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Biomedical subjects

G Dighiero

Publications and source records attributed to G Dighiero.

At least 109 records · Page 6Linked to original sources
PubMed1990

Sera with high levels of anti-smooth muscle and anti-mitochondrial antibodies frequently bind to cytoskeleton proteins.

Using ELISA methods, 54 sera from chronic active hepatitis (CAH) patients displaying high levels of anti-smooth muscle antibodies (SMA) and 18 sera from primary biliary cirrhosis (PBC) patients with high levels of anti-M2 antibodies were examined for the presence of high antibody levels against actin, tubulin, myosin, tropomyosin, troponin, vimentin and desmin. Our results showed that: (i) in CAH with high SMA activity, increased antibody levels were found in 51.9% of sera for actin, 31.5% for myosin, 35.2% for tubulin, 34.0% for tropomyosin, 11.3% for troponin, 22.6% for vimentin and 43.4% for desmin, compared with natural antibody levels in 21 normal sera; (ii) Similar high levels of these antibodies were found in the case of PBC; (iii) in most cases, sera simultaneously bound to several antigens of the panel; and (iv) approximately 26% of the CAH sera were found to be negative with the seven antigens examined while 22% were reacted with a cytoskeleton protein (CP) other than actin. These results indicate that current opinion associating SMA with anti-actin activity in CAH is confirmed for only 50% of cases and that although a good correlation between SMA and anti-CP antibodies can be obtained, there is still a significant percentage of SMA for which the putative antigen recognized needs to be determined.

Animals↗
PubMed1990

Major Trypanosoma cruzi antigenic determinant in Chagas' heart disease shares homology with the systemic lupus erythematosus ribosomal P protein epitope.

A Trypanosoma cruzi lambda gt11 cDNA clone, JL5, expressed a recombinant protein which was found to react predominantly with chronic Chagas' heart disease sera. The cloned 35-residue-long peptide was identified as the carboxyl-terminal portion of a T. cruzi ribosomal P protein. The JL5 13 carboxyl-terminal residues shared a high degree of homology with the systemic lupus erythematosus (SLE) ribosomal P protein epitope. Synthetic peptides comprising the 13 (R-13), 10 (R-10), and 7 (R-7) carboxyl-terminal residues of the JL5 protein were used to study, by enzyme-linked immunosorbent assay, the specificity of the Chagas' disease anti-JL5 and SLE anti-P antibodies. The R-13 peptide defined a linear antigenic determinant of the JL5 recombinant protein. As was proved for JL5, R-13 defined antibody specificities which were significantly increased in chronic Chagas' heart disease patients. Only SLE anti-P positive sera were found to react with JL5 and R-13. Fine epitope mapping showed that Chagas' disease anti-JL5 and SLE anti-P antibodies define similar epitopes within the R-13 peptide. The binding of the SLE sera to JL5 was completely blocked by the R-13 peptide, indicating that the shared specificity between anti-JL5 and anti-P autoantibodies was exclusively limited to the conserved linear epitope(s) within the R-13 peptide. The prevalence of high anti-R-13 antibody titers in Chagas' heart disease patients supports the hypothesis that postulates the existence of autoimmune disorders in Chagas' heart disease.

Amino Acid Sequence↗
PubMed1990

Evidence that the B lymphocyte proliferating in B-CLL and in other B-cell malignancies is frequently committed to production of natural autoantibodies.

Autoreactive B-cells constitute a substantial part of B-cell repertoire. They frequently secrete polyspecific natural autoantibodies which are the expression of germinal genes. During recent years, considerable evidence has accumulated indicating that autoreactive B-cells frequently undergo malignant transformation. This evidence arose from the study of monoclonal immunoglobulins (MIgs) and from recent studies of chronic lymphocytic leukemia (CLL) and non Hodgkin lymphoma (NHL) B lymphocytes. The present review, includes two sections. The first one reviews evidence supporting the idea that autoreactive B-cells constitute a substantial part of autoreactive B-cell repertoire. The second one is devoted to review evidence favouring the view that this autoreactive B-cell repertoire is frequently involved in B-cell malignancies.

Antibodies, Monoclonal↗
PubMed1989

Antinuclear and related autoantibodies in sera of healthy subjects with IgA deficiency.

The sera of 49 healthy IgA-deficient (SIgAD) subjects were evaluated for the presence of autoantibodies directed against 10 different nuclear and cytoskeletal antigens, as well as for the presence of the common lupus anti-DNA idiotype (16/6 Id). Twenty-nine sera were from IgG subclass-deficient subjects (4 = IgG2, 25 = IgG3), and 25 from normal healthy subjects, used as controls. The incidence of antinuclear but not anti-cytoskeletal antibodies were found to be significantly greater in the SIgAD group, as compared to the IgG-deficient subjects and the normal controls. Overall, 39% of SIgAD sera demonstrated polyreactivity, namely reactivity against more than one nuclear antigen. The incidence of specific antibody detection ranged from 37% against cardiolipin to 12% against RNP in the IgA-deficient group, albeit not with statistical significance in all cases when compared to the control group. Isotype evaluation of the antinuclear and related antibodies in the SIgAD group showed a greater tendency towards IgG. This increased incidence of autoantibody production in SIgAD may preceed the development of an overt autoimmune disease in the future.

Agammaglobulinemia↗
PubMed1988

Antitubulin antibodies. II. Natural autoantibodies and induced antibodies recognize different epitopes on the tubulin molecule.

Natural and induced antitubulin antibodies were compared for their epitope recognition on alpha- and beta-tubulin subunits by immunoenzymatic assays and Western blot techniques on partially digested tubulin molecules. Our results indicated that natural autoantibodies recognized different epitopes from those recognized by induced antibodies, because: 1) all polyspecific natural autoantibodies tested so far recognized the same or very overlapping epitopes in the central part of both alpha- and beta-subunits (between positions 100 and 300 on the tubulin amino acid sequence) and that this epitope differed from the various epitopes recognized by induced antitubulin antibodies on the amino-terminal or carboxy-terminal parts of the tubulin subunits; 2) one human myeloma protein (monoclonal (m)IgA, kappa) with a monospecific antitubulin activity bound to an epitope around position 310 on both alpha- and beta-subunits and a second human mIg (mIgM, kappa) with a monospecific anti-beta activity bound to an epitope on the carboxy-terminal part of the subunit around amino acid position 350. Both epitopes differed from epitopes recognized by induced antitubulin antibodies. These results thus confirmed our previous findings indicating that natural and induced antitubulin antibodies do not share cross-reactive idiotopes.

Animals↗
PubMed1988

Detection of private and recurrent idiotopes on natural anti-tubulin antibodies by monoclonal anti-idiotopic antibodies.

Two monoclonal anti-idiotopic antibodies (anti-Id) were raised in mice against a human monoclonal IgA,K displaying a monospecific anti-tubulin (anti-alpha- and anti-beta-tubulin) activity. One anti-Id (IgG,K) recognized a private idiotope, TID 3.2, present only on the IgA,K immunogen, close to or within the antigen-combining site. The other anti-Id (IgM,K) recognized a recurrent idiotope, TID 7.1, outside the paratope and present in normal human and BALB/c mouse serum, on 2 of 11 polyspecific human monoclonal immunoglobulins and on 6 of 11 murine natural monoclonal auto-antibodies exhibiting a widespread anticytoskeletal protein-binding activity. Both the idiotopes were absent on two induced anti-tubulin antibodies exhibiting a monospecific anti-alpha- and anti-beta-tubulin specificity. Utilizing competitive and additivity immunoassays, we could show that the polyspecific human and mouse anticytoskeletal antibodies tested, whether bearing the TID 7.1 Id or not, appeared to compete in variable degrees for epitopes on the tubulin molecule recognized by the monoclonal IgA,K but distinct from the epitopes recognized by the induced monospecific anti-tubulin antibodies. The high incidence of the recurrent TID 7.1 idiotope in man and mouse suggests an important physiologic and perhaps regulatory function of this idiotope. Furthermore our data suggest that a restricted family of germ-line genes, highly conserved during phylogeny, may encode for these idiotope-bearing Ig molecules.

Animals↗
PubMed1988

Comparative study of VH gene family usage by newborn xid and non-xid mice, newborn NZB and adult NZB mice, and by splenic and peritoneal cavity B cell compartments.

RNA from 170 different Ig-secreting hybridomas was hybridized with VH gene probes 7183, QUPC52, S107, J558, J606, 36-60, V31, X-24 and V-GAM 3.8, with the aim of comparing xid to non-xid mice, neonatal NZB to adult NZB, and the peritoneal cavity with the splenic compartments for VH gene family expression. Our results indicate that (a) defective F1 male xid mice express with high frequency 36-60 and J606 5' proximal VH families, when compared to non-xid F1 females of the same matings. (b) Neonatal NZB mice express 3' proximal 7183 and QUPC52 families with high frequency, when compared to adult mice and to the expected values derived from VH complexity. (c) Natural antibodies against cytoskeleton proteins, DNA, rabbit IgG and 2,4,6-trinitrophenyl did not appear to prefer a particular VH family. The only difference found is related to age; neonatal clones preferentially employ 7183 and QUPC52 while J558 predominates among adult clones. (d) All the 15 antibodies directed against bromelin-treated mouse red blood cells failed to hybridize with any of the nine VH probes employed. These results confirm previous findings indicating the highly homogeneous pattern of these latter antibodies, and suggest that they are encoded by a new VH family (VH11).

Animals↗
PubMed1988

Immunochemical studies of polyspecific natural autoantibodies: charge, lipid reactivity, Fab'2 fragments activity and complement fixation.

Polyspecific natural autoantibodies (NAAb) are antibodies present in normal unimmunized animals and are able to react with very dissimilar antigens (Ag). To better delineate the characteristics of polyspecificity, we subjected monoclonal NAAb to four different immunochemical studies: (1) Two-dimensional gel electrophoresis performed on eight NAAb did not reveal any obvious relationship between charge and antigen specificities; (2) NAAb widely polyspecific on proteins and nucleic acid were reactive with lipids bearing either phosphate, sulfate or carboxyl polar groups; (3) pepsin digestion of polyspecific IgM NAAb yielded Fab'2 fragments which maintained their multireactivities, but exhibited a decrease in reactivity as compared to that seen with monospecific mAb (induced); (4) two different assays were used to analyse the complement fixation ability of IgM NAAb. While very weak or no complement fixation was observed with a classical complement fixation test (fluid phase), when a complement enzyme immunoassay was used where Ag is immobilized on a solid phase, polyspecific NAAb fixed reproducible and easily detectable amounts of complement.

Animals↗
PubMed1988

Selective depletion of low-density CD8+, CD16+ lymphocytes during HIV infection.

Two color cytofluorometric analyses of CD3-, CD16+, Leu 19+ natural killer cells (NK) were assessed in HIV seropositive patients, high-risk seronegative homosexuals, and healthy heterosexuals. A selective depletion of lymphocytes bearing NK phenotypes was found among HIV-positive infected patients. When the CD16+ lymphocyte compartment was further dissected, lymphoid cells bearing simultaneously low cell-surface density CD8 and CD16 (Leu 11a or Leu 11c) or Leu 19 epitopes were selectively and significantly decreased. This important depletion of CD8+ NK cells, which in most cases are CD3-, accounts for the decline in low-density CD8+ lymphocytes in HIV positive group, while a significant increase occurs in their CTL pool. Furthermore, in HIV negative high-risk homosexuals, a less profound but significant reduction of this lymphocyte subset was also found. Whether the involvement of the NK compartment, especially NK cells expressing the CD8 marker, may influence the outcome of individuals infected with HIV is still an open question.

Antibodies, Monoclonal↗
PubMed1988

Comparative analysis of natural antibody specificities among hybridomas originating from spleen and peritoneal cavity of adult NZB and BALB/c mice.

A preliminary experiment showed that the supernatants of in vitro cultured peritoneal cells (rich in Ly-1 B cell subset shown to secrete most IgM autoantibodies against bromelain-treated mouse red blood cells (BrMRBC) and DNA) from different mouse strains did not contain any significant antibody activity against DNA and cytoskeleton proteins, although the presence of anti-BrMRBC antibodies was clearly evident. Therefore, we investigated comparative natural antibody (NAb) specificities against an antigen panel (DNA, cytoskeleton proteins, IgG, bovine serum albumin (BSA), BrMRBC, trinitrophenyl (TNP), and trimethylammonium (TMA) haptens) among Ig-secreting hybridoma collections from the splenic (158) and peritoneal (230) immune compartments of autoimmune New Zealand black (NZB) and lipopolysaccharide (LPS)-stimulated BALB/c mice. The data showed: (i) isotypic restriction (mu and gamma 3 only), predominance of TMA ion-reactive (including BrMRBC) but negligible anti-DNA-reactive antibody specificities, and lack of simultaneous polyspecific widespread reactivity (i.e. at least four or more antigens) against DNA and cytoskeleton proteins in the peritoneal cavity; (ii) predominance of simultaneous widespread polyspecific reactivity against DNA and cytoskeleton proteins but negligible or no TMA hapten-reactive antibody specificities in the spleen. These observations reflect certain differences in the B cell repertoire of peritoneal cavity (rich in Ly-1 B cells) compared with spleen. The NAb against BrMRBC and those reactive with DNA and cytoskeleton proteins, which have been suggested to be secreted by the Ly-1 B cell subset, are distinguishable on the basis of the presence of separate recurrent idiotypes and preferential localization of B lymphocytes directed against these autoantigens.

Animals↗
PubMed1988

Comparative analysis of CD4-4B4 and CD4-2H4 lymphocyte subpopulations in HIV negative homosexual, HIV seropositive and healthy subjects.

A comparative analysis of subsets (4B4 and 2H4) within the CD4 lymphocyte subpopulation was made by double marker analysis among 23 healthy heterosexual, 16 healthy HIV seronegative high-risk homosexuals and 82 HIV seropositive subjects. Data show that the significant increase in CD4 lymphocytes observed among seronegative homosexuals corresponds mainly to an increase in CD4-4B4 positive cells while CD4-2H4 subset levels remain comparable to healthy heterosexual controls. A decrease both in CD4-4B4 and CD4-2H4, parallel to a decrease in CD4 subpopulation, was observed in asymptomatic seropositive carriers (SPC) and patients with ARC syndrome (AIDS-related complex) or AIDS (acquired immunodeficiency syndrome). Interestingly, an absolute decrease in CD4 subpopulation in patients with asymptomatic lymph node enlargement (LAS), is chiefly accounted for by a decrease in CD4-4B4 subset. The values of CD4-2H4 subset are significantly higher than those observed for SPC patients and are close to the normal values. These observations are of interest, as no differences between SPC and LAS patients could be detected when CD3, CD4 and CD8 subpopulations were studied.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Do natural autoantibodies play an important role in the elimination of senescent or damaged red blood cells?

Natural autoantibodies (NAAbs) are an important constituent of circulating immunoglobins. Some demonstrate polyspecific reactivity and high idiotypic connectivity. For example, they are reactive with DNA and cytoskeleton protein; others exhibit restricted binding specificity. Among several hypotheses, we have explored the possibility that NAAbs constitute a physiologic system in the organism that participates in the elimination of dead tissues and cellular debris by opsonization and phagocytosis.

Autoantibodies↗
PubMed1988

An attempt to explain disordered immunity and hypogammaglobulinemia in B-CLL.

Most CLL cases correspond to proliferation of a B-cell clone characterized by: low amounts of surface Ig (SIg); presence of receptors for mouse red blood cells; expression of a 67 Kd antigenic determinant (CD5) initially described to be a pan-T cell antigen. These peculiar characteristics differentiate the CLL B lymphocyte from B lymphocytes proliferating in other B-cell malignancies. These so-called CD5 + B cells constitute a minority of B cells in adults, although they predominate during foetal life. This latter fact induced a majority of authors to assume that CLL B lymphocytes correspond to proliferation of an immature B-cell clone. However, this hypothesis does not explain the particular high frequency with which hypogammaglobulinemia and autoimmune phenomena directed against blood cell components are found in B-CLL, as well as the difficulty to include CD5 antigen in most differentiation pathways of B-cells. In this work, we shall discuss the available evidence coming from Ly 1-B cells (mouse counterpart of CD5 B cells), indicating that these cells correspond to a separate B lineage. We shall also discuss the evidence for hypogammaglobulinemia being mainly a B cell defect caused by dilution or inhibition of normal CD5 negative B cells and disordered autoimmunity as a consequence of a disturbance of the idiotypic network, which normally antagonizes autoimmune clones.

Agammaglobulinemia↗
PubMed1988

CD4, CD8 and NK subsets in B-CLL.

Although B-CLL is a hematological disorder characterized by clonal proliferation of B-cells, in most cases an increase in absolute numbers of T cells is observed. This increase is probably polyclonal in nature, since most data indicate that T lymphocytes are not progeny of the malignant clone in B-CLL. As CD4, CD8 and NK cells correspond to heterogeneous populations, in this work we tried to better define these subpopulations. Thus, CD4 subpopulations were displayed by using double labelling techniques into helper inducer subset (CD4+CDW29+) and suppressor inducer subset (CD4+CD45R+). CD8 subpopulations were delineated according to density expression of CD8 and reactivity with CD16 and CD11b in: suppressive cells defined by high density (HD) CD8 and reactivity with CD11b; NK cells defined by low density (LD) CD8 and binding to CD16; CTL cells by LD or HD CD8 and absence of expression of CD16 and CD11b. Our results concerning 47 normal control donors and 27 B-CLLs indicated that: although percentages of cells expressing CD3, CD4, CD8 and NK markers are decreased, absolute values of these subpopulations were increased; there exists an imbalance concerning CD4 and CD8, given by a more important increase of CD8 than CD4 subpopulations, but both are significantly augmented when compared to the normal range; within CD4 subpopulations, there is an important increase of CD4 CDW29 subset (helper inducer) whereas the CD4 CD45R (suppressor inducer) is not augmented in stage A patients and decreases in stage C patients; all the 3 identified CD8 subpopulations (NK, suppressors and CTLs) appeared to be increased; in 3 cases of clonal remission CLL studied, all T cell and NK subpopulations were recovering to normal percentages.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

High levels of anti-cytoskeleton autoantibodies are frequently associated with chronic GVHD.

Twenty-two patients (acute myeloid leukaemia 13, acute lymphoid leukaemia 5, chronic myeloid leukaemia 4) with an average age of 25 years (range 8-36 years), had received allogeneic bone marrow transplantation (BMT) from an HLA identical sibling. The BMT recipients were followed up for a period of 4-65 months. All patients were given cyclophosphamide, total body irradiation and methotrexate in order to prevent graft-versus-host disease (GvHD). Eleven of 22 patients exhibited chronic graft versus host disease (cGvHD) (extensive in five, limited in six at the time of the study) assessed by clinical and histological parameters. Serum samples were collected from these patients, before BMT (except in one case) and then every 2 or 3 months. Sequential studies to determine the presence of autoantibodies against cytoskeletal proteins (actin, tubulin, myosin), dsDNA and dDNA in these sera were performed by an ELISA method. Simultaneously, immunoelectrophoresis and measurement of complement fractions C3, C4 were performed on each sample. High levels of autoantibodies against cytoskeletal proteins were found in 10/11 patients with cGvHD and were absent in 11/11 patients without cGvHD; none of them exhibited anti-DNA activity. At the same time, C4 levels were decreased in seven of these patients with cGvHD. Monoclonal immunoglobulins IgG and IgM (2-15 g/l) were found in 8/11, but the antibody activity was never found to be located within the M component. These results show a direct relationship between the presence of these autoantibodies and occurrence of cGvHD and indicate that they may constitute an immunological marker related to this complication. However, their predictive value is not clearly evident in this retrospective series as in some patients they preceded clinical signs of cGvHD, whereas in others they were associated with the onset of cGvHD.

Adolescent↗
PubMed1987

Does the CLL B lymphocyte correspond to expansion of an immature B clone or to expansion of a distinct subpopulation of B cells?

Most CLL cases correspond to proliferation of a B-cell clone characterized by (1) low amounts of SmIg, (2) the presence of receptors for mouse red blood cells, (3) the presence of a 67-kd antigenic determinant recognized by CD5 monoclonal antibodies, also present in normal T cells, (4) the ability of these cells to differentiate in vitro, and (5) the ability at least for some clones to differentiate and secrete immunoglobulins in vivo. The normal counterpart to this B-cell clone corresponds to a small subpopulation of lymphocytes, present at the edge of the germinal center in human lymph nodes. Interestingly, this subpopulation appears to constitute a substantial part of the B-cell population in 20-week-old fetal lymph nodes and spleen. These results have induced most authors to assume that the CLL B lymphocyte corresponds to proliferation of an immature B-cell clone, arrested at an intermediate stage between pre-B cells and mature B cells. However, this hypothesis does not explain the high frequency with which hypogammaglobulinemia and autoimmune hemolytic anemia are found in B CLL. In this work, we discuss the possibility that the CLL B lymphocyte corresponds to proliferation of a B-cell line, whose counterpart in the mouse is the Ly1 B, Lyb5+ subpopulation.

Animals↗