In vitro effect of antibodies to DNA on the template activity of DNA

Inhibition of in vitro transcription by adenosine antibodies

Antibodies against adenosine markedly inhibited in vitro transcription in isolated BHK 21 nuclei in a dose-dependent manner. The inhibition was specific as it could be completely reversed by the addition of homologous hapten. Addition of RNA at low concentration reversed the inhibition, whereas excess DNA did not have any effect. Adenosine antibodies also inhibited in vitro transcription with calf thymus DNA and E. coli RNA polymerase. Antibodies that react with DNA but not with RNA such as anti-dpA, anti-dpC and anti-DNA failed to inhibit in vitro transcription in isolated nuclei as well as with calf thymus DNA and E. coli RNA polymerase. The results strongly indicate that the binding of adenosine antibodies to RNA is responsible for the inhibition of transcription.

Inflammatory myopathy: a review of etiologic and pathogenetic factors

Human idiopathic inflammatory myopathy is an acquired disorder with an annual incidence of two to five cases per million. A genetic influence on host susceptibility may also play a role. With the marked heterogeneity of the disease one of the major challenges is to identify subsets that might share a more uniform pathogenesis and manifest a less diverse profile of clinical findings, histopathological abnormalities, and natural history. Dermatomyositis can be distinguished by clinical appearance and pathological changes, but the recognition of additional disease subsets remains very inexact. Current evidence suggests that dermatomyositis occurs as a result of a vasculopathy, but immune mechanisms involved in other categories of idiopathic inflammatory myopathy may also involve cell-mediated immunity and possibly multiple mechanisms. Even though viral-induced muscle inflammation occurs in humans, there is no convincing evidence for a viral cause of idiopathic inflammatory myopathy. Experimental allergic myositis may be produced by the injection of animals with skeletal muscle homogenates and complete Freund's adjuvant, but the myositogenic factor is unknown and the parallels between experimental allergic myositis and human idiopathic inflammatory myopathy are limited.

Immunocytochemical localization studies of myelin basic protein

The location of myelin encephalitogenic or basic protein (BP) in peripheral nervous system (PNS) and central nervous system (CNS) was investigated by immunofluorescence and horseradish peroxidase (HRP) immunocytochemistry. BP or cross-reacting material could be clearly localized to myelin by immunofluorescence and light microscope HRP immunocytochemistry. Fine structural studies proved to be much more difficult, especially in the CNS, due to problems in tissue fixation and penetration of reagents. Sequential fixation in aldehyde followed by ethanol or methanol provided the best conditions for ultrastructural indirect immunocytochemical studies. In PNS tissue, anti-BP was localized exclusively to the intraperiod line of myelin. Because of limitations in technique, the localization of BP in CNS myelin could not be unequivocally determined. In both PNS and CNS tissue, no anti-BP binding to nonmyelin cellular or membranous elements was detected.

Effect of systemic lupus erythematosus antibodies against DNA on RNA synthesis

The majority of tested systemic lupus erythematosus (SLE) sera inhibited RNA synthesis in vitro on the stage of RNA chain elongation. Two sera were also active in inhibiting the binding of the enzyme to the template. No correlation has been found between the sera activity in filter radioimmunoassay, their specificity to double- or single-stranded DNA, and the degree of RNA synthesis inhibition.