Drug reaction with eosinophilia and systemic symptoms: A drug-induced hypersensitivity syndrome with variable clinical features

Drug reaction with eosinophilia and systemic symptoms (DRESS) or drug-induced hypersensitivity syndrome (DIHS) involves a unique and severe adverse drug reaction. Patients present with fever, rash, lymphadenopathy, hematological abnormalities, systemic illness, and may suffer from prolonged courses. Although the precise pathogenesis of DRESS/DIHS is not fully understood, it is widely considered to be an immunological reaction to a drug or drug metabolites. In this review article, we discuss the historical aspects of nosology, variable clinical and histopathological features, advantages and disadvantages of using an international Registry of Severe Cutaneous Adverse Reactions (RegiSCAR) and Japanese DIHS criteria, pathogenesis, treatment, and long-term sequelae of DRESS/DIHS. Early recognition of this syndrome, withdrawal of suspected culprit drugs, and adequate supportive care are mainstays of improving patient prognosis and reducing morbidities and mortality. Moreover, some DRESS/DIHS patients may develop long-term sequelae, especially autoimmune diseases and end organ failure. Physicians should be aware of these possibilities in patients after DRESS/DIHS and cautiously follow-up symptoms and laboratory tests for early detection of these sequelae.     

Severe drug‐induced skin reactions: clinical pattern,diagnostics and therapy

The spectrum of severe drug‐induced skin reactions includes not only Stevens‐Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) but also generalized bullous fixed drug eruption (GBFDE), acute generalized exanthematous pustulosis (AGEP) and hypersensitivity syndrome (HSS), also called drug reaction with eosinophilia and systemic symptoms (DRESS). These reactions differ in clinical presentation as well as prognosis, causative agents and therapy. Therefore, the appropriate diagnostic measures should be undertaken rapidly, in order to prove the diagnosis. In addition to a thorough clinical examination, a skin biopsy should be taken and specific laboratory investigations should be done if AGEP or HSS/DRESS is suspected. Since these reactions are drug‐induced, the causative agent should be rapidly identified and withdrawn. Besides adequate supportive therapy, systemic immunomodulatory treatments may be considered. Despite intensive care management, the prognosis in SJS and TEN is often poor and influenced by the amount of skin detachment as well as the age of the patients and the pre‐existing underlying conditions. Severe sequelae may develop in survivors and affect especially mucosal sites. The prognosis of GBFDE is better but recurrent events may lead to more severe involvement. In HSS/DRESS sequelae have been also described as well as long lasting and recurrent courses, whereas AGEP usually heals without problems.     

Stevens–Johnson syndrome and toxic epidermal necrolysis due to anticonvulsants share certain clinical and laboratory features with drug‐induced hypersensitivity syndrome,despite differences in cutaneous presentations

Background. Drug‐induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS) syndrome is characterized by late disease onset, fever, rash, hepatic dysfunction, haematological abnormalities, lymphadenopathy and often, human herpesvirus (HHV) reactivation. The diagnosis of DIHS is based on the combined presence of these findings. Anticonvulsants are a major cause of DIHS and may also cause Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We examined whether SJS/TEN due to anticonvulsants display similar clinical and laboratory features seen in DIHS. Methods. Patients diagnosed with SJS or TEN due to anticonvulsants (n = 8) were examined and their clinical features and laboratory findings were compared with patients with anticonvulsant‐related DIHS (n = 6). Results. Seven of the eight patients with SJS/TEN developed symptoms > 3 weeks after starting anticonvulsants. Hepatic dysfunction was present in six patients with SJS/TEN and five patients with DIHS. Leucocytosis and/or eosinophilia was noted in seven patients with SJS/TEN and four patients with DIHS. Only one patient in the SJS/TEN group had atypical lymphocytosis; this was present in four patients with DIHS. Reactivation of HHV‐6 was detected in one of the four patients tested in the SJS/TEN group, although it was seen in five of the six patients with DIHS. Conclusions. TSJS/TEN due to anticonvulsants may exhibit some clinical and laboratory features of DIHS. The nature of the cutaneous involvement should be emphasized in the diagnosis of DIHS.     

Differences in immunological alterations and underlying viral infections in two well-defined severe drug eruptions

Background. Similar drugs (e.g. anticonvulsants) have been implicated in the development of two distinct forms of severe cutaneous drug reactions, Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and drug–induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS). Aim. To investigate immunological alterations and underlying viral infections that could contribute to the variability in the clinical presentations of these diseases. Methods. We retrospectively analysed clinical variables, serum immunoglobulin levels, numbers of circulating white blood cells, lymphocytes and their subsets, serum levels of several cytokines, and underlying viral infections in both drug reactions, using samples obtained at onset from 9 patients with SJS/TEN and 19 patients with DIHS/DRESS. Results. There were significant differences between the two drug eruptions in the duration of drug intake before onset, the levels of IgG, IgA and IgM, the numbers of circulating white blood cell, lymphocyte, CD3+ T cell and CD8+ T cells, the serum levels of interferon-γ, and the titres of anti-herpes simplex virus IgG at onset. Conclusions. The difference in the pattern of immune responses shaped in part by previous and underlying viral infections at the time of drug exposure could cause a marked deviation in the pathological phenotype of severe drug eruptions. Elucidating these host factors may provide a basis for therapeutic approaches in patients with severe drug reactions.     

Differential diagnosis of severe cutaneous drug eruptions

Adverse cutaneous reactions to drugs are frequent, mostly secondary to antibacterials, however, serious adverse cutaneous reactions are infrequent. Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are a spectrum of the same disease. They are the more severe drug eruptions, with a mortality around 30% for TEN. The confusion between erythema multiforme major and SJS means that erythema multiforme major is the main differential diagnosis. Skin disorders involving desquamation, in particular after pustulosis, are also common differential diagnoses. Mechanical or autoimmune blistering are also potential misdiagnoses of TEN/SJS. Hypersensitivity Syndrome (HSS) or Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) is a severe cutaneous drug reaction with often a long duration of eruption and serious other organ involvement. Exfoliative dermatitis, whether caused by psoriasis, dermatitis or lymphoma, can be thought of as a differential diagnosis of DRESS/HSS. Angio-immunoblastic lymphadenopathy, viral eruption and vasculitis are other differential diagnoses of DRESS/HSS. Prompt recognition of a severe drug reaction and withdrawal of the culprit drug is often the most important therapeutic action. Alternatively, a delay in starting a specific treatment for a disease misdiagnosed as a drug eruption could be deleterious.     

Pharmacogenetics of cutaneous adverse drug reactions

Drug-induced hypersensitivity reactions are of major medical concern because they are associated with high morbidity and high mortality. In addition, individual patients' reactions are impossible to predict in each patient. In the field of severe cutaneous adverse drug reactions (cutaneous ADR) such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug-induced hypersensitivity syndrome (DHIS) or drug rash with eosinophilia and systemic symptoms (DRESS), major advances have recently been gained through studies of an association between HLA alleles and drug hypersensitivity induced by specific drugs. The results of these pharmacogenomic studies allow prediction of the risk of adverse reactions in patients treated with certain drugs, including carbamazepine and other aromatic antiepileptic drugs, allopurinol and abacavir. However, different ethnic populations show variations in the genetic associations. A strong association between carbamazepine-induced SJS/TEN and HLA-B*1502 has been found in Southeast Asian patients but not in Caucasian and Japanese patients. Moderate associations between aromatic amine anticonvulsants and other HLA alleles have been proposed in Japanese patients. In contrast, HLA-B*5801 was found to be associated with allopurinol-induced cutaneous ADR, including SJS/TEN and DIHS/DRESS, in Caucasian and Asian patients, including the Japanese. These differences may, at least in part, be due to the differences in allele frequency in different ethnic populations. This article reviews the progress in pharmacogenomics, associated mainly with carbamazepine and allopurinol in different ethnic populations. Pharmacogenetic screening based on associations between adverse reactions and specific HLA alleles helps to avoid serious conditions associated with drug hypersensitivity.     

Drug rash with eosinophilia and systemic symptoms vs toxic epidermal necrolysis: the dilemma of classification

According to contemporary vernacular, when the cutaneous manifestations of drug rash with eosinophilia and systemic signs (DRESS) syndrome are those of Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN), the condition is defined as "DRESS syndrome with severe cutaneous reactions". In this article, we have presented arguments for and against including patients with skin lesions of the SJS/TEN syndromes who also have fever (practically all of the patients) and internal organ involvement (most of the patients) under the definition of DRESS syndrome. After weighing the arguments for and against this alteration of definition, we conclude that it makes more sense for patients with SJS/TEN to be classified as such and not be lumped together under the misleading label of DRESS syndrome.     

Identification of thymus and activation-regulated chemokine (TARC/CCL17) as a potential marker for early indication of disease and prediction of disease activity in drug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS)

BackgroundDrug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS) is a serious acute drug reaction with fever, cutaneous eruption, lymphadenopathy, and several visceral dysfunctions. Eosinophilia is a common hematological abnormality in DIHS/DRESS suggesting that the Th2-type immune response is involved. Thymus and activation-regulated chemokine (TARC/CCL17) is a family of CC chemokines known to play an important role in Th2-mediated immune-inflammatory processes.ObjectiveWe investigated the pathogenic role of TARC in patients with DIHS.MethodsSera were obtained from 8 patients with DIHS, 7 patients with Stevens–Johnson syndrome/Toxic epidermal necrolysis (SJS/TEN), and 14 patients with drug-induced maculopapular exanthema (MPE). Serum TARC levels were measured by ELISA. TARC levels were then compared with clinical symptoms and various hematological parameters. In addition, a biopsy was taken from the lesional skin of patients with DIHS and stained with anti-TARC Ab and anti-CD11c Ab.ResultsSerum TARC levels in patients with DIHS were significantly higher than those in patients with SJS/TEN and MPE during the acute phase. Serum TARC levels in DIHS patients correlated with skin eruptions, serum sIL-2R levels, eosinophil counts, and serum IL-5 levels. Immunohistochemical staining revealed that TARC was mainly expressed on CD11c+ dermal dendritic cells in patients with DIHS.ConclusionSerum TARC levels may be associated with the initial presentation of DIHS as well as disease activity during the course. Thus, they could be useful as an indicator for early diagnosis and assessment of disease activity in DIHS. CD11c+ dendritic cells may be the main source of TARC in patients with DIHS.     

Severe drug‐induced skin reactions: clinical features,diagnosis, etiology,and therapy

Drugs can induce severe skin reactions that differ in clinical presentation, prognosis, and therapy. The spectrum of these reactions not only includes bullous reactions such as Stevens‐Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and generalized bullous fixed drug eruption (GBFDE) but also acute generalized exanthematous pustulosis (AGEP) and drug reaction with eosinophilia and systemic symptoms (DRESS). If AGEP or DRESS is suspected, the diagnosis should be confirmed by thorough clinical examination, a skin biopsy, and specific laboratory tests. Crucial for the patient's prognosis, the causative agent should be rapidly identified and discontinued. It is therefore important to know the most frequent triggers of severe drug reactions, some of which may induce various reaction patterns. Depending on the clinical diagnosis, symptomatic and adequate supportive therapy, as well as systemic immunomodulatory treatments are used. The prognosis in SJS/TEN is often poor and depends on the patient's age and underlying conditions as well as the extent of skin detachment. The prognosis of GBFDE is somewhat better, but recurrences may lead to more severe disease manifestations. In DRESS, protracted and recurrent courses have been described, whereas AGEP usually resolves without problems.     

A patch testing and cross‐sensitivity study of carbamazepine‐induced severe cutaneous adverse drug reactions

Background The usefulness of the drug patch testing for Stevens–Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) is still controversial. Recent studies have shown that HLA‐B*1502 is strongly associated with CBZ‐SJS/TEN in Chinese and Southeast Asian populations. Objective To evaluate the usefulness of patch tests for patients with carbamazepine (CBZ)‐induced SJS, TEN and drug reaction with eosinophilia and systemic symptoms (DRESS) and the cross‐reactivity in patch tests among the aromatic antiepileptic drugs. Methods We measure the frequency of positive patch test reactions and cross‐sensitivity to structure‐related aromatic anti‐epileptic drugs (AEDs) for patients after SJS/TEN or DRESS episodes caused by CBZ. CBZ and other structure‐related AEDs used for patch testing were prepared in 10% and 30% petrolatum. Secondary measures included the association of HLA‐B*1502 genotype and frequency of possible side effects from the patch tests. Results Positive patch test reactions to 30% CBZ in the CBZ‐SJS/TEN were 62.5% (10/16), and 70% (7/10) in the CBZ‐DRESS. None of the 10 healthy controls displayed a positive reaction to tested agents. Cross‐sensitivity to other aromatic AEDs was observed in both the CBZ‐SJS/TEN and the CBZ‐DRESS. Only the HLA‐B*1502 genotype was present and strongly associated with the CBZ‐SJS/TEN, but not with the CBZ‐DRESS. Conclusion Drug patch testing is a safe and useful method for the identification of CBZ as the culprit drug of SJS/TEN as well as DRESS. Testing of chemically or pharmacologically related AEDs may provide information on cross‐reactivity for these patients.     

Pustular‐type drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms due to carbamazepine with systemic muscle involvement

Drug‐induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) is a severe reaction usually associated with maculopapular eruptions and systemic involvement. Here we report the first case, to our knowledge, of DIHS/DRESS due to carbamazepine with acute generalized pustular bacterid‐like (AGPB‐like) eruptions and skeletal muscle involvement. Reviewing our case and the published work, we discuss pustular‐type DIHS/DRESS which, in most cases, involves acute generalized exanthematous pustulosis (AGEP)‐like skin eruptions in response to carbamazepine. Pustular eruptions may appear in relatively few cases of DIHS/DRESS, in particular, when the causative drug is carbamazepine and, even in cases of intractable pustular bacterid‐like eruptions, a reaction to a drug should be suspected. Skeletal muscle involvement may be associated with DIHS/DRESS as one of its systemic manifestations.     

Facial pustules due to drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms may histopathologically mimic eosinophilic pustular folliculitis: A case report

Pustules with facial and/or neck edema is one characteristic feature of drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) at the early stage. Although several retrospective histopathologic studies on DIHS/DRESS have been reported, the detailed histopathologic findings of facial pustules for DIHS/DRESS are unavailable. We herein report a case of DIHS/DRESS with facial pustules that was histopathologically similar to eosinophilic pustular folliculitis (EPF). Eosinophilic infiltration into expanded follicles and sebaceous glands, which is highly characteristic of EPF, was detected in pustules due to DIHS/DRESS in this case. There are numerous pathophysiological similarities between DIHS/DRESS and EPF, which may cause their histopathologic similarity. Our findings suggest that facial pustules of DIHS/DRESS may histopathologically mimic EPF.     

A multicentre study to determine the value and safety of drug patch tests for the three main classes of severe cutaneous adverse drug reactions

Background Drug patch tests (PTs) can reproduce delayed hypersensitivity to drugs and entail a moderate re‐exposure of patients to offending drugs. Objectives To determine the value of PTs for identifying the responsible drug in severe cutaneous adverse drug reactions (SCARs) such as acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS) and Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Methods In a multicentre study, PTs were conducted on patients referred for DRESS, AGEP or SJS/TEN within 1 year of their SCAR. All drugs administered in the 2 months prior to and the week following the onset of the SCAR were tested. Results Among the 134 patients included (48 male, 86 female; mean age 51·7 years), positive drug PTs were obtained for 24 different drugs. These included positive tests for 64% (46/72) of patients with DRESS, 58% (26/45) of those with AGEP and 24% (4/17) of those with SJS/TEN, with only one relapse of AGEP. The value of PTs depended on the type of drug and the type of SCAR (e.g. carbamazepine was positive in 11/13 DRESS cases but none of the five SJS/TEN cases). PTs were frequently positive for beta lactams (22 cases), pristinamycin (11 cases) and in DRESS with pump proton inhibitors (five cases), but were usually negative for allopurinol and salazopyrin. Of 18 patients with DRESS, eight had virus reactivation and positive PTs. In DRESS, multiple drug reactivity was frequent (18% of cases), with patients remaining sensitized many years later. Conclusions PTs are useful and safe for identifying agents inducing SCAR.     

Late-onset interstitial nephritis in a patient with drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms

Drug-induced hypersensitivity syndrome (DIHS), also referred to as drug reaction with eosinophilia and systemic symptoms (DRESS), is a severe hypersensitivity drug reaction affecting the skin and multiple internal organ systems. We report a 47-year-old man with DIHS/DRESS and comorbidities (fulminant type 1 diabetes mellitus, valsartan-induced photosensitivity, vitiligo and acute interstitial nephritis). Although acute interstitial nephritis usually appears in the early phase, his is a rare case of acute interstitial nephritis more than 2 years after the onset of DIHS/DRESS.     

Drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms due to lamotrigine differs from that due to other drugs

Drug‐induced hypersensitivity syndrome (DIHS), also referred to as drug reaction with eosinophilia and systemic symptoms (DRESS), is a multi‐organ systemic drug reaction characterized by hematological abnormalities and reactivation of human herpesvirus‐6 (HHV‐6). DIHS/DRESS is typically associated with a limited number of drugs, such as the anticonvulsants. Our group has treated 12 patients for DIHS/DRESS due to lamotrigine (LTG), but their presentation differed from that of patients with DIHS/DRESS caused by other drugs. The aim of the present study was to identify significant differences between DIHS/DRESS caused by LTG versus other drugs. We retrospectively reviewed data of 12 patients with DIHS/DRESS caused by LTG and 32 patients with DIHS/DRESS due to other drugs. The increase in alanine aminotransferase level was significantly milder in the LTG group than the DIHS/DRESS group due to other drugs. The percentage of atypical lymphocytes in the blood during DIHS/DRESS was lower in the LTG group. Serum levels of lactate dehydrogenase and thymus and activation‐regulated chemokine were also lower in the LTG group. There were fewer DIHS/DRESS patients with HHV‐6 reactivation in the LTG group than in the group treated with other drugs. Lymphocyte transformation after DIHS/DRESS onset was faster in the LTG group. The two groups did not differ with respect to the interval from first drug intake to rash, white blood cell count, blood eosinophilia or DRESS score. There were no significant histopathological differences between the two groups. The features of LTG‐associated DIHS/DRESS and DIHS/DRESS due to other drugs differ.     

Syndrome of inappropriate secretion of antidiuretic hormone associated with limbic encephalitis in a patient with drug-induced hypersensitivity syndrome

Drug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS) is a severe multiorgan reaction with reactivation of herpesviruses. Various features are often seen during the course of the disease. Many aspects of this syndrome suggest close similarities between DIHS/DRESS and graft-versus-host disease. We describe a patient with phenobarbital-induced hypersensitivity syndrome who revealed syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with limbic encephalitis during the course of the disease. In view of previous reports that SIADH and limbic encephalitis are caused by reactivation of latent herpesviruses after transplantation, both conditions may be secondarily caused by reactivation of latent herpesviruses, which is typically observed in DIHS/DRESS. These neurological symptoms should be added to a growing list of important complications of DIHS/DRESS because of the high mortality rate associated with them.     

Long‐term complications of Stevens–Johnson syndrome/toxic epidermal necrolysis (SJS/TEN): the spectrum of chronic problems in patients who survive an episode of SJS/TEN necessitates multidisciplinary follow‐up

Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe adverse reactions to drugs that cause a life‐threatening eruption of mucocutaneous blistering and epithelial sloughing. While the acute complications of SJS/TEN are well described, it is increasingly recognized that survivors may develop delayed sequelae, some of which can be associated with significant morbidity. Studies of long‐term SJS/TEN outcomes mostly focus on mucocutaneous and ocular complications. However, other internal organs, such as the respiratory tract and gastrointestinal tract, can be affected. Psychological sequelae are also frequent following the trauma of widespread epidermal necrolysis. An appreciation of the ‘chronic’ phase of SJS/TEN is needed by clinicians caring for individuals who have survived the acute illness. This review aims to provide an update on the breadth and range of sequelae that can affect patients in the months and years following an acute episode of SJS/TEN.     

Update on pathobiology in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrosis (TEN) are rare but life-threatening severe cutaneous adverse reactions (SCARs), which are mainly induced by a variety of drugs. Once considered to be unpredictable, significant progress has been achieved in understanding the pathological mechanisms underlying such reactions. Recent studies suggested that SJS/TEN is a specific immune reaction where human leukocyte antigen (HLA) alleles specific for certain drugs in defined populations are involved in the activation of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Upon the activation, various cytotoxic and immunological signals, including but not limited to Fas/Fas ligand, perforin/granzyme B, and granulysin are launched to mediate the disseminated keratinocyte death in SJS/TEN. This review provides an update on the pathobiology of SJS/TEN in both the genomic and immunologic perspectives. The knowledge gained from these cutting-edge studies will form the basis for better prevention and management of SJS/TEN.     

Clinical manifestations and outcomes in 17 cases of Stevens–Johnson syndrome and toxic epidermal necrolysis

The clinical features and outcomes of 17 patients with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) were retrospectively reviewed. There were 11 males and six females with an average age of 61.5 years. Ten patients with SJS (seven males, three females) and seven patients with TEN (four males, three females) were identified. Antibiotics, mainly beta-lactams, were the most common cause of SJS/TEN in this series. The mean skin loss in TEN was 45.7% total body surface area in contrast to the lesser skin loss (< 10%) observed in three patients with SJS. Complications included septicaemia, pneumonia and multi-organ failure, mainly in the TEN group. Two patients died from TEN-related complications and one patient with SJS died from unrelated causes. Ocular involvement and skin pigmentary changes represented the most significant long-term sequelae.     

HLA-A31 strongly associates with carbamazepine-induced adverse drug reactions but not with carbamazepine-induced lymphocyte proliferation in a Japanese population

Carbamazepine (CBZ) is the most frequent culprit drug for severe cutaneous adverse drug reactions (ADR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and drug-induced hypersensitivity syndrome (DIHS). A strong association between human leukocyte antigen (HLA)-B*1502 and CBZ-induced SJS/TEN has been reported in Han Chinese, Thai, Malaysian and Indian populations, but not in Caucasian or Japanese populations. Recent studies showed an association between HLA-A*3101 and CBZ-induced ADR in Caucasian and Japanese populations. We conducted a case-control study to determine HLA genotyping of patients with CBZ-induced ADR in a Japanese population. Fifteen patients with CBZ-induced ADR and 33 subjects who had taken CBZ for more than 3 months without evidence of any ADR as a control were enrolled. In addition, the results of a CBZ-induced lymphocyte stimulation test were compared between the groups. A strong association was found between HLA-A31 and CBZ-induced ADR (P < 0.001), and a weak association was found between HLA-A11 and HLA-B51 with CBZ-induced ADR. No HLA-B*1502 was found in either patients or control subjects. The mean CBZ-induced lymphocyte stimulation index was significantly high in patients with CBZ-induced ADR compared with CBZ-tolerant patients (P < 0.001); however, no significant difference was seen between HLA-A31-positive subjects and HLA-A31-negative subjects in either group. These findings suggest that HLA-A31 is strongly associated with CBZ-induced ADR in the Japanese, but does not determine CBZ-induced lymphocyte proliferation.