Drug-induced Lupus: Clinical and Serological Studies

Drug-Induced Lupus Associated with Synthetic Conjugated Estrogens

Objective:

To report a case of drug-induced lupus (DIL) in a patient taking Cenestin, a combination product of synthetic conjugated estrogens.

Case Summary:

A 54-year-old white female presented with a 4 month history of bilateral arm pain that developed and progressively worsened after initiating Cenestin 0.625 mg daily. The patient's symptoms, findings on physical examination (eg, degenerative changes of the acromioclavicular joint), and laboratory test results (eg, antinuclear antibody titer 1–640 [normal <1–40]) were suggestive of DIL. Her symptoms rapidly resolved with discontinuation of Cenestin and promptly resumed with reinitiation of the drug. Laboratory test values also improved significantly with discontinuation of Cenestin. Based on these findings and the Naranjo probability scale score, this reaction was probably associated with Cenestin.

Discussion:

DIL differs from systemic lupus erythematosus in that it is caused by prolonged exposure at adequate doses to a drug rather than being an autoimmune reaction. The most commonly reported and studied medications are hydralazine, quinidine, and procainamide. Other medications have been associated with DIL; however, data are limited in these reports, especially with estrogen. There have been no previous reports in the literature of synthetic estrogen products associated with DIL.

Conclusions:

A diagnosis of DIL can be very challenging to make, especially since there are no clear criteria on which to base it. While estrogen has rarely been reported to be associated with DIL, it may be considered as a possible cause.

Epigenomic deregulation in the immune system

Proper immune function is the result of multiple cell commitment and differentiation steps, and adequate control of activation mechanisms. Deregulation of transcriptional programs in immune cells leads to the development of hematological malignancies, autoimmune diseases or immunodeficiencies. In this sense, epigenetic control of gene expression plays an essential role in the correct function of the immune system and the integrity of identity of relevant cell types. Epigenetic deregulation can result as a consequence of genetic changes in transcription factors, elements of signaling pathways or epigenetic enzymes, or as an effect of a variety of environmental factors. On top of genetic predisposition, viral infection and other external factors influence the development of immune-related diseases. In recent years, major strides have been made towards understanding the contribution of genetics in these immune disorders. Less progress has been made in dissecting the contribution of epigenetic factors in their etiology. Herein, it is presented what is currently known about epigenetic alterations in immune system associated disorders. It is also discussed how epigenomic analysis can help to understand the molecular basis of these diseases and how this information can be used in the clinical setting.

Pulmonary manifestations of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that primarily affects young women. The respiratory system is more commonly involved in SLE than in any other collagen vascular disease. SLE may affect virtually all components of the respiratory system, including the upper airway, lung parenchyma, pulmonary vasculature, pleura, and respiratory muscles. Respiratory system involvement ranges from symptomatic to fulminant and life threatening. This article reviews the pulmonary manifestations of SLE, including drug-induced SLE.

Quinidine-induced rheumatic syndromes

Quinidine is a commonly used antiarrhythmic agent that is rarely associated with rheumatologic toxicity. However, quinidine-induced lupus, antinuclear antibody negative lupus-like syndrome, polymyalgia rheumatica-like illness, muscle weakness, and isolated creatine phosphokinase elevation have all been reported. We present one case of quinidine drug-induced lupus and another of a quinidine-induced polymyalgia rheumatica-like illness, and review the English literature for rheumatologic toxicity due to quinidine. Prompt recognition of quinidine associated rheumatologic toxicity is important because discontinuation of the medication leads to rapid resolution of clinical symptoms.

Thiazide diuretics induce cutaneous lupus-like adverse reaction

One of the side effects reported in patients taking thiazide diuretics is photosensitivity. We report two patients who developed lupus-like skin lesions while taking thiazide diuretics. One patient developed erythematous scaling papules, patches and plaques on the upper extremities and trunk resembling subacute cutaneous lupus erythematosus. Histopathology of a skin biopsy from the trunk showed basal cell layer liquefaction and lichenoid interface changes suggestive of lupus erythematosus. The skin lesions resolved completely within two months of discontinuing thiazide therapy. The second patient developed multiple flesh colored urticarial plaques on the trunk one year after beginning thiazide therapy. Slight lichenoid interface changes were noted on a skin biopsy, along with dense mucin deposition in the papillary and deep dermis, suggestive of tumid lupus erythematosus. The skin lesions persisted despite discontinuing thiazide therapy, necessitating systemic corticosteroid treatment. Both patients had circulating anti-SSA/Ro autoantibodies and antinuclear antibodies. These two patients illustrate that thiazide diuretics may induce a cutaneous lupus erythematosus-like adverse reaction and production of anti-SSA/Ro autoantibodies as demonstrated by immunodiffusion, immunoblot and immunoprecipitation testing.

Role of T cell DNA methylation in lupus syndromes

Current theories postulate that exposure to certain environmental agents will induce lupus in genetically predisposed individuals. However, the mechanisms by which environmental agents interact with the immune system to trigger lupus is unclear. Recent work has shown that some environmental agents associated with lupus, such as procainamide, hydralazine and ultraviolet light, will inhibit T cell DNA methylation, increase LFA-1 expression and induce autoreactivity. In addition, T cells isolated from patients with active lupus have hypomethlated DNA, diminished DNA methyltransferase activity and overexpress LFA-1 on an autoreactive subset of cells which spontaneously lyses autologous macrophages. More recent work has shown that the adoptive transfer of murine T cells made autoreactive with DNA methylation inhibitors is sufficient to cause a lupus-like disease in otherwise healthy syngeneic recipients. Together, these results support a new model of autoimmunity, in which certain environmental agents modify T cells by inhibiting DNA methylation and altering expression of certain genes, thereby inducing autoreactivity. The autoreactive cells then interact with the host to produce a lupus-like disease.

Transformation of lupus-inducing drugs to cytotoxic products by activated neutrophils

Drug-induced lupus is a serious side effect of certain medications, but the chemical features that confer this property and the underlying pathogenesis are puzzling. Prototypes of all six therapeutic classes of lupus-inducing drugs were highly cytotoxic only in the presence of activated neutrophils. Removal of extracellular hydrogen peroxide before, but not after, exposure of the drug to activated neutrophils prevented cytotoxicity. Neutrophil-dependent cytotoxicity required the enzymatic action of myeloperoxidase, resulting in the chemical transformation of the drug to a reactive product. The capacity of drugs to serve as myeloperoxidase substrates in vitro was associated with the ability to induce lupus in vivo.

Lupus erythematosus-like syndrome induced by thiamazole and propylthiouracil

A 17-year-old Japanese woman developed a lupus erythematosus-like syndrome during treatment for Graves' disease with thiamazole and propylthiouracil. Erythema, arthralgia, and low grade fever developed during therapy with thiamazole; purplish-red erythema developed during therapy with propylthiouracil. Antinuclear antibodies, anti-single-stranded DNA antibodies, and anti-double-stranded DNA antibodies were positive throughout the administration of these two drugs. Eruptions and other symptoms improved after their discontinuation. The titers of autoantibodies also decreased two months after withdrawal. The patient had HLA DR4.

Pleural effusion associated with chronic dantrolene administration

OBJECTIVE

To report a case of pleural effusion associated with chronic dantrolene administration.

DESIGN

Case report.

SETTING

Private, university-affiliated, teaching hospital.

RESULTS

Twelve years after the initiation of low-dose dantrolene therapy for chronic spasticity, a 35-year-old man developed a pleural effusion with pleural and peripheral eosinophilia. This reaction gradually resolved over several months after discontinuation of the dantrolene therapy.

CONCLUSIONS

In patients treated with chronic dantrolene therapy, the presence of pleural effusions should raise the suspicion of dantrolene-induced disease. Withdrawal of dantrolene therapy has generally been associated with an alleviation of signs and symptoms within several months.

Procainamide-induced lupus in the elderly

The usual aids to diagnosis--such as symptoms and antinuclear antibodies--do not reliably distinguish this important entity from idiopathic SLE. Age, sex, and antibody type are often clues, but in some cases, only time and clinical course will tell.

Systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is the most common of the connective tissue disorders and can involve virtually any organ in the body. It is associated with pleuropulmonary manifestations in well over 50% of cases. Pleuritis with or without pleural effusion is the most common manifestation and can be particularly troublesome to manage but is rarely life-threatening. More serious manifestations in the lung include acute lupus pneumonitis with or without alveolar haemorrhage, chronic lupus pneumonitis and pulmonary hypertension. These all contribute significantly to overall mortality in SLE. The association between SLE and the antiphospholipid syndrome, leading to venous thrombosis and pulmonary embolism, is well recognized. Up to 20% of all cases of SLE present in childhood and many of these have pulmonary features at presentation or during the course of their illness. Sepsis is one of the main causes of death in SLE and pulmonary sepsis in these often immunocompromised patients contributes a significant proportion. Several drugs can produce a clinical syndrome that has many of the clinical and immunological features of SLE. Pleuritis may be seen in up to half of these cases of drug induced SLE. The development of SLE and conditions such as sarcoidosis or asbestosis in the same patient may represent a simple coincidence but there is some evidence for a closer association between these disorders.

Autoantibody specificity in drug-induced lupus and neutrophil-mediated metabolism of lupus-inducing drugs

A long-term side effect of therapy with a variety of drugs is a syndrome resembling the idiopathic autoimmune disease, systemic lupus erythematosus. Essentially all patients with drug-induced lupus display autoantibodies to nuclear histone components whose specificity appears to be related to the higher order structure of histones existing in chromatin. IgG antibodies to H1 and the (H2A-H2B)-DNA complex were observed in most patients with lupus induced by procainamide, hydralazine, and quinidine, whereas the H3-H4 tetramer, comprising half the mass of the nucleosome core particle, was largely nonantigenic. IgM antibodies to (H2A-H2B)-containing chromatin subunits were common also. IgM reactivity was observed with the DNA-free H3-H4 tetramer and with H1, especially in hydralazine-induced lupus. These results suggest that IgM antihistone antibodies may result from autoimmunization with a nonnative form of chromatin, whereas IgG antibodies may be selected for reactivity with H1 and a native form of the (H2A-H2B)-DNA subunit of the nucleosome. The chemical basis for induction of autoimmunity by drugs is unclear because lupus-inducing drugs do not have a common structural feature or biological activity nor are they capable of specific reactions with histones, the principal target antigen. However, in the presence of activated neutrophils, procainamide is transformed metabolically to the cytotoxic procainamide-hydroxylamine. Mixing experiments and cell-free studies demonstrated that procainamide was cooxidized with H2O2 by myeloperoxidase released when neutrophils undergo the respiratory burst and degranulation reactions. Preliminary results indicate other lupus-inducing drugs are also biotransformed by this mechanism suggesting that a common denominator linking these drugs may be the capacity to be oxidized to reactive metabolites by the action of activated phagocytic cells.

The clinical genetics of lupus

Genetic aspects of lupus are reviewed, including recognition of genetic and clinical heterogeneity, genetic factors in the aetiology and heritability of disease, reproductive implications and genetic counselling of patients. Despite a large literature on the genetic epidemiology and immunogenetics of lupus, it remains difficult to apply the results of laboratory findings to the circumstances of individual patients. Generally, lupus is not transmitted as a simple Mendelian trait, and genetic counselling is based on the multifactorial model of disease aetiology with interaction of multiple genetic and environmental factors. Further studies are needed to clarify the heritability of lupus and improve the data for recurrence risk prediction in lupus families.

Antibodies to histones in systemic lupus erythematosus: prevalence, specificity, and relationship to clinical and laboratory features

Antibodies to histones (AHA) are commonly found in patients with systemic lupus erythematosus (SLE). However, the full profile of AHA and their clinical associations remains unclear. A total of 111 patients with SLE were studied, including 13 patients in whom multiple serum samples were available over several years. IgM, IgG, and IgA antibodies to total core histones, histone complexes, and individual histones were determined by highly sensitive enzyme linked immunosorbent assays (ELISAs). Antibodies to histones were detected in 74% of serum samples, though only at low levels in half of these. Antibodies to each of the individual histones (H1, H2A, H2B, H3, H4) occurred with similar frequencies except for IgG and IgA antibodies to H4, which were uncommon. In contrast, antibodies to the histone complexes H2A-H2B and H3-H4 were detected in only two serum samples and thus do not appear to be a feature of SLE. All three major isotypes of AHA were common and usually occurred with similar frequencies to one another for the various histone specificities. There were few clinical or laboratory associations with AHA; the strongest was between IgG antibodies to total core histones and antibodies to native DNA. Similarly, there was no association between the presence of AHA and disease activity. However, for the patients as a group and in one patient alone, periods of SLE disease activity were associated with higher levels of AHA. Although the profile of antibodies to individual histones varied with time, no profile was identified that corresponded with any specific disease manifestations. It is concluded from this study that although AHA are common in patients with SLE, their clinical value in this syndrome must, at present, be considered limited.

Evidence for impaired T cell DNA methylation in systemic lupus erythematosus and rheumatoid arthritis

Procainamide and hydralazine inhibit T cell DNA methylation and induce autoreactivity in cloned CD4+ T cells. These drugs also induce an autoimmune syndrome, suggesting a possible relationship between DNA hypomethylation, T cell autoreactivity, and certain autoimmune diseases. To test this relationship, DNA methylation was studied in T cells from patients with rheumatoid arthritis and patients with systemic lupus erythematosus, and was found to be impaired. These results support a relationship between DNA hypomethylation and some forms of autoimmune disease.

D-penicillamine-induced lupus erythematosus

We describe a patient who presented with polyarthritis, pleurisy, rash, and a positive antinuclear antibody result after 5 years of D-penicillamine therapy. D-penicillamine-induced antinuclear antibodies were mainly high-titer IgG directed against the (H2A-H2B)-DNA complex. Weak IgM activity with H1 and H2B was also observed. Withdrawal of D-penicillamine therapy resulted in improvement in clinical symptoms and gradual resolution of serologic abnormalities.

CD4+ cells treated with DNA methylation inhibitors induce autologous B cell differentiation

The DNA methylation inhibitor 5-azacytidine induces autoreactivity in cloned CD4+ T cells, but the functional consequences of this response are unknown. We now report that CD4+ T cells treated with 5-azacytidine respond to autologous antigen-presenting cells and induce autologous B cell differentiation without exogenous antigen or mitogen. This mechanism could play a role in some autoimmune diseases characterized by T cell DNA hypomethylation and polyclonal B cell activation.

Severe retinal vaso-occlusive disease secondary to procainamide-induced lupus

Systemic lupus erythematosus (SLE) is known to cause various forms of ocular problems, including severe retinal vaso-occlusive disease. Procainamide is one of many drugs that may cause a lupus-like syndrome which resembles SLE but can be distinguished through clinical features and laboratory studies. Presented is a patient with severe vaso-occlusive retinopathy on high-dose procainamide therapy. Associated clinical, laboratory, and pathologic findings suggest the diagnosis of drug-induced lupus and exclude other vasculitic or inflammatory etiologies. This represents the first documented case of retinal disease attributed to procainamide-induced lupus.

Synovial fluid characteristics and the lupus erythematosus cell phenomenon in drug-induced lupus. Findings in three patients and review of pertinent literature

The characteristics of synovial fluid obtained from 3 patients with drug-induced lupus erythematosus are described. Two patients had "inflammatory" counts of synovial leukocytes, in the range of 2,500-39,000/mm3, with mononuclear predominance in 1 patient and neutrophil predominance in the other. The third patient had "noninflammatory" fluid, with mononuclear predominance. Lupus erythematosus cells formed in vivo were observed in the synovial fluid of 2 of the patients. Biopsy of the synovium of 1 patient showed nonspecific chronic inflammatory changes. Our findings in these patients with drug-induced lupus are indistinguishable from those previously described in patients with idiopathic lupus erythematosus.

Methyldopa-induced systemic lupus erythematosus

Thirteen months after starting methyldopa therapy, a 55-year-old white male patient presented with a syndrome of hemolytic anemia, arthritis, photosensitivity, and a positive antinuclear antibody test result. Methyldopa-induced antinuclear antibodies were mainly IgG, directed against class H1 histones. Antibodies to native DNA and nonhistone proteins were not detected. Upon withdrawal of methyldopa therapy, and with a short course of prednisone and danazol therapy, the patient's symptoms and hemolytic anemia resolved. His clinical symptoms and serologic abnormalities returned to normal and remained negative after 2 years of followup.

Scleritis as the presenting manifestation of procainamide-induced lupus

Scleritis developed in a patient using procainamide as part of a drug-induced lupus syndrome. Systemic findings, which developed after the onset of ocular signs and symptoms, included arthralgias, myalgias, weight loss, and markedly elevated antinuclear antibody (ANA) titers and antihistone titers. The clinical picture and laboratory abnormalities improved after discontinuation of the drug. Although systemic findings secondary to drug-induced lupus have been well described in the medical literature, this case represents the first detailed ophthalmologic documentation of scleritis as the presenting manifestation of procainamide-induced lupus.

Dose-dependent induction of anti-native DNA antibodies in cats by propylthiouracil

Cats receiving propylthiouracil (PTU) develop antinuclear antibodies (ANA) and an immune-mediated disease syndrome characterized by anorexia, lymphadenopathy, weight loss, and Coombs-positive hemolytic anemia. Investigation of the ANA specificity indicated that the predominant ANA activity consistent of anti-native DNA (nDNA) antibodies. The formation of anti-nDNA antibodies and immune-mediated disease syndrome appeared to be dose-dependent, even in cats in which a response had been induced on 4 prior occasions. These results supply further evidence that PTU-induced autoimmunity is not the result of a simple drug allergy. Rather, it appears that PTU induces a lupus-like syndrome, including the hallmark sign of systemic lupus erythematosus, anti-nDNA antibodies.

Sulfasalazine-induced lupus erythematosus

Pneumonitis, bilateral pleural effusions, echocardiographic evidence of cardiac tamponade, and positive autoantibodies developed in a 43-year-old man, who was receiving long-term sulfasalazine therapy for chronic ulcerative colitis. After cessation of the sulfasalazine and completion of a six-week course of corticosteroids, these problems resolved over a period of four to six months. It is suggested that the patient had sulfasalazine-induced lupus, which manifested with serositis and pulmonary parenchymal involvement in the absence of joint symptoms. Physicians who use sulfasalazine to treat patients with inflammatory bowel disease should be aware of the signs of sulfasalazine-induced lupus syndrome.

Pulmonary hypertension in hydralazine induced systemic lupus erythematosus: association with C4 null allele

A patient who developed pulmonary hypertension and systemic lupus erythematosus as a complication of hydralazine therapy is reported. She was a slow acetylator and in addition was found to have a null allele at the C4A locus.

Serologic changes during induction of lupus-like disease by procainamide

Procainamide-induced lupus is a well-recognized syndrome, but the events leading up to clinical symptoms are obscure. In the present study, serologic changes in a 69-year-old man were monitored during his treatment with procainamide and after discontinuation of procainamide because of symptoms of drug-induced lupus. Antihistone antibodies of unique specificity and in vivo complement activation were detected after one year of procainamide therapy during a period prior to development of significant clinical symptoms. Antihistone antibodies and complement activation substantially increased during a full-blown episode of lupus-like symptoms. Progressive return to normal laboratory findings occurred after procainamide was discontinued. The antihistone/complement profile may be useful in the diagnosis of drug-induced lupus and warn of impending clinical deterioration in patients with minimal symptoms.

The musculoskeletal manifestations of cystic fibrosis

Twenty-seven patients with CF and joint complaints were reviewed. Twelve patients had arthritis, 11 had HPO, and four had symptoms of mechanical neck and back pain. We have confirmed the association of CF with an episodic form of arthritis. For the first time, we have reported that a subgroup of these patients later develop persistent synovitis with progressive asymmetric, erosive disease. The etiology of CF arthritis is unclear, but may relate to chronic infection and immune complex mechanisms. CF arthritis can be contrasted with CF induced HPO, which is associated with worse lung disease, a male predominance, and an older mean age of onset of symptoms. Mechanical neck and back pain may relate to an associated scoliosis or kyphosis in CF.

Drug-induced lupus. Genetic, clinical, and laboratory features

Drug-induced lupus is a disorder similar to idiopathic systemic lupus erythematosus in terms of manifestations. However, these entities have significant serologic and clinical differences, which call into question the concept that they represent an identical disease process. Nonetheless, further research into the drug-induced disease will enhance our understanding and management of this clinically significant iatrogenic disease and will likely contribute to our comprehension of the pathogenesis of autoimmunity.

No demonstrable relationship between IgM and IgG antinuclear antibody levels and acetylator phenotype in patients with systemic lupus erythematosus

To ascertain the possible influence of acetylator phenotype on antinuclear antibodies in systemic lupus erythematosus (SLE), we assayed sera from 11 rapid acetylators and 10 slow acetylators for IgM and IgG antibodies to chromatin, histones, denatured DNA, and native DNA. Whereas the majority of SLE patients of both acetylator phenotypes had elevated levels of antibodies to all 4 antigens compared with normal controls, there was no difference in antibody activities between slow acetylator patients versus rapid acetylator patients for these antigens. We conclude that levels of antibody to chromatin, histones, and DNA in SLE patients are similar irrespective of acetylator phenotype, and that if a protective effect of slow acetylation on spontaneous development of antinuclear antibodies does occur, a prospective study of presymptomatic individuals at high risk for lupus may be required to reveal this effect.

IgG antibodies to the histone complex H2A-H2B characterize procainamide-induced lupus

Patients treated with procainamide and other drugs commonly develop antinuclear antibodies and occasionally symptoms of lupus erythematosus. However, the pathological events which lead to clinical symptoms in some patients but only abnormal serology in others have not been established. The present study examines the incidence, amount, immunoglobulin class, and antigen-binding specificity of anti-histone and anti-denatured DNA (anti-dDNA) antibodies in three groups of patients. These comprised a prospective study of patients treated with procainamide, patients with clinical drug-induced lupus symptoms, and a group undergoing therapy for many years without any symptoms. Procainamide elicited IgG and IgM anti-dDNA antibodies concordantly. Anti-histone IgM antibodies also appeared de novo during this period but IgG anti-histone antibodies were detected less frequently. Asymptomatic patients tended to have an antibody profile consisting of highly elevated anti-dDNA, IgM antibodies reactive with all histones and IgG antibodies specific for only one or two histone classes. In contrast symptomatic patients usually had little anti-dDNA or antibodies to individual histones but had pronounced IgG antibodies to the histone complex H2A-H2B. This unique antibody was characteristics of procainamide-induced lupus and was not detected in patients whose disease was induced by hydralazine. Anti-(H2A-H2B) decreased after procainamide was discontinued, concomitant with subsidence of symptoms. The finding that autoantibodies elicited by procainamide in patients with lupus symptoms have a characteristic immunoglobulin class and specificity may be of pathogenic significance and suggests that patients susceptible to procainamide-induced lupus have a unique immune response. In addition, this information could be of diagnostic value in predicting which procainamide-treated patients will develop overt symptoms of lupus.

Pleuro-pulmonary manifestations of systemic lupus erythematosus: clinical features of its subgroups. Prognostic and therapeutic implications

Correct identification of the subsets of pulmonary lupus has an unquestioned importance in planning the proper therapeutic regimen in this extremely variegated disease. Asymptomatic pulmonary lupus needs no treatment; however, pulmonary involvement in lupus may be life threatening, in which case prompt and aggressive treatment is mandatory. The different aspects of pulmonary lupus are demonstrated through the clinical histories of patients who suffered from pleuro-pulmonary lupus. The following entities are presented: lupus pneumonitis, lymphocytic interstitial pneumonia, pulmonary hypertension, pulmonary hemorrhage, pulmonary embolism associated with circulating lupus anticoagulant, lupus pleuritis and weakness of the diaphragm.

Antinuclear antibodies in autoimmune disease. Significance and pathogenicity

A large number of antigen-antibody systems have been described in association with connective tissue diseases. However, with the exception of antibodies to dsDNA, none of them have yet been successfully implicated in the pathogenesis of autoimmune diseases. It is also unclear why specific ANA are associated just with certain diseases, for example, anti-Sm with systemic lupus erythematosus. Although many questions remain about what triggers ANA production and whether these antibodies are innocent bystanders or disease inducers or enhancers, ANA serology can still be very useful to the clinician.

Antinuclear antibodies as indicators for the procainamide-induced systemic lupus erythematosus-like syndrome and its clinical presentations

Fifty patients on a regimen of procainamide were studied in regard to the association between antinuclear antibodies (ANA) and the development of drug-induced systemic lupus erythematosus (SLE)-like syndrome. Four groups were identified: Group 1 was ANA-positive, with clinical manifestations (serologic and clinical findings); Group 2 was ANA-positive, without clinical manifestations (serologic findings only); Group 3 was ANA negative (no patients with clinical manifestations); and Group 4 had SLE persisting after discontinuance of procainamide. The leukocyte-specific ANA (LSANA) patterns were predominant, with peripheral LSANA confined to Groups 1 and 4. Furthermore, the titer of the homogeneous LSANA, to which peripheral LSANA converts on dilution, was clinically significant. A homogeneous LSANA titer of 160 or greater was seen essentially only in patients with clinical manifestations of the SLE-like syndrome. Serial ANA determinations are therefore necessary to monitor patients receiving procainamide.