPOSE OF REVIEW

Quinolones are potent antibacterial agents that can cause drug hypersensitivity reactions affecting different organs. A better understanding of the underlying mechanism and the level of crossreactivity within different quinolones is needed to handle and prevent these diseases.

RECENT FINDINGS

The adverse side-effects caused by quinolones are the result of different immunological mechanisms and cause quite different diseases. The development of an assay detecting quinolone-specific IgE revealed specific antibodies in more than 50% of patients with immediate-type reactions, and the majority of sera also reacted with related compounds. In maculopapular drug exanthemas caused by ciprofloxacin, specific T cells could be detected and cloned. They reacted with ciprofloxacin directly, and crossreactivity to related compounds was detected in approximately 50% of the clones.

SUMMARY

Quinolones can cause drug hypersensitivity reactions by different immunological mechanisms. In-vitro analysis suggests that crossreactivity is common.

Quinolone-photoconjugated major histocompatibility complex class II-binding peptides with lysine are antigenic for T cells mediating murine quinolone photoallergy

Fluoroquinolone antibacterial agents cause photosensitivity dermatitis as an adverse effect and can function immunologically as photohapten. In a murine model of quinolone photoallergy, Langerhans cells are photomodified with a systemically given quinolone upon ultraviolet A irradiation of skin and thus present photohaptenic moieties to sensitize and restimulate T cells. The aim of this study is to determine the site of peptides/proteins photobound to quinolones and to assess the T cell antigenicity of quinolone-photocoupled peptides using Langerhans cells as photoadduct-presenting cells. On an amino acid composition analysis, lysine was preferentially degraded in bovine serum albumin that was ultraviolet A-conjugated with a representative quinolone ofloxacin. An affinity chromatographic study using a quinolone photoadduct-specific monoclonal antibody as ligand demonstrated preferential photocoupling of ofloxacin with a lysine-containing peptide. CD4+ T cells were purified from lymph nodes of BALB/c mice sensitized subcutaneously with ofloxacin-photomodified epidermal cells and from those sensitized epicutaneously via barrier-disrupted skin with a major histocompatibility complex class II (I-Ad)-binding, ofloxacin-photoconjugated peptide. These immune T cells proliferated in vitro in response to Langerhans cells loaded with class II-binding, lysine-containing peptides when photomodified with ofloxacin. Furthermore, epicutaneous application of the ofloxacin-photoconjugated peptide was able to prime mice for subsequent elicitation of photoallergy evoked with systemic ofloxacin and ultraviolet A light. This study suggests that lysine affords quinolone photocoupling of peptides and quinolone-photomodified peptides on class II molecules stimulate pathogenetic T cells in quinolone photoallergy.

Immune responses to photohaptens: implications for the mechanisms of photosensitivity to exogenous agents

A photohaptenic moiety is one of the salient properties of photoallergic chemicals. Clinically, it is likely that photohaptens are the main causative substances in photoallergic contact dermatitis and drug photoallergy. Photohaptens bind covalently to protein under exposure to ultraviolet A light (UVA). Because of this photocoupling ability, cells are easily photoderivatized with a photohapten by UVA irradiation, becoming immunogenic photohapten-modified cells. Langerhans cells photomodified with a photohapten can stimulate immune T cells when photomodification is performed with a non-phototoxic dose of UVA.