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PubMed1976

Radiation leukemia in C57BL/6 mice. II. Lack of ecotropic virus expression in the majority of lymphomas.

The expression of endogenous ecotropic viruses in radiation-induced thymomas of C57BL/6 mice was examined. Competition radioimmunoassays for AKR MuLV gp71, p30, and p12 were used for viral antigen expression. 3 of 40 lymphomas had readily detectable ecotropic gp71 at levels of 95-689 ng/mg protein; the remainder of the tumors had no detectable gp71 (less than 1.0 ng/mg protein). 30 thymomas were characterized by the presence of MuLV p30 at levels of 1-10 ng/mg protein, levels that were comparable to those found in thymus extracts from age-matched, nonirradiated control. 10 tumors were characterized by having p30 levels of 10-30 ng/mg protein. In one tumor significant levels of AKR MuLV p12 were detectable. Since B-tropic and N-tropic viruses from C57BL/6 mice have glycoproteins (gp71) indistinguishable from AKR MuLV gp71 and the N-tropic virus had a p12 serologically identical to AKR MuLV p12, these results demonstrate that overt endogenous B-tropic virus was detectable in 2 of 40 thymomas and endogenous N-tropic virus was detectable in 1 of 40 thymomas. The lack of overt expression of gp71 or p12 was also confirmed by cytotoxicity assays using monospecific antisera to these viral proteins. Radiation-induced lymphomas were also examined for the presence of reverse transcriptase after chromatography of tissue extracts on poly G-Sepharose. One tumor, which was characterized by the lack of gp71, also had no detectable reverse transcriptase; whereas one tumor with gp71 was characterized by readily detectable levels of reverse transcriptase in cellular extracts. The presence of viral RNA was examined using AKR cDNA. Low levels of RNA capable of hybridizing with AKR cDNA were found in age-matched, nonirradiated mice; these hybrids had Tm's of 72 degrees C, while hybrids with AKR MuLV 70S RNA had Tm's of 80 degrees C. In 1 of 12 thymomas the concentration of hybridizable RNA and the Tm of the hybrids were identical to control values. In 9 of 12 thymomas the concentration of hybridizable sequences increased approximately three-to fivefold and the Tm of these hybrids varied from 73 to 75 degrees C. In 1 of 12 thymomas the concentration of hybridizable sequences increased over 100-fold, hybridized completely with AKR MuLV cDNA, and the hybrids had Tm's of 79 degrees C. This thymoma was also characterized by the presence of the AKR MuLV type of gp71 and p12. One tumor was characterized by a 10-to 100-fold increase in hybridizable sequences, which only partially hybridized with AKR MuLV cDNA, and hybrids had a Tm of 73 degrees C. This tumor was characterized by the presence of AKR MuLV gp71 but not AKR MuLV p12. The results taken together demonstrate that overt endogenous ecotropic virus expression is only rarely detectable in radiation-induced thymomas of C57BL/6 mice.

AKR murine leukemia virus↗
PubMed1989

Purification and characterization of Ki antigen and detection of anti-Ki antibody by enzyme-linked immunosorbent assay in patients with systemic lupus erythematosus.

Ki antigen from rabbit thymus extract was purified by ammonium sulfate precipitation, anti-Ki affinity chromatography, and high pressure liquid chromatography gel filtration. The purified Ki antigen gave a single polypeptide with an MW of 32,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it specifically reacted with anti-Ki antibody by immunoblotting. The isoelectric point of the Ki antigen was found by isoelectric focusing to be 4.3. An enzyme-linked immunosorbent assay using the purified Ki antigen was established, and the clinical significance of the anti-Ki antibody in systemic lupus erythematosus (SLE) was studied. Thirty of 140 patients with SLE (21.4%) had anti-Ki antibody by enzyme-linked immunosorbent assay, whereas 11 (7.9%) were positive by double immunodiffusion. Analysis of clinical and serologic data on patients with SLE suggested a higher prevalence of central nervous system involvement in patients with anti-Ki antibody.

Antibodies↗
PubMed2002

Autoimmune responses to proliferating cell nuclear antigen multiprotein complexes involved in cell proliferation are strongly associated with their structure and biologic function in patients with systemic lupus erythematosus.

OBJECTIVE: To analyze the reaction of lupus sera with proliferating cell nuclear antigen (PCNA) multiprotein complexes (PCNA complexes), which are part of the protein machinery involved in cell proliferation. METHODS: PCNA complexes were purified from rabbit thymus extract by affinity chromatography using anti-PCNA monoclonal antibodies (TOB7, TO17, and TO30); monomeric and trimeric PCNA forms (AK-PCNA) were purified using anti-PCNA serum AK. The reactions to these antigens of 10 anti-PCNA-positive and 40 anti-PCNA-negative sera selected from 560 lupus patients were tested by immunoblotting, immunoprecipitation, and enzyme-linked immunosorbent assays (ELISAs). RESULTS: With one exception (serum OK), anti-PCNA-positive sera reacted exclusively with only the 34-kd polypeptide. In contrast, 14 of 40 anti-PCNA-negative sera reacted with multiple proteins within PCNA complexes. Most anti-PCNA-positive sera probably recognize as epitopes the binding sites for other proteins on PCNA, which are likely hidden when PCNA is complexed with other proteins. As a consequence, only serum OK reacted with the PCNA complex in a series of ELISAs. Using AK-PCNA as a competitive inhibitor, it was determined that serum OK reacts with both the 58-kd polypeptide and the 34-kd PCNA within complexes. Together with the results of a longitudinal analysis, these results suggest that the immune system of patient OK likely recognized the complexed PCNA protein, after which the autoimmune response spread to other elements of the complexes. CONCLUSION: Intermolecular-intrastructural help, leading to the spread of autoimmune response from PCNA to other proteins associated with its biologic function, plays a crucial role in the induction of the autoimmune response seen in lupus patients.

Antibodies, Monoclonal↗
PubMed1985

The association between Mi-2 antibodies and dermatomyositis.

Antibodies to Mi, an antigen in calf thymus extract, have been demonstrated by complement fixation inhibition in polymyositis (PM) and dermatomyositis (DM) sera but not in the sera of individuals without myositis. The original Mi reference serum defined 2 precipitating antibodies, using immunodiffusion (ID). Anti-Mi-1 was not active in complement fixation. We have now studied in further detail anti-Mi-2, which appears to be the antibody in Mi serum that fixes complement. Mi-2 antigen was purified by immuno-affinity chromatography. An enzyme-linked immunosorbent assay (ELISA) to measure Mi-2 antibody, using this antigen, was used to test the sera of 139 myositis patients: 52 had DM and 87 had PM. Control sera from 35 normal subjects and 93 patients with other connective tissue diseases were also tested. Only 13 sera were considered definitely positive for anti-Mi-2. All were from patients who had myositis, 11 of whom had DM. Only DM sera had anti-Mi-2 by ID, and all sera with anti-Mi-2 by ID were positive by ELISA. A number of other sera, including many from patients with other connective tissue diseases and 2 from normal subjects (all without precipitating antibodies) had lower elevations which were of uncertain significance. Detection of anti-Mi-2 by ID as well as by ELISA was significantly more frequent in DM than in PM. Anti-Mi-2 appears to be closely linked to DM, and is the first specific serologic marker for this form of myositis.

Antibody Specificity↗
PubMed1987

An immunoassay differentiating sera with antibodies to Sm alone, antibodies to Sm/RNP complex, and antibodies to RNP alone.

Combined DEAE-Sephacel and hydroxyapatite chromatography resulted in a separation of free Sm antigen from the Sm/RNP complex in rabbit thymus extracts. In Western blots, the free Sm preparation contained an immunoreactive 14-kd (D) protein, whereas the Sm/RNP complex contained, in addition to the 14-kd protein, a 68-kd-reactive protein and its putative degradation fragments. Ethidium bromide staining of these preparations separated by agarose gel electrophoresis showed that the Sm/RNP preparation contained RNA, but the free Sm preparation did not. These preparations were used as antigens in an enzyme-linked immunosorbent assay (ELISA). Sera characterized as anti-Sm only, anti-Sm/RNP, and anti-RNP only were assayed. A quotient (Q) was derived from the ELISA optical density obtained with Sm/RNP as antigen divided by the optical density obtained with free Sm as antigen. Q values less than 4.0 characterized sera with anti-Sm only, values of 4.0-12.0 were observed in sera with anti-Sm plus anti-RNP, and values greater than 12.0 in sera with anti-RNP only. Sera with antibodies to other nuclear antigens were not reactive in this system. It has traditionally been difficult to identify sera with anti-RNP when this is present simultaneously with, and in lower concentration than, anti-Sm. With this method, such sera can be identified by their Q value, which falls in an intermediate region between a lower Q for anti-Sm and a higher Q for anti-RNP.

Autoantibodies↗
PubMed1987

Indications for immunotherapy.

Underlying immunodeficiency should be suspected in every patient, irrespective of age, who has recurrent, persistent, severe, or unusual infections. Defects in immunity can be classified into primary or secondary disorders involving specific or nonspecific immune mechanisms. Several forms of primary and secondary immunodeficiency exist for which various immunotherapeutic modalities are available. Significant among these are immunoglobulins commercially available for intravenous infusion. Other therapies include transplantation of tissue such as bone marrow, fetal liver, and fetal thymus. Enzyme replacement therapy is being developed, as is the use of products unique to immunocompetent cells, such as thymus extract, thymosin, interleukins, and transfer factor. Forms of nonspecific immune modulators and stimulators are other possibilities, especially in the context of the immunotherapy of tumors.

Humans↗
PubMed1993

Antibodies to Sm, RNP and SSB detected by solid-phase ELISAs using recombinant antigens: a comparison study with counter immunoelectrophoresis and immunoblotting.

Sera from 64 patients with systemic lupus erythematosus (SLE) were tested for the presence of anti-Sm, anti-RNP, and anti-SSB antibodies using commercially available solid-phase enzyme-linked immunosorbent assays (ELISAs) and recombinant nuclear proteins as substrates. The results were compared to those obtained with counterimmunoelectrophoresis (CIE) and immunoblotting (IBT) using a rabbit thymus extract (RTE) as the substrate. The ELISAs detected antibodies to Sm, RNP, and SSB in, respectively, 25%, 36%, and 15% of the SLE sera. Neither IBT-positive/ELISA-negative nor CIE-positive/ELISA-negative sera were found, regardless of the specificity considered, suggesting that ELISAs using recombinant nuclear antigens are highly sensitive. Discrepancies were observed between the results obtained with these different techniques. In addition to sera positive by both IBT and ELISA but negative by CIE, a substantial number of sera had ELISA-detectable anti-Sm, anti-RNP, and anti-SSB antibodies which failed to react with the corresponding polypeptides by IBT. The reasons for ELISA/IBT discrepancies were explored; however, no single explanation was found. Instead, a higher sensitivity of the ELISA to detect antibodies directed against certain polypeptides, the possible inability of IBT using RTE as the substrate to detect antibodies reacting with conformational antigenic determinants, and false-positive reactions in the ELISAs were suggested. Thus, it is still advisable to perform both IBT and ELISAs simultaneously in well-defined autoimmune diseases to further analyze the potential advantages of ELISAs using recombinant antigens.

Animals↗
PubMed1987

In vitro effect of a thymic epithelial culture supernate or thymosin fraction 5 on rabbit platelet aggregation and intracellular cyclic AMP levels.

Supernates of thymic epithelial cell culture (STEC) strongly inhibit aggregation induced by addition of adenosine diphosphate (ADP: 1 microM) or thrombin (0.5 unit per ml) to washed platelet suspensions and accelerated the restoration from ADP-triggered aggregation. At the same time, STEC increased the level of platelet adenosine 3',5'-cyclic monophosphate (cyclic AMP) in a dose-dependent manner. Depending on the concentration used, thymosin fraction 5 increased the level of intracellular cyclic AMP ranging between 5 and 100 micrograms per ml, as well as inhibiting ADP-induced platelet aggregation. The activities of both STEC and thymosin fraction 5 were found to act exclusively on cyclic AMP phosphodiesterase activity in platelets. In contrast the supernates from Chang, HeLa, or HCC-M cells did not affect platelet aggregation induced by ADP, but slightly increased the cyclic AMP level (Chang, HeLa). Within 2 min after the treatment with STEC, more than 50% of the maximum inhibitory activity on platelet aggregation and increases in intracellular cyclic AMP were observed. These activities disappeared following STEC treatment with pronase E. STEC activity was found predominantly in the 1,000-50,000-dalton fractions. These activities were not altered when STEC was treated by adenosine deaminase. The level of prostaglandin E (PGE) derivatives in STEC was about two times that found in the control culture medium. These data suggest that the biological activity of STEC in the platelets might be attributed to thymosinlike polypeptides and PGE1.

Adenosine Deaminase↗
PubMed1995

Autoantibodies in sera from patients with L-tryptophan-associated eosinophilia-myalgia syndrome. Demonstration of unique antigen-antibody specificities.

The purpose of this study was to determine whether specific autoantibodies could be identified that are associated with eosinophilia-myalgia syndrome (EMS). Sera from 44 patients with EMS were tested by indirect immunofluorescence, immunodiffusion against calf thymus extract, and immunoprecipitation from HeLa cell extract. Antinuclear antibodies were detected in the sera of 24/39 patients with EMS (61.5%) by indirect immunofluorescence against HEp-2 cells. Seven patients (16%) were demonstrated to have specific autoantibodies by immunoprecipitation in which at least two shared patterns were noted. In three sera immunoprecipitation identified a similar 63-kDa band (Ab-1). An additional four sera shared a pattern of bands consisting of a strong 110-kDa protein and a weak 95-kDa protein (Ab-2). Absorption of HeLa extract with a strongly positive Ab-2 serum confirmed that the four patients shared the same antibody. In conclusion, the detection of these autoantibodies provides evidence of autoimmunity in EMS, and may distinguish this syndrome from clinically related conditions.

Autoantibodies↗
PubMed1996

Autoantibodies recognizing proteins copurified with PCNA in patients with connective tissue diseases.

OBJECTIVE: Proliferating cell nuclear antigen (PCNA), one of the target antigen recognized by lupus sera, has been reported to be present as a subnuclear multi-peptide complex. But autoantibodies reacting with components of PCNA complex are poorly understood. To study the specificity of those autoantibodies, immunoreactivities of autoimmune sera against purified PCNA antigen were studied. METHODS: PCNA antigens were purified from rabbit thymus extract by affinity column using murine monoclonal antibodies (mAbs) to PCNA, TOB7, TO17 and TO30. Immunoreactivities of autoimmune sera against purified PCNA were analyzed by WB. RESULTS: PCNA antigen purified by serum AK predominantly showed a 34 kD band specific for PCNA in SDS-PAGE. When antigens were purified by anti-PCNA mAb TOB7 and TO30 which are known to be targeting different epitopes on PCNA antigen, SDS-PAGE analysis showed various mol. wt of proteins in addition to the 34 kD PCNA while both AK and mAbs reacted only with 34 kD PCNA in WB. In WB using PCNA purified by TOB7, various immunoreactivities were observed at 150, 66, 58, 48, 45, 37, 32 and 16 kDa in sera from patients with connective tissue diseases. CONCLUSIONS: These results suggested that many of the proteins copurified with PCNA were also targets of autoimmune responses and these autoantibody expression may be induced through antigen-driven mechanisms.

Animals↗
PubMed1989

Higher incidences of anti-SS-A/Ro and anti-SS-B/La autoantibodies in Japanese patients with autoimmune disorders--studies of antigens and antibodies using the immunoblotting method.

A specific and sensitive assay was performed to detect both anti-SS-A/Ro and anti-SS-B/La antibodies in sera of patients with autoimmune diseases, including systemic lupus erythematosus (SLE), progressive systemic sclerosis (PSS), Sjögren's syndrome (SS), discoid lupus erythematosus (DLE), mixed connective tissue disease (MCTD), generalized morphea (GM), and dermatomyositis (DM). The SS-A/Ro and SS-B/La antigens were prepared from human spleen (HSE) and cultured human cell line (KB cells, KBE), white rabbit thymus extract (RTE) was used as the SS-B/La antigen marker. The antigens were partially purified by DEAE cellulose column chromatography. Immunoblotting showed that the SS-A/Ro antibody reacts mainly with the 58-kDa peptide of the partially purified antigen. Sera containing both the SS-A/Ro and SS-B/La antibodies reacted with the 40-kDa peptide of RTE, and the 58-kDa, 42-kDa, and 40-kDa peptides of HSE and KBE. We found that some of the SS-A/Ro antisera could further react with the 64-kDa peptide of HSE and KBE. The 58-kDa peptide is rich in its cytoplasmic fraction of KB cells, and the 4-kDa peptide in nucleoplasmic fraction. The KB cell line is a better source of the antigens than human spleen extract. The immunoblotting method clearly showed that the positivity rates of SS-A/Ro and/or SS-B/La autoantibodies were higher in sera from Japanese patients with SLE compared with titers reported for Caucasians but not in sera from healthy volunteers.

Autoantibodies↗
PubMed1984

Identification of thymostimulin secreting cells in calf thymus by immunoperoxidase method.

An anti- thymostimulin (TS) serum was tested on calf thymus to study the localization of the hormonal factor. The immunoperoxidase method was applied to tissue fixed in Bouin's fluid and embedded in paraffin, or to tissue fixed in paraformaldehyde and embedded in Epon for semi-thin sections. Immuno-reactivity was shown, with DAB- Fluka , in reticulo-epithelial cells in the medulla, and between the cortex and the medulla, while with DAB-Sigma reactivity was found in the cortex as well. The external cells of Hassall's corpuscles were also reactive. Myoid cells were not reactive. In semi-thin sections a weak reactivity was noted at the periphery of a few lymphocytes. Comparison with the localization of other thymic factors, and the possibility of a functional cycle of the epithelial cells synthesizing one or more factors are discussed.

Animals↗
PubMed1984

Antibodies to a nuclear/nucleolar antigen in patients with polymyositis overlap syndromes.

A precipitating antigen-antibody system has been characterized that occurs in patients with polymyositis. At least half of the patients not only have polymyositis but also have scleroderma. The proposed name for this antigen found in calf thymus extract (CTE) is PM-Scl, to indicate the almost universal presence of polymyositis and the frequent occurrence of scleroderma in the patients who make antibodies to this antigen. The antigen is probably nucleolar since all sera which precipitate with the PM-Scl antigen stain the nucleoli of Hep2 cells by indirect immunofluorescence. The PM-Scl immune system is a distinctive one different from the other known precipitins that occur in patients with polymyositis and dermatomyositis including Jo1, nRNP, and Mi. This PM-Scl antigen and its antibody represent one system which constitutes part of the reactions previously designated as PM1. Interlaboratory exchange of sera and extracts have established the unique nature of this reaction which occurs in patients with inflammatory myopathy.

Antigen-Antibody Reactions↗
PubMed1978

The biochemistry of lymphocyte-derived mediators of immunological inflammation.

Evidence is presented to indicate that there exists in lymphoid tissue, as a result of transforming lymphocytes, a new lymphokine which is chemotactically specific for lymphocytes, called 'lymphotactin'. Lymphotactin has been purified to electrophoretic homogeneity; has a molecular weight of 10,500 D and an isoelectric point of 5.9. Its role in amplifying the immune defense system by recruitment of naive lymphocytes into propinquity with the challenging antigens is suggested. Purification of macrophage migration inhibitory factor from thymus extracts to electrophoretic homogeneity leads to a compound of molecular weight of 36,500 D and an IEP of 6.9. Chemically it contains sialic acid and o-methyl glucopyranoside as its only carbohydrates. Purified MIF activates the macrophage phagocytically. Skin reactive factor and lymph node permeability factor have been isolated and purified and are found to be inhibited by pepstatin and antihistamine and to have an isoelectric point of pH 4.2 and a molecular weight of 50,000--100,000 D. It is believed that this anionic permeability increasing agent actually arises from the lysosomes of macrophages and lymphoblasts (the normal small lymphocyte having essentially no lysosomal organelles). The mononuclear cell infiltration characteristic of crude SRF and LNPF may proceed from their being contaminated with lymphotactin.

Animals↗