The role of histones as nuclear autoantigens in drug-related lupus erythematosus

Hydralazine-associated glomerulonephritis

Nine patients (6 men, 3 women) with rapidly progressive glomerulonephritis developing during hydralazine therapy were seen. Early cessation of hydralazine treatment resulted in improvement in seven patients, while continued hydralazine treatment resulted in permanent renal insufficiency in two. The clinical symptoms of systemic illness associated with the hydralazine syndrome were absent in most patients. Antinuclear antibody test was positive in all, and six investigated patients had antibodies to histones. All patients had anemia, high ESR, and microscopic hematuria. Five of the nine patients were rapid drug acetylators. Renal biopsies from eight patients revealed a uniform histologic picture with segmental necrosis of glomeruli and extracapillary proliferation. Immunofluorescence investigation was positive in all and electron microscopy revealed deposits in the glomerular capillary walls in five of seven specimens. This renal disease may represent a late and monosymptomatic manifestation of the hydralazine syndrome.

Prospective study of low-dose cyclosporine A in patients with refractory lupus nephritis

We evaluated the efficacy and safety of low-dose cyclosporine A (CsA) in patients with refractory lupus nephritis. Nine patients with systemic lupus erythematosus who had lupus nephritis resistant to previous treatment with glucocorticoids and immunosuppressants other than CsA were enrolled in a prospective, open-label study. All patients initially received 2.5 mg/kg per day of CsA; the dosage was adjusted to reach a blood trough level of 80-150 ng/ml. The urinary protein concentration decreased significantly 2 weeks after the initiation of treatment. After 30 weeks of CsA treatment, the mean urinary protein concentration was more than 50% lower than the baseline value, and urinary casts had decreased significantly. There were no significant changes in the levels of serum creatinine, serum anti-double-stranded DNA antibodies, or CH50 during any part of the study. The dose of glucocorticoids was significantly tapered by approximately 50%, without any disease flare. Hypertension developed in one patient, but was controlled with antihypertensive agents. Our results suggest that low-dose CsA therapy is an effective and less toxic alternative to conventional cyclophosphamide therapy for the management of refractory lupus nephritis.

In vivo and in vitro effects of hydralazine on cellular growth, differentiation, and chromatin structure

The effects of hydralazine (1-hydrazinophthalazine), an antihypertensive drug, on mammalian cell growth, viability, and differentiation were assessed using Friend leukemia cells, Chinese hamster ovary cells, human lymphocytes, and rat lymphocytes, testicular germ cells, and epididymal sperm. Cultured cells in exponential phase growth were more susceptible to hydralazine cytotoxicity than stationary phase (G0) cells. Growth inhibition was associated with a dose-related slowdown of cell progression through S phase and was observed prior to a decrease of cell viability. At high drug concentrations, progression in all phases of the cell cycle was partially or totally inhibited. Hydralazine did not have an effect on the proliferation and differentiation of testicular germ cells in spontaneously hypertensive rats receiving 0-90 mg/kg/day (up to 20 times the dose used in humans) of hydralazine for a 12-week period. Hydralazine-exposed, histone-containing somatic cells and protamine-containing sperm cells failed to show any alterations in stainability with a DNA-intercalating dye nor in the susceptibility of nuclear DNA to undergo acid-induced denaturation in situ. The data suggest that hydralazine causes a dose-related suppression of mammalian cell growth with S phase appearing to be the most susceptible to hydralazine cytotoxicity. Furthermore, the interaction of hydralazine with chromatin at concentrations leading to antigenicity did not inhibit DNA staining with the intercalating dye acridine orange, suggesting that the drug does not competitively intercalate at a detectable level. Association of hydralazine with chromatin did not cause a detectable level of stabilization or destabilization of the DNA to denaturation in situ.

Increased presence of common systemic lupus erythematosus (SLE) anti-DNA idiotypes (16/6 Id, 32/15 Id) is induced by procainamide

Sixty-seven patients on treatment with procainamide were examined for the presence of two common idiotypes of anti-DNA antibodies (16/6 Id and 32/15 Id). These idiotypes have been shown previously to have clinical relevance in patients with systemic lupus erythematosus (SLE). An enzyme-linked immunosorbent assay (ELISA) with rabbit anti-Id antibodies revealed increased concentrations of the 16/6 Id and 32/15 Id in 25 (37%) and 16 (24%) patients, respectively. Five of eight patients with drug-induced lupus had elevated titers of both idiotypes. A high correlation (R = 0.56, P less than 0.001 for 16/6 Id) was found between Id levels and anti-single-stranded DNA (ssDNA) antibody titers and between 16/6 Id titers and antihistone antibodies (IgG, R = 0.43; IgM, R = 0.25). It seems that procainamide, a component known to be associated with drug-induced lupus, may induce an increased production of common anti-DNA idiotypes in apparently normal subjects.

Detection of anti-histone activity in sera of patients with monoclonal gammopathies

Sera from 249 patients with monoclonal gammopathies (85 multiple myeloma, 92 benign monoclonal gammopathies, 53 cryoglobulinemia, 19 Waldenström's macroglobulinemia) were examined for the presence of anti-histone activity. Thirty-four sera were found positive. In 12 of these cases the serum monoclonal immunoglobulins were purified and in all, the anti-histone activity appeared to reside in the monoclonal component. None of the patients had symptomatology of lupus despite high titers of anti-histone activity. This study demonstrates an anti-histone activity of monoclonal components of patients with monoclonal gammopathies.

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.

Effects of long-term procainamide therapy on immunoglobulin synthesis

Procainamide is a potent inducer of autoantibodies. In order to evaluate the immunologic effects of this drug in vivo, 23 cardiac disease patients who had received procainamide for at least 6 months and an equal number of matched cardiac disease control subjects were studied, and percentage of circulating T cell subsets, concanavalin A-induced suppressor cell activity, and pokeweed mitogen--stimulated generation of immunoglobulin-secreting cells was quantitated. There was no significant difference between patient and control groups in the percentage of T cell subsets defined by OKT4 and OKT8 monoclonal antibodies or in concanavalin A-induced suppressor cell activity. The numbers of pokeweed mitogen--induced immunoglobulin-secreting cells were markedly decreased in the patient group, as measured by the protein A-augmented reverse hemolytic plaque assay (3,000 +/- 644, mean +/- SEM in patients versus 10,826 +/- 1,529, mean +/- SEM in control subjects, P less than 0.005). Removal of the adherent cell fraction did not improve the hyporesponsiveness. When B and T cell fractions of 6 patients were mixed with normal T and B cell fractions, all of the patients demonstrated diminished B cell responses, and one-half also had diminished T cell responses. Addition of patient adherent cells to a co-culture of normal B cells with deficient patient T cells restored plaque formation to normal levels, suggesting that the T cell defect was correctable by a macrophage-derived factor. The data obtained suggest that procainamide exerts an immuno-suppressive action on both B and T cell function in patients receiving this drug.

The binding of antihistone antibodies to Crithidia luciliae kinetoplasts is growth cycle-dependent

The Crithidia luciliae immunofluorescence (CLIF) assay is widely used to test for native DNA (nDNA) antibodies in the diagnosis and management of systemic lupus erythematosus. However, sera from patients with drug-induced lupus erythematosus or rheumatoid arthritis, which should not contain nDNA antibodies, occasionally react with the CL kinetoplast. We examined 36 sera from patients with systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, and drug-induced lupus erythematosus, who had positive CLIF tests. All 36 sera were also antinuclear antibody-positive with homogeneous and/or peripheral staining patterns on mouse kidney substrates. After hydrochloric acid extraction of the CL smears to remove histone and other nuclear protein antigens, 14 of the 36 sera no longer produced a positive result on the CLIF test. Ten of these 14 sera again gave a positive CLIF result after the hydrochloric acid-extracted Crithidia substrate had been reconstituted with purified histone. These studies demonstrated that kinetoplast binding was due to antihistone antibodies in at least 10 of 36 initially CLIF-positive sera. Antihistone antibodies were then purified with a histone-affinity column, and these purified antibodies were reactive with CL kinetoplasts. Thus, the CLIF test is not specific for nDNA antibodies. Additional studies using CL from different days of culture indicated that histone antigen expression in the CL kinetoplast was a function of the life cycle of this organism and is most readily detected 2 days after initiation of culture.

Antinuclear antibody determination: the present state of diagnostic and clinical relevance

Determination of antinuclear antibodies (ANA) will gain in diagnostic significance if a specific type of ANA can be related to a defined clinical disorder. The past decade has brought us quite a lot of papers dedicated to this subject. Yet, with exception of the DNA/anti-DNA system, observed correlations have remained scarce or contradictory. Also, still little is known about the pathogenic role of ANA. Perhaps more recent approaches using biochemical technologies will provide us with highly purified nuclear antigens necessary to study possible correlations at a more sophisticated level.

The prevalence of antibodies to histones induced by procainamide in old people, in cancer patients, and in rheumatoid-like disease

Antibodies to histones were found to be most commonly responsible for the positive antinuclear antibody (ANA) test in asymptomatic patients treated with procainamide, in old people, in patients with neoplastic diseases, and in young women affected with a rheumatoid-like disease. Only in a very few patients were antibodies to dDNA and nucleoproteins demonstrated. Antibodies to nDNA were not found. The antibodies to histones were demonstrated by two methods: absorption of ANA-positive sera with a histone solution and subsequent performance of an ANA test; and acid elution of histones from thyroid sections followed by histone reconstitution.