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Biomedical subjects

R Schmits

Publications and source records attributed to R Schmits.

33 records · Page 2Linked to original sources
PubMed1996

LFA-1-deficient mice show normal CTL responses to virus but fail to reject immunogenic tumor.

The leukocyte integrin LFA-1 (CD11a/CD18) plays an important role in lymphocyte recirculation and homotypic interactions. Leukocytes from mice lacking CD11a displayed defects in in vitro homotypic aggregation, in proliferation in mixed lymphocyte reactions, and in response to mitogen. Mutant mice mounted normal cytotoxic T cell (CTL) responses against systemic LCMV and VSV infections and showed normal ex vivo CTL function. However, LFA-1-deficient mice did not reject immunogenic tumors grafted into footpads and did not demonstrate priming response against tumor-specific antigen. Thus CD11a deficiency causes a selective defect in induction of peripheral immune responses whereas responses to systemic infection are normal.

Animals↗
PubMed1996

Impaired negative selection of T cells in Hodgkin's disease antigen CD30-deficient mice.

CD30 is found on Reed-Sternberg cells of Hodgkin's disease and on a variety of non-Hodgkin's lymphoma cells and is up-regulated on cells after Epstein-Barr virus, human T cell leukemia virus, and HIV infections. We report here that the thymus in CD30-deficient mice contains elevated numbers of thymocytes. Activation-induced death of thymocytes after CD3 cross-linking is impaired both in vitro and in vivo. Breeding the CD30 mutation separately into alpha beta TCR-or gamma delta TCR-transgenic mice revealed a gross defect in negative but not positive selection. Thus, like TNF-receptors and Fas/Apo-1, the CD30 receptor is involved in cell death signaling. It is also an important coreceptor that participates in thymic deletion.

Animals↗
PubMed1995

Human neoplasms elicit multiple specific immune responses in the autologous host.

Expression of cDNA libraries from human melanoma, renal cancer, astrocytoma, and Hodgkin disease in Escherichia coli and screening for clones reactive with high-titer IgG antibodies in autologous patient serum lead to the discovery of at least four antigens with a restricted expression pattern in each tumor. Besides antigens known to elicit T-cell responses, such as MAGE-1 and tyrosinase, numerous additional antigens that were overexpressed or specifically expressed in tumors of the same type were identified. Sequence analyses suggest that many of these molecules, besides being the target of a specific immune response, might be of relevance for tumor growth. Antibodies to a given antigen were usually confined to patients with the same tumor type. The unexpected frequency of human tumor antigens, which can be readily defined at the molecular level by the serological analysis of autologous tumor cDNA expression cloning, indicates that human neoplasms elicit multiple specific immune responses in the autologous host and provides diagnostic and therapeutic approaches to human cancer.

Antibodies, Neoplasm↗
PubMed1995

Deregulated T cell activation and autoimmunity in mice lacking interleukin-2 receptor beta.

In mice lacking the interleukin-2 receptor beta chain (IL-2R beta), T cells were shown to be spontaneously activated, resulting in exhaustive differentiation of B cells into plasma cells and the appearance of high serum concentrations of immunoglobulins G1 and E as well as autoantibodies that cause hemolytic anemia. Marked infiltrative granulocytopoiesis was also apparent, and the animals died after about 12 weeks. Depletion of CD4+ T cells in mutant mice rescued B cells without reversion of granulocyte abnormalities. T cells did not proliferate in response to polyclonal activators, nor could antigen-specific immune responses be elicited. Thus, IL-2R beta is required to keep the activation programs of T cells under control, to maintain homeostasis, and to prevent autoimmunity.

Animals↗
PubMed1995

MSH2 deficient mice are viable and susceptible to lymphoid tumours.

Alterations of the human MSH2 gene, a homologue of the bacterial MutS mismatch repair gene, co-segregate with the majority of hereditary non-polyposis colon cancer (HNPCC) cases. We have generated homozygous MSH2-/- mice. Surprisingly, these mice were found to be viable, produced offspring in a mendelian ratio and bred through at least two generations. Starting at two months of age homozygous-/- mice began, with high frequency, to develop lymphoid tumours that contained microsatellite instabilities. These data establish a direct link between MSH2 deficiency and the pathogenesis of cancer. These mutant mice should be good models to study the progression of tumours and also to screen carcinogenic and anti-cancer agents.

Animals↗
PubMed1993

A CD16/CD30 bispecific monoclonal antibody induces lysis of Hodgkin's cells by unstimulated natural killer cells in vitro and in vivo.

In order to target NK cells against the Hodgkin's-derived cell line L540, we developed bispecific monoclonal antibodies (Bi-MAbs) by somatic hybridization of the 2 mouse hybridoma cell line HRS-3 and A9 which produce monoclonal antibodies (MAbs) with reactivity against the Hodgkin and Reed-Sternberg cell-associated CD30 antigen and the CD16 antigen (Fc gamma III receptor), respectively. The CD16 MAb-producing cell line A9 was selected as a partner for HRS-3 because of its efficiency in inducing lysis of the A9 hybridoma cells by resting NK cells. The hybrid hybridoma cell line HRS-3/A9 produced the supernatant with the strongest bispecific reactivity and was repeatedly subcloned and used for ascites production. Crude supernatant and purified HRS-3/A9 Bi-MAb triggered specific lysis of the CD30+ Hodgkin's-derived cell line L540, but not of the CD30- cell line HPB-ALL by unstimulated peripheral-blood lymphocytes and NK-cell-enriched populations. Moreover, treatment of SCID mice bearing heterotransplanted human Hodgkin's tumors with HRS-3/A9 and human peripheral blood lymphocytes induced specific complete tumor regression in 10/10 animals. We thus report successful tumor treatment in an in vivo model using NK-cell-associated Bi-MAbs and show that the Bi-MAb HRS-3/A9 is an efficient promoter of the anti-tumor effects of NK cells in vitro and in vivo.

Animals↗
PubMed1993

Monoclonal antibody FW6 defines an epitope on alpha 3/4-monofucosylated polylactosaminoglycans expressed by fetal and colon carcinoma-associated mucins.

A mouse IgM monoclonal antibody FW6 was established after immunization of mice with mucins from human amniotic fluid and was characterized with regard to its binding epitope. According to a series of biochemical criteria the epitope is located on O-linked neutral carbohydrates of M(r) 700,000 and M(r) 570,000 mucins in human amniotic fluid. The epitope is presumed to contain alpha 3/4-linked fucose and terminal beta 3/4-linked galactose that are labile to the fucosidase I from almond emulsion or to the galactosidase from bovine testes, respectively. Immunoreactive fractions of glycan alditols from human amniotic fluid mucins were partially characterized by fast atom bombardment-mass spectrometry and methylation analysis to be composed of monofucosylated polylactosamine-type deca- or nonasaccharides. According to antibody competition studies, inhibition assays with defined carbohydrates and binding assays on neoglycolipids monoclonal antibody FW6 are presumed to recognize a novel epitope that is distinct from known carbohydrate markers of the Lex/Ley family associated with colonic carcinomas. The selective reactivity of this monoclonal antibody to the majority of human colonic carcinomas and its nonreactivity to normal colonic mucosa may render this antibody as a valuable tool in cancer diagnosis or cancer treatment.

Amino Sugars↗
PubMed1992

Monoclonal antibody FW6 generated against a mucin-carbohydrate of human amniotic fluid recognises a colonic tumour-associated epitope.

Mucus glycoproteins of human amniotic fluid were used to generate a monoclonal antibody (MAb) FW6, which stained the intestine of a 24 week stage fetus. In adults, 76% of colonic adenocarcinomas (13/17) showed strong expression of the FW6 epitope, but it was not detected in the histologically normal mucosae adjacent to the tumours or in normal left colon mucosa. In addition, MAb FW6 stained large cell carcinomas of the lung (2/3), gastric carcinomas (5/11), and ovary adenocarcinomas (3/4). The expression in carcinomas can also be called ectopic for testing normal tissues. MAb FW6 was also reactive with pyloric mucus glands, Brunner's glands of the duodenum, Paneth cells of the ileum, pancreatic ducts, absorptive cells of the right colon, bronchiolar glands, kidney urothelia, and with a restricted number of normal mucinous tubuli of salivary gland. It was demonstrated to be under the control of the secretion gene only in intestinal Paneth cells and absorptive cells of the right colon. Comparative histochemical analysis comprising a panel of MAbs suggests that the corresponding epitope of the MAb FW6 is a type II chain related carbohydrate structure belonging to the Lex/Ley-antigen family, but is different from short chain Lex and Ley.

Amniotic Fluid↗
PubMed1992

Soluble CD8, CD25 and CD30 antigens as prognostic markers in patients with untreated Hodgkin's lymphoma.

In a search for serum markers with prognostic value and specificity for disease activity in Hodgkin's lymphoma, we evaluated the clinical significance of soluble suppressor/cytotoxic T-cell antigen (sCD8), soluble interleukin-2 receptor (sCD25) and soluble Hodgkin's associated antigen (sCD30) levels in the serum of 90 patients with untreated Hodgkin's lymphoma (HD). HD patients in advanced stages had significantly higher sCD8 and sCD25 levels than normal controls. The rate of detectable sCD30, which was absent in healthy controls, depended on stage and histological subtype, and was 22% for the entire group. Low sCD25 levels (< 1000 U/ml) predicted an excellent prognosis (100% event-free survival), while patients with high sCD8 levels (> 750 U/ml) or the demonstration of sCD30 had a poor outcome. Therefore, all three markers have prognostic significance. However, only sCD30 correlated strictly with disease activity and seems to be of value for the follow-up of patients in remission.

Adolescent↗
PubMed1992

The clinical significance of cytokines and soluble forms of membrane-derived activation antigens in the serum of patients with Hodgkin's disease.

In a search for specific serum markers with prognostic impact in Hodgkin's Disease (HD), we evaluated the clinical significance of several cytokines (IL-1 beta, IL-2, IL-3, IL-6, G-CSF, GM-CSF, TNF-alpha) and soluble forms of membrane-derived antigens (sCD4, sCD8, sCD23, sCD25, sCD30) in the serum of patients with untreated HD. Elevations of three groups of serum factors were observed: Firstly, elevations of the hematopoietic cytokines GM-CSF (detected in 39%), IL-6 (57%) and IL-3 (13%), which occurred simultaneously in the majority of the cases; secondly, simultaneous elevations of the inflammatory cytokines TNF-alpha and IL-1 beta (detected in 7%); and finally, elevations of membrane-derived activation antigens sCD8, sCD25, and sCD30. While the cytokine levels did not correlate with other obvious parameters, the membrane-derived activation antigens sCD8, sCD25 and sCD30 were associated with a poor prognosis. Only sCD30 correlated with disease activity and holds promise for the follow-up of patients in remission. Further investigations of these parameters at the cellular level might help to elucidate the enigmatic biology of HD.

Antigens, CD↗
PubMed1991

Low serum interleukin-2 receptor levels correlate with a good prognosis in patients with Hodgkin's lymphoma.

In order to evaluate the clinical significance of soluble interleukin-2 receptor (sIL-2R) levels in the serum of patients with Hodgkin's disease (HD), we tested the pretreatment sera of 82 patients. The HD patients had significantly higher sIL-2R levels than normal controls (4787 U/ml versus 290 U/ml; P less than 0.001). In patients presenting with B-symptoms, the median sIL-2R levels were significantly higher than in patients without B-symptoms (7978 versus 2128 U/ml; P less than 0.01). Patients in stage IVB had the highest sIL-2R levels (10,450 U/ml). Of 77 patients evaluable for response, all patients with sIL-2R levels less than 1000 U/ml achieved complete remission and no relapses occurred in this group after a median of 20 months. The fact that sIL-2R levels dropped after therapy, even in patients who suffered from progressive disease, suggests that Hodgkin and Reed-Sternberg cells are only a minor source of sIL-2R in HD. Therefore sIL-2R levels are of limited value as a marker of disease activity. However, pretreatment sIL-2R levels less than 1000 U/ml define a subgroup of adult HD patients with an excellent prognosis, and this fact might be helpful for the design of more custom-tailored therapy programs.

Adolescent↗
PubMed1991

The clinical significance of serum CD8 antigen levels in adult patients with Hodgkin's disease.

Increased suppressor T-cell activity has been observed in patients with Hodgkin's disease. In order to evaluate the clinical significance of soluble CD8 antigen (sCD8), which is released from CD8+ suppressor/cytotoxic T-lymphocytes, we determined sCD8 levels in the sera of 82 consecutive patients with newly diagnosed untreated Hodgkin's lymphoma who were entered into prospective trials of the German Hodgkin's Disease Study Group. sCD8 levels were significantly higher (p less than 0.01) in stage IV (781 U/ml, n = 19) than in stages I-IIIB (443 U/ml; n = 63). Patients with B-symptoms (n = 36) had slightly higher levels (611 U/ml) than patients without (n = 46) systemic symptoms (447 U/ml; p = 0.08). In 77 patients evaluable for response, the complete remission (CR) rate of patients with sCD8 less than 750 U/ml was higher (54/60 or 90%) than that of patients with sCD8 greater than 750 U/ml 11/17 or 65%; p = 0.01). The time to treatment failure was significantly longer in patients with sCD8 less than 750 U/ml (p = 0.008), even among the group with stages IIIB/IV only (p = 0.04). Our data suggest that the pretreatment levels of sCD8 in adult patients with Hodgkin's lymphoma have prognostic relevance, and that they should be determined especially in patients with advanced disease. Increased understanding of the role of sCD8 may shed light on the pathogenesis of Hodgkin's disease.

Adolescent↗
PubMed1990

Detection of a soluble form of the CD30 antigen in sera of patients with lymphoma, adult T-cell leukemia and infectious mononucleosis.

Using a sandwich enzyme-linked immunosorbent assay (ELISA) we were able to detect a soluble form of the CD30 antigen (CD30s) in the supernatant of cell lines expressing membrane-bound CD30 and in T and B cells after transformation with human T-cell leukemia virus (HTLV-I) and Epstein-Barr-Virus (EBV). While CD30s was not found in 250 healthy controls, it was detected in the sera of patients with Hodgkin's disease (23/100), anaplastic large-cell (6/9), angioimmunoblastic (2/2) and one unclassified high-grade non-Hodgkin's lymphoma (NHL), as well as in 18/20 patients with acute adult T-cell leukemia (ATL, HTLV-I-positive). It was absent in a large number of patients with other high-grade NHL, all low-grade NHLs, acute or chronic leukemias and solid tumors. The only non-malignant disease with detectable levels of CD30s was infectious mononucleosis (9/10). The membrane-bound form of CD30 has a molecular weight of 120 kDa. Western blot analysis revealed that CD30s in the serum of patients has a molecular weight of 88 kDa, identical to the antigen released by cell lines in vitro. CD30s disappeared in all originally positive cases after successful treatment and reappeared in relapsing patients. Thus, CD30s may be useful as a specific marker for disease activity of certain types of lymphoma and ATL.

Adult↗
PubMed1977

Stable nonaqueous pentobarbital sodium solutions for use in laboratory animals.

The degradation kinetics of pentobarbital sodium in propylene glycol-based solutions were studied along with the in vivo effects in laboratory animals. The degradation rate constant was directly proportional to the water concentration in propylene glycol-water solvent systems. An activation energy of 23.4 kcal/mole was obtained in propylene glycol-water (1:1). Pentobarbital sodium solutions in anhydrous propylene glycol and 9:1 mixtures of propylene glycol with ethanol, glycerin, or dimethylacetamide gave relatively slow degradation rates at 100 degrees with all projected 25 degrees t 99% values greater than 4.5 years. Intravenous administration of pentobarbital sodium in various anhydrous propylene glycol-based vehicles to rats produced no hemolysis of gross organ damage that would interfere with pathological evaluations. Results of an intraperitoneal sleeptime study indicated that pentobarbital sodium produced consistent hypnotic effect when administered as an aqueous solution or in anhydrous propylene glycol-based vehicles.

Animals↗