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.

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.

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.

Prognostic factors for hematotoxicity of chemotherapy in aggressive non-Hodgkin's lymphoma.

BACKGROUND: Little is known on the heterogeneity of hematotoxicity in patients receiving multicycle chemotherapy. PATIENTS AND METHODS: We analyzed data of 1399 patients with aggressive lymphoma from trials using CHOP (combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone)-like therapies. Multivariate modeling was carried out for leukocytopenia, thrombocytopenia and anemia and the models were validated by two large independent datasets from trials with/without usage of the CD20-antibody rituximab. RESULTS: On the basis of these models, we are able to predict the remarkable heterogeneity of hematotoxicity and propose to use risk groups. Regarding leukocytopenia, the low toxicity risk group experienced World Health Organization grade 4 in <10% of the cycles while the high toxicity risk group in almost all cycles. For thrombocytopenia, groups were detectable with almost no grade 3 or 4 toxicity and others where two out of three cycles were affected. In a separate set of models, the first cycle toxicity was the strongest predictor for later hematotoxicity. The risk for leukocytopenia was associated with infections, antibiotic use, hospitalization and treatment-related mortality, indicating the clinical usefulness of the models. For the first time, a Web-based tool is made available to easily predict the hematotoxicity in clinical practice (www.toxcalculator.com). CONCLUSION: This analysis has implications for patient management and prophylaxis.

Dose-escalated CHOEP for the treatment of young patients with aggressive non-Hodgkin's lymphoma: I. A randomized dose escalation and feasibility study with bi- and tri-weekly regimens.

BACKGROUND: To determine the maximum tolerated dose of a bi- and tri-weekly combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone plus etoposide (CHOEP) regimen without stem-cell support. PATIENTS AND METHODS: Randomized phase I/II multicenter four-level (cyclophosphamide: 1000-1200-1400-1600 mg/m2; doxorubicin: 55-60-65-70 mg/m2; etoposide: 375-450-525-600 mg/m2) dose escalation study with CHOEP-14 and CHOEP-21 in young patients (18-60 years) with newly diagnosed aggressive non-Hodgkin's lymphoma. Dose-limiting toxicity was defined as thrombocytopenia <80,000/mm3 and leukocytopenia <2500/mm3 on days 16 (CHOEP-14) and 23 (CHOEP-21) or prolonged (>4 days) leukocytopenia (<1000/mm3) or thrombocytopenia (<20,000/mm3). RESULTS: One hundred and thirty-nine patients (high-CHOEP-14: 47, high-CHOEP-21: 92) were randomly allocated to the study. Maximal tolerated dose was level 2 for CHOEP-14 and level 4 for CHOEP-21. With a less favorable profile of patients in CHOEP-14, 4-year event-free survival was 47.9% after high-CHOEP-14 and 66.2% after high-CHOEP-21, 4-year overall survival 62.1% after high-CHOEP-14 and 73.4% after high-CHOEP-21, respectively. CONCLUSION: Significant dose escalations of CHOEP are possible with granulocyte colony-stimulating factor support, with different chemotherapy models favoring the maximally escalated bi- or tri-weekly regimen, respectively. Because a higher total dose can be achieved with six cycles of the tri-weekly compared with the biweekly regimen, CHOEP-21 at dose escalation level 3 was chosen for a nationwide randomized comparison with baseline CHOEP-21 in a subsequent phase III trial.

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.

Gene-modified spontaneous Epstein-Barr virus-transformed lymphoblastoid cell lines as autologous cancer vaccines: mutated p21 ras oncogene as a model.

The transfer of genes coding for tumor antigens (Ags) into Ag-presenting cells is a promising strategy to develop cancer vaccines for patients not limited by major histocompatibility complex restriction. To test whether autologous lymphoblastoid cell lines (LCL) can be used as an alternative to dendritic cells for Ag presentation, we established LCL by spontaneous growth in cyclosporin-containing medium in vitro (SP-LCL). SP-LCL, which have an advantage over B95-8-transfected LCL in that they carry no risk of introducing a new infectious agent when used for vaccination, served as a permanent source for transfection with an episomal Epstein-Barr virus-based expression vector encoding the Ki-ras p21 oncogene carrying a point mutation at codon 12 (muRas) as a model tumor Ag. The ability of muRas-transfected SP-LCL (muRas-LCL) to induce immunoreactivity was determined in vitro. After electroporation with an optimized protocol, muRas-LCL expressed mutated ras peptides for a considerable period of time (at least 8 weeks) on the cell surface. The transfection procedure did not affect the expression of the costimulatory molecules B7.1, intercellular adhesion molecule-1, and leukocyte function associated Ag-3 by SP-LCL. muRas-LCL were able to induce muRas-specific cytotoxic T lymphocytes from three of three healthy donors and one of one patient with pancreatic carcinoma. Our results suggest that the gene transfer of muRas sequences to SP-LCL leads to an endogenous processing of this Ag in the major histocompatibility complex class I pathway and to functional presentation of antigenic peptides to CD8+ T lymphocytes. Autologous SP-LCL can serve as an unlimited renewable source for autologous cellular vaccines and appear to be good candidates as presenters for a wide range of human tumor Ags.

Systematic search and molecular characterization of the antigenic targets of myeloma immunoglobulins: a monoclonal IgA from a female patient targeting sperm-specific cylicin II.

The identification of the antigenic stimuli of B-cell neoplasms might be of considerable importance since a causal relationship between these neoplasms and antigenic stimulation has been suggested. To date the identification of such antigens has been erratic and accidental. For a systematic search and molecular characterization of human proteins that are antigenic target structures of myeloma-associated immunoglobulins, we applied SEREX (serological analysis of antigens by recombinant cDNA expression cloning) using a testis cDNA expression library and myeloma proteins from 42 patients. A monoclonal IgA from a female patient was shown to target sperm-specific cylicin II. The specificity of the reaction was confirmed by the characteristic staining of the equatorial belt of human sperm heads by the patient's myeloma protein. Serological analysis of recombinantly expressed cDNAs is a straightforward and high throughput approach for the molecular characterization of the targets of myeloma-associated immunoglobulins. The analysis of the antigenic spectrum of immunoglobulins associated with B-cell neoplasms will provide valuable information for the understanding of the pathogenesis of these diseases.

Lack of in vivo function of CD31 in vascular thrombosis.

A murine model of endothelial cell injury-based vascular thrombosis was used to test the role of platelet-endothelial cell adhesion molecule-1 (PECAM-1, CD31) in blood cell aggregate formation and vessel occlusion in vivo. Photochemically-induced thrombus formation was analyzed in detail using intravital fluorescence microscopy of individual microvessels in cremaster muscle preparations of CD31-deficient and wildtype mice. In venules, epi-illumination induced rapid thrombus formation with first platelet deposition after 0.56 +/- 0.11 min and complete vessel occlusion within 5.05 +/- 0.45 min. In arterioles, thrombus formation was markedly delayed with first platelet deposition after 3.03 +/- 0.47 min and complete vessel occlusion within 10.04 +/- 1.26 min. Kinetics of thrombus formation in both venules (first platelet deposition: 0.52 +/- 0.1 min; vessel occlusion: 5.03 +/- 0.52 min) and arterioles (first platelet deposition: 3.06 +/- 0.68 min; vessel occlusion: 10.02 +/- 1.38 min) of CD31-deficient mice was found almost identical compared with that in wildtype animals. Tail bleeding time was 233 +/- 24 s in wildtype and 243 +/- 32 s in CD31-deficient mice. Moreover, CD31-deficient and wildtype mice revealed comparable interaction of leukocytes to endothelium. This study shows for the first time in vivo that CD31 is not critically involved in blood cell thrombus formation upon endothelial cell injury.

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.

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.

The cervical lymph node preparation: a novel approach to study lymphocyte homing by intravital microscopy.

OBJECTIVE: Lymphocyte recirculation constitutes an integral part of the adaptive immune system. Blood-borne lymphocytes migrate into secondary lymphoid organs, crossing the vascular wall of site-specific high endothelial venules (HEVs). We created a preparation of the cervical lymph node in mice to study lymphocyte homing in vivo. METHODS AND RESULTS: Our novel approach allowed the detailed analysis of hemodynamics and lymphocyte-HEV endothelium interactions by means of intravital fluorescence microscopy. We confirm the key roles of L-selectin and LFA-1 for lymphocyte homing. Blockade of L-selectin function inhibited lymphocyte rolling and firm adhesion by 92% and 66%. In LFA-1-deficient mice, lymphocyte firm adhesion was reduced by 70%. In addition to the microcirculation studies, the cervical lymph node preparation allowed for visualization of afferent lymphatic transport, which is mainly derived from the oral mucosa. CONCLUSION: This study reports a novel technical tool for the detailed in vivo analysis of adaptive immune responses.

Analysis of the B cell repertoire against autoantigens in patients with giant cell arteritis and polymyalgia rheumatica.

The analysis of the antibody repertoire of patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) might identify target antigens of the autoimmune response with potential relevance to our understanding of the pathogenesis of the disease and to the development of serodiagnostic tests. To detect such antigens, we screened a cDNA library derived from normal human testis for antigens reacting with IgG antibodies in the 1 : 250 diluted sera of three patients with untreated GCA using SEREX, the serological identification of antigens by recombinant cDNA expression cloning. Of 100 000 clones screened with each serum, six, 28 and six clones, respectively, were positive, representing a total of 33 different antigens. Most of the antigens reacted only with the serum used for identification and/or at a similar frequency with normal control sera. However, lamin C and the nuclear antigen of 14 kD reacted specifically with 32% of GCA/PMR, but with none of the control sera, while human cytokeratin 15, mitochondrial cytochrome oxidase subunit II, and a new gene product were detected preferentially, but not exclusively by sera from GCA/PMR patients. We conclude that patients with GCA/PMR develop antibodies against a broad spectrum of human autoantigens. Antibodies against human lamin C, the nuclear autoantigen of 14 kD as well as human cytokeratin 15, mitochondrial cytochrome oxidase subunit II and the product of a new gene should be investigated further to determine their value as tools for the diagnosis and/or the definition of clinical subgroups of patients with GCA/PMR.

Critical role of leukocyte function-associated antigen-1 in liver accumulation of CD4+NKT cells.

In contrast to peripheral lymphoid organs, a high percentage of T cells in the liver are CD4+NKT cells. We asked whether adhesion molecules play any role in the accumulation of CD4+NKT cells in the liver. Liver CD4+NKT cells expressed ICAM-1 and high levels of LFA-1. In the livers of LFA-1-deficient mice, the number of CD4+NKT cells was markedly decreased. This reduction was restricted to the liver, and no reduction was found in the other organs analyzed. In contrast, the number of liver CD4+NKT cells in ICAM-1-deficient mice was only marginally reduced. In a reciprocal radiation thymocyte reconstitution system with LFA-1-deficient and wild-type mice, LFA-1 expressed on liver cells other than CD4+NKT cells was required for an accumulation of CD4+NKT cells in the liver. These results demonstrate a crucial role for LFA-1 in the accumulation of CD4+NKT cells in the liver.

Cooperation between CD44 and LFA-1/CD11a adhesion receptors in lymphokine-activated killer cell cytotoxicity.

IL-2-activated NK cells exhibit cytotoxic activity against a wide variety of tumor cells in a non-MHC-restricted fashion and in the absence of prior sensitization. The molecular mechanisms that regulate the cytotoxicity and attachment of activated killer cells to tumor target cells are not known. We provide genetic evidence in CD44(-/-) and LFA-1(-/-) mice that the cell adhesion receptors LFA-1 and CD44 regulate the cytotoxic activity of IL-2-activated NK cells against a variety of different tumor cells. This defect in cytotoxicity was significantly enhanced in mice that carried a double mutation of both CD44 and LFA-1. In vitro differentiation, TNF-alpha and IFN-gamma production, and expression of the cytolytic effector molecules perforin and Fas-L were comparable among IL-2-activated NK cells from LFA-1(-/-), CD44(-/-), CD44(-/-)LFA-1(-/-), and control mice. However, CD44(-/-), LFA-1(-/-), and CD44(-/-)LFA-1(-/-) IL-2-activated NK cells showed impaired binding and conjugate formation with target cells. We also show that hyaluronic acid is the principal ligand on tumor cells for CD44-mediated cytotoxicity of IL-2-activated NK cells. These results provide the first genetic evidence of the role of adhesion receptors in IL-2-activated NK killing. These data also indicate that distinct adhesion receptors cooperate to mediate binding between effector and target cells required for the initiation of "natural" cytotoxicity.

Lymphocyte function antigen 1 (LFA-1) mediates early tumour necrosis factor alpha-induced leucocyte adhesion in venules.

A co-ordinated expression of specific adhesion molecules regulates leucocyte-endothelium interactions in the microcirculation. In the present study, we used intravital microscopy of the cremaster muscle in CD11a gene-targeted mice to examine the role of lymphocyte function antigen 1 (LFA-1, CD11a/CD18) in tumour necrosis factor alpha (TNF-alpha)-induced leucocyte rolling and firm adhesion in venules. We found that 30 min after TNF-alpha administration leucocyte rolling was unchanged compared with phosphate-buffered saline (PBS)-treated mice and similar in LFA-1-deficient and wild-type animals. In contrast, firm leucocyte adhesion in venules increased by almost 10-fold following 30 min of TNF-alpha challenge in LFA-1-expressing animals, whereas no increase was observed in LFA-1-deficient mice. Four hours after intrascrotal administration of TNF-alpha, venular leucocyte adhesion was found to be markedly increased, but similar in extent to LFA-1-deficient and wild-type mice. Histological examination of haematoxylin-eosin-stained tissue sections revealed that approximately 90% of the leucocytes in the TNF-alpha-stimulated venules in both wild-type and LFA-1-deficient mice were polymorphonuclear. Taken together, our functional in vivo data demonstrate that LFA-1 is an important adhesion molecule in early TNF-alpha-induced venular leucocyte adhesion.

Cutting edge: contribution of NK cells to the homing of thymic CD4+NKT cells to the liver.

In contrast to peripheral lymphoid organs, in the liver a high proportion of T cells are CD4+NKT cells. We have previously reported that LFA-1 plays a pivotal role in the homing of thymic CD4+NKT cells to the liver. In the present study, we further assessed which cell type participates in the homing of thymic CD4+NKT cells to the liver. The accumulation of donor thymocyte-derived CD4+NKT cells in the liver of SCID mice that had been reconstituted with thymocytes from C57BL/6 mice was severely impaired by in vivo depletion of NK cells, but not Kupffer cells in recipients. These results suggest that NK cells participate in the homing of thymic CD4+NKT cells to the liver. We assume that LFA-1 expressed on NK cells is involved in this mechanism.

Participation of leukocyte function-associated antigen-1 and NK cells in the homing of thymic CD8+NKT cells to the liver.

A distinct CD8+NKT cell population expressing TCRalpha/beta or TCRgamma/delta has been identified in liver and thymus. We wondered whether cell adhesion molecules play a role in the homing of CD8+NKT cells to the liver. The number of liver CD8+NKT cells was markedly reduced in leukocyte function-associated antigen (LFA)-1-/- mice compared with wild-type (WT) mice. The reduction was restricted to the liver only and no measurable alterations were found in other organs. In the liver of SCID mice reconstituted with thymocytes from LFA-1-/- or WT mice, the number of donor-derived CD8+NKT cells was comparable and the vast majority of these cells expressed TCRalpha/beta. In a reciprocal radiation thymocyte reconstitution system with LFA-1-/- and WT mice, LFA-1 expressed on liver cells other than CD8+NKT cells appeared to be required for the homing of thymic CD8+NKT cells to the liver. The accumulation of donor thymocyte-derived CD8+NKT cells in the liver of SCID mice was severely impaired by in vivo depletion of NK cells, but not of Kupffer cells. These results not only indicate that thymus provides a source for CD8+NKT cells expressing TCRalpha/beta in the liver, but also suggest that LFA-1 expressed on NK cells is involved in the homing of thymic CD8+NKT cells to the liver.

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.

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.