bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and release of erythroid colony- and burst-potentiating activities by purified populations of murine peritoneal macrophages
Authors: Kurland JI , Meyers PA , Moore MAS
Published: June 2004

We investigated the effects of murine resident peritoneal macrophages on the in vitro proliferation of erythropoietin (Ep)-sensitive committed precursors colony-forming unit-erythroid (CFU-E) and burst-forming unit-erythroid (BFU-E) with a two-layer cloning system of methylcellulose and semisolid agar. The addition of increasing numbers of macrophages to the agar underlayer resulted in a progressive increase in the numbers of both CFU-E and BFU-E that proliferated in the presence of Ep. CFU-E, but not BFU-E, proliferated to form colonies in the absence Qf exogenously added Ep, and this proliferation was enhanced in a dose-dependent fashion by the presence of macrophages in the underlayer. The enhancing effects of a given number of macrophages and a given concentration of Ep were greater than the sum of the individual effects of macrophages and Ep alone. This erythropoietic syngerism was more evident with BFU-E because burst formation was not seen in the absence of exogenously added Ep. Macrophage underlayers stimulated three to five times the number of erythroid bursts seen with Ep alone. Cell-free agar underlayers or agar underlayers prepared with nonadherent peritoneal cells or unseparated cells from thymus, lymph node, or spleen failed to augment Ep- dependent erythroid colony formation. No enhancement of CFU-E or BFU-E was demonstrable after depletion ofadherent cells from peritoneal cell suspensions by passage over columns of Sephadex G-10. Analysis by sedimentation velocity of peritoneal cells confirmed that the cells responsible for elaborating the erythroid-enhancing activity were macrophages on the basis of morphologic, histochemical, and functional criteria. Serum- free media conditioned by macrophages in the absence of Ep contained the erythroid-enhancing activities, which indicated that Ep was not required for the elaboration of these diffusible substances. These studies indicate that although macrophages are not obligate for the growth of erythroid precursors, they serve as an important source of diffusible factors that reduce the in vitro requirement for Ep.
Structural studies on induced antibodies with defined idiotypic specificities. IX. Framework differences in the heavy- and light-chain-variable regions of monoclonal anti-p-azophenylarsonate antibodies from A/J mice differing with respect to a cross-reactive idiotype.
Authors: Estess P , Lamoyi E , Nisonoff A , Capra J D
Published: June 2004

Amino terminal amino acid sequence analyses have been performed on the heavy and light chains of induced monoclonal antibodies with specificity for the hapten p-azophenylarsonate. Four of the eight antibodies react with conventional antisera to the previously described A/J anti-arsonate cross-reactive idiotype (CRI). Of the 16 chains analyzed, all but one contain sequence differences in their first framework segment (residues 1-30) that distinguish them from the heavy- and light-chain sequences found in anti-arsonate antibodies isolated from A/J serum or ascites fluid. The presence of such framework differences appears to be independent of whether or not the hybridoma antibodies bear the CRI. In spite of the framework substitutions, all four of the CRI-positive hybridoma antibodies have variable (V)-region frameworks that are very similar to each other and to the CRI-positive molecules found in A/J serum. Two of the four CRI-negative molecules are also structurally similar to the serum antibodies. Two others, however, are strikingly different from any serum anti-arsonate antibody thus far described and appear to reflect a completely separate repertoire of anti-arsonate antibodies in the A/J MOUSE. In addition, serological analyses with an anti-idiotypic antiserum generated against a CRI-positive hybridoma product suggest that each monoclonal antibody may possess individual antigenic specificities different from the determinant(s) detected with the conventional rabbit anti-CRI. The consistent appearance of framework substitutions in what has been thought to be a homogeneous antibody population has important implications for our understanding of the generation of antibody diversity and for the precise chemical definition of an idiotype.
Antigen- and receptor-driven regulatory mechanisms. III. Induction of delayed type hypersensitivity to azobenzenearsonate with anti-cross-reactive idiotypic antibodies.
Authors: Sy M S , Brown A R , Benacerraf B , Greene M I
Published: June 2004

Delayed-type hypersensitivity (DTH) to p-azobenzenearsonate (ABA) can be induced in A/J mice with intravenous injection of minute amounts of anti-cross-reactive idiotypic (CRI) antibodies, providing that the animals have been pretreated 2 d earlier with low doses of cyclophosphamide (50 mg/kg). However intravenous injection of the F(ab')2 fragments of the anti-CRI antibodies or subcutaneous administration with anti-CRI antibodies induces comparable immunity in both cyclophosphamide-pretreated and normal nontreated animals. Furthermore adoptive transfer experiments indicate that lymph node cells taken from animals sensitized with anti-CRI 4 d earlier can adoptively transfer immunity to naive recipients. Transfer of immunity is mediated by a population of thymus-dependent (T) cells, which express idiotypic structures on their surface. Treatment of effector cells with either anti-theta serum or anti-idiotypic antibodies plus complement completely abrogated their ability to transfer immunity. In addition idiotype-bearing suppressor T cells induced with ABA-coupled spleen cells inhibit the development of ABA-specific DTH induced with anti-CRI antibodies. Genetic analysis revealed that the ability of anti-CRI antibodies to induce ABA-specific DTH was linked to Igh-1 heavy-chain allotype. Anti-idiotypic antibodies to the major CRI associated with anti-ABA antibodies in A/J mice failed to induce significant immunity in BALB/c mice (H-2d, Igh-1a). Nevertheless, they were able to induce significant immunity in C.AL20 mice (H-2d, Igh-1d) which possess a heavy-chain allotype similar to that of A/J mice.
Hepatocyte-tumor cell interaction in vitro. I. Conditions for rosette formation and inhibition by anti-H-2 antibody.
Authors: Schirrmacher V , Cheingsong-Popov R , Arnheiter H
Published: June 2004

Murine hepatocytes, isolated by an in situ collagenase-perfusion technique and cultured in Petri dishes, were shown to form rosettes with liver-metastasizing syngeneic tumor cells. Pretreatment of the tumor cells with neuraminidase generally increased the binding, whereas pretreatment of the liver cells with neuraminidase abolished the binding completely. The tumor-cell binding may be mediated by the previously described lectin-like receptor of hepatocytes that also was sensitive to neuraminidase treatment and that bound desialylated cells better than normal cells. Anti-H-2 sera could efficiently inhibit the rosette formation of metastatic tumor cells with the hepatocytes, which points to a possible role of H-2 molecules in this interaction of neoplastic and normal cells.
Quantitation of influenza virus antigens on infected target cells and their recognition by cross-reactive cytotoxic T cells.
Authors: Hackett C J , Askonas B A , Webster R G , van Wyke K
Published: June 2004

Monoclonal antibody to type-A influenza virus matrix (M)-protein was used to quantitate the appearance of M-protein on abortively infected P815 cells. After 16 h of infection with different type-A viruses, only a low amount of M-protein appears on the surface of infected cells (approximately 10(3) site/cell) in contrast to approximately 10(5) hemagglutinin molecules on each cell surface. However, virus replication is required for M-protein appearance. Analysis of solubilized membranes purified from 16-h-infected cells shows approximately 10(4) M-protein molecule/cell in the plasma membrane, a content that is consistent with the observed low surface expression, and that indicates that most of the M-protein is localized internally. We found no evidence that cross-reactive cytotoxic T cells could recognize M-protein; neither monoclonal antibody or hyperimmune anti-M-protein antiserum could inhibit T cell killing, either alone or in combination with monoclonal anti-H-2 antibody. Taken together, the low level of M-protein appearance and lack of T cell blocking by anti-M-protein antibody leaves doubt that M-protein is the antigen recognized by cross-reactive cytotoxic T cells.
Role of I-region gene products in macrophage induction of an antibody response. II. Restriction at the level of T cell in recognition of I-J-subregion macrophage determinants.
Authors: Niederhuber J E , Allen P
Published: June 2004

The effect of specific anti-I-J reagents on macrophage-T cell interactions was studied in an in vitro antibody response to burro erythrocytes. Macrophages were prepared from the spleens of F1 hybrid mice whose parental strains differed at the I-J subregion. Two F1 hybrids were used for these experiments, [B10.A(3R) X B10.A(5R)]F1 and [B10.S(9R) X B10.HTT]F1. F1 macrophages responded equally well with F1 T-B cells or with T-B cells of either parental strain. When F1 macrophages were pretreated with anti-I-J serum (without complement) specific for one parental haplotype, they were only able to cooperate with T helper (TH) cells of the unblocked haplotype and with F1 TH cells. Identical results were obtained with (Jb X Jk)F1 and (Js X Jk)F1 mice. The results indicate that TH cells possess genetically restricted receptors for macrophage I-J-subregion gene products and that the interaction between this receptor and the macrophage I-J-subregion determinants is essential for the initiation of a primary in vitro antibody response to an erythrocyte antigen.
Role of alloantigens in natural killing. Allogeneic but not autologous tumor biopsy cells are sensitive for interferon-induced cytotoxicity of human blood lymphcoytes.
Authors: Vánky F T , Argov S A , Einhorn S A , Klein E
Published: June 2004

Blood lymphocytes of patients with solid tumors were assayed for cytotoxicity against autologous and allogeneic primary tumor cells. The lymphocytes killed autologous tumor cells in 7 of 25 cases (28%) and allogeneic tumor cells in 2 of 37 tests (5%). Lymphocytes from healthy donors were rarely cytotoxic for the biopsy cells, which indicates that these cells have low natural kill sensitivity. The autoreactivity that may reflect the immunological recognition of tumor cells was not altered by pretreatment of the effectors with interferon (IF). In contrast, killing of allogeneic tumor biopsy cells was induced by IF in approximately 50% of tests, with the lymphocytes of both the tumor patients and the healthy donors. The mechanism of the alloreactivity is most likely a consequence of IF-induced polyclonal activation of cytotoxic potential and the lymphocytes that are committed to recognize the alloantigens expressed on the particular target manifest the killing function. When the biopsy cells were explanted and kept in culture for 5-6 d, their susceptibility for the lymphocyte damage increased, and they were killed by the IF-treated cells also in autologous combinations. Whether this change in sensitivity is a result of qualitative or quantitative changes in antigen expression or of other changes in the properties of the cell membrane is unknown.
Contribution of dendritic cells to stimulation of the murine syngeneic mixed leukocyte reaction.
Authors: Nussenzweig M C , Steinman R M
Published: June 2004

We have studied the proliferative response of unprimed T cells to syngeneic dendritic cells (DC) (syngeneic mixed leukocyte reaction [SMLR]) in cultures of mouse spleen and lymph node. T cells purified by passage over nylon wool contain few DC and exhibits little proliferative activity during several days of culture. Addition of small numbers of purified syngeneic DC induces substantial, dose-dependent, T cell-proliferative responses that peak at day 4-5. B cells purified on anti-Ig-coated plates do not respond to DC at all doses tested. DC culture medium does not induce proliferation, and coculture of DC and T cells is required. Purified mouse B and T lymphocytes stimulate SMLR weakly if at all. Likewise, peritoneal and spleen macrophages are weak or inactive. Therefore, DC are potent and possibly unique primary cells for stimulating the SMLR in mice. sIg- spleen and lymph node cells show extensive background proliferative responses in vitro, and fail to respond to small numbers of purified DC. If the sIg- cells are treated with anti-Ia and complement, or passed over nylon wool, DC are removed and proliferative activity falls. Proliferative activity is restored by adding back DC at levels similar to those present in sIg- cells (1-2%). Thus, DC-dependent, T cell proliferation probably occurs in all spleen and lymph node cultures. As expected from previous work (6), DC are also potent inducers of allogeneic MLR. On a per DC basis, the syngeneic response is 10 times weaker than the allogeneic MLR, and it is not accompanied by the development of cytotoxic lymphocytes. The magnitude of the SMLR was not altered by antigen priming, and DC maintained in isologous rather than fetal calf serum were active stimulators. Therefore, syngeneic stimulation appears to be an intrinsic property of DC, and modification by exogenous agents does not seem to be required. Coculture of DC and T cells results in the development of cell clusters that can be isolated and characterized directly. The clusters account for 10-20% of the viable cells in the culture, but contain greater than 80% of the responding T cells and stimulating DC by morphologic and surface-marker criteria. The efficient physical association of DC and responding T cells implies specific cell-cell recognition. We conclude that the SMLR reflects the ability of T cells, or some subpopulation of T cells, to interact with and proliferate in response to small numbers of DC.
Lymphocyte cooperation is required for amplification of macrophage procoagulant activity.
Authors: Levy G A , Edgington T S
Published: June 2004

Murine splenic lymphoid cells have been shown to possess basal procoagulant activity. This activity was localized to most macrophages by assay of cell populations, as well as by a direct plaque assay that permitted identification of expressed procoagulant activity of individual viable cells as well as content. Both content and viable expression of procoagulant activity was markedly increased by exposure to bacterial lipopolysaccharide, reaching a maximum after 6 h. The quantitative increase in procoagulant activity content and viable expression was limited to the macrophage population. Separated populations of lymphocytes or macrophages could not be stimulated by lipopolysaccharide to increase procoagulant activity, whereas the addition of lymphocytes to macrophages at a 3-4:1 ratio maximally reconstituted the amplification of procoagulant activity. Further evidence of cellular collaboration followed from observation that only lymphocytes that had been exposed to lipopolysaccharide were capable of triggering the increase in macrophage procoagulant activity. This appears to represent a new form of lymphocyte-macrophage cooperation in an effector pathway that may participate in some forms of immunologic responses and contribute to the phenotypic features of certain immunologic tissue lesions.
Lymphocyte membrane IgG and secreted IgG are structurally and allotypically distinct.
Authors: Oi V T , Bryan V M , Herzenberg L A , Herzenberg L A
Published: June 2004

We have demonstrated that there are structurally distinct membrane and secreted IgG2a immunoglobulin molecules. The membrane heavy chain is both larger and more acidic than the secreted molecule. This difference is not a result of different N-glycosidic-linked oligosaccharide chains. The membrane heavy chain also is antigenically different from its secreted homologue. This is based on the fact that secreted IgG2a molecules express an allotypic determinant absent on membrane molecules. We discussed the genetic control and gene organization of membrane and secreted immunoglobulin heavy chain sequences and suggest mechanisms controlling the expression of the simian virus 40 genome as models for alternate gene expression of membrane and secreted heavy chain polypeptide chains from the same DNA sequence. The possible biological significance of the membrane immunoglobulin acting as a recognition site for regulatory T cells also is discussed. The difference between membrane and secreted immunoglobulin is proposed as a possible explanation for the manner in which T cells interact with IgG on memory B cells in the presence of a large excess of IgG present in body fluids.
The role of specific antibody in alternative complement pathway-mediated opsonophagocytosis of type III, group B Streptococcus.
Authors: Edwards M S , Nicholson-Weller A , Baker C J , Kasper D L
Published: June 2004

The native capsular polysaccharide antigen of type III, group B Streptococcus contains a terminal sialic acid residue on each repeating unit that masks all end-group galactopyranose residues and prevents alternative pathway complement activation by adult human sera in the absence of type-specific antibody. The critical role of the sialic acid residues in allowing the organism to evade activating the alternative complement pathway was shown when neuraminidase treatment of the organism converted the bacteria to activators of the alternative pathway as assessed in agammaglobulinemic serum. The requirement for specific antibody in permitting alternative pathway activation by the fully sialated bacteria was shown when sera that contained low levels of specific antibody failed to activate this pathway, and when prior absorption of serum that contained higher type-specific antibody levels with the capsular antigen failed to activate this pathway. The use of C2-deficient sera showed that the calssical pathway was not required for antibody-dependent alternative pathway activation. The use of isotonic, pH 7.5, veronal-NaCl buffer that contained 1% gelatin and that was supplemented to 4 mM Mg++ and 16 mM EGTA and adjusted to pH 7.5 (MgEGTA) ruled out the participation of the C1-bypass pathway. The presence of sialic acid on the bacterial surface is one means of evading an important mechanism of natural immunity, namely activation of complement by the alternative pathway. Only specific antibody, i.e., acquired immunity, can overcome this virulence factor.
Self H-2 antigens influence the specificity of alloreactive cells.
Authors: Hünig T , Bevan M J
Published: June 2004

We have tested Jerne's hypothesis (9) that the phenomenon alloreactivity is explained by the existence of T cells that express germline-encoded receptors specific for major histocompatibility complex antigens and that these cells undergo no change in specificity during thymic differentiation. T cells from [F1 leads to Parent] bone marrow radiation chimeras reactive to conventional antigens are known to have a self preference, i.e., [A X B leads to A] chimeras respond better to H-2A-plus-antigen than to H-2B-plus-antigen. We show here that alloreactive cells from such chimeras also have a self preference. Thus, H-2k-specific alloreactive T cells from [H-2b X H-2d leads to H-2b] and [H-2b X H-2d leads to H-2d] chimeras cross-react more on TNP-modified H-2b or H-2d targets, respectively. In contrast to Jerne's prediction, the results suggest that the receptor repertoire of alloreactive F1 cells is influenced by H-2 antigens on radiation-resistant cells present during T cell ontogeny. By this criterion of having a self preference in H-2 restriction, alloreactive T cells appear to be similar to T cells that respond to conventional antigens.
Recognition of histocompatibility determinants controls reactivity of auto-sensitized lymphocytes against neural tissues.
Authors: Cunningham J , de Vere-Tyndall A , McCullagh P
Published: June 2004

Thoracic duct lymphocytes from rats sensitized against syngeneic spinal cord rapidly produce damage in cultures of syngeneic cerebellar cells but coexist indefintely with allogeneic cultures. Lymphocytes from donors that have been sensitized against allogeneic spinal cord attack cultures of syngeneic and specific allogeneic cerebellum but not cells from rats of a third, unrelated strain.
T200 cell surface glycoprotein of the mouse. Polymorphism defined by the Ly-5 system of alloantigens.
Authors: Omary M B , Trowbridge I S , Scheid M P
Published: June 2004

The cell line BW5147, and a mutant T200-negative cell line derived from BW5147, were studed by immunoprecipitation and peptide mapping, with xenogeneic monoclonal anti-T200 serum and with Ly-5 alloantiserum. It appears that the Ly-5 system defines a structural polymorphism of the cell surface glycoprotein T200, and that the monoclonal anti-T200 serum defines a feature of T200 that is common to mice of both Ly-5a and Ly-5b genotypes and may be invariable in the species.
Clonal analysis of cytolytic T lymphocyte specificity. I. Phenotypically distinct sets of clones as the cellular basis of cross-reactivity to alloantigens.
Authors: Taswell C , MacDonald H R , Cerottini J C
Published: June 2004

The cellular basis of the cytolytic cross-reactivity observed in primary allogeneic (C56BL/6 anti-DBA/2 and C57BL/6 anti-C3H/He) mixed-leukocyte cultures (MLC) was investigated by analysis of the specificity of clonal progeny derived from individual cytolytic T lymphocyte (CTL) precursor cells (CTL-P) contained within these populations. A sensitive mixed-leukocyte microculture (micro-MLC) technique was used with limiting dilution analysis by Poisson statistics to determine the frequency of CTL-P reactive against both specific and third-party (P815 and AKRA) target cells, to calculate the probability that each micro-MLC was a clone derived from a single CTL-P, and to examine the specificity of each micro-MLC assayed separately against both target cells. A total of 287 phenotypically specific, heteroclitic, and cross-reactive micro-MLC from the 2 different strain combinations were observed with a relative frequency of 81, 11, and 8%, respectively, and were calculated to have mean clone probability of 90 and 99% when based, respectively, upon the frequencies of CTL-P reactive against the specific and third-party target cells. These clones were estimated to have an approximate size of 6 X 10(4) cells, which corresponded to roughly 16 cell doublings during the 7 d of culture. 22 clones were successfully subcloned and in virtually every case, the subclones retained the specificity phenotype of the original clone from which they were derived. These results provide direct evidence for three phenotypically distinct sets of CTL as the cellular basis of cross-reactivity in MLC populations assayed against two different target cells.
Gene complementation. Neither Ir-GLphi gene need be present in the proliferative T cell to generate an immune response to Poly(Glu55Lys36Phe9)n.
Authors: Longo D L , Schwartz R H
Published: June 2004

The cellular requirements for immune response (Ir) gene expression in a T cell proliferative response under dual Ir gene control were examined with radiation-induced bone marrow chimeras. The response to poly(Glu55Lys36Phe9)n (GLphi) requires two responder alleles that in the [B10.A X B10.A(18R)]F1 map in I-Ab and I-Ek/Cd. Chimeras in which a mixture of the nonresponder B10.A parental cells (which possess only I-Ek/Cd) and the nonresponder B10.A(18R) parental cells (which possess only I-Ab) were allowed to mature in a responder F1 environment did not respond to GLphi, which suggests that at least one cell participating in the response needed to possess both responder alleles to function. When T cells from such A + 18R leads to F1 chimeras were primed in the presence of responder antigen-presenting cells (APC), the chimeric T cells responded to GLphi, which suggests that both responder alleles must be expressed in the APC but not necessarily in the T cell. Interestingly, acutely irradiated F1 animals were found not to be an adequate source of responder APC for priming the proliferating T cell because of the rapid turnover of peripheral APC after irradiation. In adoptive transfer experiments, T cell-depleted bone marrow had to be used as a source of responder APC. When bone marrow cells from (B10.A X B10)F1 responder animals were allowed to mature in a low-responder B10 of B10.A parental environment, neither chimera, F1 leads to A or F1 leads to B, could respond to GLphi. This demonstrated that the presence of high-responder APC, which derive from the donor bone marrow, was not sufficient to generate a GLphi response. It appears that in addition it is essential for the T lymphocytes to mature in a high-responder environment. Finally, B10.A(4R) T cells, which possess neither Ir-GLphi responder allele, could be educated to mount a GLphi-proliferative response provided that they matured in a responder environment and were primed with APC expressing both responder alleles. Therefore, the gene products of the complementing Ir-GLphi responder alleles appear to function as a single restriction element at the level of the APC. T cells that do not possess responder alleles are not intrinsically defective, because they could be made phenotypic responders if they developed in an environment in which responder major histocompatibility complex (MHC) products were learned as self and if antigen was presented to them by APC expressing responder MHC products.
Homology between a histidine-rich protein from Plasmodium lophurae and a protein associated with the knob-like protrusions on membranes of erythrocytes infected with Plasmodium falciparum.
Authors: Kilejian A
Published: June 2004

The incorporation of several radioactive amino acids into the knob protein of Plasmodium falciparum was compared. Histidine showed better incorporation than proline. A protein hydrolysate, which had all major amino acids except histidine and methionine, showed relatively poor incorporation as compared with proline, and no labeling could be detected with methionine or leucine. These results strongly suggest that the amino acid composition of the knob protein has the same peculiarities as that of a histidine-rich protein characterized from P. lophurae. Immunoelectron microscopy suggested possible immunological cross-reactivity between these two proteins.
Chromosomal location of the structural gene cluster encoding murine immunoglobulin heavy chains.
Authors: D'Eustachio P , Pravtcheva D , Marcu K , Ruddle F H
Published: June 2004

To determine the chromosomal location of mouse immunoglobulin heavy chain structural genes unambiguously, a panel of somatic cell hybrids was scored for the presence of DNA sequences homologous to gamma 2b-, mu-, and alpha-heavy chain-constant region DNA probe molecules. The hybrids, formed between mouse and hamster cells, contained various combinations of mouse chromosomes plus a full set of hamster chromosomes. Hybrids that retained mouse chromosome 12 reacted with the probes, whereas hybrids that had lost the chromosome, or its distal half, failed to react. These results indicate that structural genes for the gamma 2b-, mu-, and alpha-heavy chain-constant regions map to the distal half of this chromosome.
Role of arginase in killing of schistosomula of schistosoma mansoni
Authors: Olds GR , Ellner JJ , Kearse LA , Kazura JW , Mahmoud AAF
Published: June 2004

Nonspecific resistance to the multicellular organism Schistosoma mansoni can be induced in mice by several infectious agents. We utilized the observed genetic restriction of such acquired resistance to study the mediators of killing of the larval stage of S. mansoni in vitro. Adherent peritoneal cell monolayers from Corynebacterium parvum-treated C57BL/6J but not from C. parvum-treated BALB/cJ mice killed an increased proportion of schistosomula in 24 h. Activated macrophages (Mφ) from both strains exhibited enhanced H(2)0(2) production after incubation with the parasites or phorbol myristate acetate. Thus H(2)0(2) production was not associated with schistosomula killing. Moreover, schistosomula killing was unaffected by catalase or superoxide dismutase. In contrast, activated C57BL/6J (but not BALB/cJ) Mφ released fourfold more arginase into supernates than control Mφ. Schistosomula killing by these Mφ correlated with arginase content of the supernates, was exaggerated in arginine-poor medium, and could be blocked by the addition of arginine. Exogenous bovine arginase added to Fischer's medium without macrophages produced comparable parasite mortality. Our data suggest that arginase is a critical mediator of in vitro killing of this multicellular organism by activated macrophages.
Pathways followed by membrane recovered from the surface of plasma cells and myeloma cells
Authors: Ottosen PD , Courtoy PJ , Farquhar MG
Published: June 2004

Evidence for recovery of surface membrane and its fusion with Golgi cisternae has been obtained previously in several glandular cells. This study was conducted to determine whether or not membrane is similarly retrieved from the surfaces of plasma cells from lymph nodes (of rats immunized with horseradish peroxidase [HRP]) and mouse myeloma cells (RPC 5.4 and X63 Ag 8 cell lines). Electron-dense tracers (cationic and anionic ferritin, HRP) were used to trace the pathways followed by surface membrane recovered by endocytosis, and immunocytochemistry was used to identify the secretory compartments.

When plasma cells or myeloma cells were incubated with cationized ferritin (CF), it bound to the cell surfaces and was taken up in endocytic vesicles, for the most part bound to the vesicle membrane. After 30-60 min, it was found increasingly within lysosomes and in several secretory compartments- notably in multiple stacked Golgi cisternae and secretory vacuoles. By immunocytochemistry the secretory product (immunoglobulins) and CF could be demonstrated in the same Golgi components. When myeloma cells were incubated with native (anionic) ferritin or in HRP, these tracers were taken up in much smaller amounts, primarily within the contents of endocytic vesicles. With continued incubation, they appeared only in lysosomes. When cells were doubly incubated, first in CF and then in HRP, both tracers were taken up (often within the same endocytic vesicle), but they maintained their same destinations as when incubated in a single tracer alone: the content marker, HRP, was localized exclusively within the lysosomal system, whereas the membrane marker, CF, was found within elements along the secretory pathway as well as within lysosomes.

The findings demonstrate the existence of considerable membrane traffic between the cell membrane and the Golgi cisternae and lysosomes in both normal plasma cells and myeloma cells. Because myeloma cells behave like the glandular cells studied previously with regard to pathways of retrieved surface membrane, they represent a suitable and promising system for further studies of mechanisms and pathways of membrane retrieval and recycling in secretory cells.
Mode of regulation of natural killer cell activity by interferon
Authors: Minato N , Reid L , Cantor H , Lengyel P , Bloom BR
Published: June 2004

Whereas xenogeneic tumors such as baby hamster kidney or HeLa cells grow in nude mice, the same cells persistently infected with a variety of viruses are rejected. Spleen cells from normal nude mice were found to be induced to produce interferon and to exert natural killer (NK) activity on virus persistently infected (PI) tumor cells, and not on uninfected parental cells in vitro. The phenotype of the interferon-producing cells and the NK effector cells was found to be the same namely, Qa 5(+), Ly 5(+), ganglio-N- tetraosylceramide, with 35 percent of the NK cells also expressing Thy 1.2.

NK activity against virus PI tumor cell lines could be nonspecifically augmented both in vivo and in vitro by prior contact with virus PI tumor cells. It was unambiguously demonstrated with chemically homogeneous mouse interferon that interferon, and not a contaminant, was responsible for the augmentation of NK activity in vitro. Studies on the mode of interferon action in augmenting NK activity revealed that the target cell for interferon action was serologically distinct from the NK effector cell. Anti-Ly 5 + complement (C)-treated spleen cells were depleted of NK activity and the ability to produce interferon, but, upon incubation with interferon for 1-3 h, regained both NK activity and susceptibility to anti-Ly 5 + C. Treatment with anti-Qa 5 + C eliminated NK activity, which could not be restored by the addition of interferon. We conclude that interferon produced by Ly 5(+) cells in response to virus PI tumor cells acts on Ly 5(-) precursor cells and induces their differentiation into functional Ly 5(+) NK effector cells.
Genetic control of a shared idiotype among antibodies directed to distinct specificities.
Authors: Ju S T , Benacerraf B , Dorf M E
Published: June 2004

We developed an idiotypic radioimmunoassay system that detects shared idiotypic determinants, termed GTGL idiotype, on antibodies bearing distinct antigen-binding specificities in various mouse strains. Either poly-(Glu, Tyr) (GT)- or poly-(Glu, Lys) (GL)-related determinants are able to induce anti-GT and anti-GL (GTGL)-idiotypic antibodies. Strain distribution studies indicate that GTGL-idiotypic antibodies are readily induced and frequently expressed in antisera obtained from 25 different mouse strains immunized either with GT-related or GL-related polymers. The ability to express GTGL-idiotypic antibodies is a dominant trait and is controlled by Igh-linked gene(s). In addition, we demonstrated that in anticopolymer of L-glutamine acid60- L-alanine30-L-tyrosine (GAT) and anticopolymer of L-glutamic acid54-L-lysine35-L-phenylalanine11(GLphi) antisera, both antibodies uniquely specific to GAT or GLphi, respectively, and antibodies bearing dual specificities for GAT and GLphi, expressed GTGL idiotype. The genetic implications of these findings are discussed. X
Development of specific receptors for N-formylated chemotactic peptides in a human monocyte cell line stimulated with lymphokines
Authors: Pike MC , Fischer DG , Koren HS , Snyderman R
Published: June 2004

A human monocyte-like cell line, U937, when grown in continuous culture, does not secrete lysosomal enzymes or migrate towards chemotactic factors. When the cells are stimulated by lymphokines, however, they develop the ability both to migrate directionally and to secrete enzymes in response to several types of chemoattractants. The development, by stimulated cells, of chemotactic and secretory responses to one class of chemoattractants, the N- formylated peptides, is accompanied by the appearance on the cells of specific binding sites for these substances. Using tritiated N-formyl- methionyl-leueyl-phenylalanine (fMet-Leu-[(3)H]Phe) as a ligand, it was determined that unstimulated U937 cells possess no detectable binding sites. However, after stimulation with lymphocyte culture supernates for 24, 48, and 72 h, they developed 4,505 (+/-) 1,138, 22,150(+/-) 4,030, and 37,200 (+/-) 8,000 sites/cell, respectively. The dissociation constants for the interaction of fMet-Leu-[SH]Phe with the binding sites were approximately the same regardless of stimulation time and ranged between 15 and 30 nM. The binding of fMet-Leu-[(3)H]Phe by stimulated U937 cells was rapid and readily reversed by the addition of a large excess of unlabeled peptide. The affinity of a series of N-formylated peptides for binding to U937 cells exactly reflected the potency of the peptides in inducing lysosomal enzyme secretion and chemotaxis. The availability of a continuous human monocytic cell line that can be induced to express receptors for N-formylated peptides will provide a useful tool not only for the characterization of such receptors but also for the delineation of regulatory mechanisms involved in cellular differentiation and the chemotactic response.
Expression of leukemogenic recombinant viruses associated with a recessive gene in HRS/J mice.
Authors: Green N , Hiai H , Elder J H , Schwartz R S , Khiroya R H , Thomas C Y , Tsichlis P N , Coffin J M
Published: June 2004

HRS/J inbred mice carry a mutant autosomal recessive gene (hr), which in homozygotes coincides with susceptibility to spontaneous thymic leukemia. Unlike their heterozygote (hr/+) littermates, hr/hr homozygotes express high levels of xenotropic virus during the preleukemic period, and viruses with a broadened host range (termed polytropic viruses) can be isolated from their preleukemic and leukemic tissues. Because hr/hr and hr/+ mice are otherwise genetically identical, the virological differences between them support the role of polytropic viruses in the generation of thymic leukemia. In the present report we show that the HRS/J polytropic viruses are env gene recombinants with unique oligonucleotide and peptide maps. These polytropic viruses appear to arise by recombination between ecotropic virus and an unidentified genome related, but not identical to, the endogenous xenotropic viruses. Moreover, polytropic viruses not only accelerate leukemogenesis in HRS/J mice, but also induce thymic leukemia in the low leukemia strain CBA/J. By contrast, cloned ecotropic and xenotropic viruses have no leukemogenic action.
Role of the major histocompatibility gene products in regulating the antibody response to dinitrophenylated poly(L-Glu55,L-Ala35,L-Phe9)n.
Authors: Pierce S K , Klinman N R , Maurer P H , Merryman C F
Published: June 2004

These studies were carried out to investigate the potential helper T cell repertoire specific for the random copolymer poly(L-Glu55,L-Ala35, L-Phe9)n(GL phi 9) of responder, nonresponder, and (responder x nonresponder)F1 murine strains. We tested the ability of these T cells to collaborate with dinitrophenyl (DNP)-specific primary and secondary B lymphocytes of each strain in response to the antigen CNP-GL phi 9 in the splenic-fragment culture system. The results of these experiments show that there are GL phi 9-specific T lymphocytes in the responder, nonresponder, and F1 strains; but that these three GL phi 9-specific T cell populations differ in their collaborative potential. Responder T cells are able to collaborate with their own syngeneic responder B cells as well as the allogeneic nonresponder B cells in a syngeneic fashion. The F1 T cell population resembles that of the nonresponder in its ability to collaborate with only responder B cells in a syngeneic fashion. Analysis carried out using appropriately selected mouse strains indicate that these results are unlikely to be a result of positive or negative allogeneic effects. The results obtained suggest that individuals within a given murine strain do possess the capacity to collaborate in a syngeneic fashion with B cells of any other MHC-allogeneic strain as well as their own MHC-identical B cells. The nonresponder status in the response to GL phi 9 appears to be the result of a deletion of T cells capable of recognizing antigen in the context of B cells of the nonresponder haplotype. Thus, the MHC gene products appear to play a determinative role in shaping the expressed helper T cell specificity repertoire within an individual mouse strain.
Cytopathogenic mechanisms of Entamoeba histolytica.
Authors: Ravdin J I , Croft B Y , Guerrant R L
Published: June 2004

Cinemicrography of Entamoeba histolytica destruction of Chinese hamster ovary (CHO) cells shows that ameba cytopathogenicity consists of separate components: a contact-dependent cytolethal effect, and phagocytosis. Cells not in contact with amebae remain intact. Quantitation of ameba destruction of CHO cells by applying the one-hit hypothesis confirms that the cytoethal effect of amebae is contact dependent. Studies with 111Indium oxine-labeled cells provide further evidence of extracellular killing by E. histolytica and indicate that > 94% of the target cells are killed before phagocytosis. When we examined for a cytotoxin release by E. histolytica, we found no effect on CHO cells with filtrates of amebae, and a nonspecific effect of cell rounding and release with sonicates of amebae. The ameba sonicate effect was time-dose dependent, was not cytolethal, was reversible, and was inhibited by alpha II macroglobulin. Cytochalasin B altered ameba motility and morphology, and monolayer experiments confirmed that cytochalasins A, B, or D inhibited CHO cell destruction by E. histolytica. Cytochalasin D also inhibited extracellular killing of CHO cells by amebae in pellets, apparently independent of effects on ameba motility or phagocytosis. Colchicine and vinblastine, alone or in combination with cytochalasin D, did not inhibit E. histolytica cytopathogenicity, which indicates that microtubule function is not required for target cell killing by amebae.
Trypanosoma cruzi. Factors modifying ingestion and fate of blood form trypomastigotes.
Authors: Nogueira N , Chaplan S , Cohn Z
Published: June 2004

Blood form trypomastigotes of the Y and CL strains of Trypanosoma cruzi were tested for their ability to enter and infect mouse peritoneal macrophages. Both strains failed to enter macrophages in appreciable numbers, whereas metacyclic trypomastigotes purified from acellular cultures were ingested with ease. Macrophage parasitization was enhanced manyfold after the removal of an antiphagocytic substance by trypsinization. This occurred without modification of parasite viability. Opsonization with hyperimmune mouse serum also enhanced the uptake of blood form trypomastigotes by macrophages. This effect was mediated by the macrophage Fc receptor. The effects of serum and trypsinization were additive at high parasite:cell ratios. Neither trypsin-mediated nor antibody-dependent opsonization of the organisms modified the fate of either strain within resident macrophages. However, lymphokine-activated macrophages were capable of destroying both strains, and antibody opsonization further enhanced this process.
IgA-dependent, monocyte-mediated, antibacterial activity.
Authors: Lowell G H , Smith L F , Griffiss J M , Brandt B L
Published: June 2004

IgA purified from the sera of patients convalescing from disseminated group C meningococcal disease induced human monocyte-mediated anti-meningococcal activity in vitro in the absence of complement. Both IgA- and IgG-dependent activity were directed against the group C meningococcal polysaccharide (Csss) capsule. The amount of IgA that was effective bound less than 1 ng of Csss. Antibacterial activity was dependent upon the length and the temperature of the test incubation and on the concentration of monocytes. The implications of this mechanism for local cell-mediated antibacterial immunity are discussed.
Biogenesis of membrane-bound and secreted immunoglobulins. I. Two distinct translation products of human mu-chain, with identical N-termini and different C-termini.
Authors: McCune J M , Lingappa V R , Fu S M , Blobel G , Kunkel H G
Published: June 2004

Structural differences between the heavy chain of membrane-bound IgM (mu m) and the heavy chain of secreted IgM (mu s) were investigated. The primary translation products of the mu-chain, free of posttranslational modifications, were synthesized in a wheat-germ cell-free system, programmed with messenger RNA derived from human lymphoblastoid cell lines positive for both membrane-bound and secreted IgM. Encoded in this sytem were two mu-chains, which shared N-terminal signal peptides and which differed both in molecular weight and in C-terminal amino acid sequence. In vivo pulse labeling of cells confirmed that, as intermediates in the rough endoplasmic reticulum, these two forms expressed the same idiotype and maintained their difference in molecular weight and in C-terminal sequence. By correlation with pulse-chase kinetics and with immunofluorescence, one form of mu-chain represents mu m, and the other, mu s. Because the molecular weight difference between the two is manifest at the level of their primary translation products, these studies demonstrate that mu m is distinguished from mu s by a difference in primary structure, at least in part at the C-terminus.
Augmentation of in vitro humoral immune responses in the mouse by an antibody to IgD.
Authors: Finkelham F D , Woods V L , Wilburn S B , Mond J J , Stein K E , Berning A , Scher I
Published: June 2004

Heterologous anti-delta-chain antibodies have an adjuvant effect on specific in vivo humoral immune responses to simultaneously, or subsequently, injected antigens in the rat and rhesus monkey. We have used a hybridoma-secreted antibody that binds murine delta-chain of the allotype (4.22aM delta a) to study this phenomenon in the mouse and to investigate the mechanism of this effect. Injection of 4.22aM delta a into BALB/c mice removes almost all surface IgD (sIgD) from splenic B lymphocites. sIgD does not reappear until the serum level of 4.22aM delta a decreased 5-7 d after injection. 4.22aM delta a fails to induce detectable proliferation or to raise total serum Ig levels substantially above control values. However, 4.22aM dalta a injected 24 h before antigen elicits an approximately twofold enhancement of serum IgM and a 3- to 10-fold enhancement of serum IgG anti-trintriphenyl (TNP) antibodies in response to immunization with optimal doses of TNP-Ficoll or TNP-sheep red blood cells (TNP-SRBC). 4.22aM delta a injected 1 wk before or 3 d after TNP-SRBC, however, has no effect on IgG anti-TNP levels. The adjuvant effect of anti-delta-chain antibody was markedly decreased when suboptimal antigen doses were used. Furthermore, even in the case of TNP-Ficoll, a relatively T-independent antigen, the ability of 4.22aM dalta a to enhance the anti-TNP antibody response was T cell dependent. Our data suggest that the binding of anti-delta-chain antibody to cell sIgD may partially activate B lymphocytes and make them more capable of differentiating into antibody-secreting cells when stimulated by antigen-specific T cell help.
Linkage between the frequency of muscular weakness and loci that regulate immune responsiveness in murine experimental myasthenia gravis.
Authors: Berman P W , Patrick J
Published: June 2004

Mice immunized with acetylcholine receptor (AChR) purified from Torpedo californica form anti-AChR antibodies and often develop muscular weakness and flaccid paralysis closely resembling the human disease myasthenia gravis. This condition, termed experimental myasthenia gravis (EMG), is strain dependent in that the frequency of paralysis is much greater in some strains than in others. Differences in the frequency of EMG might result from differences in the immune system or the neuromuscular junction. In these studies, we have identified two loci, the major histocompatibility complex (H-2) region on chromosome 17 and the region that contains the structural genes for the constant region of immunoglobulin heavy chains (IgCH region) on chromosome 12, which significantly effect the probability with which a mouse immunized with T. californica AChR can be expected to become paralyzed. One genotype (H-2b, Ig-1b) correlated with high susceptibility to EMG in four strains with three dissimilar backgrounds. These studies demonstrate that susceptibility to EMG is a heritable trait determined by at least two distinct loci that are linked to regions of the mouse genome that regulate immune responsiveness.