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DNA-dependent protein kinase (DNA-PK) consists of a DNA binding subunit (Ku autoantigen), and a catalytic subunit (DNA-PKcs). In the present study, human autoantibodies that recognize novel antigenic determinants of DNA-PK were identified. One type of autoantibody stabilized the interaction of DNA-PKcs with Ku and recognized the DNA-PKcs–Ku complex, but not biochemically purified DNA-PKcs. Another type recognized purified DNA-PKcs. Autoantibodies to Ku (p70/p80 heterodimer), ‘stabilizing’ antibodies, and antibodies to DNA-PKcs comprise a linked autoantibody set, since antibodies recognizing purified DNA-PKcs were strongly associated with stabilizing antibodies, whereas stabilizing antibodies were strongly associated with anti-Ku. This hierarchical pattern of autoantibodies specific for components of DNA-PK (anti-Ku>stabilizing antibodies>anti-DNA-PKcs) may have implications for the pathogenesis of autoimmunity to DNA-PK and other chromatin particles. The data raise the possibility that altered antigen processing and/or stabilization of the DNA-PKcs–Ku complex due to autoantibody binding could play a role in spreading autoimmunity from Ku to the weakly associated antigen DNA-PKcs.

Antiglycyl tRNA synthetase is an unusual autoantibody specificity associated with polymyositis and dermatomyositis complicated by interstitial lung disease. We report here autoantibodies to glycyl tRNA synthetase in a patient with systemic lupus erythematosus and interstitial lung disease. During the course of her disease, the patient developed elevated muscle enzymes and worsening pulmonary function. A quantitative immunoprecipitation technique was developed to evaluate the relationship between autoantibody production and clinical manifestations in this patient. Increasing serum antiglycyl tRNA synthetase antibody levels correlated with the severity of the patient's interstitial lung disease and with the level of creatine phosphokinase.These results suggest that certain autoantibodies, such as antiglycyl tRNA synthetase, might reflect an underlying pathologic process (in this case, myositis and interstitial lung disease) irrespective of disease diagnosis, and that quantitative immunoprecipitation may be a useful technique for investigating the relationship between specific autoantibody production and organ involvement in systemic autoimmune disease, Quantitation of these autoantibodies may be useful clinically in monitoring disease activity and/or response to therapy.

We report a woman with systemic lupus erythematosus (SLE) with diffuse proliferative glomerulonephritis and anti-dsDNA antibodies whose serum contained autoantibodies specific for the phosphorylated form of RNA polymerase II (RNAP IIO), Su and ribosomal P antigen, as well as anti-topoisomerase I antibodies, a marker for scleroderma (SSc). Over 6 years, the patient exhibited clinical manifestations consistent with SLE without clinical evidence of scleroderma. The reactivity of her serum autoantibodies with the phosphoproteins ribosomal P, topoisomerase I, and RNAP IIO is consistent with recognition of autoepitopes comprised in part of phosphate groups. This may explain the unexpected coexistence of marker autoantibodies for SLE and scleroderma, possibly with implications for the mechanisms of autoantibody generation.

Objective. To examine humoral immune responses to the native Ku antigen and to evaluate the role of autoantibodies in stabilizing intermolecular contacts between the p70 and p80 Ku subunits. Methods. Recombinant free human p70 and p80 Ku subunits and p70/p80 heterodimers were expressed in Sf9 (insect) cells using baculovirus vectors. Affinity-purified recombinant human p70, p80, and p70/p80 dimer were studied by enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation to evaluate autoantibody specificities in sera from 58 patients with systemic autoimmune disease. Results. Anti-Ku antibodies were detected by ELISA or immunoprecipitation using K562 cell Ku antigen. All of the sera were reactive with the native recombinant p70, p80, or p70/p80 antigens: 47% were anti-p70+,anti-p80+ and 32% were anti-p70-,anti-p80+, but only 3% were anti-p70+,anti-p80-. Unexpectedly, 18% of the sera recognized the p70/p80 dimer but did not recognize native p70 or p80 alone. A subset of sera containing autoantibodies that prevent the dissociation of p70 from p80 by high salt and detergent treatment was identified; monoclonal antibody (MAb) 162, a murine anti-Ku MAb, displays the same property. Autoantibodies that stabilize the p70-p80 interaction were found most frequently in sera containing both anti-p70 and anti-p80 antibodies. Conclusion. Autoantibodies to the native p80 sub-unit of Ku are more common than are anti-p70 antibodies. When anti-p70 antibodies were detected, they generally were found together with anti-p80. A novel type of autoantibody capable of stabilizing the p70/p80 heterodimer was identified in human sera for the first time. These “stabilizing” autoantibodies are found in sera containing both anti-p70 and anti-p80 antibodies, and also are produced by mice immunized with human Ku antigen. Autoimmunity to Ku may be initiated with an immune response to p80, followed by spreading to p70. We hypothesize that stabilizing antibodies could facilitate the spreading of autoimmunity from one subunit of Ku to another by altering the processing of p70 or p80 by antigen-presenting cells.

Publisher Summary This chapter discusses the pathogenetic role and methods of detection of Ku and Ki autoantibodies. Autoantibodies specific for Ku are associated strongly with an unusual disease subset in Japanese patients with systemic autoimmunity; whereas, they are associated primarily with systemic lupus erythematosus and overlap syndromes in Americans. Ki autoantibodies are associated with scleroderma, rheumatoid arthritis, Sjogren's syndrome, and other autoimmune diseases. Autoantibodies to the Ku and p350 antigens are directed against DNA-dependent protein kinase (DNA-PK), a multiprotein complex consisting of a DNA-binding component, and a catalytic subunit. Autoantibodies reactive with p70, p80, p350, and antibodies that stabilize the quaternary structure of DNAPK constitute a linked set. The chapter clarifies the initial confusion regarding the relationship of the Ki and Ku antigens.

In this study we followed up the effects of acute (ten days) and chronic (two months) stereotaxic lesions of NB in rats on: 1.) cellularity of lymphatic organs, 2.) humoral and 3.) cellular immunity and 4.) in vitro functional reactivity of splenocytes to polyclonal mitogens. Experiments were done on (AoxDA) F1 male rats, aged 4 months and maintained in standard laboratory conditions. The coordinates for bilateral stereotaxic lesions were taken from atlas of Pellegrino. Electrolysis was performed unipolarly at the anode with 10 mA for 10s. Histological verification of the lesions was performed by the method of Wolf. For the evaluation of humoral or cell mediated immunity standard plaque forming cell assay to sheep red blood cells (SRBC) or transplantation of allogeneic skin were used. The data have shown that bilateral electrolytic lesions of NB cause the prolongation of rejection time to allogeneic skin, transplanted on tenth p.o. (15.8+-0.4 days versus 12.8+-0.5 in intact control, p

The present study was designed to clarify mechanisms involved in suppression of cell-mediated immunity reported in patients undergoing major surgery with general anesthesia by determining the effects of halothane anesthesia with and without surgery on the growth of Sarcoma I (Sa I), a tumor allogeneic to BALB/c mice. Mice were given subcutaneous injections of 5 X 10(6) tumor cells from A/Jax mice and then immediately exposed to 0.5%-1.0% halothane for 1 hr without surgery (n = 7) or with surgery (midline laparotomy; n = 12). In control groups mice were also injected with tumor cells but were not exposed to prolonged halothane anesthesia. Some of them received only Sa I (n = 6), while the rest (n = 7) were also laparotomized. The rejection time of Sa I in mice exposed to halothane anesthesia was significantly longer (15.4 +/- 1.25 days) than in untreated controls (12.0 +/- 0.68 days) (P less than 0.05). In the mice exposed to halothane tumor growth was also greater. Surgical stress per se did not significantly affect growth or rejection time of Sa I (11.0 +/- 0.66 vs 12.0 +/- 0.68 days). Similarly, the combination of surgical stress with halothane anesthesia did not affect the immunosuppression associated with halothane alone (12.9 +/- 1.3 vs 15.4 +/- 1.25; P less than 0.05). The results indicate that halothane anesthesia per se may be associated with impairment of cell-mediated immunity under experimental conditions.