bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production of auto-anti-idiotypic antibody during the normal immune response to TNP-ficoll. II. Hapten-reversible inhibition of anti-TNP plaque-forming cells by immune serum as an assay for auto-anti-idiotypic antibody
Authors: Goidl EA , Shrater AF , Siskind GW , Thorbecke GJ 
Published: June 2004

Sera taken from AKR/J mice 7 d after the intravenous injection of 2,4,6-trinitrophenyl-lys-Ficoll (TNP-F) caused a specific inhibition of anti- trinitrophenol (TNP) plaque-forming cells (PFC) in vitro. This inhibition was reversed by the incorporation of 10(-8)-10(-7) M 2,4,6-trinitrophenyl- ε-amino-n-caproic acid (TNP-EACA) into the agar during the PFC assay. The factor responsible for the hapten-reversible PFC inhibition was removed from serum by passage through an anti-immunoglobulin column or through a 2,4,-dinitrophenyl-human-serum-albumin-bromoacetylcellulose plus anti-TNP- antibody column, but not by DNP-HSA-BAC alone. It was concluded that this immunoglobulin-like substance, lacking anti-TNP activity but reacting with anti-TNP antibody of AKR/J origin, was most likely an auto-anti-idiotypie antibody that had been produced during the normal course of the response of AKR/J mice to TNP-F. Pools of anti-idiotypic-antibody-containing antisera inhibited anti-TNP plaque formation to varying degrees when tested on d-4 PFC from different mice of the same inbred strain, suggesting a variability in idiotype expression.
4 d after transfer of immune (7 d after 10 μg TNP-F, administered intravenously) AKR/J spleen cells plus 10 μg TNP-F into syngeneic mice, the number of PFC detectable in the recipients' spleens could be markedly augmented by the inclusion of TNP-EACA in the agar during the PFC assay. Incubation of spleen cells containing such hapten-augmentable PFC with TNP- EACA yielded a factor in the supernate that caused a specific, in vitro, hapten-reversible inhibition of anti-TNP PFC. Studies with immunoadsorbents indicated that this PFC-inhibiting factor was antigenically immunoglobulin- like, lacked anti-TNP-antibody activity, but reacted with anti-TNP antibody of AKR/J origin. The results are consistent with the view that this PFC inhibitor is auto-anti-idiotypic antibody that is involved in the normal regulation of the immune response.
It is proposed that hapten-reversible inhibition of plaque formation can be employed as an assay for anti-idiotypic antibody and the conditions for such an assay are described. It is further proposed that the detection of hapten-augmentable PFC suggests the presence of auto-anti-idiotypic antibody.
Thymic reconstitution of nude F1 mice with one or both parental thymus grafts
Authors: Zinkernagel RM , Althage A , Callahan G 
Published: June 2004

Thymus-derived lymphocytes (T cells) have two outstanding characteristics that distinguish them from other lymphocytes: (a) they express two specificities, one for self-antigens, the major transplantation antigens (H) coded by the major histocompatibility gene complex (MHC), and a second specificity for foreign antigenic determinants. (b) T cells must undergo differentiation or maturation in the thymus (1, 2). Apparently, an important step in T-cell differentiation in the thymus is the selection of T-cells' restriction specificity for self-H. This interpretation stems from experiments with chimeras formed by lethally irradiating parental type mice and reconstituting them with F(1) stem cells: the maturing F(1) T cells expressed predominantly the restriction specificities for the recipient parental MHC type (3-8). Alternatively, adult F(1) mice that were thymectomized, lethally irradiated, reconstituted with bone marrow, and then engrafted with a parental thymus had T cells that were restricted predominantly to the thymus donors' H-2 (4-8).
The present study first extends these observations to nude mice that are born without a thymus and therefore do not develop functional T cells and second, attempts to study the possibility that suppression may be responsible for the apparent influence of the radioresistant portion of the thymus on T- cell restriction specificities.
We tested the immunocompetence and restriction specificities expressed by lymphocytes from F(1) nude mice reconstituted with both parental thymus grafts; our expectation was that suppression of the expression of T-cell restriction specificity should result either in complete immunoincompetence or emergence of only one of the two possible sets of restriction specificities. Nude F(1)mice that simultaneously received thymus gratis from both parents developed spleen cells restricted to both parental H-2 types. These results are compatible with the idea that the thymus' influence on T- cell restriction is via positive selection rather than by suppression.
Integration of a virus membrane protein intothe lipid bilayer of target cells as a prerequisite for immune cytolysis. Specific cytolysis after virosome- target cell fusion
Authors: Morein B , Barz D , Koszinowski U , Schirrmacher V 
Published: June 2004

Structural requirements for membrane antigens on target cells to mediate immune cytolysis were studied in a model system with purified membrane proteins from Semliki Forest virus (SFV). These SFV spike proteins were isolated in the form of detergent- and lipid-free protein micelles (29S complexes) or, after reconstitution into lipid vesicles, in the form of virosomes. Both the 29S complexes and the virosomes were found to bind well to murine tumor cells (P815 or Eb). When these cells, however, were used as target cells in complement-dependent lysis or in antibody-dependent cell- mediated cytotoxicity assays in the presence of anti-SFV serum, they were not lysed, although they effectively bound the antibody and consumed complement. The same tumor cells infected with SFV served as positive controls in both assays.
Different results were obtained when inactivated Sendai virus was added as a fusion reagent to the cells coated with either virosomes or 29S complexes. Under these conditions the virosome-coated cells became susceptible to SFV- specific lysis, whereas the 29S complex-coated cells remained resistant. Evidence that the susceptibility to lysis ofvirosome-coated cells was dependent on active fusion and, therefore, integration of the viral antigens into the lipid bilayer of the target cells was derived from control experiments with enzyme-treated Sendai virus preparations.
The 29S complexes and the virosomes partially and selectively blocked the target cell lysis by anti-H-2 sera but not by anti-non-H-2 sera confirming our previous finding that major histocompatibility antigens serve as receptors for SFV. The general significance of these findings for mechanisms of immune cytolysis is dicussed.
The receptor specificity of alloreactive T cells. Distinction between stimulator K, I, and Dr Products and degeneracy of third-party H-2 recognition by low-affinity T cells
Authors: Nagy ZA , Elliott BE 
Published: June 2004

The specificity of binding of stimulator-derived H-2 antigens by mixed lymphocyte culture (MLC)-activated T blasts was investigated under conditions of antigen excess. We have shown that the detectable proportion of alloantigen-binding blasts from primary MLC is a function of antigen concentration, and can represent up to more than 90 percent of total blasts, when the antigen is presented in the appropriate form (on mitomycin-treated viable stimulator cells, or membrane vesicles prepared from lipopolysaccharide blasts), and at nonlimiting concentration. Thus stimulator alloantigen-binding directly parallels the proliferative response and is not restricted to a subpopulation of T blasts. However, the marked dependence of the binding on antigen concentration indicates that cells with a wide range of receptor affinities for the stimulating determinants are involved. In view of this possibility, the specificity of binding by these cells was studied. We have demonstrated that stimulator K, I, and D region products are bound by nonoverlapping subpopulations of blasts, the sum of which may represent 93 percent of total blasts. Thus, specific distinction by these cells between different H-2 region products is not affected by the putative heterogeneity in terms of receptor affinities. However, specificity with respect to unrelated H-2 haplotypes is strictly dependent on antigen concentration. A preferential binding of stimulator membrane vesicles occurs at limiting concentrations; whereas the majority of blasts bind stimulator and third- party vesicles equally well at high vesicle concentrations. The binding of both vesicle types is specific in that it can be inhibited with the relevant anti-H-2 sera. Furthermore, stimulator and third-party vesicles seem to compete for binding sites on the same cells, as shown by cold antigen inhibition.
From these results, we propose that there is an imperfect distinction between stimulator and third-party H-2 antigens by the majority of primary MLC blasts. In contrast, highly selected long-term MLC blasts do not bind third-party H-2 antigens at any concentration, and seem to have high affinity for the stimulating antigens.
We conclude that large numbers of clones with low-affinity (cross- reactive) receptors are generated in primary MLC, most of which become eliminated during long-term selection. This implies that the frequency of cells strictly specific for nonshared stimulating determinants must be minute.
T-suppressor cells sensitive to cyclophosphamide and to its in vitro active derivative 4-hydroperoxycyclophosphamide control the mitogenic response of murine splenic B cells to dextran sulfate. A direct proof for different sensitivities of lymphocyte subsets to cyclophosphamide
Authors: Diamantstein T , Willinger E , Reiman J 
Published: June 2004

As measured by [(3)H]thymidine uptake, spleen cells of mice injected 7 d previously with a single dose of cyclophosphamide (Cy) (125 mg x kg (-1)) gave an enhanced response to dextran sulfate (DS), a diminished response to lipopolysaccharide (LPS), and a normal response to concanavalin A. Addition of syngeneic thymocytes to spleen cells inhibited the enhanced response of the cells to DS and slightly enhanced their response to LPS. Pretreatment of thymocytes by 4-hydroxyperoxycyclophosphamide (4HP-Cy) in vitro (an in vitro active derivative of Cy) abrogated the effect of thymocytes on the DS response but not on the LPS response. Pretreatment of spleen cells by small doses of 4HP-Cy (0.1-1.0 μg. ml(-1)) in vitro enhanced the capacity of the cells to respond to DS but either did not affect, or even diminished their capacity to respond to LPS. The enhancement of the DS response by 4HP-Cy treatment could not be detected using spleen cells depleted of T cells or lacking functioning T cells. 4HP-Cy doses more than 3 μg ml(-1) diminished or abolished the capacity of the spleen cells to respond to LPS as well as their capacity to respond to DS.
The results show (a) that in contrast to the LPS-reactive B-lymphocyte subset, the proliferative capacity of DS-reactive subset is negatively controlled by a Cy- and 4HP-Cy-sensitive T-cell subset and (b) that these T- suppressor cells are more sensitive to Cy and 4HP-Cy (to their respective active alkylating metabolites) than B lymphocytes and T cells carrying other immunological functions.
Analysis of rat hemopoietic cells on the fluorescence-activated cell sorter. I. Isolation of pluripotent hemopoietic stem cells and granulocyte-macrophage progenitor cells
Authors: Goldschneider I , Metcalf D , Battye F , Mandel T 
Published: June 2004

A scheme is presented whereby pluripotent hemopoietic stem cells (PHSC) from rat bone marrow can be enriched 320-fold with the aid of the fluorescence- activated cell sorter. This scheme is based on the observations that PHSC are strongly positive for Thy-1 antigen (upper 10th percentile); have light- scattering properties (size distribution) between those of bone marrow lymphocytes and myeloid progenitor cells; and are relatively resistant to cortisone. It is estimated that PHSC may constitute 80 percent of the cells isolated according to these parameters. Candidate PHSC are described at the light and electron microscopic levels. At least two populations of accessory cells appear to influence the number and/or the nature of the hemopoietic colonies that form in the in vivo spleen colony-forming unit assay. Putative amplifier cells are strongly Thy-1(+) and cortisone sensitive; putative suppressor cells are weakly Thy-1(+) and cortisone resistant.
Three subsets of granulocyte (G) -macrophage (M) progenitor cells (in vitro colony-forming cells [CFC]) are identified on the basis of relative fluorescence intensity for Thy-1 antigen: G-CFC are strongly Thy-l(+); M-CFC are weakly Thy-l(+); and cells that produce mixed G and M CFC have intermediate levels of Thy-1. GM-cluster-forming cells and mature G and M are Thy-1(-). The results suggest that G-CFC are bipotential cells that give rise to G and M-CFC; and that the latter produce mature M through a cluster- forming cell intermediate.
Thy-1 antigen is also demonstrated on members of the eosinophil, megakaryocyte, erythrocyte, and lymphocyte cell series in rat bone marrow. In each instance, the relative concentration of Thy-1 antigen is inversely related to the state of cellular differentiation.
T cell growth factor receptors. Quantitation, specificity, and biological relevance
Authors: Robb RJ , Munck A , Smith KA 
Published: June 2004

To examine directly the hypothesis that T cell growth factor (TCGF) interacts with target cells in a fashion similar to polypeptide hormones, the binding of radiolabeled TCGF to various cell populations was investigated. The results indicate that TCGF interacts with activated T cells via a receptor through which it initiates the T cell proliferative response.
Internally radiolabeled TCGF, prepared from a human T leukemia cell line and purified by gel filtration and isoelectric focusing, retained biological activity and was uniform with respect to size and charge. Binding of radiolabeled TCGF to TCGF-dependent cytolytic T cells occurred rapidly (within 15 rain at 37 degrees C) and was both saturable and largely reversible. In addition, at 37 degrees C, a receptor- and lysosome-dependent degradation of TCGF occurred. Radiolabeled TCGF binding was specific for activated, TCGF-responsive T cells. Whereas unstimulated lymphocytes of human or murine origin and lipopolysaccharide-activated B cell blasts expressed few if any detectable binding sites, lectin- or alloantigen-activated cells had easily detectable binding sites. Moreover, compared with lectin- or alloantigen-activated T cells, long-term TCGF-dependent cytolytic and helper T cell lines and TCGF-dependent neo-plastic T cell lines bound TCGF with a similar affinity (dissociation constant of 5-25 pM) and expressed a similar number of receptor sites per cell (5,000-15,000). In contrast, a number of TCGF-independent cell lines of T cell, B cell, or myeloid origin did not bind detectable quantities of radiolabeled TCGF. Binding of radiolabeled TCGF to TCGF-responsive cells was specific, in that among several growth factors and polypeptide hormones tested, only TCGF competed for binding. Finally, the relative magnitude of T cell proliferation induced by a given concentration of TCGF closely paralleled the fraction of occupied receptor sites. As the extent of T cell clonal expansion depends on TCGF and on the TCGF receptor, the dissection of the molecular events surrounding the interaction of TCGF and its receptor that these studies permit, should provide new insight into the hormonelike regulation of the immune response by this lymphokine.
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.
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.
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.