The effect of native and single stranded DNA on the platelet release reaction. Enhancement of aggregated IgG-induced serotonin release.

Native (n) but not single stranded (ss) DNA was found to induce release of 3H-serotonin (5-HT) from platelets of the majority of normal individuals. However, ssDNA markedly enhanced 5-HT release induced by heat-aggregated IgG (aggIgG), while less enhancement was seen using nDNA. Similar enhancement was produced by polyinosinic acid but not by polyinosinic:polycytidylic acid. The ability of ssDNA to potentiate aggIgG-induced 5-HT release seemed specific for aggIgG, since no effect on ADP or epinephrine-induced release was observed and thrombin-induced release was inhibited. In contrast, nDNA in high concentrations (100 micrograms/ml) potentiated ADP, epinephrine, and thrombin-induced 5-HT release. These results suggest that ss-and nDNA may interact with platelets by different mechanisms and provide a means by which DNA, released at sites of tissue injury, could modulate the role of platelets in the inflammatory response. The ability of DNA to enhance the aggIgG-induced platelet release reaction may be important in immune complex diseases such as systemic lupus erythematosus.

Familial systemic lupus erythematosus: immunogenetic studies in eight families.

Familial SLE provides a unique opportunity to study the relationships of previously associated genetic factors (HLA and complement component deficiencies) to the occurrence of SLE, other immune disorders, and autoantibodies in families. Thus, eight families containing two or more affected members with SLE (n = 22) and their relatives (n = 40) were examined for HLA genotypes, complement components and autoantibodies. Among the 40 non-SLE relatives, 7 (18%) had other immune diseases, including thyroid disease in 2, rheumatoid arthritis in 2, ITP in 2, and Henoch-Schönlein purpura in one. This compared to 4 of the 22 SLE patients (also 18%) of whom 3 had thyroid disease and one PSS. Eleven non-SLE relatives (28%) had ANA, which was in high-titer in 5 (13%). Eleven (28%) had antibodies to ssDNA, and one had a BFP. Only the SLE patients had antidsDNA, Ro(SSA), Sm or nRNP. A heterozygous C2 deficiency (C2D) was found in only one of the seven kindreds studied, and followed an A25, B18 DR7 haplotype. Heterozygous C2D, however, was inherited by only one of three family members with SLE. HLA-DR2 occurred in 36% and DR3 in 36% of SLE patients, which was not significantly different from either non-SLE family members or unrelated local controls. Sib pair analysis of seven sets presented here and seven from two published reports, demonstrated only random distribution with SLE. Similarly, other immune disorders and autoantibodies followed no consistent HLA haplotypes or DR specificities. Interestingly, DR2 and/or DR3 were found in five of the six patients (83%) having anti-ro(SSA) antibodies (p = NS). These data strongly suggest that genetic factors (other than HLA and complement component deficiencies) and/or environmental factors are necessary for the expression of SLE and other immune abnormalities in lupus families.

Mechanisms of abnormal platelet aggregation in systemic lupus erythematosus.

Platelet aggregation was measured in 14 patients with systemic lupus erythematosus (SLE) and 13 normal controls. Ten SLE patients (group I) showed decreased responsiveness to collagen, while aggregation was normal in 4 (group II). Group I patients also responded poorly to epinephrine. Platelets from SLE patients did not differ from controls in the production of malondialdehyde in response to N-ethylmaleimide, suggesting intact prostaglandin synthetic pathways. However, a significant decrease (P less than 0.005) in platelet levels of the dense granule constituent, serotonin, was noted in group I SLE patients. Treatment of SLE platelet-rich plasma with deoxyribonuclease (DNase) resulted in enhancement of collagen-induced aggregation in 4 group I SLE patients, but not in 1 group II or 8 normal individuals. These results suggest that defective aggregation in SLE platelets may be partially related to a storage pool deficiency state. However, the ability to restore aggregation to collagen by digestion of platelet-rich plasma with DNase indicates that the defect is reversible and that it is perhaps mediated by plasma or platelet-associated DNA.

Decreased platelet serotonin levels in systemic lupus erythematosus.

Platelet serotonin levels were measured in 41 patients with systemic lupus erythematosus (SLE) and 36 normal controls. SLE patients had significantly lower mean serotonin levels (243 +/- 131 versus 414 +/- 175 ng/10(9) platelets, P less than 0.001); the lowest levels occurred in those patients with active disease. No differences in mean platelet serotonin levels were found when we compared patients with or without a history of renal disease, thrombocytopenia, or neuropsychiatric involvement. Decreased release of platelet granule constituents, as measured by plasma levels of the alpha-granule protein, beta-thromboglobulin.

Survivorship in systemic lupus erythematosus: effect of antibody to extractable nuclear antigen.

The course of 81 patients with systemic lupus erythematosus (SLE) who had sera tested for antibody to extractable nuclear antigen (ENA) was studied to determine the effect of the presence of antiENA antibody on survivorship. There were no differences in percent survival between the patients with and without antibody to ENA or those with and without antibody to the ribonucleoprotein (RNP) component of ENA. We conclude that there is no prognostic advantage to the presence of either antiENA or antiRNP antibody in patients with SLE.

The measurement of antibodies to extractable nuclear antigen.

By the use of a combination of Ouchterlony immunodiffusion and hemagglutination, it was found that 30 of 81 sera (37%) from patients who had systemic lupus erythematosus (SLE) had antibodies to the ribonucleoprotein component of extractable nuclear antigen, and 37 (46%) had antibody to the Sm antigen. Immunodiffusion was more sensitive for detection of anti-ribonucleoprotein, while hemagglutination detected more anti-Sm. Both technics are necessary to define qualitatively the types of antibodies present in SLE sera.

The metabolism of nucleic acids in mice.

The metabolism of three forms of nucleic acid, native-DNA (N-DNA), single strand DNA (SS-DNA), and polyinosinic-polycytidylic acid (poly I : C), was investigated in vivo in randomly bred Swiss-Webster mice. Clearance of these substances from the circulation and tissue localization were determined at selected time intervals following the intravenous injection of 125I-labelled compounds. N- and ss-DNA were removed from the circulation more rapidly than was poly I : C. All three materials localized principally in reticuloendothelial-rich organs, i.e. liver and spleen. N-DNA was degraded by the liver more slowly than was poly I : C or ss-DNA. At 4 h following injection, the liver contained 26%, 13%, and 10% of the injected doses, respectively. Three days after injection, 4.5% of the N-DNA persisted in the liver, as compared to only 0.6% of the poly I : C, and 0.2% of the ss-DNA. The possiblity that these differences in metabolism of N-DNA, poly I: C, and ss-DNA may be related to their differing immunogenic potentials in experimental systems is discussed.

Limited anti-DNA antibody specificity in systemic lupus erythematosus.

Twenty-one sera from 11 patients with systemic lupus erythematosus were titrated with 125I-ss-calf thymus DNA to determine their maximum capacity to bind DNA. Only five sera were capable of binding greater than 90% of the input DNA. The remaining sixteen sera showed maximum DNA binding levels between 35% and 85%. The inability of these sera to bind all of the input DNA is shown to be dependent on variations in the molecular weight of the DNA antigen. The possibility that these differences in DNA binding reflect differences in antigenic specificity is discussed.

Neuropsychiatric manifestations of systemic lupus erythematosus: diagnosis, clinical spectrum, and relationship to other features of the disease.

1. Among patients with SLE, 71 (51%) had significant neuropsychiatric problems during the course of the disease. In 52 (37%), the nervous system manifestations were secondary to SLE. 2. The most frequent manifestations were psychiatric dysfunction, seizures, long tract signs, cranial neuropathy, and peripheral neuropathy. 3. Psychiatric abnormalities secondary to SLE were characterized by organic features (present in 22 of 24) and by the association of neurologic lesions which were often diffuse or multifocal. 4. An abnormal cerebrospinal fluid was found in 32% of neuropsychiatric episodes in which specimens were obtained. The most frequently abnormal study was the electroencephalogram (71%), and the least frequent was the brain scan (8%). These studies did not correlate with specific clinical patterns. 5. In 63% of the patients, NP manifestations preceded the diagnosis of SLE or occurred within the first year of diagnosed disease, and in most episodes were associated with evidence of clinical and/or serologic activity of the underlying illness. 6. Only two clinical features showed significant and striking correlations with neuropsychiatric involvement, namely vasculitis and thrombocytopenia. The possible pathogenic implications have been discussed. 7. Only 2 of the 140 patients were felt to have steroid-induced psychoses. In approximately one-half of the NP episodes secondary to SLE, patients were receiving no corticosteriods on presentation. Of those developing while patients were on steroids, the majority occurred on low doses or after tapering from higher levels. 8. The immediate prognosis for improvement in neuropsychiatric function was good with 84% of episodes showing complete or partial resolution. Corticosteroids appeared to be of benefit in a substantial number of patients although their precise role is difficult to quantitate. 9. Five and 10 years survivals for the overall population were 94% and 82%, respectively. There were no significant differences in survival for patients with or without nervous system involvement.

Persistence of DNA in the circulation of immunized rabbits.

The clearance of deoxyribonucleic acid (DNA) from the circulation was studied in non-immunized New Zealand rabbits and in rabbits immunized with heat-denatured, single-strand DNA (ss-DNA). Animals were injected intravenously with 1-3 mug/kg of 125-I-calf thymus ss-DNA. Initial clearance rates were -0.154 +/- 0.005 per cent (dose/ml/min) in non-immunized rabbits as compared to rates of -0.064 to -0.123 per cent (dose/ml/min) in rabbits immunized with ss-DNA. In immunized rabbits, clearance rates were inversely correlated with relative amounts of antibody, and increased amounts of circulating radiolabel were precipitable with 50 per cent saturated ammonium sulfate, suggesting binding to rabbit immunoglobulin. Thus, the presence of antibody to ss-DNA may delay the usually rapid clearance of ss-DNA from the blood. This observation is similar to that made for a variety of small molecular weight materials, such as insulin, digoxin, and morphine, and is in contrast to that for multivalent protein antigens, such as serum albumin and thyroglobulin. Persistence of DNA in the circulation may be important in the pathogenesis of DNA-anti-DNA-induced immune complex disease.