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Biomedical subjects

J Hamburger

Publications and source records attributed to J Hamburger.

At least 73 records · Page 4Linked to original sources
PubMed1984

Anti-pancreatic immunity. In vitro studies of cellular and humoral immune reactions directed toward pancreatic islets.

It has been suggested that the immune system may be responsible for the destruction of insulin secreting cells in some types of diabetes. In order to test this hypothesis, we studied the consequences of immune-mediated reactions on the function of pancreatic islet cells in vitro. A model was set up in vitro where mouse pancreatic islet cells are exposed to human lymphocytes or sera + complement then stimulated for the release of insulin or glucagon. A selective inhibition of insulin secretion, but not of glucagon secretion, was observed in the presence of lymphocytes from 37 out of 40 insulin-dependent diabetic (IDD) patients and in the presence of sera (+ complement) from 22 out of 40. Lymphocytes were found inhibitory in almost all patients in both groups, with and without associated autoimmune diseases. In contrast, inhibitory sera were observed almost only in patients with associated autoimmune diseases or recent onset diabetes. The selective inhibition of insulin secretion, but not of glucagon secretion, suggests that lymphocytes or sera may be involved in a destructive process of insulin secreting cells in vivo. This cell-mediated effect depends on direct T lymphocyte cytotoxicity, rather than antibody-dependent cell cytotoxicity, as suggested by the lack of any effect of aggregated immunoglobulins on the reaction. In contrast, when C57BL/6 mice were immunized by mastocytoma cells from a DBA2 strain, their lymphocytes and sera blocked both secretions of insulin and glucagon when incubated in vitro with DBA2 islet cells. This non-selective inhibition may be due to anti-H2 immunity, rather than immunity directed against insulin secreting cells.

Adolescent↗
PubMed1983

In vitro and in vivo histamine-producing cell-stimulating factor (or IL3) production during Nippostrongylus brasiliensis infection: coincidence with self-cure phenomenon.

Spleen cells from Nippostrongylus brasiliensis-infected mice produce large amounts of histamine in response to adult worm antigen. This phenomenon results from the production of HCSF (histamine-producing cell-stimulating factor, probably related to IL3) by sensitized lymphocytes. This factor acts on its target cells (presumably mast cell precursors) by inducing a rapid increase in histamine synthesis. Similarly, parasite infection generates enhanced histamine production by spleen cells in response to concanavalin A (Con A). This results from increases in both HCSF production and the HCSF sensitivity of its target cells. In all cases, maximal histamine and HCSF productions are obtained on day 8 after infection and coincide with parasite rejection. Methyl prednisolone suppresses HCSF production by infected mouse spleen cells in response to worm antigen or Con A. HCSF activity is found in vivo on day 8 in the sera of infected mice, 4 h after they are challenged with an i.v. injection of adult worm antigen. No activity is detected in the sera of normal mice with or without antigen injection. Sera from infected mice that did not receive the antigen exhibit a slight HCSF activity on day 8. Our data bring the first evidence of the existence of an in vivo production of HCSF.

Animals↗
PubMed1983

The use of lyophilized Schistosoma mansoni eggs as antigenic particles in a radioimmunoassay.

Lyophilized eggs of Schistosoma mansoni, when incubated briefly with serum from infected mice, bind antibodies, as made evident by subsequent binding of fluorescein labelled anti-IgG or 125I-labelled Protein A. On the basis of these findings, a radioimmunoassay was devised which employs whole lyophilized eggs (500 or 250 eggs/serum sample) as antigenic particles and 125I-labelled Protein A as a probe for antibody binding. Only 10 microliters of serum are required to obtain 90% of the maximal binding. Kinetic studies indicated that 70% of the maximal seropositivity develops in mice between five and six weeks after a light infection, reaches a maximum at eight weeks and fluctuates around a high plateau thereafter. Pre-incubation of the test serum with soluble egg antigen (SEA) considerably inhibits antibody binding to the eggs, suggesting that SEA-like antigens participate in the reaction.

Animals↗
PubMed1983

Evidence for a lymphokine enhancing arginase activity during allograft rejection.

The production of urea and ornithine is increased greatly in spleen cell cultures of an allograft recipient in the presence of donor cells (secondary MLC) in comparison to that of primary MLC (without previous allograft). This phenomenon appears after 24 hr of culture and reaches its maximum at 48 hr. The greatest increase in urea production is observed when the recipient spleen cells are collected at the time of allograft rejection. To obtain this extra production of urea, the stimulating cells in MLC should specifically be of the donor type or at least bear one homology with donor cells at the K or D locus. The increased production of urea and ornithine during MLC results from the action of a lymphokine released by recipient cells in the presence of donor cells. This factor acts upon cells present in bone marrow, spleen, and elicited peritoneal cells but is absent or is present in smaller quantities in thymus and lymph node cells. Target cells of this factor possess numerous macrophage features and could be immature cells of the macrophage line. The lymphokine responsible for this phenomenon is heat-stable, destroyed by trypsin, chymotrypsin, and neuraminidase, and has a m.w. around 32,000. It acts upon its target cells by increasing arginase activity, which results in the production of a large amount of ornithine, an important precursor of polyamine biosynthesis.

Amino Acids↗
PubMed1983

Anti-pancreatic immunity in genetically diabetic mice.

The anti-pancreatic immune reaction of genetically diabetic homozygote C57Bl/KsJ db/db mice was studied with an in vitro test using murine islet of Langerhans cells as target cells. C57Bl/KsJ db/db spleen lymphocytes inhibited insulin secretion by the islet cells. This inhibition was abolished when T cells were eliminated by treatment with anti-Thy 1.2 monoclonal antibody in the presence of complement. Together with this cell-mediated cytotoxicity, complement-dependent antibody (CDA) and antibody-dependent cell cytotoxicity (ADCC) were found in the sera of these mice. A longitudinal study showed that this anti-pancreatic toxicity was detectable as early as the 10th day of life and lasted throughout the entire life span of the animal. None of these anomalies was found in control heterozygote mice.

Aging↗
PubMed1982

[Inhibition of insulin secretion of mouse pancreatic cells by T lymphocytes of insulin-dependent diabetics].

We previously showed that circulating lymphocytes from more than 90% of insulin-dependent diabetics, block extra insulin secretion induced by stimulatory media in mouse pancreatic cells in vitro, without altering the secretion of glucagon. The present work demonstrates that this phenomenon depends on lymphocytes having the OKT3 marker, i.e., thymodependent lymphocytes. However, OKT4+ T helper cells are not required for the above phenomenon as proved by experiments using monoclonal sera against the OKT4 marker. When diabetes is associated with other autoimmune diseases, the pancreatic lymphocyte cytotoxicity observed in vitro is inhibited by the addition of a normal lymphocyte population; this could indicate that a "suppressor" factor is lacking in these patients. Conversely, addition of normal lymphocytes does not prevent lymphocyte cytotoxicity in diabetics without associated autoimmune diseases. Such a difference confirms the present trend to make a distinction between these two categories of diabetes.

Adolescent↗
PubMed1982

Characterization of a purified glycoprotein from Schistosoma mansoni eggs: specificity, stability, and the involvement of carbohydrate and peptide moieties in its serologic activity.

A major egg glycoprotein (MEG) was purified from a crude soluble extract of Schistosoma mansoni ova (Egyptian strain) by successive steps of lectin affinity and ion-exchange chromatography. Radioiodinated MEG exhibited a single precipitation band upon immunodiffusion against antiserum from chronically infected mice, and ran as a single band on PAGE (Rf 0.38) and SDS-PAGE (Rf 0.36). Its estimated m.w. was 70,000. The degree of stage and species specificity of MEG and the effect of various treatments on its serologic reactivity were determined by radioimmunoassay (RIA). A low degree of cross-reactivity between MEG and similarly prepared soluble antigens from adult worms and cercariae was demonstrated by RIA inhibition tests, whereas a high degree of cross-reactivity was found between MEG and a crude soluble S. haematobium egg antigen. In similar RIA inhibition tests, the Puerto Rican S. mansoni had a lower degree of cross-reactivity with S. haematobium than the Egyptian strain. MEG was four times more abundant in SEA from a Puerto Rican strain of S. mansoni than in SEA from the Egyptian strain. The serologic reactivity of MEG was stable to heat at 100 degrees C for 60 min, to 0.1 N NaOH or HCl, and to 10% TCA. Treatment of MEG with pronase caused a limited fragmentation of the molecule and some loss of its serologic reactivity. Periodate oxidation resulted in a substantial loss of molecular mass and of serologic reactivity, leaving a low residual activity that is only partially cross-reactive with the bulk of MEG. These results suggest the importance of both carbohydrate and peptide moieties of MEG for its serologic reactivity.

Animals↗
PubMed1982

Analysis and preliminary purification of glycoproteins isolated from eggs in the urine of patients with Schistosoma haematobium infection.

Preliminary analysis and purification of glycoproteins from Schistosoma haematobium eggs were carried out with a small quantity of antigenic material obtained from the urine of infected human patients. A soluble egg extract was 125I-labeled and was fractionated by lectin affinity chromatography for separating egg glycoproteins. The crude glycoprotein fraction was run on SDS-PAGE to yield three polydisperse peaks with Rf values of 0.31, 0.57, and 0.84. 125I-labeled egg glycoproteins were further fractionated by ion exchange chromatography to yield four peaks or shoulders. One of these peaks constituted the major labeled egg glycoprotein of S. haematobium (MEGL-H) in a relatively pure form as determined by SDS-PAGE, and its estimated m.w. was 70,000. This glycoprotein was consistently and highly reactive serologically with a serum pool from schistosomiasis haematobia patients by a Farr-type radioimmunoassay (RIA). A limited cross-specificity study of inhibition RIA indicated that S. mansoni eggs contain components that cross-react only partially with MEGL-H. These results focus attention on MEGL-H as a potential serodiagnostic probe.

Female↗
PubMed1981

Histamine production during the anti-allograft response. Demonstration of a new lymphokine enhancing histamine synthesis.

Histamine production is greatly increased during culture of allograft recipient spleen cells in the presence of immunizing cells (secondary mixed leukocyte cultures [MLC]) as compared to that found in primary MLC (i.e., without previous allograft). This phenomenon appears after 24 h of culture and reaches its maximum at 48 h. Optimal increased histamine production is observed when MLC is performed with spleen cells removed from mice during rejection. This increased production of histamine during secondary MLC results from the action of a lymphokine: the histamine-producing cell stimulating factor (HCSF). This factor is released by T lymphocytes. Its production requires specific stimulation of the recipient lymphocytes because increase in histamine production during secondary MLC can be only observed when recipient cells are cultured with stimulating cells bearing at least one homology at K or D loci with immunizing cells. HCSF acts on a cell which is present in bone marrow, spleen, blood, and peritoneal cells but absent in thymus or lymph node cells. This target cell is found in the less-dense layer of a discontinuous Ficoll-gradient of bone marrow cells. HCSF is heat stable, destroyed by trypsin treatment, and has a molecular weight between 50,000 and 100,000. It acts on its target cells by increasing histidine decarboxylase activity.

Animals↗
PubMed1981

Lymphocytes from diabetics suppress insulin release in vitro.

The insulin response of isolated islet cells to glucose and theophylline in vitro was studied after incubation with lymphocytes. The test was employed to explore cell-mediated immunity in diabetics. A significant inhibition of insulin response to glucose and theophylline as compared to insulin release in a "basal" medium was found after incubation with blood lymphocytes from 21 out of 23 insulin-dependent diabetics (mean secretion index 18 +/- 18 versus 118 + 8 (SEM) % in control subjects). Most of the patients studied had associated autoimmune diseases: all of these displayed inhibition of insulin release. In six cases, the diabetes had a recent onset with no associated autoimmune disease: four of them displayed the same inhibition. No inhibition was found in the 26 control subjects and in seven non-insulin-dependent diabetics (mean secretion index 134 +/- 17 versus 145 +/- 23 (SEM) % in four control subjects). Lymphocytes inhibiting islet cell response were not cytotoxic against mouse fibroblasts. Twenty-two insulin-dependent diabetics showed islet cell antibodies to human and/or mouse pancreatic islets. However, an inhibition of insulin release was found with no detectable islet cell antibodies in one case, and the converse in two cases. Lymphocyte cytotoxicity to islet cells could play a role in the natural history of insulin-dependent diabetes.

Adolescent↗
PubMed1981

Complement-fixing Islet cell antibodies from some diabetic patients alter insulin release in vitro.

To explore humoral immunity in insulin-dependent diabetic (IDDM) patients, we studied insulin release from isolated mouse islets stimulated by glucose + theophylline after incubation with the sera of these patients and complement. Eleven of 21 IDDM sera suppressed the stimulated insulin release while the arginine-stimulated glucagon release remained unchanged. Morphologic evidence and the trypan-blue exclusion test suggested that the suppression of insulin release was due to a cytotoxic effect of the sera. No beta-cell inhibition of morphologic damage was detectable in the presence of sera from 30 healthy subjects, 8 non-insulin-dependent diabetic patients, and 5 nondiabetic patients with autoimmune diseases. Beta-cell inhibition by IDDM sera was not observed when complement was omitted. After serum fractionation, the cytotoxic potency of IDDM sera was located in the immunoglobulin G fraction. Using human islets, insulin release was suppressed by 3 of 6 IDDM sera. Complement-dependent cytotoxicity was found in 1 of 5 recent-onset IDDM patients and 11 of 16 IDDM patients with autoimmune phenomena. It was associated in all cases with the presence of islet cell antibodies as detected by immunofluorescence, and with the presence of circulating lymphocytes which suppressed insulin release in vitro. Complement-fixing antibodies may contribute to the selective beta-cell damage in IDDM.

Adolescent↗
PubMed1981

Serobiological differentiation between antischistosomal (Schistosoma mansoni) antisera.

Sera from chronically infected mice and from mice immunized with a soluble worm extract were both cytotoxic in vitro to schistosomula and exhibited similar antibody titers when tested by the indirect fluorescent antibody (IFA) technique with unmodified schistosomula. However, only the former type of antiserum was passively protective and highly reactive by IFA technique with schistosomula modified by heat or by successive heat and pronase treatments. These results indicate that in vitro cytotoxic antibody activity and passive protectivity are unrelated antischistosomal activities and suggest therefore that quantitatively or qualitatively different antibodies may be involved in their execution. It is yet unclear whether antibodies to the "treatment resistant" determinants are involved in protection, although they reach maximal expression between 10 and 16 weeks after infection, at which time protective immunity was demonstrable. The treated schistosomula are capable of inducing antibodies in mice and the antisera raised against them exhibited different patterns of activity when cross-tested by the IFA technique with untreated and treated schistosomula. The antigenic hierarchy of the "treatment resistant" determinants is discussed in view of the various serological findings.

Animals↗