Antinuclear factor in rapid and slow acetylator patients treated with isoniazid

N-acetyltransferase: the practical consequences of polymorphic activity in man

Over the years, numerous studies have supported the premise that individuals possessing the "slow acetylator" phenotype are more at risk from developing drug side-effects. Most prominent amongst these reports are those concerned with hepatotoxicity and peripheral neuropathy following treatment with isoniazid, lupus-like symptoms during procainamide therapy and experiencing hypersensitivity reactions to the various sulphonamide derivatives. Similarly, "slow acetylators" undergoing heavy exposure to arylamines and related carcinogens are more likely to develop bladder cancer. Contrariwise, there appears a slight risk of "rapid acetylators" developing pancreatic tumours.Other therapeutic agents for which polymorphic N-acetylation plays a minor role in their metabolism have been investigated but any impact of this metabolic difference on clinical efficacy or associated toxicity is still under question. In the search for clues as to the underlying aetiology, patient groups with many disease states have been examined for association with differences in N-acetylation and the majority have provided data that could be interpreted as equivocal. Studies have given contradictory, often opposing, results, calculated risk factors that are (perhaps) just significant but certainly not high, and patients within the cohorts who are always exceptions. Undoubtedly, other as yet unappreciated factors are at play.

Drug-induced lupus erythematosus: an update on drugs and mechanisms

PURPOSE OF REVIEW

Rapid introduction of newly developed drugs in the absence of clear understanding of the pathophysiologic mechanisms behind drug-induced lupus erythematosus (DILE) can sometimes make DILE difficult to recognize in clinical practice. The purpose of this review is to summarize drugs most recently reported to be involved in DILE and discuss the current landscape of diverse mechanisms involved.

RECENT FINDINGS

A large number of proton pump inhibitor (PPI)-induced subacute cutaneous lupus erythematosus cases have been reported, suggesting a shift over time in the spectrum of drugs implicated in DILE. Twenty-two articles comprising 29 DILE case reports published within the last 2 years are summarized in this review, including 12 (41.4%) systemic DILE. Antitumor necrosis factor (anti-TNF) drugs were the most frequently (41.7%) reported to introduce systemic DILE in these cases. Chemotherapeutic drugs were the most common drug class (54.5%) involved in subacute cutaneous lupus erythematosus, with an observed higher incidence in female patients. Enhanced neutrophil extracellular trap (NET) formation induced by procainamide and hydralazine could be a new mechanism contributing to the pathogenesis of DILE.

SUMMARY

The list of drugs implicated in triggering DILE is expanding as new drugs with novel mechanisms of action are being developed. It is important to recognize culprit drugs that may induce lupus erythematosus, as discontinuation usually results in improvement of drug-induced manifestations. Characterizing the mechanisms involved might help better understand the cause of idiopathic autoimmunity.

Acetylator phenotype in patients with hydralazine-induced lupoid syndrome

The acteylator phenotype has been determined (isoniazid half-life) in 31 patients, 25 of them women, who had exhibited a lupus erythematosus-like syndrome during treatment with hydralazine. Twenty-nine patients were slow acetylators, one was rapid (probably spontaneous SLE) and one uncertain. Only two patients had been given more than 200 mg of hydralazine daily. The mean duration of therapy was 32 months at the onset of symtoms. These were not serious but rather long-standing. Our study confirms that patients who risk developing hydralazine lupus are slow acetylators, especially females, treated with more than 100 mg daily. Rapid acetylators seem to develop this side-effect rarely, if at all.

Polymorphic acetylator phenotype and systemic lupus erythematosus

Out of 69 patients with spontaneous systemic lupus erythematosus (SLE), phenotyped for polymorphic acetylation with sulphadimidine, 52 (75%) were slow acetylators. In the subgroup of SLE patients with chronic biologically false positive seroreactions for syphilis the percentage of slow acetylators was even higher, 88%. In the majority of the slow acetylators the disease had started later and had followed a milder course than in rapid acetylators. Cutaneous reactions suspected to be drug-induced were seen in 19 (17 slow acetylators) during an observation period of 3--7 years. The reactions were mostly of exanthematous or urticarial type but also fixed type of eruption was seen. Provocation tests with the suspected drug were performed in 14 patients. In 5 cases it could be demonstrated that the eruption was caused by the drug. The predominance of slow acetylators among our patients with spontaneous SLE was the same as has been observed in drug-induced SLE. This suggests a similar genetic background.

Autoantibodies in patients treated for active pulmonary tuberculosis

The genesis of auto-immune antibodies directed against the own tissue antigens of a host may be due to the host's immune response to mycobacteria. The prospective study included 110 patients treated for active pulmonary tuberculosis and the control group of 60 healthy subjects, volontary blood donors. Applying the method of indirect immnunofluorescence and cryostat sections of rat organs and human larynx cancer epithelial cell line (HEp-2 cells), the prescence of the following autoantibodies in the serum of the examined patients was examined: anti,nclear (ANA), anticardiac (ACA), antimitochondrial (AMA), antiparietal (APA), anti smooth muscular (ASMA), antithyroidal (ATA), rheumnatoid factor (RF). These autoantibodies were determined in the course oftreatment and five years later. Low levels of some examined autoantibodies were detected in the serum of a number of the examined patients. No significant difference in the presence of the analysed antibodies was registered between the sexes. In the course of the treatment a reversible hyper-gammaglobulinemia developed, which was at least partially due to the presence of autoantibodies in the patients blood serum. Besides possibly involved mechanisms of molecular mimicry and polyclonal lymphocyte activation, the presence of antinuclear antibodies in the patient's serum is at least partially due to isoniazide treatment. The finding of other autoantibodies is nonspecific and not related to the mycobacterial infection or antituberculosis drug administration.

Isoniazid-induced lupus erythematosus presenting with cardiac tamponade

An estimated incidence of drug-induced lupus erythematosus caused by all drugs is 15,000 to 20,000 cases a year, and represents approximately 5 to 10% of the total number of patients with systemic lupus erythematosus. Approximately 22% of the patients treated with isoniazid for a mean of 6 months develop antinuclear antibodies. Isoniazid-induced lupus erythematosus affects either sex equally and the most common presenting feature is arthralgia or arthritis with anemia. Fever and pleuritis occur in approximately half of the cases, and pericarditis in approximately 30% of cases. IgG antibody to the (H2A-H2B)-DNA complex appears specific for the isoniazid-induced lupus erythematosus. The drug-induced lupus presenting with cardiac tamponade is a recognized feature of many drugs such as hydralazine, procainamide, and sulfasalazine. Reported here is a case of isoniazid-induced lupus erythematosus presenting with cardiac tamponade. A 73-year-old man was treated with isoniazid for 8 months at a dose of 300 mg a day. The patient responded to the withdrawal of the isoniazid therapy and placement of a pericardial window. The existing literature on the subject is reviewed.

IgA antihistone antibodies in isoniazid-treated tuberculosis patients

A retrospective study of tuberculosis patients treated with isoniazid was undertaken in order to establish the prevalence and specificity of antibodies against histones, chromatin and denatured DNA. Each patient had an average of 2.7 +/- 0.4 antibody activities out of the 8 tested antigens using ELISA. These reactivities tended to be higher for non-native forms of the antigens such as denatured histones and DNA with essentially no reactivity to the (H2A-H2B)-DNA subunit of chromatin. Greater than half of the patients were isotype restricted to only IgA or IgM antihistone antibodies, and IgA antihistone antibodies were the most common and reactive. Thirty-five percent of the patients had elevated levels of one or more immunoglobulin classes, and the IgA level was strongly correlated with IgA antihistone activity. These results suggest that isoniazid treatment results in modest increases in antihistone antibodies of the specificities and class typical of drug-induced autoimmunity in the absence of lupus-like disease. The IgA antihistone predominance suggests that serum antoantibodies may be the consequence of stimulation by isoniazid of lymphocytes in the gut-associated Peyer's patches or intestinal lymphoid follicles.

Idiosyncratic drug reactions: a mechanistic evaluation of risk factors

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Survey of the human acetylator polymorphism in spontaneous disorders

There is ample evidence that the human acetylator phenotypes are associated with drug induced phenomena. It is principally the slow acetylators who exhibit toxic adverse effects because of their relative inability to detoxify the original drug compounds. In rare instances, however, it is the rapid acetylators who are at a disadvantage. In the matter of association of spontaneous disease with either acetylator phenotype, there are two groups of disorders to consider. First, disorders in which carcinogenic amines are known to be an aetiological factor. This is because these amines are substrates for the polymorphic N-acetyltransferase activity and hence there is a possible rational basis for searching for an association. Secondly, other disorders where searches for associations are based more on hunches. In the first group there is a definite statistical association between cancer of the bladder and the slow acetylator phenotype. In prevalence studies the slow phenotype is 39% more associated with bladder cancer than is the rapid phenotype. On the basis of the evidence now available it is not possible to say whether this association is because slow acetylators develop the disease more frequently or whether they survive longer. In the second group the relevant studies show (1) a greatly increased prevalence of slow acetylators in Gilbert's disease; (2) a confirmed association between the rapid acetylator phenotype and diabetes; (3) a possible association between the rapid acetylator phenotype and breast cancer; (4) a possible association between the slow acetylator phenotype and leprosy in Chinese patients; (5) an earlier age of onset of thyrotoxicosis (Graves' disease) in slow acetylators than in rapid acetylators; (6) no evidence of an association between either phenotype and spontaneous systemic lupus erythematosus.

The association of the slow acetylator phenotype with bladder cancer

There is an association between exposure to aromatic amines and the development of bladder cancer. Aromatic amines such as are known to occur in tobacco smoke are polymorphically acetylated. One hundred bladder cancer patients have been acetylator phenotyped. Only three of them were non-smokers at the time of diagnosis. This new series, together with four previous series (each with its own control), have been statistically analysed together. The results show a significant association between the slow acetylator phenotype and bladder cancer. The slow acetylator phenotype is associated about 39% more with bladder cancer than is the rapid acetylator phenotype. This association can be interpreted in one of two ways: (1) rapid acetylators may be protected against developing bladder cancer because they are better able to render amines non-carcinogenic by acetylation, or (2) slow acetylators have greater survival with bladder cancer than rapid acetylators. Further evidence will be required to differentiate between these alternatives.

Human acetylator polymorphism: estimate of allele frequency in Libya and details of global distribution

Acetylator phenotyping by means of a sulphadimidine tests revealed 65% of Libyan Arabs to be slow acetylators. Hence the frequency of the allele controlling slow acetylation (As) is estimated as q = 0.81 +/- 0.05. This estimate is similar to those previously recorded in European and adjacent Middle Eastern populations.

Acetylator phenotype in systemic lupus erythematosus

The acetylation rate of sulfamethazine was studied in 25 patients with systemic lupus erythematosus (SLE). Seventeen of 25SLE patients, 68%, were slow acetylators compared to the reported incidence of 52% in the general population. There was no correlation between the acetylator phenotype in SLE patients and the various clinical manifestations or the activity of the disease. Lupus patients who were slow acetylators had a lower lymphocyte response to phytomitogens compared to rapid acetylators.

Antinuclear antibodies (ANA): immunologic and clinical significance

The methods currently used for the detection of ANA have been analyzed, with emphasis on their practical application to the diagnosis of the CTD. The use of the indirect IF-ANA test was recommended as a screening procedure to detect ANA. The need to standardize the technique using a single substrate and fluorescent conjugates with uniform F/P ratios was stressed. Most importantly, the value of titrating ANA for the diagnosis of the CTD was discussed. ANA titers higher than 1/500 are usually very significant clinically, often found in spontaneous or drug-induced SLE and few other CTD. The immunologic aspects of ANA and their potential value as aids in the diagnosis and management of the CTD were discussed. Anti-nDNA antibodies have been found to have a high degree of specificity for SLE and high titers of these antibodies correlate well with low levels of serum complement and severity of kidney involvement. The spectrum of ANA in the sera from patients with SLE has been expanded with the finding of anti-Sm antibodies which, when detected by gel precipitation with prototype serum, have been found so far only in SLE. Some of these antibodies have been found to have prognostic significance. Patients with MCTD and a group of patients with SLE have high titers of serum ANA with specificity for an RNase-sensitive component of ENA. The group of SLE patients defined by the presence of these antibodies (anti-Mo) have a better prognosis and in general develop only mild nephritis or have no kidney involvement at all. High titers of pure antinucleolar antibodies probably are found almost exclusively in the sera of patients with scleroderma. Some ANA have organ specificity, and GS-ANA have been found in all patients with Felty's syndrome and in a large proportion of patients with RA. One of the great advances in the field has been the recognition that ANA can be induced in the human and in experimental animals by the use of a number of therapeutic agents. Some of these agents can also induce a clinical picture resembling spontaneous SLE, though kidney involvement does not occur or is extremely mild. It is interesting that the whole spectrum of ANA can be found in drug-induced LE except anti-nDNA antibodies which have been associated to the pathogenesis of immune complex nephritis in spontaneous SLE. There is no doubt that research on ANA has contributed a great deal to the understanding of the CTD and will continue to be a valuable tool for the clinician and the investigator.

Drug-induced antinuclear antibodies and lupus syndromes

Drugs capable of triggering the onset of systemic lupus erythematosus may be divided into those that do so by pharmacological properties of their own and those that do so by eliciting allergic reactions which bring about lupus. Drugs in the first group vary in their potency to activate lupus. They all elicit antinuclear antibodies in the majority of patients who receive them but they only cause lupus in a small percentage of patients. This dichotomy suggests that a predisposition is required for the development of lupus upon intake of these drugs. The mechanism whereby these drugs elicit antinuclear antibodies seems to relate to coupling to and/or modification of, nuclear antigens. The patterns of antinuclear antibodies elicited by these drugs in individuals who receive them correlate well with their known reactivity with various nuclear antigens.