One-off streptococcal serologic testing in young children with recurrent tonsillitis

OBJECTIVES

Recurrent acute tonsillitis in children under 4 years of age is usually viral, making antibiotic therapy inappropriate and the indication for tonsillectomy uncertain. Identifying those young children with bacterial infections is therefore important. The purpose of this study was to determine whether one-off streptococcal serologic testing is a useful tool in assessing recurrent acute tonsillitis in young children.

METHODS

We performed a retrospective study of 45 children (35 male and 10 female) under the age of 4 years who were found by a staff otolaryngologist to have recurrent acute tonsillitis over a 5-year period and had one-off serologic testing for anti-streptolysin O titers and anti-deoxyribonuclease B levels. Data were collected by chart review.

RESULTS

Three children (6.7%) had clearly positive titers for either one or both streptococcal antibodies. Children with negative serologic results were significantly less likely to have shown a significant response to antibiotic therapy for their acute episodes (26% versus 100%; p = .026). Nine children (20%) eventually underwent tonsillectomy, all of whom had negative serologic results.

CONCLUSIONS

Anti-streptolysin O and anti-deoxyribonuclease B levels may aid clinical evaluation of recurrent acute tonsillitis in young children in differentiating between those cases due to group A beta-hemolytic Streptococcus and those that are viral in origin.

Anti-DNA antibody derived from a systemic lupus erythematosus (SLE) patient forms histone-DNA-anti-DNA complexes that bind to rat glomeruli in vivo

Histone can mediate the binding of both free DNA and DNA complexed to anti-DNA antibody to the glomerular capillary wall. We tested whether performed histone-DNA-anti-DNA immune complexes (IC) could bind to the glomerular capillary wall. The immune complex, generated with anti-DNA antibody derived from an SLE patient and excess of 125I-DNA followed by digestion with DNase, was mixed with histones. The complex containing 4 micrograms DNA was injected via the aorta into the left kidney of rats. At 15 min, 1-3% of the histone-DNA-anti-DNA antibody complex bound (measured as 125I-DNA), when histone was omitted less than 0-1% of the DNA-anti-DNA antibody complex bound. By immunofluorescence human immunoglobulins and histones, representing the IC, could be observed in a capillary pattern; but no complement deposition was detected. Electron microscopy revealed discrete, electron dense deposits in a subendothelial, subepithelial and mesangial localization at 15 min. These results provide direct evidence that antibodies from serum of SLE patients can form soluble histone-DNA-anti-DNA immune complexes that bind to the glomerular capillary wall in vivo.

Specificities and genetic characteristics of nucleosome-reactive antibodies from autoimmune mice

Antinuclear antibodies are present in the serum of individuals with systemic autoimmune diseases such as SLE. Most autoantibodies characterized to date are directed against isolated nuclear molecules such as DNA or histones. We have obtained from spontaneously autoimmune mice six IgG mAb that recognize conformational nucleosome epitopes, but do not react with individual histones or DNA. For three of these mAb, the epitope is at least partially present in the H2A-H2B-DNA nucleosome subparticle, although their binding characteristics differ from those of conventional anti-H2A-H2B-DNA antibodies. All six mAb use VH or Vkappa genes which are recurrently utilized in anti-DNA and other antinuclear antibodies. The V regions of the nucleosome-reactive mAb also contain charged (mostly cationic) residues at sites that are likely to be critical for interaction with nucleosomal antigens. These results suggest that the usage of certain V gene segments in conjunction with suitable V(D)J rearrangements may confer reactivity to nucleosomal antigens. B cells producing such autoantibodies are probably expanded early during the autoimmune process. Somatic mutations in the V regions of nucleosome-reactive mAb may modulate their specificities and result in the acquisition of binding patterns restricted to individual chromatin components such as DNA.

Antigen-specific induction of antibodies against native mammalian DNA in nonautoimmune mice

Spontaneous anti-DNA antibodies in autoimmune mice have the characteristics of antibody produced by Ag-specific, clonally selective B cell stimulation. The nature of the somatically derived antibody V region structures recurrent among spontaneous anti-DNA antibodies suggests that DNA or DNA-protein complexes may provide the antigenic stimulus for autoimmune anti-DNA antibody. In order to test this hypothesis directly, we have immunized normal, nonautoimmune-predisposed mice with complexes formed with DNA and an immunogenic, DNA-binding peptide. The highly immunogenic peptide, Fus1, forms an internal domain of a 128-amino acid ubiquitin-fusion protein from Trypanosoma cruzi. DNA-Fus1 complexes formed with native calf thymus DNA induced anti-DNA antibody in normal, nonautoimmune-predisposed mice that is similar in isotype and specificity to spontaneous anti-DNA antibody in (NZB x NZW)F1 autoimmune mice. The progressive nature of the development of dsDNA specificity in the immunized mice was also analogous to what is observed in the spontaneous anti-DNA antibody response of autoimmune (NZB X NZW)F1 mice. DNA-Fus1 immunized mice that produced IgG that bound to dsDNA had low to moderate levels of proteinuria and glomerular deposits of IgG. This experimental immunization system may be useful for understanding the immunologic basis for autoimmunity to DNA.

[Antibodies against deoxyribonucleoproteins in circulating immune complexes in the blood of patients with autoimmune diseases]

In 40 patients with various autoimmune diseases antibodies against desoxyribonucleoprotein (DNP) were assessed by enzyme immunoanalysis (ELISA) in serum and after dissociation of the isolated precipitate of circulating immune complexes (CIC) in the presence of polyethylene glycol. The results indicate that antibodies against DNP are not specific for systemic lupus erythematosus (SLE) and can be detected in serum and in particular in CIC in various autoimmune conditions. In SLE they may be important for evaluation of the activity of the disease, in particular if estimated concurrently in serum and in CIC.

Immunogenic DNA-related factors. Nucleosomes spontaneously released from normal murine lymphoid cells stimulate proliferation and immunoglobulin synthesis of normal mouse lymphocytes

The cell-free supernatants of normal spleen and thymus lymphocytes in short-term culture release low molecular weight (LMW) DNA protein molecules that have an immunoproliferative effect (polyclonal B cell activation) in vitro. We have determined that the protein-LMW DNA complexes responsible for these effects are nucleosomal constituents of chromatin, since the mitogenically active fractions of these cell-free supernatants contain the constituents of core histones (H3, H2A, H2B, H4) together with LMW DNA (140-180 bp), and since the immunoproliferative effects of these cell-free supernatants could be mimicked by various other nucleoprotein preparations (including calf thymus and chicken erythrocyte nucleosomes). The spontaneous cellular release of cleaved chromatin constituents in vitro can be attributed to a form of programmed cell death termed apoptosis, since the cultured spleen cells exhibited (a) morphologic evidence consistent with this process by electron microscopy, and (b) evidence of intracellular cleavage of chromatin which, like apoptosis, could be blocked with ZnSO4. This resulted in inhibition of the extracellular release of nucleosomal constituents as well as the immunoproliferative effects of the cell-free supernatants. The immunoproliferative effect of nucleosomes released from cells during apoptosis could be responsible for previously observed spontaneous in vitro anti-DNA and anti-histone antibody responses of murine spleen cells, and in vivo in normal lymphoid tissues, resulting in renewed cellular proliferation after cell death. In pathological states, this could result in abnormal polyclonal B cell proliferation and autoantibody formation.

Lupus erythematosus cell formation by a monoclonal antibody derived from an autoimmune MRL/Mp-lpr/lpr mouse

An MRP-2 monoclonal antibody (MoAb) was primarily a product of hybridoma selected by binding to poly(ADP-ribose) from a lupus prone MRL/Mp-lpr/lpr (MRL/l) mouse, and was shown to cross-react with single-stranded (ss) DNA. Detailed examination revealed that MRP-2 MoAb bound to a conformational epitope formed between double-stranded (ds) DNA and total histone: both H3 and H4 were essential for the formation of this conformational epitope with dsDNA. Because of this characteristic of the MoAb, its ability to induce lupus erythematosus (LE) cells was examined in an indirect LE test with peripheral blood of MRL/Mp-+/+ (MRL/n) mice, which develop a mild form of lupus after the age of one year. MRP-2 MoAb was found to induce hematoxylin bodies, LE rosettes and LE cells, but a direct LE test using MRL/n mouse blood did not induce LE cell phenomena. This is the first demonstration of induction of LE cells by a MoAb that binds to dsDNA-histone complexes.

Characterization of antinuclear antibodies induced in rabbits by rinderpest virus infection

Rabbits infected with the L strain of rinderpest virus (RV) produced high titres of antinuclear antibodies (ANA) which reached a maximum two weeks after inoculation but rapidly disappeared by 6-8 weeks. These ANAs reacted with HeLa cells by indirect immunofluorescence test resulting in a homogeneous nuclear fluorescence. In order to investigate the target antigens of ANAs, the effects on the nuclear fluorescence pattern of pretreating HeLa cells were examined: DNase 1 treatment resulted in a decrease in the fluorescence whereas no changes were evident after RNase A treatment. Some group of sera showed decreased fluorescence in the cells from which histones were acid extracted, but other groups did not change in fluorescence. Sera which had failed to react with acid extracted cells gave positive fluorescence following histone reconstitution. The results indicate that DNA and nucleohistone are the major target antigens for ANAs. In addition, antibodies against nucleoli and extractable nuclear antigens were induced in some rabbits.

Nuclear acceptor sites for sex steroid hormone receptors in chromatin

The steroid receptor interactions in vitro with specific acceptor sites composed of acceptor protein-DNA complexes fulfill many of the criteria of a physiologically significant binding system. Chromatin acceptor sites for many steroid receptors (especially for the progesterone and estrogen receptor) are specific since they are saturable and competitive with unlabelled receptors, have high affinity for the receptor, distinguish between functional and nonfunctional receptors and demonstrate target tissue specificity. Pure DNA as acceptor sites does not display many of these properties. Therefore, it is clear that certain chromatin proteins provide the necessary specificity for the acceptor sites for the steroid receptors. For the progesterone receptor in the chick oviduct, these nuclear sites appear to contain specific chromosomal proteins as well as specific DNA sequences. The substitution of other chromosomal proteins or the genomic DNAs from evolutionarily distant organisms results in a loss of the specific nuclear binding. The nuclear acceptor sites appear to be resistant to the DNase activity which is not characteristic of transcriptionally active domains of the genome. Further studies using the ovalbumin gene sequences from genomic clones also indicate that none of the sequences within this domain and the 3-k flanking regions appear to contain the specific acceptor sequences. These observations have led to development of a model suggesting that the steroid receptors bind to acceptor sites distant from the structural genes the steroids ultimately regulate. Neighboring these acceptor sites are regulatory genes which code for regulatory substances which in turn (as secondary messengers) regulate at great distances the expression of the structural gene. This model might better fit the sex steroids which require 1-2 h to measurably alter gene transcription, as opposed to the glucocorticoids which more rapidly alter gene expression.

Characterization and antigenic specificity of chlorpromazine-induced antinuclear antibodies

Prolonged treatment with chlorpromazine is often associated with the development of antinuclear antibodies, an immunoglobulin M lupus anticoagulant, and polyclonal serum IgM elevation, but not with clinical features of systemic lupus erythematosus (SLE). Sera from 62 long-term psychiatric patients given treatment daily with 100 mg or more of chlorpromazine for at least 1 year were screened for antinuclear antibodies by indirect immunoperoxidase assay using HEp-2 cells. In 26 samples, antinuclear antibody titers greater than or equal to 1:40 with a homogeneous pattern were seen when anti-human IgM was used as the second antibody, three sera samples reacted with IgG, and four samples reacted with both IgG and IgM antisera. The antinuclear antibody antigenic reactivity was investigated by using histone and nonhistone nuclear antigens by enzyme-linked immunosorbent assay and passive hemagglutination techniques. Forty serum samples reacted with histone. Twenty-five samples reacted with deoxyribonucleoprotein (DNP), 28 with single-stranded DNA, and two with double-stranded DNA. No reaction was obtained with the extractable nuclear antigens RNP or Sm. These results indicate that chlorpromazine-induced antinuclear antibodies, like the antinuclear antibodies induced by hydralazine and procainamide, react mainly with histone nuclear antigens. Unlike the hydralazine and procainamide response, in which both IgG and IgM antibodies are demonstrated, the chlorpromazine-induced autoantibodies are predominantly of the IgM class.

Autoantibodies and their relation to rheumatic diseases

The use of tissue culture substrates for immunofluorescence determinations of nuclear, cytoplasmic, and mitotic cell-related autoantibodies has resulted in the delineation of diverse new specificities, whose clinical correlates are now becoming apparent. This review details both major and minor autoantibody specificities, the status of knowledge regarding their target antigens, and the relation of these serologic systems to distinctive rheumatic disease syndromes.

Antinuclear antibodies as indicators for the procainamide-induced systemic lupus erythematosus-like syndrome and its clinical presentations

Fifty patients on a regimen of procainamide were studied in regard to the association between antinuclear antibodies (ANA) and the development of drug-induced systemic lupus erythematosus (SLE)-like syndrome. Four groups were identified: Group 1 was ANA-positive, with clinical manifestations (serologic and clinical findings); Group 2 was ANA-positive, without clinical manifestations (serologic findings only); Group 3 was ANA negative (no patients with clinical manifestations); and Group 4 had SLE persisting after discontinuance of procainamide. The leukocyte-specific ANA (LSANA) patterns were predominant, with peripheral LSANA confined to Groups 1 and 4. Furthermore, the titer of the homogeneous LSANA, to which peripheral LSANA converts on dilution, was clinically significant. A homogeneous LSANA titer of 160 or greater was seen essentially only in patients with clinical manifestations of the SLE-like syndrome. Serial ANA determinations are therefore necessary to monitor patients receiving procainamide.

[Physiological significance of specific immunoglobulins in regulating steroidogenesis in adrenal cortex cells]

The data obtained suggest the existence of physiological immunoglobulin mechanisms regulating the functions of the cells including hormone--producing ones. Serologically identical antigens were revealed both in the blood and the extracts from adrenocortical cell nuclei of intact rats. Apart from that, autoantibodies to deoxyribonucleoprotein (DNP) of adrenocortical cells were found in the blood sera of normal animals. Immunoglobulins G (ig G) against adrenocortical cell nuclei, DNP and the nuclei partially devoid of DNP, were produced. The specific IgG were shown to stimulate the steroidogenesis in target cells. The penetration of the specific antibodies into the target cell nuclei in vivo was proved. The data obtained support the hypothesis of the nuclear mechanisms of antibody--caused cytostimulation.

Effect of selective ultraviolet phototherapy on DNA and antinuclear antibody titers in psoriatic patients

The sera of 21 psoriatics treated by selective ultraviolet phototherapy (SUP) for 1-7 months were screened for IgG- and IgM-anti-DNA antibodies and antinuclear antibodies (ANAs) by standardized ELISA and the indirect immunofluorescence technique. No patients developed IgG-antibodies against native DNA under SUP, but two patients increased their IgM-antibody titers five- and tenfold, respectively. The IgG- and IgM-anti-single-stranded-(ss)DNA antibody titers remained unaltered in 38% and 57% of the patients. In 43% and 24%, respectively, they rose to a maximum of three times their original; and in 20% they decreased to a minimum of 40% of their pretherapeutic titers. After 1 month therapy no patient had produced ANAs, but all three patients showing ANAs before therapy had increased titers (one titer step). These remained on the elevated level or were even further increased by one-titer step during progressive therapy. Two patients out of 14 developed low titers of IgM-(1:20) or IgA-(1:40)ANAs against deoxyribonucleoprotein (DNP), initially after 3 months of irradiation; in one of them IgG-ANAs (titer 1:10) against DNP were additionally formed after 6 months of therapy. Our results suggest that lesions in DNA and DNP generated by SUP trigger an immune response to nuclear antigens.

Immunospecificity of nonhistone chromatin proteins tightly bound to DNA from chicken thrombocytes and erythrocytes

Erythroid cell-specific antisera capable of detecting tightly bound nonhistone chromatin protein--DNA complexes were obtained by injecting rabbits with dehistonized chicken reticulocyte chromatin. The antisera showed no crossreactivity with chromatin of thrombocytes which are regarded as cells genealogically closely related with erythrocytes. The lack of thrombocyte chromatin immunoactivity was not caused by conformational constrains. Tightly bound nonhistone protein--DNA complexes isolated from thrombocyte chromatin showed no immunological similarity with these of erythrocyte chromatin.

Anti-DNA, anti-deoxyribonucleoprotein and rheumatoid factor measured by ELISA in patients with systemic lupus erythematosus, Sjögren's syndrome and rheumatoid arthritis

Serum concentrations of anti-DNA and anti-deoxyribonucleoprotein (NP) antibodies were measured in parallel by standardized ELISA methods with a polyvalent anti-immunoglobulin conjugate in patients with systemic lupus erythematosus (SLE), Sjögren's syndrome (SS) and rheumatoid arthritis (RA). High levels of these antibodies predominated in systemic lupus erythematosus. While an appreciable incidence of antibodies also occurred in SS and RA, they were mostly at lower levels. By using heavy chain-specific anti-immunoglobulin conjugates, IgG antibodies to both DNA and NP were found in SLE more frequently and at higher levels than were IgM antibodies. In contrast, IgM antibodies to DNA and NP predominated in SS and RA. The immunoglobulin class of the anti-DNA and anti-NP responses in a given SLE patient were not infrequently different. For example, a patient might show a very high IgG but low IgM anti-DNA value, with the reverse being true for anti-NP. IgG anti-DNA antibodies were significantly associated with depressions of C3. During changes in SLE serology, normalization of DNA binding by Farr radioimmunoassay and/or complement was most frequently associated with normalization of the IgG anti-DNA antibody concentrations. In patients simultaneously possessing elevated levels of anti-DNA, anti-NP and rheumatoid factor (RF), absorption with aggregated human IgG usually decreased only the RF activity. In some, however, such absorption decreased all three antibody values simultaneously. The latter findings support observations that some RF possess antinuclear properties.

Relationship between immune response to hydralazine and to deoxyribonuclease in patients receiving hydralazine

In a prospective study of 21 hypertensive patients receiving hydralazine for 1 year, we found a close relationship between development of antibodies to deoxyribonucleoprotein (DNP) and to hydralazine but no evidence for cross-reactivity between antibodies to these two antigens. Of 8 patients who developed increased levels of antiDNP, 7 also developed antibodies to hydralazine. Inhibition of the reaction between DNP and antiDNP as measured by radioimmunoassay in 3 patients with hydralazine lupus could not be achieved with large amounts of hydralazine. However, antibodies to DNP produced in guinea pigs immunized with hydralazine conjugates could be inhibited with hydralazine in accordance with previous studies by others on rabbits. In the human, antibodies to DNP which develop during hydralazine administration are not due to cross-reactive antibodies nor do they appear as a result of immune response to an in vivo hydralazine DNP conjugate.

Studies on autoantibodies to deoxyribonucleic acid and deoxyribonucleoprotein with enzyme-immunoassay (ELISA)

Simple, rapid, quantitative, and reproducible ELISA procedures were developed for the determination of antibodies to DNA and NP in human sera. The results are reported in International Units per milliliter, based on the WHO reference preparation of anti-nuclear factor serum. The results of both tests are significantly correlated with anti-dsDNA values obtained by an RIA (Farr technic) and by the Crithidia luciliae IF assay. The anti-DNA and anti-NP ELISA test results were more frequently positive in SLE sera than were screening tests for anti-dsDNA by the Crithidia procedure or anti-NP detection by a latex agglutination test. Parallel tests in 284 sera from patients for anti-DNA and anti-NP by ELISA showed a significant correlation between the two antibody values. However, 17% of the specimens were positive for antibodies to one antigen but not the other, whereas other specimens showed a strong predominance of one antibody over the other. Absorption studies confirmed the differing antibody specificities measured by the two assays. The ELISA anti-DNA results were inhibited by native DNA, NP, and denatured DNA in increasing order of efficiency. In contrast, the antibodies against NP were strongly inhibited by NP but only very slightly by dsDNA or denatured DNA. Other antigens, including histones, ribonucleic acid, extractable nuclear antigens, and aggregated human IgG, inhibited only slightly or not at all in either assay.

Chromatin subunits elicit species-specific antibodies against nucleoprotein antigenic determinants

Nucleosomes composed of 195 base pairs of DNA associated with histones H2A, H2B, H3, and H4 purified from chicken erythrocyte nuclei were used to elicit antibodies in rabbits. Specific serological reaction between the antisera and the nucleosomes is demonstrated by immunodiffusion, immunofluorescence, microcomplement fixation, solid-phase radioimmunoassay, immunosedimentation, and polyacrylamide gel electrophoresis of 5'-32P end-labeled nucleosomes. The antisera did not react with DNA extracted from these nucleosomes, core histones, or the cross-linked histone octamer from chicken erythocytes, calf thymus total histones, or chromosomal proteins HMG-1 or HMG-17. Nucleosome antigenicity was not affected by redigestion with micrococcal nuclease. Digestion with DNase I brought about 50% loss of reactivity while digestion with trypsin or proteinase K resulted in total loss of activity. The antisera reacted strongly with trimer, dimer, and monomer nucleosomes as well as with the core particle (145 base pairs of DNA) and subnucleosome (greater than 145 base pairs) obtained from chicken. It reacted less well with nucleosomes obtained from HeLa cells and was almost totally devoid of activity against chromatin particles obtained from rat liver or wheat germ. Experiments employing the technique of transferring proteins from a polyacrylamide gel to diazobenzyloxymethyl paper and visualization of antigens by autoradiography excluded the possibility that the serum contains antibodies against tissue-specific antigens which are found in small amounts but are very immunogenic. It is concluded that most of the anitbodies in the sera are directed against nucleoprotein antigenic determinants composed of the N-terminal portion of the histones and segments of DNA. Antibody binding is dependent on contact between the histone and DNA segments and is independent of the integrity of the entire nucleosome. Thus, certain histone DNA contacts remain intact even though the structure of the nucleosome has been disrupted.

Prospective study of immune response to hydralazine and development of antideoxyribonucleoprotein in patients receiving hydralazine

To examine the relationship between the immune responses to hydralazine, a drug known to induce systemic lupus erythematosus, and to deoxyribonucleoprotein (DNP) we followed prospectively 21 hypertensive patients treated with hydralazine for the first time. Within one year, antibodies to hydralazine developed in 16 of these patients and anti-DNP in seven of these. In one patient whose serum had a positive antinuclear antibody test prior to treatment, a mild hydralazine systemic lupus erythematosus syndrome developed preceded by rises in the levels of both anti-hydralazine and anti-DNP. Studies by radioimmunoassay on serums of three additional patients, not followed in this study but known to have hydralazine-induced systemic lupus erythematosus, revealed no evidence for either (1) cross-reactivity between anti-DNP and anti-hydralazine or (2) antibodies specific for a hydralazine-DNP complex. In some way, perhaps related to the mechanism by which carrier molecules enhance the immunogenuity of haptens, hydralazine increases the antigenicity of DNP. This effect depends on the development of immunity to hydralazine as well.

Evidence for a subset of rheumatoid factors that cross-react with DNA-histone and have a distinct cross-idiotype

Cross-reactivity of a monoclonal rheumatoid factor with an antigen present on IgG and DNA-nucleoprotein was demonstrated, and evidence presented that the combining site of the antibody was involved in the reaction. The antigen on the DNA-nucleoprotein was shown to involve both DNA and histone fraction H2A + H2B and was trypsin sensitive. The relative binding affinity of the antibody appeared to be greater for IgG than the DNA-histone antigen. Similar polyclonal cross-reactive rheumatoid factors were found in a variety of diseases. A high incidence was found among patients with rheumatoid arthritis and mixed connective tissue disease. None were detected in patients with systemic lupus erythematosus and idiopathic cryoglobulinemia. Studies on one representative isolated polyclonal rheumatoid factor demonstrated the same reactivity with DNA-histone H2A + H2B as the monoclonal antibody. Cross-idiotype studies using antigen-binding inhibition methods demonstrated the same cross-idiotype on the polyclonal and the monoclonal rheumatoid factor which reacted with DNA-histone. This cross-idiotype was shown to be distinct from the cross-idiotypes previously demonstrated on monoclonal IgM proteins with anti-gamma-globulin activity.

Cell-specific antigens in chicken erythroid nuclei: species specificity

Antisera raised to dehistonized chicken reticulocyte chromatin were tested for their cell and species specificity. Quantitative microcomplement fixation and immunohistochemical localization revealed the presence in chromatin of erythroid cell-specific nonhistone protein antigen(s). The antigenic specificity was shown to depend on the association of the antigenic protein(s) with deoxyribonucleic acid (DNA). Although the antisera were exceptionally cell specific, they cross-reacted with erythroid cells of other avian species. The extent of cross-reactivity was found to approximate the phylogenetic distances of the tested avian species. Erythroid cells from fish and amphibians were not reactive. Reconstitution experiments of partially purified chicken reticulocyte chromosomal nonhistone protein antigens with DNAs isolated from several vertebrate species showed that the species specificity of the antigenic complexes is determined principally by the species origin of the nonhistone proteins. Our results show that a cell-specific chromosomal nonhistone protein(s) has undergone evolutionary change and the relative immunological differences are consistent with the accepted phylogenetic distances of the species examined.

Recent progress in the study of autoantibodies to nuclear antigens

Autoantibodies to nuclear antigens can now be classified according to their immunologic specificities. They include antibodies that react with DNA, deoxyribonucleoprotein, nuclear histones, and nuclear acidic protein antigens. It has been established that there are several antinuclear antibodies that react with nuclear acidic proteins, and these include antibodies to Sm antigen, nuclear ribonucleoprotein, and SS-A and SS-B antigens. It has also been established that certain systemic rheumatic diseases, such as systemic lupus erythematosus, Sjögren's syndrome, and scleroderma, are characterized by antibodies of some specificities and not of others. Thus, distinct profiles of antibodies to nuclear antigens may be present, and these may be used as diagnostic aids. Further characterization of these specific nuclear antigen-antibody systems may help in unraveling the etiology and pathogenetic mechanims of these diseases.

Lupus erythematosus latex tests compared with the immunofluorescence method for antinuclear factor

Two commercially available lupus erythematosus (LE) latex tests were compared against positive antinuclear antibody (ANF) sera of known titers. The Lederle SLE Latex Test Kit was found to be more specific and relatively more sensitive, particulary with high ANF titers, than the Hyland LE Test Kit. The latex test is a rapid, simple method which, when positive, can be suggestive of systemic lupus erythematosus (SLE) or other collagen disease. However, at present this test cannot replace the immunofluorescence method for detecting ANF. Where there is any clinical suggestion of SLE or a related condition, all negative results should be tested by immunofluorescence methods.

Tissue-specific chromosomal non-histone protein interactions with DNA

A group of chromosomal non-histone proteins with affinity for DNA (NP) was isolated from rat liver and Novikoff hepatoma. This fraction, which represents less than 5% of the total chromatin protein content, binds preferentially to unique, double-stranded sequences of fractionated homologous DNA. The interactions are strong at low ionic strength (Km = 6.7 X 10(-9) M) and decrease with rising salt concentration. Complexes of the NP protein fraction with homologous DNA are immunologically tissue-specific. As determined by microcomplement fixation, the NP proteins in Novikoff hepatoma are associated with the transcriptionally active, diffuse fraction of chromatin.

A serum protein associated with chromatin of cultured fibroblasts

Antibodies to chromatin proteins from human and mouse fibroblasts which have been cultured for more than 25 generations with heterologous serum show specificity for a homologous alpha-serum protein. These results indicate that among the chromatin-associated proteins there is one (or more) which has extensive structural similarity to a serum protein. This is the first direct evidence that a serumlike protein or proteins could be chromatin associated in vivo, as has been suggested by experiments showing in vitro interaction between DNA and certain serum proteins.

Profiles of antinuclear antibodies in systemic rheumatic diseases

The prevalence of different antinuclear antibodies was examined in systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, progressive systemic sclerosis, dermatomyositis, discoid lupus erythematosus, and mixed connective tissue disease. Antibody to Sm antigen (a nuclear acidic protein) was found almost exclusively in serums of patients with systemic lupus erythematosus, suggesting that this antibody might be a "marker" antibody for this disease. However, antibodies to native DNA and to nuclear ribonucleoprotein were found in a variety of systemic rheumatic diseases. In systemic lupus erythematosus, antibody to native DNA was present in high titer but in other rheumatic diseases in low titer. Antibody to nuclear ribonucleoprotein occurred in certain other systemic rheumatic diseases besides the mixed connective tissue disease syndrome. These studies showed that there were distinct profiles of antinuclear antibodies in certain systemic rheumatic diseases, characterized by the presence or absence of certain antibodies and by differences in their mean titers.