bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytomegalovirus causes a latent infection in undifferentiated cells and is activated by induction of cell differentiation
Authors: Dutko FJ , Oldstone MBA
Published: June 2004

Murine cytomegalovirus (MCMV) does not productively infect OTT6050AF1 BrdU, F9, or PCC4 undifferentiated murine teratocarcinoma cell lines, as shown by immunofluorescence assays for viral antigens and by plaque assays for infectious virus. However, these cells were infected by a variety of other viruses. MCMV does productively infect PYS2 and OTT F12 differentiated murine teratocarcinoma cell lines.

The replication of MCMV in the pluripotent PCC4 cell line was examined in detail. Undifferentiated PCC4 cells could be differentiated when propagated in the presence of dimethylacetamide, as judged by changes in the expression of H-2 antigens on the cell surface. Several viruses, including lymphocytic choriomeningitis virus, herpes simplex virus type 1, and vesicular stomatitis virus, replicated to a similar extent in differentiated and undifferentiated PCC4 cells. MCMV did productively infect differentiated PCC4 cells. In contrast, MCMV did not produce infectious virus, viral antigens, or substantial viral RNA in undifferentiated PCC4 cells.

The molecular block of MCMV replication occurred at the level of MCMV RNA transcription. Undifferentiated PCC4 cells have receptors for MCMV and bind similar amounts of radiolabeled virus as differentiated PCC4 cells. After MCMV binds to its receptors on undifferentiated cells, MCMV penetrates the plasma membrane and is transported to the cells' nuclei. MCMV DNA was present in the cytoplasm, and small amounts of MCMV RNA (less than 17 percent of that found in MCMV-infected differentiated PCC4 cells) were found in the nucleus. However, MCMV RNA was not detected in the cytoplasm of undifferentiated cells.

A latent infection was established by infecting undifferentiated PCC4 cells with MCMV, inactivating residual infectivity with antibodies to MCMV, and propagating cells under conditions that maintained the undifferentiated state. These MCMV-infected undifferentiated cells did not produce infectious virus, viral antigens, or viral RNA but did contain viral DNA detectable by DNA-DNA hybridization kinetics. Latency was terminated and infectious virus was made when such undifferentiated cells were induced to differentiate.
Deficient interleukin 2 activity in MRL/Mp and C57BL/6J mice bearing the lpr gene.
Authors: Wofsy D , Murphy E D , Roths J B , Dauphinée M J , Kipper S B , Talal N
Published: June 2004

Spleen cells from MRL-lpr and B6-lpr mice have a marked defect in the ability to produce interleukin 2 (IL-2) in response to concanavalin A stimulation. This defect precedes the onset of clinical illness, increases with age, and eventually becomes virtually absolute. It is not due to cellular suppression of IL-2 production, nor does it reflect the presence of a soluble inhibitor of IL-2 activity. Failure to restore IL-2 production with macrophage-replacing factors, such as interleukin 1 and phorbol myristic acetate, suggests that IL-2 deficiency reflects a primary T cell defect rather than a macrophage defect. MRL-lpr and B6-lpr spleen cells also have an age-dependent reduction in IL-2 response that apparently results from a deficiency of cell surface receptors for IL-2. Congenic MRL-+/+ and B6-+/+ mice, which lack the lpr gene responsible for accelerated autoimmunity and lymphoproliferation, have normal IL-2 activity. These findings suggest that a defect in IL-2 activity may contribute to impaired immunoregulation in mice bearing the lpr gene. The absence of such a defect in MRL-+/+ and B6-+/+ mice further suggests that a single autosomal recessive gene is responsible for IL-2 deficiency.
Antigen receptors on murine T lymphocytes in contact sensitivity. I. Functional inhibition of effector T cells by monovalent 2,4-dinitrophenol: implication for a two-receptor model.
Authors: Moorhead J W
Published: June 2004

Experiments were done to investigate the nature of the antigen receptor on lymph node(LN) T cells from mice sensitized to 2,4-dinitrofluorobenzene (DNFB). LN cells or purified T cells were treated in vitro with monovalent or different multivalent 2,4-dinitrophenol (DNP) ligands. The effect of this treatment was measured by testing the ability of the cells to transfer contact sensitivity (CS) to DNFB into naive recipients. We found that treatment of the T cells in vitro with either epsilon-DNP-L-lysine or DNP-protein conjugates inhibits the transfer of CS in a dose-dependent way. The inhibition is hapten specific and is not mediated by activation of suppressor cells. Inhibition of the T cells by hapten in vitro is rapid (15-30 min) and temperature independent but requires divalent cations in the treatment medium. In addition, it was found that hapten-treated T cells are unable to adsorb specific anti-idiotype antibody, and this inhibition of adsorption is hapten specific. Collectively, these data indicate that DNFB-immune T cells express a receptor specific for the hapten DNP and provide evidence that supports a two-receptor model for T cell recognition of antigen.
Activation of Fc receptor-bearing lymphocytes by immune complexes. II. Killer lymphocytes mediate Fc ligand-induced lymphokine production.
Authors: Neville M E , Lischner H W
Published: June 2004

Cells that participate in immune complex-induced production of leukocyte migration inhibitory factor (LIF) activity can be concentrated in a population making up 2-4% of human peripheral blood lymphocytes in which greater than 90% of the cells are active in a single cell antibody-dependent cellular cytotoxicity assay. When so concentrated, such killer (K) cell preparations are as efficient in producing LIF activity as mitogen activated T lymphocytes. Other Fc receptor (FcR)-bearing lymphocytes, including natural killer (NK) cells, do not produce measurable LIF activity when incubated with immune complexes (additional evidence that the K and NK cells among ligands to the FcR of the appropriate lymphocytes, possibly without need for exogenous receptor bridging, is the only requirement for their activation to immune complex-induced lymphokine production (ICLP). It is probable that ICLP by K cells palays a role in antibody-mediated effector functions in vivo.
Adherent Ia+ murine tumor lines with characteristics of dendritic cells. I. Morphology, surface phenotype, and induction of syngeneic mixed lymphocyte reactions.
Authors: Cohen D A , Kaplan A M
Published: June 2004

Several adherent cell lines that express surface Ia antigens have been cloned from the P388 leukemia. These cell lines express many morphological and functional similarities to dendritic cells of the spleen. Adherent clones express H-2 gene products from the I and D regions, but do not possess Fc or C3b receptors or surface Ig. The cytoplasm of the adherent P388 clones has an abundance of mitochondria but few phagolysosomes. The adherent clones all strongly stimulate the proliferation of syngeneic or allogeneic T lymphocytes in the absence of antigen; however, cytotoxic T cells directed against the stimulators are induced only during allogeneic stimulation. Nonadherent clones of P388, which also express Ia antigens, do not stimulate either allogeneic or syngeneic T cell proliferation. The isolation of Ia-bearing adherent cell lines makes it possible to study Ia-mediated events in both antigen-dependent and independent immune systems using homogeneous accessory cell populations.
Detection of the human T cell lymphoma virus p19 in cells of some patients with cutaneous T cell lymphoma and leukemia using a monoclonal antibody.
Authors: Robert-Guroff M , Ruscetti F W , Posner L E , Poiesz B J , Gallo R C
Published: June 2004

A monoclonal antibody specific for the internal p19 protein of a type-C retrovirus (HTLV) isolated from human neoplastic T cells has been developed. Its specificity has been shown by radioimmune precipitation and by affinity chromatography of iodinated HTLV proteins. By indirect immune fluorescence this antibody recognizes only HTLV-producing cells. Examination of cells from patients with cutaneous T cell lymphomas and leukemias and with other types of lymphomas and leukemias indicated that HTLV p19 expression is rare. The monoclonal antibody will be useful in determining the natural reservoir of HTLV, possibly in a subset of mature T cell neoplasias.
Identification of a hemagglutinin-specific idiotype associated with reovirus recognition shared by lymphoid and neural cells.
Authors: Nepom J T , Weiner H L , Dichter M A , Tardieu M , Spriggs D R , Gramm C F , Powers M L , Fields B N , Greene M I
Published: June 2004

A xenogeneic antiserum raised to antireovirus immunoglobulin was used to define an idiotypic determinant present on antibodies to reovirus type 3 hemagglutinin. The same idiotype was identified on nonimmune lymphoid cells and on neuronal cells that specifically bind the hemagglutinin of type 3 reovirus. This idiotypic determinant, called Id3, is shared by (a) a monoclonal antibody to the neutralization site of hemagglutinin from type 3 reovirus; (b) BALB/c serum antibodies to the hemagglutinin of reovirus type 3; (c) R1.1, a murine thymoma cell line that binds reovirus type 3; (d) primary cultures of murine neuronal cells. The presence of an idiotype shared by antihemagglutinin antibodies and by structures on nonlymphoid cells suggests a general relationship between disparate receptors that recognize a common determinant. Furthermore, this suggests a novel approach for the study of viral receptor interactions and for analysis of mechanisms of autoimmune responses.
Modification of T cell antinuclease idiotype expression by in vivo administration of anti-idiotype.
Authors: Miller G G , Nadler P I , Hodes R J , Sachs D H
Published: June 2004

Immunization of BALB/c mice with nuclease leads to the production of anti-nuclease antibodies bearing a set of cross-reactive idiotypes (Id) distinct from those produced by B10.D2 mice after similar immunization. In both strains, such immunization with nuclease also leads to the production of splenic T helper cells (TH), which provide nuclease-specific help in an in vitro plaque-forming cell response to nuclease-TNP. Pig anti-(BALB/c antinuclease) anti-idiotypic antibodies (pig anti-BALB/c Id) react only with TH of nuclease-primed BALB/c and not with B10.D2 animals. After administration of pig anti-BALB/c Id in complete Freund's adjuvant to BALB/c and B10.D2 mice, Id-bearing nonantigen-binding molecules were induced in both strains. Such treatment also resulted in the induction of nuclease-specific splenic TH cells in both strains. BALB/c TH cells induced by anti-Id, like the majority of nuclease-primed BALB/c TH cells, bore BALB/c Id, as shown by their functional elimination with anti-Id plus complement. B10.D2 TH cells induced by anti-Id, unlike TH cells from nuclease-primed B10.D2 mice, also bore BALB/c idiotypic determinants by the same criterion. Thus, it appears that one can manipulate the expression of Id on serum immunoglobulins and on antigen-specific TH cells by administration of exogenous anti-Id reagents. These results have implications both for network interactions in the immune response and for the genetic basis of Igh-C linked Id expression.
Organization, structure, and assembly of immunoglobulin heavy chain diversity DNA segments.
Authors: Kurosawa Y , Tonegawa S
Published: June 2004

We have identified, cloned, and sequenced eight different DNA segments encoding the diversity (D) regions of mouse immunoglobulin heavy-chain genes. Like the two D segments previously characterized (16, 17), all eight D segments are flanked by characteristic heptamers and nonamers separated by 12-bp spacers. These 10 D segments, and several more D segments identified but not yet sequenced, can be classified into three families based on the extent of sequence homology. The SP2 family consists of nine highly homologous D segments that are all 17-bp long and clustered in a chromosomal region of approximately 60 kb. The FL16 family consists of up to four D segments, two of which were mapped in the 5' end region of the SP2-D cluster. The two FL16D segments are 23 and 17 bp long. The third, the Q52 family, is a single-member family of the 10-bp-long DQ52, located 700 bp 5' to the JH cluster. We argue that the D-region sequences of the majority of heavy chain genes arise from these germline D segments by various somatic mechanisms, including joining of multiple D segments. We present a specific model of D-D joining that does not violate the 12/23-bp spacer rule.
Monoclonal anti-IgG autoantibodies derived from lipopolysaccharide-activated spleen cells of 129/Sv mice
Authors: Van Snick JL , Coulie P
Published: June 2004

In some colonies, 129/Sv mice produce, upon aging, a rheumatoid factor (RF) that is specific for mouse IgG2a but fails to react with IgG2a of the b allotype. It is not known whether this narrow specificity is due to the absence of other RF specificities in the repertoire of these mice or to the selective activation of the production of anti-IgG2a autoantibodies by a specific stimulus. To analyze the RF repertoire of 129/Sv mice, we have derived hybridomas from their spleen cells 3 d after an intraperitoneal injection of lipopolysaccharide. We have obtained 68 hybridomas secreting a monoclonal IgM with RF activity. This represents approximately 3 percent of the total number of hybridomas generated in four hybridizations. In addition, one monoclonal IgA RF was derived from unstimulated 129/Sv spleen cells.

The specificities of these monoclonal RF were examined by testing their ability to bind to a panel of homologous and heterologous IgG preparations. The majority of the IgM RF reacted exclusively with a single mouse IgG subclass: 58 with IgG1, and 1 with IgG2a. Eight bound preferentially to IgG1 but cross-reacted to some extent with IgG2a and one was specific for a determinant shared by IgG1, IgG2a, and IgG3. The IgA RF derived from unstimulated spleen cells was primarily directed against IgG2a but cross- reacted somewhat with IgG2b. Identical results were obtained with two different monoclonal IgG1 and IgG2a proteins of the a allotype. No allotypic specificity was found for the anti-IgG1 RF, which all reacted well with IgG1 of the b allotype. In contrast, the IgM anti-IgG2a antibody exhibited such allotypic specificity because it failed to react with IgG2a of the b allotype. When tested on heterologous IgG preparations, all anti-IgG1 RF reacted better with rat IgG1, rat IgG2c, bovine IgG2, goat IgG2, and rabbit IgG than with mouse IgG1, demonstrating a particular homology between these Ig. On the basis of additional cross-reactions with other IgG, including rat IgG2a, rat IgG2b, bovine IgG1, goat IgG1, human IgG, and chicken IgG, seven different anti-IgG1 clonotypes could be identified. However, despite their heterogeneity, nearly all antigenic determinants recognized by anti-IgG 1 RF appeared to be located in the hinge region of the molecule. Total lack of binding to IgG1 Fab fragments was indeed observed, and only one antibody reacted with IgG1 Fc fragments. Unlike the anti-IgG1 RF, the IgM and the IgA anti-IgG2a antibodies did not cross-react with any heterologous IgG of the same panel.

Altogether, t 1 different RF clonotypes could be distinguished on the basis of their fine specificity. The anti-IgG2a specificity of the RF spontaneously produced by 129/ Sv mice is thus not due to the absence of other RF specificities in the repertoire of these mice.
Mitochondrial N-formylmethionyl proteins as chemoattractants for neutrophils.
Authors: Carp H
Published: June 2004

Mitochondria synthesize several hydrophobic proteins. Like bacteria, mitochondria initiate protein synthesis with an N-formylmethionine residue. Because N-formylmethionyl peptides have been found to be chemotactic for polymorphonuclear leukocytes (PMN), mitochondria isolated from cultured human cells and purified bovine mitochondrial proteins were tested for PMN chemotactic activity in vitro. Nondisrupted mitochondria were not chemotactic. However, intact mitochondria that had been incubated with a lysosomal lysate did stimulate PMN migration. Antibodies directed against two mitochondrial enzymes, cytochrome oxidase and ATPase, (both of which contain mitochondrially synthesized subunits) but not anti-C3 or anti-C5 decreased mitochondrially derived chemotactic activity. In addition, purified bovine mitochondrial N-formylmethionyl proteins stimulated PMN migration in vitro, whereas nonformylated mitochondrial proteins did not. Furthermore, the chemotactic activity of purified mitochondrial proteins and disrupted mitochondria was decreased by the formyl peptide antagonist butyloxycarbonyl-phenylalanine-leucine-phenylalanine-leucine-phenylalanine. Finally, disrupted mitochondria and purified mitochondrial proteins stimulated PMN-directed migration (chemotaxis), according to accepted criteria. In addition to other chemotactic factors, release of N-formylmethionyl proteins from mitochondria at sites of tissue damage, may play a role in the accumulation of inflammatory cells at these sites.
Effect of glucocorticosteroids on epidermal Langerhans cells.
Authors: Belsito D V , Flotte T J , Lim H W , Baer R L , Thorbecke G J , Gigli I
Published: June 2004

The effects of topical and systemic administration of various glucocorticoids on the density of epidermal Langerhans cells (LC) were studied in guinea pigs. Glucocorticoids, such as betamethasone dipropionate and valerate, caused a marked decrease in LC demonstrable by staining for cell membrane ATPase activity and Ia antigens. By electronmicroscopy, LC also showed morphologic alterations. The observed decrements in LC density correlated with the concentration and known vasoconstrictive potency of the glucocorticoids administered. The anti-inflammatory action of glucocorticoids in skin disorders may, at least in part, be through their ability to alter epidermal LC, thus interfering with the antigen-presenting functions of these cells.
Postnatal expansion of the natural killer and keller cell population in humans identified by the monoclonal HNK-1 antibody.
Authors: Abo T , Cooper M D , Balch C M
Published: June 2004

Human natural killer (NK) and killer (K) cells were directly enumerated using a monoclonal antibody (HNK-1) and an immunofluorescence assay. The frequency of cells bearing surface HNK-1 antigen was very low in the newborn (less than 1.0%) and increased progressively through childhood and into adult life. This was correlated with an age-related increase in functional NK and K cell activities. Males had a slightly higher proportion of HNK-1+ cells than females. In addition to HNK-1 expression on the surface membrane, a prominent cytoplasmic expression of HNK-1 antigen was found in some but not all surface HNK-1+ cells. The cytoplasmic accumulation of HNK-1 molecules appeared to occur in more mature cells of this lineage.
Human monoclonal anti-keyhole limpet hemocyanin antibody-secreting hybridoma produced from peripheral blood B lymphocytes of a keyhole limpet hemocyanin-immune individual.
Authors: Lane H C , Shelhamer J H , Mostowski H S , Fauci A S
Published: June 2004

A human IgMk monoclonal antibody, 2F7, of predetermined specificity, has been produced by the fusion of human peripheral blood lymphocytes with the nonsecreting mouse myeloma line SP-1. The heterohybridoma has remained stable for over 8 mo, with culture supernatants containing up to 30 micrograms/ml of specific IgM. The antibody has been shown to be capable of inducing a blastogenic response in the absence of antigen in the peripheral blood lymphocytes of normal subjects immune to the antigen. The ability to choose an antigen, immunize a human subject to that antigen, and then use the peripheral blood lymphocytes from that subject to produce antigen-specific human monoclonal antibodies should be of great value in a wide variety of investigative, diagnostic, and therapeutic endeavors.U
The collagenase of Entamoeba histolytica.
Authors: MuÑoz M L , Calderón J , Rojkind M
Published: June 2004

The present work was designed to investigate the capacity of trophozoites of Entamoeba histolytica to adhere to and digest human collagen types I and III in vitro. The time-course of binding of ameba to both human collagen types I and III was similar. However, the kinetics of detachment were different for each collagen type. Trophozoites of E. histolytica cultured on heat-reconstituted type I collagen gels produced a well-defined area of lysis. Quantitative studies using 14C-labeled collagen revealed that after 24 h of incubation, Entamoeba digested three and a half times more type I than type III collagen, thus suggesting the presence of a collagenase with higher specificity for type I collagen. This activity was optimum with trophozoites harvested after 42 h in culture (1.5 X 10(5) trophozoites/ml). The digestion of type I collagen was a function of the number of trophozoites, and was inhibited by EDTA, L-cysteine, and serum, but not by soybean trypsin inhibitor, phenylmethanesulfonyl fluoride, or N-ethylmaleimide (NEM). Electrophoretic analysis of the type I collagen fragments revealed three main classes of polypeptides of 75,000, 50,000, and 25,000 daltons. Subsequent proteolysis of these collagen fragments was probably carried out by other proteases derived from trophozoites. This activity was inhibited with 10 mM NEM. Collagenase activity appeared to be located at the plasma membrane and direct contact of the ameba with the substrate is required for collagen digestion. The results suggest that collagenase activity of E. histolytica may play an important role in tissue invasion.
Leukotriene generation by eosinophils.
Authors: Jörg A , Henderson W R , Murphy R C , Klebanoff S J
Published: June 2004

Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spectra, spectral shift on treatment with lipoxygenase, incorporation of [14C]arachidonic acid, gas chromatography-mass spectrometry, and comparison of retention times on HPLC to authentic standards. The eosinophil products characterized were 5-(S), 12-(R)-dihydroxy-6-cis-8, 10-trans-14-cis-eicosatetraenoic acid (leukotriene B4) and its 5-(S), 12-(R)-6-trans and 5-(S), 12-(S)-6-trans isomers, 5-(S)-hydroxy-6-(R)-S-glutathionyl-7,9-trans-11, 14-cis-eicosatetraenoic acid (leukotriene C4) and its 11-trans isomer, and 5-(S)-hydroxy-6-(R)-S-cysteinylglycine-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene D4).
Destruction of leishmania mexicana amazonensis amastigotes within macrophages in culture by phenazine methosulfate and other electron carriers
Authors: Rabinovitch M , Dedet J-P , Ryter A , Robineaux R , Topper G , Brunet E
Published: June 2004

Exposure of macrophages infected with Leishmania mexicana amazonensis to phenazine methosulfate (PMS) resulted in rapid damage and disappearance of the intracellular amastigotes without obvious ill effects to the host cells. The reduction of the percent infection was related to the concentration of PMS and to the duration of the pulse. Most Leishmania disappeared within 2 h of a 2-h pulse with 10 μM of the drug. In contrast, pretreatment of the macrophages with PMS followed by removal of the drug before infection did not result in disappearance of the parasites. The pH of the PMS medium markedly influenced the disappearance of Leishmania: maximum effect was observed at pH 8.0, while the effect was negligible at pH 6.3. The pH effect may be related to pseudobase formation by the PMS cation. Dose-response curves for PMS were similar for resident, elicited, or activated macrophages. Observations by time-lapse cinemicrography documented the explosion-like fragmentation of the amastigotes within 1-2 h of exposure of infected macrophages to the drug. Parasite-derived granules and vacuoles were seen to scatter within the parasitophorous vacuoles. This early damage to the parasites was confirmed by transmission electron microscopic observations. Infected macrophages incubated with PMS displayed detectable vacuolar fluorescence, indicating that PMS or a metabolite of PMS had access to the vacuoles.

A series of other electron carriers, including phenyl methanes, phenazines, oxazines, a xanthene, and a naphthoquinone, given continuously for 18 h, also induced the disappearance of the Leishmania. The most potent was crystal violet, active at 70 nM. The presence of apolar substituents enhanced activity and this is probably related to increased permeation of the dyes. Finally, PMS, as well as other electron carriers examined, also reduced the growth of Leishmania promastigotes in culture.

The results are compatible with a direct effect of the drugs on the intracellular amastigotes, involving only a permissive participation of the macrophages. We propose that the diverse agents destroy the amastigotes by redox-cycling generation of active oxygen metabolites at or near the parasites. Alternatively, the effect of the drugs could be mediated by toxic free radical reduction species of the drugs or by interference with electron flow or with the intermediary metabolism of Leishmania.
The collaborative phenotype of secondary B cells is determined by T lymphocytes during in vivo immunization.
Authors: Speck N A , Pierce S K
Published: June 2004

Previous studies have demonstrated that the B cells in immune and nonimmune mice manifest different major histocompatibility complex (MHC) collaborative phenotypes with antigen-specific T cells. Immune, or secondary B cells require syngeneic-like MHC recognition by collaborating T cells, and in its absence fail to be stimulated. Primary B cells manifest a much less stringent requisite for MHC recognition by T cells, and under conditions in which secondary B cells fail to be stimulated, primary B cells are stimulated to secrete IgM antibody. Experiments were conducted to determine whether the acquisition of the secondary B cells' MHC collaborative phenotype was dependent on the presence of T cells during in vivo immunization. B cell populations from T dependently and T independently immunized conventional BALB/c and athymic BALB/c nu/nu mice were compared in their ability to collaborate with allogeneic T cells. Although antigen alone promotes the differentiation of several secondary B cell characteristics, including an increase in the frequency of antigen-specific B cells and a preference for IgG1 antibody synthesis in vitro, the acquisition of the secondary B cells' MHC collaborative phenotype was dependent on the presence of T cells during in vivo immunization. B cell populations from T dependently and T independently immunized conventional BALB/c and athymic BALB/c nu/nu mice were compared in their ability to collaborate with allogeneic T cells. Although antigen alone promotes the differentiation of several secondary B cell characteristics, including an increase in the frequency of antigen-specific B cells and a preference of IgG1 antibody synthesis in vitro, the acquisition of the secondary B cells' MHC collaborative phenotype was found to be dependent on the presence of T cells during in vivo immunization. Thus, the restriction imposed on T cell-B-cell-collaborative interactions in secondary humoral immune responses appears to be the result of T dependent antigen-driven events.
IL-2-mediated T cell proliferation in humans is blocked by a monoclonal antibody directed against monomorphic determinants of HLA-DR antigens.
Authors: Moretta A , Accolla R S , Cerottini J C
Published: June 2004

We have studied the effect on the interleukin (IL-) 2-dependent human T cell growth of two distinct monoclonal antibodies (Mab), D1-12 and 4F2, with specificity for common determinant of human Ia antigens and for a differentiation antigen expressed on all activated T cells, respectively. Strong inhibition of cell growth was found in cultures supplemented with the anti-Ia D1-12 Mab but not in cultures supplemented with 4F2 Mab. These results were obtained when either total mixed leukocyte culture (MLC) T cells or an MLC-derived T cell clone were used as indicator cell systems for IL-2 activity. The inhibition of cell growth appears to be mediated by a direct interaction of D1-12 Mab with the cells and not by a direct inactivation of the growth factor, as addition of the antibody to murine MLC T cells, which do not express the determinant defined by D1-12 Mab, resulted in no inhibition of their proliferation induced by the same source of human IL-2.
T cell replacing factor substitutes for an I-J+ idiotype-specific T helper cell.
Authors: Jayaraman S , Swierkosz J E , Bellone C J
Published: June 2004

An in vitro system for the study of idiotype (Id) expression on antitrimethylamino hapten antibody-producing cells and its regulation by two classes of helper T cells is described. These cells are distinguished in four ways: one requires a hapten-carrier bridge and gives a good response that is low in Id; it does not bind to Id-coated dishes and is not affected by anti-I-J plus complement. The other requires antigen but not a hapten-carrier bridge, is bound by Id-coated dishes and is killed by anti-I-J and complement. The Id-specific cell appears to be antigen specific and acts via a soluble factor(s).
Requirement for three signals in "T-independent" (lipopolysaccharide-induced) as well as in T-dependent B cell responses.
Authors: Zubler R H , Glasebrook A L
Published: June 2004

The requirements for different activation signals in the generation of plaque-forming cell (PFC) responses by positively selected B (surface immunoglobulin-positive) cells were analyzed in low-density cultures to minimize the possible effects of contaminating T cells. Using this system, it is demonstrated that not only in T helper cell (TH)-dependent but also in lipopolysaccharide (LPS)-dependent (i.e., so-called T-independent) PFC responses, the resting B cells have to receive at least three different signals: (a) a major histocompatibility complex (MHC)-specific TH signal that can be bypassed by LPS, (b) an antigen signal, and (c) a second TH signal medicated by MHC- and antigen-unspecific helper factor(s) for B cell responses (BHF) that cannot by bypassed by LPS. Specifically, contact of surface immunoglobulin-positive cells with cloned allo-I-A-specific TH or LPS induced a polyclonal PFC response without significant proliferation, whereas contact with BHF alone (obtained as supernatants from different cloned TH, EL-4 thymoma cells, or secondary mixed leukocyte culture cells) had no effect. Only when LPS, antigen, and BHF, or, alternatively, allo-TH (producing themselves BHF) and antigen were present did clonally expanded PFC responses occur. Thus, the data indicate that both an LPS (or specific TH) signal and an antigen signal are required to render the B cells responsive to BHF. BHF seems to act essentially as a nonspecific growth factor, whereas differentiation into antibody-secreting cells appears to be a preprogrammed consequence of B cell activation by an LPS or specific TH signal.
Naturally occurring autologous anti-idiotypic antibodies. Participation in immune complex formation in selective IgA deficiency.
Authors: Cunningham-Rundles C
Published: June 2004

50% of individuals of selective IgA deficiency have high serum titers of antibody to bovine proteins, and high levels of circulating immune complexes that contain bovine antigens. Because in animal studies, immunization with antigen-antibody complexes is a very effective means of producing anti-idiotypic antibodies, we sought such autoantibodies in two sera known to have large amounts of anticasein. After IgG isolation and two-stage affinity chromatography, IgG-like material (molecular weights of H and L chains on SDS-PAGE), with binding activity for the F(ab')2 of anticasein were isolated from both sera. Pooled human gamma globulin or IgG myeloma proteins did not inhibit binding of specific anti-anticaseins to the corresponding anticasein, but sodium caseinate did block this binding (by 80 and 95%) indicating that most of these autoantibodies have affinity for the casein-binding site. Naturally occurring anti-idiotypic antibodies have been difficult to conclusively demonstrate in human sera; consequently, these experiments provide evidence of a unique model which may be used to explore the network theory of immunoglobulin regulation in humans.
Regulation of in vitro cytotoxic T lymphocyte generation. I. Evidence that killer cell precursors differentiate to effector cells in two steps.
Authors: Schwartz A , Sutton S L , Gershon R K
Published: June 2004

The differentiation of cytotoxic T lymphocyte precursor cells (CTL-P) into CTL effector cells is a two-step process. In the first step, naïve CTL-P (CTL-PN) become activated (CTL-PA) but do not yet have the capacity to kill target cells. CTL-PA can be distinguished from CTL-PN because the former are far less sensitive than the latter to the effects of in vitro-generated suppressor cells. Thus, the addition of suppressor T cells (Ts) to a fresh MLC can totally inhibit the production of CTL from CTL-PN, whereas the same Ts only minimally affect the generation of CTL from CTL-PA. It is not known whether these Ts act directly on CTL-PN or on a helper cell needed for activation to CTL-PA. The production of CTL-PA can take place in allogeneic mixed leukocyte cultures (MLC) treated with the drug pyrilamine, or when heat-inactivated stimulator cells are used. Each of these treatments inhibits the differentiation of CTL-PA to CTL. However, if pyrilamine is removed, a nonspecific MLC-derived signal can induce these CTL-PA to become CTL, even in the presence of significant numbers of Ts. This two step process of differentiation of CTL-P to CTL may be analogous to the way naïve B cells become antibody-producing cells.
Antigen receptors on murine T lymphocytes in contact sensitivity. III. Mechanism of negative feedback regulation by auto-anti-idiotypic antibody.
Authors: Moorhead J W
Published: June 2004

Contact sensitivity (CS) to 2,4-dinitrofluorobenzene (DNFB) is maximal 6 d after sensitization but declines rapidly. Previous studies have shown that this rapid decline is due to auto-anti-idiotypic (anti-Id) antibodies produced by the host. The present study was done to investigate the mechanism(s) involved in his down-regulation of the effector phase of the CS reaction. Using transfer of CS to mimic the natural effector phase, we found that the inhibition of transfer by treating DNFB-sensitized lymph node (LN) cells with either auto-anti-Id or syngeneic anti-Id serum is complement (C) independent. This inhibition requires Ia+ T cells in the immune population. Depleting immune LN cells of Ia+ T cells rendered them insensitive to inhibition by anti-Id alone, although the same population is inhibited by anti-Id plus C. This cell population is rendered sensitive to inhibited by anti-Id alone by addition of untreated DNFB-sensitized LN cells, but not by addition of normal LN cells. Further studies showed that the suppression of immunity by anti-Id-activated Ia+ T cells is not systemic, but rather occurs locally at the skin test site and is antigen nonspecific. We interpret these data to indicate that the natural regulation of CS to DNFB by auto-anti-Id antibodies is an active process that involves a negative feedback regulatory loop.
Human b-cell differentiation. I. Analysis of immunoglobulin heavy chain switching using monoclonal anti-immunoglobulin M, G, and A antibodies and pokeweed mitogen-induced plasma cell differentiation.
Authors: Kuritani T , Cooper M D
Published: June 2004

Monoclonal antibodies were used to examine the immunoglobulin isotypes expressed by B lymphocyte precursors of IgM, IgG, IgA, and IgA2 plasma cells. Plasma-cell differentiation was induced by the addition of pokeweed mitogen to cultures of blood mononuclear cells. Anti-mu, -gamma, -alpha, and -alpha 1 antibodies were used in some experiments to inhibit differentiation of B lymphocytes bearing these heavy chain isotypes, and for selective removal of B lymphocyte precursors before culture with pokeweed mitogen in other experiments. Three major subpopulations of B lymphocyte precursors were identified: (a) a subpopulation of surface (s) IgM+ precursors of IgM plasma cells that did not express IgG or IgA isotypes, (b) a subpopulation of sIgG+ precursors of IgG plasma cells of which approximately one-half bore some IgM and none had detectable IgA receptors, and (c) a subpopulation of sIgA+ precursors of IgA plasma cells; one half of these precursors could be shown to express functional IgM receptors but none were found to express IgG receptors. The sIgA subpopulation could be further subdivided into sIgA1+ precursors of IgA1 plasma cells and IgA1-negative precursors of IgA2 plasma cells. These results suggest that normal human B cells can switch from mu directly to each of the other heavy chain isotypes, and that these represent the main switch pathways.
Depletion of epidermal langerhans cells and Ia immunogenicity from tape-stripped mouse skin.
Authors: Streilein J W , Lonsberry L W , Bergstresser P R
Published: June 2004

To explore the relationships among Ia antigen expression, epidermal Langerhans cells, and the immunogenicity of skin allografts, cellophane tape-stripping was used in H-2 congenic and recombinant mice of defined immunogenetic disparity. Tape-stripping of murine abdominal wall skin achieved almost complete depletion of epidermal Langerhans cells within a few hours of application, as measured by cell surface ATPase and expression of Ia antigens. Tape-stripping also reduced, to a considerable degree (but not absolutely), the Ia immunogenicity of skin allografts prepared from stripped surfaces. No comparable reduction in immunogenicity of class I major histocompatibility determinants was observed, suggesting that Langerhans cells are relatively unimportant in the presentation of H-2K antigens in skin grafts. Langerhans cells reappear within 24 h of tape-stripping to anatomically intact skin, but are detectable in orthotopically grafted only after the graft has been in residence for 4 d, i.e., shortly after it has acquired a blood supply. Repopulating Langerhans cells at that time and thereafter are exclusively of host origin. These results indicate that the traffic of Langerhans cells to the skin can be extremely dynamic, especially when the epidermal surface has been markedly disturbed, and the data imply that, under normal circumstances, large numbers of Langerhans cells can be mobilized readily from an available pool of precursors.
Immunization of mice against African trypanosomiasis using anti-idiotypic antibodies.
Authors: Sacks D L , Esser K M , Sher A
Published: June 2004

Anti-idiotypic (anti-Id) antibodies were raised against three protective monoclonal antibodies, each with specificity for the variable antigen type (VAT) of a clone of Trypanosoma rhodesiense. The IgG1 fractions of each were pooled and administered to BALB/c mice 3-4 wk before homologous challenge. The course of primary parasitemia was altered in 19 of 30 anti-Id-treated animals. The immunity was manifested as either: (a) complete protection, (b) reduced parasitemia, or (c) selection against parasites bearing the original VAT. The three idiotypes (Id) were found in variable levels in serum during the course of infection in control animals. However, in all anti-Id-treated mice that displayed immunity, one Id in particular (7H11) was detectable much earlier in infection and in higher levels than in control mice or anti-Id-treated, nonimmune mice. Six of nine mice treated with the anti-7H11 Id alone also displayed immunity, manifested in this case exclusively as selection against parasites bearing the original VAT. The effect was again associated with the more rapid appearance of the Id after infection. Specificity of the anti-Id-induced immunity was supported by the failure of anti-7H11 Id treatment to alter the course of infection with a heterologous clone of T. rhodesiense. To our knowledge, this is the first report of the antigen-independent induction of antimicrobial immunity using anti-Id antibodies.
GD3, a prominent ganglioside of human melanoma. Detection and characterisation by mouse monoclonal antibody.
Authors: Pukel C S , Lloyd K O , Travassos L R , Dippold W G , Oettgen H F , Old L J
Published: June 2004

Mouse monoclonal antibody AbR24 has a high degree of specificity for human melanoma cells when tested on viable cultured cells using the protein A mixed hemagglutinin serological assay. The antigen detected by this antibody has been isolated from melanoma cells and shown to be GD3 ganglioside by compositional and partial structural analysis and by comparison with authentic GD3 in thin layer chromatography (TLC). AbR24 reacts with authentic GD3, but not with any other ganglioside tested. Using TLC and reactivity with AbR24, a wide range of cells and tissues was examined for the presence of GD3. A new serological assay, termed glycolipid-mediated immune adherence, was devised for assaying the reactivity of AbR24 with gangliosides. Melanomas (cultured cells or tumor tissue) were shown to have GD3 and GM3 as major gangliosides. Other cells and tissues examined also contained GD3, but usually only in low amounts. Melanomas (and MOLT-4, a T cell line) were characterized by a simplified ganglioside profile with GD3 and GM3 as major components. The apparent discrepancy between the ubiquitous presence of GD3 and the serological specificity of AbR24 for melanoma cells can be explained in terms of localization and concentration of GD3 in different cells.
Cellular immunity to Bacteroides fragilis capsular polysaccharide.
Authors: Shapiro M E , Onderdonk A B , Kasper D L , Finberg R W
Published: June 2004

The polysaccharide capsule of Bacteroides fragilis has been shown to be important in the virulence of the organism. The capsular polysaccharide (CP) of B. fragilis has been extensively purified. Using a murine model of intraabdominal abscess formation, we have been able to demonstrate cellular immunity to the capsular polysaccharide of B. fragilis. Immunization of C57BL/10J mice with the CP over 5 wk prevents abscess formation when the mice are challenged with B. fragilis intraperitoneally. This immunity can be transferred to naive mice with spleen cells from immune animals. The immune cells bear Thy-1.2 and Ly-2.2 antigens. The immune response has been shown to be antigen specific, but not H-2 restricted. The possibility that these immune cells are suppressor T cells is discussed. The experimental system presented provides a model for the examination of the cellular interactions responsible for abscess formation and the cellular response to bacterial pathogens.
Allelism and linkage studies of murine leukemia virus activation genes in low leukemic strains of mice.
Authors: McCubrey J , Risser R
Published: June 2004

Previously, we identified two genes, termed Inc-1 and Inb-1, that interact to enhance ecotropic murine leukemia virus induction in low virus strains of mice. Mice related to BALB/c in origin carry a locus termed Inc-1, whereas mice related to B6 carry an Inb-1 locus. Mice that carry both Inc-1 and Inb-1 yield 10- to 50-fold more virus-producing cells than parental strains on induction with halogenated pyrimidines in vitro and demonstrate enhanced murine leukemia virus production in vivo. Here, we show that mice related to BALB/c in origin, i.e., A, C3H/He, and SEC, have an Inc-1 locus that is allelic with that of BALB/c. The C57BR mouse strain has an Inb-1 locus that is allelic with that of B6, located on chromosome 8, 30 cM from Es-1. We also show that the Inc-1 locus of BALB/c mice is located on chromosome 5, 24 cM from Pgm-1 and 43 cM from Gus. Kozak and Rowe (6,8) and Ihle and co-workers (3) have shown that the ecotropic virus-inducing genes in BALB/c and B10 mice are located on chromosomes 5 and 8, respectively, with similar distances from the previously mentioned biochemical markers. Our data are consistent with two possibilities: Inc-1 and Inb-1 are part of the virus-inducing genes Cv-1 and Bv-1, respectively , or Inc-1 and Inb2-1 are tightly linked regulatory genes.
The role of self-antigen in the development of autoimmunity in Obese strain chickens with spontaneous autoallergic thyroiditis.
Authors: Pontes de Carvalho L C , Templeman J , Wick G , Roitt I M
Published: June 2004

Neonatal thyroidectomy of Obese strain (OS) chickens showed that the spontaneous development of thyroid autoimmunity in these animals was fully dependent upon the presence of autoantigen, and could not be ascribed essentially to antigen-independent mechanisms such as polyclonal lymphocyte activation or innate distortions within the idiotype network. Similarly, removal of the gland in animals with established thyroiditis demonstrated the need for antigen to maintain the autoimmune response. Thyroglobulin from normal chickens induced autoantibodies in neonatally thyroidectomized OS birds, suggesting that an abnormality in the structure of this protein is not a prerequisite for the development of autoimmunity. This contention is supported by the finding that OS and normal thyroglobulin were immunochemically indistinguishable, whether compared using OS autoantibodies or rabbit anti-chicken thyroglobulin sera.
Mechanism of augmentation of the antibody response in vitro by 2-mercaptoethanol in murine lymphocytes. I. 2-Mercaptoethanol-induced stimulation of the uptake of cystine, an essential amino acid.
Authors: Ohmori H , Yamamoto I
Published: June 2004

The mechanism of augmentation of the primary antibody response in vitro by 2-mercaptoethanol (2-ME) was investigated. By using cystine-free RPMI 1640 medium, it was demonstrated that cyst(e)ine was absolutely required for eliciting the following murine lymphocyte reactions: antibody response to sheep erythrocytes, proliferative response to concanavalin A or lipopolysaccharide (LPS), and polyclonal antibody response induced by LPS. The maximal antibody response was attained with 2.5-5 mM cysteine or half-cystine. The serial feeding of fresh cysteine markedly amplified its capacity to support antibody response particularly when cysteine concentration was suboptimal. Such an effect was not observed in the serial addition of cystine. On the other hand, the dose-response curve of cystine was dramatically shifted to lower concentrations by the addition of 2-ME (1 x 10(-5) M), which alone could not elicit the antibody response in the absence of cystine, nor could it augment furthermore the maximal response induced by 2.5 mM half-cystine. Commercially available RPMI 1640 medium contains 0.41 mM half-cystine, which proved to be a suboptimal concentration for eliciting the maximal response. 35S-cystine was incorporated into murine lymphocytes five to six times more slowly than 35S-cysteine. The rate of cystine uptake, however, was accelerated by 2.5-fold in the presence of 1 x 10(-5) M 2-ME. A close correlation was observed between dose-response profiles of 2-ME in augmenting the antibody response and the stimulation of cystine uptake. These results strongly suggest that one of the roles of 2-ME in augmenting the antibody response in vitro is to facilitate the use of cystine contained in RPMI 1640 medium only at a suboptimal concentration.