Immune response to gp120 of HIV: antibody spectrotype and inhibitory activity on T cell functions.
Explore the source record for details and available documents.
HIV↗
Biomedical subjects
O Pontesilli
Publications and source records attributed to O Pontesilli.
Spectrotype of anti-gp120 antibodies remains stable during the course of HIV disease.
Human immunodeficiency virus (HIV) infection is characterized by a progressive decline in immune functions. The behavior of B-cell clones specifically engaged in the anti-HIV response could play a relevant role in the pathogenesis of such impairment. The spectrotype observed on isoelectric focusing and reverse blotting after antigen challenge is the serum image of antigen-specific B-cell activity and may provide some insight into Ag-dependent B-cell clone recruitment. In this study, we examined the spectrotype of anti-gp120 antibodies in a group of sera from 56 HIV-infected patients, belonging to groups II, III, and IV of the Centers for Disease Control classification, as well as in a group of 31 sera from 12 patients in a 21-month follow-up evaluation (range 7-36 months). All tested sera were positive for gp120 antibodies on Western blot. In the first group of 56 HIV-infected subjects, only 19 displayed well-focused banding patterns. Among these, the spectrotype was found to be consistently oligoclonal, thus confirming clonal restriction of anti-gp120 antibodies previously described by other investigators. No correlation could be established between a particular spectrotype and phase of the disease. The follow-up evaluation in the second group of 31 sera revealed the tendency in each patient to maintain the same spectrotype throughout the course of the disease. These findings confirm clonal restriction of anti-gp120 antibodies in HIV infection and suggest that the number of B-cell clones recruited in the anti-gp120 response remains stable over the course of the disease, at least in the time range explored by us.
Adult↗
The role of CD4+ and CD8+ T cells in the destruction of islet grafts by spontaneously diabetic mice.
Spontaneous development of diabetes in the nonobese diabetic (NOD) mouse is mediated by an immunological process. In disease-transfer experiments, the activation of diabetes has been reported to require participation of both CD4+ and CD8+ T-cell subsets. These findings seem to indicate that the CD4+ cells are the helper cells for the activation of cytotoxic CD8+ cells that directly destroy islet beta cells in type I diabetes. In this report we challenge this interpretation because of two observations: (i) Destruction of syngeneic islet grafts by spontaneously diabetic NOD mice (disease recurrence) is CD4+ and not CD8+ T-cell dependent. (ii) Disease recurrence in islet tissue grafted to diabetic NOD mice is not restricted by islet major histocompatibility complex antigens. From these observations we propose that islet destruction depends on CD4+ effector T cells that are restricted by major histocompatibility complex antigens expressed on NOD antigen-presenting cells. Both of these findings argue against the CD8+ T cell as a mediator of direct islet damage. We postulate that islet damage in the NOD mouse results from a CD4+ T-cell-dependent inflammatory response.
Animals↗
Hydatid disease: analysis of parasite antigens in circulating immune complexes and in preformed hydatid antigen-antibody complexes.
Fifty-three sera from 29 patients with hydatid disease, all but one positive for specific anti-parasite antibodies and all negative for specific circulating antigens, were studied for the presence of circulating immune complexes (CIC) by conglutinin binding-assay (KgBA). Fourteen serum samples (26%) from eight patients (27%) were positive. These positive sera were pooled for each patient and the eight samples were PEG-precipitated and analysed for the presence of specific Echinococcus granulosus antigens in the CIC using a human anti-human-hydatid cyst fluid antiserum capable of recognizing the major antigenic systems of the parasite namely, antigens 4 and 5. The assays utilized for detecting antigen in CIC were: (a) blotting on nitrocellulose paper after sodium dodecil sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and specific immunological detection; (b) ultracentrifugation in acid buffer and subsequent detection of antigens by a sandwich-radioimmuno assay (RIA); (c) protein separation by isoelectric focusing (IEF) and specific immunological recognition. In addition, all positive sera were analysed for the presence of antigen in the CIC by a modified KgBA and by polyethylenglicol (PEG)-precipitation in acid buffer followed by immunological recognition of antigen. All tests gave negative results with the patients' samples, but were positive with preformed in vitro complexes between parasite antigens and corresponding antibodies. Failure to detect antigen in the CIC could be due to: 1) insufficient sensitivity of the assays used to detect hydatid antigens in CIC; 2) rapid clearance of antigen or CIC from the circulation; 3) presence of parasite antigen not recognized by the antiserum employed; 4) production of CIC as a result of polyclonal B-cell activation. This last hypothesis is supported by the demonstration of IgM-rheumatoid factor (RF) and anti-F(ab')2 antibodies respectively in 11 (44%) and 13 (52%) out of 25 patients.
Animals↗
A cytotoxic monoclonal islet cell surface antibody from the NOD mouse.
Monoclonal antibody (Mab) 1.93B7 was obtained by fusion of spleen cells from a diabetic NOD mouse with P3X63Ag8.653 myeloma cells and screening for complement mediated lysis of rat insulinoma (RIN) cells. Immunofluorescence studies revealed that this Mab binds to RIN cells but not to the rat pituitary tumour line GH3. The binding of Mab 1.93B7 to RIN cells was abolished by trypsin but not by neuraminidase treatment of the cells, suggesting that the antigen recognized is a protein. Mab 1.93B7 bound to approximately 30% of mouse (BALB/c) and rat islet cells which had been subjected to trypsin digestion and incubated as a single cell suspension for 12h to allow reexpression of trypsin sensitive antigens. Since Mab 1.93B7 is potentially pathogenic, as suggested by its reactivity to primary islet cells and its complement fixing capacity, we injected it into BALB/c and NOD mice. Cytotoxic activity against RIN cells was detected in the serum of the animals injected with Mab 1.93B7, but the Mab did not exert a diabetogenic action and failed to reverse diabetes when administered at onset in NOD mice. No modification of the course of spleen cell mediated transfer of diabetes in NOD mice was observed when the Mab was administered from the time of spleen cell inoculation to the appearance of glycosuria. The implications of the lack of an effect in vivo of Mab 1.93B7 under the conditions employed are discussed.
Animals↗
Cyclosporin A in treatment of new-onset type I diabetes mellitus.
Explore the source record for details and available documents.
Adolescent↗
Complement activation is variably affected by fibronectin preparations obtained through different procedures.
Human plasma fibronectin (FN) containing preparations (FNCP) were prepared by means of gelatin-affinity chromatography of normal plasma cryoprecipitate (FNCP-a), and by affinity chromatography of cryoprecipitate on a rabbit anti-human FN antiserum Sepharose column (FNCP-b) or of normal citrated plasma (FNCP-c). These preparations were then tested for their ability to influence certain complement (C')-dependent polymorphonuclear phagocyte activities. FNCP-a consistently inhibited humoral chemotaxis, whereas FNCP-b and -c did not. Measurement of C' activation by the C3 conversion assay revealed that only FNCP-a displayed inhibitory activity on classical and alternative pathways. Ouchterlony and immunoelectrophoretic analyses indicated substantial identity of all FNCPs. FNCP-a contained a consistent amount of lower MW contaminants (between 40 and 60 KD) which were shown not to be immunologically related to FN by Western blot analysis. Immunoblotting also revealed a single band in FNCP-a (MW approx. 210 KD) instead of the anticipated two bands which were evident in the other FNCPs. Thus, a slight modification of the FN molecule and/or the presence of low MW contaminants in the gelatin-purified preparation seem able to induce inhibitory effects on C'-dependent polymorphonuclear phagocytic activities.
Chemotaxis, Leukocyte↗
Processing and presentation of cell-associated varicella-zoster virus antigens by human monocytes.
To determine whether viral antigens associated with infected cells were processed for presentation to T cells, we cultured human blood mononuclear cells (MNC) from varicella-zoster virus (VZV) immune donors with VZV-infected fibroblasts of known HLA type which had been fixed in 0.05% glutaraldehyde. After 7-8 days of culture thymidine uptake by T4+ cells exceeded that of T8+ cells. Stimulated cells were depleted of adherent cells and restimulated with VZV-infected fibroblasts from donors matched or unmatched with the responder for HLA type in the presence or absence of fresh adherent cells. Proliferation of the VZV-specific blasts required the presence of adherent cells matched with the responder lymphocytes for HLA-DR; conversely, the VZV specific response was not restricted by the MHC of the fibroblasts used in the restimulation assay. Preincubation of the adherent cells with chloroquine inhibited the proliferative response in a dose-dependent manner. These results suggest that VZV antigens on infected cells may be processed by monocytes for presentation to T cells.
Adult↗
Circulating lymphocyte populations and autoantibodies in non-obese diabetic (NOD) mice: a longitudinal study.
Several previous observations indicate a role for the immune system in the pathogenesis of insulin-dependent diabetes mellitus (IDDM) in non-obese diabetic (NOD) mice. In order to assess the status of the immune system in this model of spontaneous diabetes we studied the phenotype of circulating lymphocytes and the humoral autoimmunity to islet cells in non-diabetic NOD mice at various ages. Lymphocyte numbers were low in young NOD mice (age less than 160 days) as compared with other strains of mice and increased later to reach values in or above the range of controls. The percentages of circulating T lymphocytes and their L3T4+ and Lyt2+ subsets were higher in NOD mice of all ages and both sexes than in controls; however, no imbalance of the L3T4+ and Lyt2+ subpopulations was found. Anti-insulin autoantibodies were detected by an ELISA assay in all the NOD mice studied throughout the entire period of observation. Autoantibodies reacting with the cytoplasm of islet cells in Bouin's fixed pancreas sections, likely to be anti-insulin antibodies, were found in 47 to 58% of the samples from NOD mice aged 75 to 150 days. Antibodies to surface antigens of rat insulinoma cells were virtually absent in young NOD mice (75-100 days) and appeared in 33 to 43% of the samples from 150 to 185 days old NOD mice. The autoantibodies and the quantitative lymphocyte abnormalities reported here, although not predictive of the appearance of overt diabetes, are likely to be involved in the pathogenesis of the disease and therefore may indicate directions for future investigations.
Aging↗
Desferoxamine blocks IL 2 receptor expression on human T lymphocytes.
Thymidine uptake by PHA-stimulated human lymphocytes is reduced in the presence of 100 microM or greater concentrations of the iron-chelating agent desferoxamine (DF). We assessed expression of IL 2 receptor, 4F2 and Ia antigens, IL 2 production, and cell cycle progression by blood mononuclear cells (MNC) stimulated by PHA in the presence or absence of DF to determine whether the lack of T cell proliferation was a manifestation of inhibition of an earlier activation event. Tac antigen expression on PHA-stimulated MNC was inhibited by DF throughout 8 days of culture, and those cells which were positive had a low density of Tac antigen as compared with controls without DF. Expression of other activation antigens, 4F2 and Ia, was not impaired by DF. The supernatants of the DF-containing and control cultures contained equivalent IL 2 activity, as measured on the HT-2 cell line. Cell cycle analysis of these cultures shows that the addition of DF at the beginning of culture blocks most cells from undergoing G0 to G1 transition, whereas later addition of DF arrests the progression of the T cell blasts through the cell cycle. Separation of cells cultured with PHA and DF into Tac+ and Tac- subsets showed that progression from G0 to G1 was restricted to the former subset. These results suggest that interference with IL 2 receptor expression might contribute to the block in mitogen-induced proliferation caused by DF.
Antigens, Surface↗
Immune complexes in hereditary angioneurotic edema (HANE)
Explore the source record for details and available documents.
Angioedema↗
IgG anti-IgE in circulating immune complexes in the hyper-IgE syndrome.
We fractionated, by gel chromatography, sera with high IgE content from atopic subjects and five cases with the hyper-IgE syndrome, and measured the presence of IgE in high molecular weight (HMW) fractions. Two out of four asthmatics and four out of five hyper-IgE had HMW IgE. The same serum fractions gave positive results for conglutinin binding IgG (all six) and IgA (three cases) as well as C1q binding complexes (five cases). IgG auto-antibodies to IgE were also detected together with IgE in HMW fractions. Anti-F(ab)'2 activity was present in five cases (one of them negative for IgG anti-IgE). Our data indicate that complexes made of IgE and IgG anti-IgE are present mainly in patients with chronic allergic symptoms and most frequent in cases of hyper-IgE syndrome.
Antibodies↗
Specific lysis of varicella zoster virus-infected B lymphoblasts by human T cells.
Epstein-Barr virus-transformed human B cells expressed cell surface varicella-zoster virus (VZV) antigens after superinfection with VZV although they did not form infectious centers in a plaque assay. The VZV-superinfected cells were lysed by autologous VZV-stimulated T-cell lines and their derivative clones. The effector cells were specific for VZV and an HLA DR antigen and were T4+. The specificity of lysis of Epstein-Barr virus-transformed, VZV-superinfected targets by prestimulated mononuclear cells in this system contrasted with the unrestricted lysis seen when the targets were VZV-infected fibroblasts.
Antigens, Viral↗
T-lymphocyte subpopulations in insulin-dependent (type I) diabetes mellitus.
Initial reports of blood T cell subsets in insulin-dependent (type I) diabetes mellitus (IDDM) are conflicting and, consequently, difficult to relate to animal models of the disease. To minimize technical artefacts, which may have contributed to previous results, we used direct immunofluorescence on whole blood and counted 3,000 lymphocytes by flow cytometer. Forty-two IDDM patients divided in three groups of 14 according to the disease duration and 12 age and sex matched controls were studied for T3, T4, T8 and HLA-DR expression. No statistically significant differences were found in their total blood lymphocyte counts or in the percentage of T3, T4 and T8 positive cells, although mild lymphopenia was found in the group of long-standing diabetics. The percentage of activated T cells, identified as T3+/DR+ cells, was significantly increased in the groups of patients studied more than a month after diagnosis and in four of 14 patients studied within a month from diagnosis. Seven new onset IDDM patients were studied for co-expression of T8 and Leu 15 antigens (putative suppressor cell phenotype), but no significant differences was found compared with controls. We conclude that T4/T8 ratio abnormalities previously reported in Ficoll separated cells are not reproduced when unseparated cells are analysed by flow cytometry, although the presence of HLA-DR+ T cells is confirmed.
Adolescent↗
Cow's milk hypersensitivity in an elderly woman: clinical and immunologic findings.
We report a case of allergy to cow's milk diagnosed in a 79-year-old woman, who had the habit of drinking large amounts of milk and other dairy products for several years. She had been an asthmatic since the age of 40. At age 65, she noticed a correlation between cheese and milk intake and onset of asthma and two episodes of shock, and she has been avoiding milk for the past 15 years. Positive skin prick tests for cow's milk proteins, grass pollens, and house dust mite were observed. Serum IgE levels were above 3,000 U/mL, with high molecular weight IgE detected by gel chromatography. RAST results confirmed the presence of sensitizations detected by skin prick tests. The patient never suffered from atopic eczema. This unusual case of food allergy with onset after the age of 40 may indicate that prolonged exposure to food antigens in predisposed individuals may lead to the development of allergy even in adult age, lasting for decades after partial elimination of the allergen from the diet.
Aged↗
Salivary IgA levels in normal children.
Salivary IgA (SlgA) levels were determined in 1,539 normal children, aged between 8 months and 6 years. In four children (0.26%), an absence and in 25 children (1.62%) a relative defect, (less than 1 mg/dl) were found. These values are similar to those encountered in an adult male population. Conversely, the mean SlgA in all age groups we examined was much lower in comparison to the adult mean. This difference is particularly great for SlgA and much smaller for total salivary proteins. There was no difference between males and females, and no relation with personal or familial history of allergic and/or infectious episodes. The conclusions of this study are as follows: Absolute and relative SlgA defects, when found, are present from birth, The complete maturation of SlgA occurs after 6 years of age, The role of SlgA in the protection against allergic or infectious episodes perhaps ought to be revised.
Age Factors↗
Characterization of parasite antigens from human hydatid cyst fluid by SDS-PAGE and IEF.
Combining high resolution power of SDS-PAGE and IEF with the specific immunological recognition of a human antiserum directed against Echinococcus granulosus antigens, we could identify, in 4 hydatid cystic fluids of human origin, 4 antigens with a molecular weight in the range 32-13 KD, and an antigen of 200 KD which, in reducing conditions, gave 2 bands of 67 and 52 KD. In addition, mainly in one of the cystic fluids, there were at least another 4 specific non-reducible bands with a molecular weight ranging from 80 to 40 KD. Specific parasite antigens, which constitute not more than 3% of total protein content of the cystic fluid, migrate, in isoelectric focusing, from a pH of less than 5 to more than 8.
Antigens, Helminth↗
Humoral inhibition of neutrophil chemotaxis in Crohn's disease.
In patients with Crohn's disease (CD) we investigated the C3 conversion of zymosan-activated serum (ZAS) and looked for the occurrence of chemotactic factor inactivation (CFI). We also studied the cell-directed inhibitory effect (CDI) of the CD patients' plasma and, in the same group, complement activation and complement-mediated deactivation. The mean value of ZAS C3 conversion in CD was no different from that of healthy controls, but in steroid-treated patients it was lower than in untreated CD. CFI occurred in 1 of the 23 CD sera tested, and CDI was observed in 6 out of the 22 patients tested. EDTA C3 conversion was present in 12 patients, and complement-mediated deactivation was associated with high values of EDTA C3 conversion. Our findings indicate that complement dysfunction and inhibitory factors of neutrophil chemotaxis are present in CD. These findings could explain the defective neutrophil migration into skin windows. Whether they are relevant to the pathogenesis of tissue injury or of infectious complications and are specific for CD, however, remains to be established.
Adult↗