bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphism of the human C3b/C4b receptor. Identification of a third allele and analysis of receptor phenotypes in families and patients with systemic lupus erythematosus.
Authors: Dykman T R , Hatch J A , Atkinson J P
Published: June 2004

We have isolated C3bR from surface-labeled erythrocytes of 180 normal individuals and 45 patients with SLE. These studies have identified a previously unrecognized C3bR molecule on E with a Mr of approximately 160,000 daltons on nonreduced SDS-polyacrylamide gels. A similar receptor phenotype is also found on other C3bR-bearing peripheral blood leukocytes. Family studies demonstrate that this approximately 160,000-dalton molecule represents a third allele that is inherited in a codominant fashion at the same locus as the two previously described C3bR alleles. In unrelated normal donors a common allele (A) determines an approximately 190,000-dalton C3bR (gene frequency 0.83), a second allele (B) determines an approximately 220,000-dalton C3bR (gene frequency = 0.16), and a third rare allele (C) determines an approximately 160,000-dalton C3bR (gene frequency = 0.01). There were no major differences in gene frequencies among Caucasians and blacks or normal individuals and patients with SLE. However, compared with normal individuals, heterozygous C3bR-AC patients with SLE express large amounts of the approximately 160,000-dalton C3bR on E. Expression of C3bR molecules among heterozygous siblings is similar, suggesting that an inherited factor controls expression of the two molecules in heterozygous donors. These observations constitute an instructive example of a structural polymorphism of an integral membrane glycoprotein and provide a structural and genetic basis for further molecular and functional analyses of C3bR in normal and patient populations.
Development of adult bone marrow stem cells in H-2-compatible and -incompatible mouse fetuses.
Authors: Fleischman R A , Mintz B
Published: June 2004

Bone marrow of normal adult mice was found, after transplacental inoculation, to contain cells still able to seed the livers of early fetuses. The recipients' own hematopoietic stem cells, with a W-mutant defect, were at a selective disadvantage. Progression of donor strain cells to the bone marrow, long-term self-renewal, and differentiation into myeloid and lymphoid derivatives was consistent with the engraftment of totipotent hematopoietic stem cells (THSC) comparable to precursors previously identified (4) in normal fetal liver. More limited stem cells, specific for the myeloid or lymphoid cell lineages, were not detected in adult bone marrow. The bone marrow THSC, however, had a generally lower capacity for self-renewal than did fetal liver THSC. They had also embarked upon irreversible changes in gene expression, including partial histocompatibility restriction. While completely allogeneic fetal liver THSC were readily accepted by fetuses, H-2 incompatibility only occasionally resulted in engraftment of adult bone marrow cells and, in these cases, was often associated with sudden death at 3-5 mo. On the other hand, H-2 compatibility, even with histocompatibility differences at other loci, was sufficient to ensure long-term success as often as with fetal liver THSC.
Possible involvement of the T4 molecule in T cell recognition of class II HLA antigens. Evidence from studies of CTL-target cell binding.
Authors: Biddison W E , Rao P E , Talle M A , Goldstein G , Shaw S
Published: June 2004

The present study examines the potential role of the T4 molecule in functional cell-cell interactions between target cells and human cytotoxic T lymphocyte (CTL) clones that are specific for HLA class II alloantigens encoded by the SB locus. There were marked differences (greater than 30-fold) between the seven SB-specific clones studied with respect to their susceptibility to inhibition by anti-T4 as well as anti-T3 antibodies. We wished to test the hypothesis that such variation among the clones would be due to differences in clonal "affinity" for antigen. To quantitate differences among the CTL clones in the tightness with which they bind target cells, the clones were analyzed using a previously published assay of susceptibility of CTL-target cell conjugates to dissociation in the presence of unlabeled targets. The results revealed that the clones that were most susceptible to inhibition by anti-T4 and anti-T3 were the weakest target cell binders, and vice versa. Anti-T4 antibody could partially induce dissociation of functional CTL-target cell conjugates in the absence of any added cold targets. For the "highest affinity" clone such anti-T4 antibody-induced dissociation could be observed at 4 degrees C but not 23 degrees C. These results indicate that the T4 molecule is functionally involved in target cell binding by CTL, and raise the possibility that although it is easiest to demonstrate the function of the T4 molecule in "low affinity" clones, that function may also be operative in the "high affinity" clones.
Regulation of B cell lymphomagenesis by a malignant Qal+ inducer T cell clone.
Authors: Reinisch C L , Sing A P , Bacon E R , Corley R B , Gershon R K
Published: June 2004

A series of Thy-1.2+ Ly-1+ Qa-1+ malignant T cell clones have been isolated from murine sarcoma virus-murine leukemia-Moloney (MSV-MuLV-M)-induced B cell lymphomas or from MSV-MuLV-M-infected B6 mice. These T cell clones enhance both antigen-independent and -dependent lymphocyte differentiation and function. They also induce the differentiation of granulocytes and erythrocytes in the stem cell compartment, a function that parallels the immunopathology of the disease in vivo. The malignant T cell appears to sustain B lymphoma growth in vivo by releasing a factor (BCGF) that promotes B cell proliferation.
Clonal heterogeneity in the requirement for T3, T4, and T8 molecules in human cytolytic T lymphocyte function.
Authors: Moretta A , Pantaleo G , Mingari M C , Moretta L , Cerottini J C
Published: June 2004

In an attempt to define the requirement of T8, T4, and T3 surface molecules in functional interactions occurring between human cytolytic T lymphocytes (CTL) and specific target cells, we have analyzed a large number of CTL clones derived from primary mixed lymphocyte culture (MLC) T cell populations for their susceptibility to inhibition by monoclonal antibodies (mAb) directed against these surface antigens. In most experiments, MLC T cells were stained with B9.4 (anti-T8) or OKT4 (anti-T4) mAb, separated into positive and negative cells using a fluorescence-activated cell sorter (FACS) and cloned under limiting conditions. While the lytic activity of the majority of T8+ CTL clones was inhibited by B9.4 mAb, approximately 15% of these clones were unaffected even in the presence of excess antibody. Flow cytofluorometric analysis of T8 antigen in individual clones did not show any correlation between the amount of T8 antigen expressed, the magnitude of cytolytic activity and the susceptibility (or lack thereof) to inhibition by B9.4 mAb. Of the 16 T4+ CTL clones analyzed, 7 were resistant to inhibition by OKT4 mAb even at doses 10-fold higher than that sufficient for complete inhibition of susceptible clones. Again, no correlation was found between the amount of T4 antigen expressed and the susceptibility to inhibition by the corresponding antibody. The same sets of T8+ and T4+ CTL clones were also analyzed for their susceptibility to inhibition by OKT3 mAb. Although all of the clones expressed the T3 surface antigen, only 15/23 T8+ clones and 9/14 T4+ clones were inhibited by anti-T3 mAb. To further document this clonal heterogeneity, we selected two T3+ T4- T8+ CTL clones that had no concomitant NK-like activity. One clone was resistant to inhibition by OKT3 mAb, whereas the other was highly susceptible. Incubation with OKT3 mAb resulted in modulation of the T3 molecules in both clones. Following modulation, however, the cytolytic activity of the resistant clones was unaffected, whereas the lytic activity of the susceptible clone was abrogated. These results thus indicate extensive clonal heterogeneity in the requirement for T3, T4, and T8 molecules in CTL function. Moreover, it appears that T3 molecules are not always physically and functionally linked to CTL receptor structures.
Human malignant and mitogen-transformed cells contain retroviral P15E-related antigen.
Authors: Cianciolo G J , Phipps D , Snyderman R
Published: June 2004

Virus-related oncogenes have been demonstrated in human tumor cells and may play a role in neoplastic transformation. Cancerous effusions contain inhibitors of monocyte function and are absorbed by monoclonal antibodies to the immunosuppressive retroviral structural protein, P15E. We therefore examined eight human malignant cell lines for P15E-related antigens, by indirect immunofluorescence. Up to 87% of fixed malignant cells were reactive with two different monoclonal anti-P15E antibodies, while under identical conditions approximately 7% of freshly isolated human mononuclear cells were positive. Differentiation of two tumor cell lines with dibutyryl cyclic AMP resulted in decreased anti-P15E reactivity. Blast transformation of human mononuclear cells with mitogens induced reactivity with anti-P15E. Thus human malignant and blast-transformed cells contain antigens related to P15E. Expression of this viral-related gene may occur during rapid cell division and be abnormally regulated in cancer cells, thus rendering them more resistant to immune destruction.
Monocytes can be induced by lipopolysaccharide-triggered T lymphocytes to express functional factor VII/VIIa protease activity.
Authors: Tsao B P , Fair D S , Curtiss L K , Edgington T S
Published: June 2004

In the present study we demonstrate that human monocytes can be induced by the model stimulus, lipopolysaccharide (LPS), to produce and assemble on their surface functional Factor VII/VIIa. This protease was not induced in relatively purified monocytes alone following exposure to LPS; but was induced in the presence of Leu-3a positive helper/inducer T cells. The Factor VII/VIIa protease activity represented 35-40% of the potential initiating activity for the extrinsic coagulation pathway and was demonstrated using functional coagulation assays, as well as in amidolytic assays for the activation of Factor X. This activity of cell-bound Factor VII/VIIa appeared to involve a tight adduct of calcium. The identity of the Factor X-activating protease as Factor VII/VIIa was confirmed by the capacity of antibody specific for Factor VII/VIIa to neutralize the cell-bound protease. Further propagation of the extrinsic pathway following generation of Factor Xa required addition of exogenous Factor Va. These results expand the repertoire of proteases that have been identified with appropriately triggered cells of the monocyte/macrophage series, and suggest that initiation and propagation of the extrinsic coagulation protease network on induced monocytes involves not only expression of the initiating cofactor molecule, tissue factor, but also production of Factor VII and its organization into the molecular assembly. Thus, in the absence of exogenous Factor VII/VIIa a directly proteolytic effector cell can be generated. Further molecular assembly of the extrinsic pathway on the monocyte surface sequentially expands the proteolytic capacity of this response. The synthesis and assembly of the extrinsic activation complex by the monocyte and its derived progeny, the macrophage, provides a mechanism by which coagulation is initiated under T cell instruction at sites of immunologic responses.
Selective modification of a private I-A allo-stimulating determinant(s) upon association of antigen with an antigen-presenting cell.
Authors: Rock K L , Benacerraf B
Published: June 2004

A large panel of alloreactive, interleukin 2 (IL-2)-producing T cell hybridomas was constructed from B10 alpha BALB/c primary mixed lymphocyte cultures (MLC). Functional hybrids had specificity for either I-Ad or I-Ed. These cells were used to probe determinants on Ia molecules in an attempt to detect molecular association between a nominal antigen and an Ia molecule on an antigen-presenting cell (APC). The response of a small number of these clones was significantly blocked by the addition of the Ir gene-controlled copolymer L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) to culture. A comparison of the inhibited and uninhibited hybrids revealed an identical dose response curve. Further, both types of hybrids were activated by the same stimulator cell and frequently recognized the identical Ia molecule on that cell. Nevertheless, the inhibitory effect of GAT was localized to the stimulator cell and not to the T cell hybrids. All of the hybrids whose stimulation was blocked had specificity for the I-A molecule, which is the gene product known to control and restrict responsiveness to GAT. Further, only GT, but not a number of other related antigens, was also specifically inhibitory, which correlates with the known associational specificity of these antigens on an APC. Finally, the same stimulator cell could be shown to coordinately lose an allostimulatory determinant(s), while it was gaining an I-Ad plus GAT determinant(s). The implications of these findings on the nature of antigen-Ia association and on the role of polymorphic Ia determinants are discussed.
A new differentiation antigen (FT-1) shared with fetal thymocytes and leukemic cells in the mouse.
Authors: Kasai M , Takashi T , Takahashi T , Tokunaga T
Published: June 2004

A mouse monoclonal antibody (IgM) was obtained by cell hybridization between X63-Ag8.653 myeloma cells and spleen cells from a BALB mouse that was immunized with GRSL leukemia cells of the GR strain. This antibody identified a unique fetal antigen, which is expressed exclusively on embryonic thymocytes of all strains tested. Therefore, the antigen defined was named fetal thymus antigen-1, FT-1. The proportion of FT-1+ fetal thymocytes detected by immunofluorescence assay sharply decreases as gestation time increases, and finally they disappear from the thymus. On the other hand, Thy-1+ cells increase in inverse proportion. The immunofluorescence studies and absorption tests showed that FT-1 antigen is not detectable on brain, liver, kidney, or lymphoid tissue cells of adult mice. However, it is expressed on some leukemia cells of various mouse strains, which demonstrated that this is the first example of an oncofetal antigen of a mouse leukemia. The molecular weight of FT-1 antigen on leukemia cells was estimated to be 130,000 by means of biosynthetic labeling with [3H]galactose and [35S]methionine. The two-dimensional gel electrophoresis pattern of FT-1 antigen shows a family of glycoproteins with extensive charge heterogeneity. It was also shown that the FT-1 antigen molecule carries the receptor for DBA lectin.
Natural killer cells activated in a human mixed lymphocyte response culture identified by expression of Leu-11 and class II histocompatibility antigens.
Authors: Phillips J H , Le A M , Lanier L L
Published: June 2004

Lymphoid cells with natural killer (NK)-like function, morphology, and antigenic phenotype have been identified in a mixed lymphocyte culture generated by co-culture of human peripheral blood mononuclear cells with an allogeneic human B lymphoblastoid cell line CCRF-SB. The majority of these mixed lymphocyte (MLR)-response activated NK cells express the Leu-11 surface antigen, but do not express certain T cell-associated antigens (Leu-1, Leu-3, and Leu-4) or the mature monocyte specific antigen, Leu-M3. Unlike most freshly isolated Leu-11+ human NK cells, the MLR-activated Leu-11+ cells expressed class II major histocompatibility antigens, DR and DC. Concomitant with expression of class II gene products, the Leu-11+,DR+ NK cells demonstrate enhanced cytotoxicity against the NK-sensitive tumor cell line K562. The presence of mitotic cells in the Leu-11+,DR+ population and the acquisition of increased levels of transferrin receptor on the cell surface were further indicators of activation of these cells. The direct precursors of the MLR-activated Leu-11+,DR+ cell were Leu-11+ cells that lacked expression of another NK-associated antigen Leu-7, i.e., Leu-7-,11+. These studies provided a definitive identification of the "NK-like" cell in MLR cultures and thus allow quantitation and isolation of these cells for further study.
Chemical synthesis of idiotopes. Evidence that antisera to the same JH1 peptide detect multiple binding site-associated idiotopes.
Authors: Seiden M V , Clevinger B , McMillan S , Srouji A , Lerner R , Davie J M
Published: June 2004

In an attempt to better understand the molecular basis of idiotypy, we have generated several site-specific antisera through immunization of animals with synthetic peptides corresponding to the (JH1) heavy chain joining segment 1 of the mouse heavy chain variable (VH) region. These anti-peptide sera identify several idiotypic determinants present on intact hybridoma and myeloma immunoglobulins. Expression of at least three of these idiotopes is correlated with the antigen specificity of the family of immunoglobulins bearing the determinant. Use of synthetic peptides may prove a powerful technique in the generation of molecularly defined antiidiotypic reagents.
Schistosoma mansoni. Anti-egg monoclonal antibodies protect against cercarial challenge in vivo.
Authors: Harn D A , Mitsuyama M , David J R
Published: June 2004

Monoclonal antibodies that bind to surface membranes of developing schistosomula and/or cercarial tails were generated from mice immunized with living schistosome eggs or soluble egg antigen. These monoclonal antibodies detected at least three different surface epitopes. One surface antigen detected by anti-egg monoclonal antibody EG1C4B1 (E.1) persisted on the surface of developing schistosomula for 96 h posttransformation . The same or a cross-reactive antigen was also detected on the surfaces of S. japonicum and S. haematobium schistosomula and cercarial tails. Monoclonal antibody E.1 killed schistosomula in vitro as well or better than infected mouse sera and transferred immunity to naive mice when administered in vivo. The monoclonal antibody reduced the number of lung worms recoverable on day 4 postchallenge by up to 85% and reduced the adult worm burden up to 41% as compared with controls. The data also show that the molecular weights of the egg antigens detected by monoclonal antibody E.1 were different from those detected on schistosomula.
The Fab fragment of a directly activating monoclonal antibody that precipitates a disulfide-linked heterodimer from a helper T cell clone blocks activation by either allogeneic Ia or antigen and self-Ia.
Authors: Kaye J , Janeway C A
Published: June 2004

We characterize a monoclonal antibody directed against the antigen/Ia receptor of a cloned helper T cell line that induced T cell clone proliferation and T cell clone-dependent B cell proliferation at antibody concentrations as low as 10(-11) M. A Fab fragment of this antibody was not stimulatory, implicating cross-linking of antigen receptors as the primary signal for T cell activation. The Fab fragment inhibited activation of this clone by both allogeneic Ia and antigen plus self-Ia, but not by the nonspecific stimulators concanavalin A and rabbit anti-mouse brain serum. This strongly supports the hypothesis that a single molecule mediates both self-Ia plus antigen and non-self-Ia recognition. This molecule is presumably the disulfide-linked heterodimer comprised of 42,000 mol wt acidic and basic subunits precipitated by this monoclonal antibody. The cell surface and internal precursor forms of this protein are also identified. In addition, the response to allogeneic Ia stimulation was more readily inhibited by the Fab fragment than was the response to antigen plus self-Ia, suggesting that alloreactivity reflects a low affinity interaction with a ligand represented at high frequency on the stimulatory cell.
Genetic and biochemical characterization of human lymphocyte cell surface antigens. The A-1A5 and A-3A4 determinants.
Authors: Peters P M , Kamarck M E , Hemler M E , Strominger J L , Ruddle F H
Published: June 2004

The genes that code for the human lymphocyte cell surface determinants defined by monoclonal antibodies A- 1A5 and A- 3A4 have been genetically mapped. All human chromosomes, except Y, were included in a series of human less than mouse lymphocyte hybrid populations that retained expression of lymphocyte-specific surface markers. Expression of the A- 1A5 and A- 3A4 antigens was quantitated by indirect immunofluorescence and fluorescence-activated cell sorter (FACS) analysis. Hybrid populations heterogeneous for antigen expression were sorted to yield antigenically homogeneous subpopulations. Isozyme analysis indicated concordant segregation of the A- 1A5 determinant with chromosome 10, and the A- 3A4 determinant with chromosome 4. In contrast to the unhybridized human parent cell line (MOLT-4), from which A- 1A5 immunoprecipitated two proteins (160,000 and 125,000 Mr), A- 1A5 only immunoprecipitated a single band (125,000 Mr) from an A- 1A5 -expressing human less than mouse hybrid. The genetic disassociation of these two proteins from the A- 1A5 -reactive complex suggests that the appearance of the 160,000 Mr protein requires a gene locus that is unlinked to the locus for the 125,000 Mr protein on chromosome 10. A third component of the A- 1A5 -reactive protein complex (210,000 Mr), which is recognized by the monoclonal antibody TS2/7, was not expressed on the parent MOLT-4 cells, but was weakly expressed on MOLT-4 less than mouse BW5147 hybrids. This allowed preliminary mapping of that determinant to either chromosome 10 or 15. The A- 3A4 antigen (approximately 45,000 Mr) is a novel cell surface structure expressed on all hematopoietic cell lines tested, and represents the first cell surface marker mapped to chromosome 4.
Heterogeneity among human collagenases demonstrated by monoclonal antibody that selectively recognizes and inhibits human neutrophil collagenase.
Authors: Hasty K A , Hibbs M S , Kang A H , Mainardi C L
Published: June 2004

The heterogeneity of human collagenases has been examined using a monoclonal antibody to neutrophil collagenase. This antibody inhibited collagenase activity and, when covalently coupled to Sepharose, bound both latent and active enzyme. Although human neutrophil collagenase was inhibited by the antibody, the activity of human skin and rheumatoid synovial collagenase was not significantly diminished in the presence of the antibody. Competitive inhibition studies also differentiated between these collagenases. Only human neutrophil collagenase effectively blocked the antibody in a competitive enzyme-linked immunosorbent assay while skin and rheumatoid synovial collagenase again failed to interact with the antibody. The unequivocal recognition of neutrophil collagenase as an immunologically distinct entity from other collagenases supports the hypothesis that neutrophil collagenase is a separate gene product from fibroblast or synovial collagenase.
Suppressor T cell growth and differentiation. Identification of a cofactor required for suppressor T cell function and distinct from interleukin 2.
Authors: Rich S , Carpino M R , Arhelger C
Published: June 2004

This report describes a Ts costimulator assay and its use to analyze cofactors required for the expression of suppressor T cell function. Activation of primed MLR-Ts (alloantigen-activated suppressor T cells suppressive of mixed leukocyte reaction) to suppressor T cell factor (TsF) production typically fails in the presence of glutaraldehyde-fixed rather than irradiated allogeneic stimulator cells. However, MLR-TsF production was restored by the addition of 48-h primary MLR supernates; MLR-derived Ts costimulator neither activated primed MLR-Ts in the absence of fixed allogeneic stimulators nor directly suppressed assay MLR. Lack of antigen specificity or genetic restriction and failure to activate unprimed MLR-Ts precursors suggested that Ts costimulator activity differed from previously described Ts inducer functions and was more closely aligned with the lymphocyte- or monocyte-derived interleukins (IL). Three findings distinguished Ts costimulator from IL-2. Depletion of IL-2 activity from MLR supernates by HT2 adsorption failed to affect Ts costimulator function. In addition, MLR supernates prepared in the presence of cyclosporin A contained no IL-2 but expressed Ts costimulator activity. Finally, gel chromatography demonstrated Ts costimulator in peaks of 21,000 and 43,000 mol wt that were largely distinct from the IL-2-containing fractions. Ts costimulator activity was also identified in phorbol myristate acetate (PMA)-induced EL4 supernates and was retained in those supernates after IL-2 depletion by HT2 adsorption. In preliminary functional characterization, MLR supernate-derived Ts costimulator triggered MLR-TsF production from irradiated MLR-Ts in the absence of proliferation. Thus a differentiative rather than proliferative stimulus required for primed MLR-Ts function appears to be provided by this Ts costimulator and has been provisionally termed Ts differentiative factor ( TsDF ). This initial characterization may thus identify one of a possibly distinctive family of interleukins required in the alloantigen-driven activation of suppressor T cells to effector function.
Murine gamma interferon activates the release of a macrophage-derived Ia-inducing factor that transfers Ia inductive capacity.
Authors: Walker E B , Maino V , Sanchez-Lanier M , Warner N , Stewart C
Published: June 2004

In this report we demonstrate that when the murine macrophage tumor cell line P- 388D1 is incubated for 48-72 h with either concanavalin A-stimulated rat spleen cell supernatant or cloned murine immune interferon (IFN-gamma), the cultured cells release a cell-free factor activity that in turn induces the cell surface expression of Ia antigen on the murine monocyte cell line WEHI-3. This IFN-gamma-stimulated, Ia-inducing activity cannot be blocked with an anti-IFN-gamma heteroantiserum that does block the induction of Ia expression on WEHI-3 by both cloned murine IFN-gamma and rat Con A supernatant. The Ia-inducing factor ( IaIF ) generated from P- 388D1 after stimulation by IFN-gamma does not demonstrate any antiviral activity. The P- 388D1 -derived IaIF is not shed plasma membrane Ia glycoprotein molecules, as demonstrated by the inability of the active component to bind specifically to an anti-I-Ad affinity column or to a protein A column after the active supernatant is first treated with an excess of anti-I-E/Cd,k monoclonal antibody.
Two genes required for diabetes in BB rats. Evidence from cyclical intercrosses and backcrosses.
Authors: Jackson R A , Buse J B , Rifai R , Pelletier D , Milford E L , Carpenter C B , Eisenbarth G S , Williams R M
Published: June 2004

The BB rat develops a syndrome of autoimmune diabetes similar to Type I diabetes of man. It also has a severe T cell lymphopenia. As part of an ongoing breeding program to transfer the diabetogenic genes of the BB rat onto inbred rat strain backgrounds, diabetic animals were used in a backcross (BC)- intercross (IC)-backcross breeding scheme with Brown Norway (BN), Lewis (L), and Wistar-Furth (WF) inbred rats. We have used monoclonal antibodies to analyze both lymphopenia and major histocompatibility (MHC) antigens (the RT1 locus in the rat) in relation to the development of diabetes. To examine T cell subsets we used a panel of monoclonal antibodies, in particular W3/25 and OX19 , which discriminate the abnormal phenotype better than W3/13. In our breeding program, at least two independent genes or gene complexes are required for the expression of diabetes. One gene determines the lymphopenia, is inherited by simple autosomal recessive genetics and is not linked to the MHC. The second gene is linked to the MHC. Both genes are necessary, but neither gene is sufficient by itself for the development of diabetes.
Immunochemical analysis of the released Leu-2 (T8) molecule.
Authors: Fujimoto J , Stewart S J , Levy R
Published: June 2004

We recently have found that the human T cell antigen Leu-2 was specifically released from Leu-2-bearing cells. The preliminary study showed that the released Leu-2 (RLeu-2) from HPB-ALL cells was composed of a single polypeptide chain of 27,000 molecular weight (mol wt), which was smaller than the subunit of the homodimeric molecule found on the cell surface. In the present study, RLeu-2 was further characterized and compared with cellular Leu-2 (CLeu-2). Metabolically radiolabeled Leu-2 was released from HPB-ALL cells and this released Leu-2 molecule had a mol wt of 27,000. Cell surface radioiodinated HPB-ALL cells were found to release radioactive Leu-2 molecules and this antigen also had the same mol wt of 27,000. In both experiments, the CLeu-2 was reconfirmed to be composed of a 33,000-mol wt subunit under reducing conditions. These experiments establish that the 27,000-mol wt single polypeptide chain of Leu-2 released from the cell is derived directly from the homodimeric Leu-2 molecule on the cell surface, presumably by a specific proteolytic cleavage. Two-dimensional gel analysis showed that CLeu-2 exhibited extensive charge heterogeneity with predominantly basic isoelectric points, whereas RLeu-2 was a group of more acidic proteins with less charge heterogeneity. Although CLeu-2 and RLeu-2 showed several different immunochemical characteristics, the homology between these two antigens was confirmed by the following results: CLeu-2 and RLeu-2 were found to share at least three different antigenic determinants, Leu-2a and Leu-2b, and those which were detected by a polyvalent rabbit antiserum. Significant similarities between CLeu-2 and RLeu-2 were demonstrated by peptide mapping analysis of these antigens. Therefore, RLeu-2 appears to be the specific, physiological product of the CLeu-2 protein.
Proliferation of peritoneal mast cells in the skin of W/Wv mice that genetically lack mast cells.
Authors: Sonoda T , Kanayama Y , Hara H , Hayashi C , Tadokoro M , Yonezawa T , Kitamura Y
Published: June 2004

Presence of mast cell precursors in the mouse peritoneal cavity was demonstrated, and the precursors were characterized. When a cell suspension, containing mast cell precursor(s), was directly injected into the skin of genetically mast cell-deficient WBB6F1 (WB X C57BL/6)-W/Wv mice, a cluster composed of approximately 2,000 mast cells appeared at the injection site. By determining the proportion of injection sites at which the mast cell cluster appeared, the concentration of mast cell precursors can be calculated by limiting dilution analysis. The concentration in the peritoneal cavity was about five times as great as the concentration in the bone marrow. Although peritoneal mast cell precursors were shown to originate from the bone marrow, physical characterization revealed that the peritoneal precursors differed from the marrow precursors. The peritoneal precursors were less susceptible to irradiation than the marrow precursors; the former were heavier than the latter. When a 95% pure mast cell suspension was prepared from the peritoneal cells by the removal of phagocytes and the density gradient centrifugation, 1 out of 16 cells had the potentiality to make a mast cell cluster in the skin of the W/Wv mice. Moreover, when a single mast cell was identified under the phase contrast microscope and picked up with the micromanipulator, 1 out of 17 mast cells made the cluster. This indicated that some peritoneal mast cells kept extensive proliferative potentiality even after morphological differentiation. In other words, some peritoneal mast cells themselves may function as the committed precursors.
Enhancement of glomerular immune complex deposition by a circulating polycation.
Authors: Barnes J L , Venkatachalam M A
Published: June 2004

It is known that polycations bind to and neutralize glomerular polyanions. Here we examine the effect of the polycation polyethyleneimine (PEI) on glomerular deposition of preformed immune complexes. Bovine serum albumin (BSA)-anti-BSA immune complexes made in 40 times antigen excess were administered following intravenous injection of PEI. Glomerular localization of immune deposits was assessed by quantitative immunofluorescence and electron microscopy and compared to controls receiving diluent without PEI followed by the same dose in immune complexes. In rats receiving PEI, deposits were localized within the glomerular basement membrane (GBM) of all peripheral capillary walls and in the mesangium. In controls, deposits localized exclusively within the mesangium in smaller amounts than after PEI. Thus, neutralization of glomerular polyanion by a circulating polycation enhances the deposition and alters the distribution of immune complexes in glomeruli.
Localization of a molecule immunochemically similar to eosinophil major basic protein in human placenta.
Authors: Maddox D E , Kephart G M , Coulam C B , Butterfield J H , Benirschke K , Gleich G J
Published: June 2004

We have recently reported that human pregnancy is characterized by a 10- to 20-fold elevation of eosinophil major basic protein (MBP) immunoreactivity in maternal blood. Here we show, by immunofluorescence, that placental tissue specifically binds antibody to MBP in and around the placental X cells and placental-site giant cells and, using thin plastic sections, that placenta has no infiltrating eosinophils. The X cells line the inner aspects of placental septal cysts, and the cyst fluid, obtained by aspiration, contains immunoreactive MBP at concentrations of 100 micrograms/ml, a sixfold greater concentration than the highest levels measured in maternal blood. The soluble MBP immunoreactivities in placental homogenates and in maternal serum chromatograph identically on Sephadex G-50, and both these gestational MBP molecules migrate as though substantially larger than the MBP found in serum from patients with hypereosinophilic syndrome or purified from the eosinophil granule. Our inability to demonstrate eosinophils in maternal blood or placental tissue, coupled with the large quantities of immunoreactive MBP highly localized in placental cysts and the chromatographic behavior of this molecule, suggest that the MBP detected in human gestation is produced by placenta.
Immune response-associated production of neopterin. Release from macrophages primarily under control of interferon-gamma.
Authors: Huber C , Batchelor J R , Fuchs D , Hausen A , Lang A , Niederwieser D , Reibnegger G , Swetly P , Troppmair J , Wachter H
Published: June 2004

Neopterin, a compound derived from GTP, represents a precursor molecule of biopterin that is an essential cofactor in neurotransmitter synthesis. We have recently reported that in vivo as well as in vitro immune responses are accompanied by an increased release of neopterin and that this phenomenon can be used for the biochemical monitoring of diseases accompanied by hyperimmune stimulation. This article deals with the cellular origin and the control of this immune response-associated neopterin release in vitro. Using highly purified or monoclonal cellular reagents we demonstrate that macrophages (M phi) stimulated with supernatants from activated T cells release large amounts of neopterin into culture supernatants. Further experiments involving induction of neopterin release from M phi with various human recombinant interferons (IFNs) or neutralization of the effect of T cell supernatants with various monoclonal anti-IFN antibodies revealed immune IFN as the active principle. It thus appears that a metabolic pathway so far exclusively known in context with the generation of an essential cofactor of neurotransmitter-synthesis during immune responses is also activated in M phi under stringent control by immune IFN-like lymphokines.
Expression of H-2Db on the cell surface in the absence of detectable beta 2 microglobulin.
Authors: Potter T A , Boyer C , Verhulst A M , Golstein P , Rajan T V
Published: June 2004

In this report we describe a variant of the C57BL/6 T lymphoma EL4 (EL4/Mar) which, in contrast to the parental cell line, expresses neither H-2Kb nor beta2-microglobulin (beta2m) but which does express H-2Db detectable by serology and by alloreactive cytotoxic T lymphocytes (CTL). This observation raises the possibility that H-2Db and perhaps other major histocompatibility complex class I molecules are normally not associated with beta2m on the cell surface. In addition, this report is the first to indicated that alloreactive CTL can interact with a beta2m-free class I antigen.
Isolation, characterization, and propagation in vitro of human glomerular endothelial cells.
Authors: Striker G E , Soderland C , Bowen-Pope D F , Gown A M , Schmer G , Johnson A , Luchtel D , Ross R , Striker L J
Published: June 2004

Human glomerular endothelial cells have been isolated, cloned, and characterized. They appeared as the first outgrowth from human glomeruli in the presence of platelet-derived growth factor, which was also a requirement for continuous growth. By phase microscopy they appeared as monolayers of polygonal cells. Von Willebrand's factor (VWF) was detected in the cytoplasm of all clones. Their intermediate filaments differed antigenically from that present in human umbilical vein endothelial cells. Like other endothelial cells, they demonstrated high levels of membrane-associated angiotensin-converting enzyme (ACE).
Selection of genetic variants of lymphocytic choriomeningitis virus in spleens of persistently infected mice. Role in suppression of cytotoxic T lymphocyte response and viral persistence.
Authors: Ahmed R , Salmi A , Butler L D , Chiller J M , Oldstone M B
Published: June 2004

We studied the mechanism of lymphocytic choriomeningitis virus (LCMV) persistence and the suppression of cytotoxic T lymphocyte (CTL) responses in BALB/c WEHI mice infected at birth with LCMV Armstrong strain. Using adoptive transfer experiments we found that spleen cells from persistently infected (carrier) mice actively suppressed the expected LCMV-specific CTL response of spleen cells from normal adult mice. The suppression was specific for the CTL response and LCMV -specific antibody responses were not affected. Associated with the specific CTL suppression was the establishment of persistent LCMV infection. The transfer of spleen or lymph node cells containing LCMV -specific CTL resulted in virus clearance and prevented establishment of the carrier state. The suppression of LCMV -specific CTL responses by carrier spleen cells is not mediated by a suppressor cell, but is due to the presence of genetic variants of LCMV in spleens of carrier mice. Such virus variants selectively suppress LCMV-specific CTL responses and cause persistent infections in immunocompetent mice. In striking contrast, wild-type LCMV Armstrong, from which these variants were generated, induces a potent CTL response in immunocompetent mice and the LCMV infection is rapidly cleared. Our results show that LCMV variants that emerge during infection in vivo play a crucial role in the suppression of virus-specific CTL responses and in the maintenance of virus persistence.
A major anti-myoglobin idiotype. Influence of H-2-linked Ir genes on idiotype expression.
Authors: Kawamura H , Kohno Y , Busch M , Gurd F R , Berzofsky J A
Published: June 2004

A rabbit antiidiotypic antiserum raised against an A.SW IgG1K monoclonal anti-sperm whale myoglobin (Mb) antibody, HAL19, and extensively absorbed with normal mouse immunoglobulin and MOPC 21 (IgG1K), was found to detect a common or major anti-Mb idiotype expressed by some but not all anti-Mb monoclonal antibodies, regardless of immunoglobulin G (IgG) subclass, and by 40-50% of the anti-Mb antibodies in immune serum from five high responder strains of mice representing five different Igh allotypes. It did not inhibit antibodies to three unrelated protein antigens. The fraction of antibodies expressing this idiotype, denoted IdHAL19, was regulated by H-2-linked genes that correlated exactly in four independent haplotypes and an F1 with the known Mb immune response (Ir) genes and may be identical to these. Whereas less than 50% of antibodies from high responder mice were inhibitable by anti-IdHAL19, greater than 80% of antibodies from low responder mice, tested at comparable final antibody concentration, were inhibitable. This result was true for both low responder haplotypes, H-2b (B10) and H-2k (B10.BR). The idiotype was found to be present on antibodies that bound to native Mb but not fragments 1-55 or 132-153 of Mb or a denatured form, S-methyl Mb. This specificity for native Mb paralleled that of the monoclonal idiotype HAL19 itself. Therefore, the production of antibodies specific for native in contrast to denatured Mb was studied in H-2-congenic high and low responder strains. Strikingly, low responders produced antibodies that reacted almost exclusively with the native conformation, whereas a larger proportion of antibodies from high responder mice also reacted with the denatured form, S-methyl Mb. Bypassing of the Ir gene defect by immunization with Mb attached to a carrier, F gamma G, resulted in low responder antisera resembling higher responder sera in both idiotype expression and conformational specificity. The simplest explanation of these results is that H-2-linked Ir genes control antibody fine specificity, which is reflected in the idiotypes of the variable regions expressed. We suggest that low responder mice produce a more limited repertoire of antibodies consisting primarily of IdHAL19-positive antibodies specific for the native conformation of Mb. High responder mice produce a greater diversity of antibodies to Mb, so that the IdHAL19-positive, conformation-specific population represents a smaller proportion of the total. Similarly, the use of carrier-specific helper T cells in low responder mice results in a greater diversity of antibodies, which dilutes out the IdHAL19 subset.(ABSTRACT TRUNCATED AT 400 WORDS)
Analysis of thymocyte MHC specificity with thymocyte hybridomas.
Authors: Yeh E T , Benacerraf B , Rock K L
Published: June 2004

Medullary, peanut agglutinin-negative (PNA-), thymocytes were activated in vitro with either exogenous interleukin 1 (IL-1) or accessory cells. T cell blasts from these cultures were subsequently fused to BW5147 to generate thymocyte hybridomas. Fusion frequencies similar to those obtained with peripheral T lymphocytes were observed. A high frequency of these hybrids are triggered to produce IL-2 in the presence of syngeneic accessory cells. Exogenous, nominal antigens do not appear to be required for this activation. Using accessory cells from a series of recombinant inbred mice, the specificity of this hybrid-accessory cell interaction could be mapped to either I-Ak or I-Ek or both. This was confirmed by blocking with alpha Ia monoclonal antibodies (mAbs). A high frequency of these self-reactive cells are also alloreactive. Interestingly, several clones were identified that appear to recognize public Ia determinants broadly shared by different alleles and genetic subregions. Such specificities appear to contrast with those of peripheral T lymphocytes whose specificity is dominated by the genetically polymorphic portion of the Ia molecule. These results document the clonal specificity occurring in the cultures of in vitro activated thymocytes and allow an analysis of at least a portion of the intrathymic repertoire for major histocompatibility complex (MHC) determinants. The implications of these findings are discussed.
In vitro alteration of receptors for vasoactive intestinal peptide changes the in vivo localization of mouse T cells.
Authors: Ottaway C A
Published: June 2004

The capacity of T lymphocytes exposed in vitro to the neuropeptide vasoactive intestinal peptide (VIP) to bind VIP in vitro and to migrate to different tissues in vivo has been studied. VIP treatment of T cells resulted in a time- and dose-dependent loss of the ability of T cells to specifically bind radioiodinated VIP. Altered binding was due to a decrease in the expression of cellular receptors for VIP on the treated cells rather than an alteration in the affinity of the cells for the neuropeptide. Alteration of VIP receptor expression was not associated with a change in the expression of Thy-1, Lyt-1, or Lyt-2 surface markers by the treated cells. VIP treatment of T cells in vitro resulted, however, in a dose-dependent decrease in the ability of the treated cells to localize in mesenteric lymph nodes (MLN) and Peyer's patches of recipient animals at early times after cell transfer, and this was due to a selective decrease in the rate of accumulation of the treated cells in these tissues. There was no alteration in the distribution of VIP-treated cells in the blood, spleen, liver, or other major organs of the recipient animals. It is concluded that the presence of VIP receptors on T cells facilitates the entry of T cells into MLN and Peyer's patches in vivo, and it is proposed that this effect is mediated by T cell-VIP interactions in the vicinity of the specialized endothelium of those tissues.
Long-term cultures of murine fetal liver retain very early B lymphoid phenotype.
Authors: Denis K A , Treiman L J , St Claire J I , Witte O N
Published: June 2004

Long-term cultures of murine fetal liver have been successfully established using a modification of our in vitro bone marrow culture system (14, 15). Fetal liver cells from midgestation BALB/c embryos were plated onto BAB-14 bone marrow stromal cell-adherent layers. After a 3-5 wk period, cell growth began to increase and these cells were expanded in number on fresh feeder layers. The cultured fetal liver cells were lymphoid in morphology, 5-20% cytoplasmic Ig-positive, but less than 1% surface Ig-positive. Southern blot analysis of the cultured fetal liver cells, as well as cultured bone marrow-derived B cells, demonstrated a population with germline Ig heavy chain loci, possibly representing very early B cell precursors. Abelson murine leukemia virus (A-MuLV) clonal transformants of such cultured fetal liver cells had a phenotypic distribution similar to that seen with fresh fetal liver transformants but distinct from those obtained with the transformation of either cultured or fresh bone marrow. All A-MuLV transformants isolated had rearrangements at the mu heavy chain locus of both chromosomes, irrespective of Ig production. In addition, most mu heavy chain producers had at least one rearranged kappa gene locus. These long-term fetal liver cultures provide large numbers of cells for studying events early in the B lymphocyte lineage. The cultured fetal liver cells retained phenotypic traits similar to fresh fetal liver B cells and distinctive from bone marrow cells cultured under similar conditions.
Low and high affinity cellular receptors for interleukin 2. Implications for the level of Tac antigen.
Authors: Robb R J , Greene W C , Rusk C M
Published: June 2004

Interleukin 2 promotes proliferation of T cells by virtue of its interaction with a high-affinity cell surface receptor. This receptor is a 55,000 mol wt glycoprotein that is also recognized by the murine monoclonal antibody, anti-Tac. Quantitative binding studies with radiolabeled IL-2 and anti-Tac, however, initially indicated far more antibody binding sites per cell than IL-2 binding sites. Extension of the IL-2 binding analysis to concentrations several thousand-fold higher than that necessary for the T cell proliferative response demonstrated the existence of a class (or classes) of low-affinity IL-2 binding sites. Inclusion of the low-affinity IL-2 binding greatly reduced the quantitative discrepancy in the ligand binding assays. That the low-affinity binding, as well as the high-affinity interaction, was associated with the Tac molecule was indicated by the finding that the antibody could substantially or totally block the entire spectrum of IL-2 binding and by the finding that IL-2 could in turn block all radiolabeled anti-Tac binding. The low-affinity sites were found on activated T cells, several human and murine T cell lines and two examples of Tac-positive B cells. The physiological role of the low-affinity IL-2 binding sites and the molecular changes in the Tac protein that give rise to the affinity differences remain open to investigation.