bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ontogeny of B lymphocytes IV. Induction signals mediating phenotypic conversion of PC.1− to PC.1+B cells
Authors: Hämmerling U. , Chin Ann F. 
Published: February 2007

AbstractThe present study presents evidence that spleen and lymph node cell populations contain a distinct subpopulation of B lymphocytes amounting to < 1 % of the total, which are committed and poised to the expression of the PC. 1 alloantigen, and which can be triggered in vitro to express PC.1. The pheno‐type of the PC.l‐inducible cells has been determined as Ig+ Ia+ complement receptor (CR)+ PC.l− which characteristically is associated with mature lymphocytes. Since the PC.l alloantigen identifies plasmacytes, the induction experiments imply that the latter cells are in principle descendents of CR+ B lymphocytes.The induction signal mediating PC.l− to PC.1+ conversion is different from that mediating early pro‐B cell induction. Inducing agents of PC.l−←PC.1 + include carbamylcholine, thymopoietin, prostaglandin F2α and 8‐bromo cyclic GMP, all of which have previously been shown to inhibit early pro‐B cell induction. Conversely, most agents inducing phenotype conversion in early pro‐B cells (e.g. lipopolysaccharide, tumor‐necrotizing serum, isoproterenol, prostaglandin E1 and dibutyryl cyclic AMP) are strong inhibitors of PC. 1 induction. The results suggest that inducible B lymphocytes are under dual control of agents imparting opposing signals to them, but that the mode in which they respond is reversed when they have matured to the CR+ state. Since PC. 1 expression coincides largely with differentiation to antibody‐forming cells, the reversal of responses to regulatory signals may be of significance as a safeguard against spurious activation of B lymphocytes.
The role of the Fc receptor (FcR) of thymus‐derived lymphocytes II. Presence of FcR on suppressor cells and direct involvement in suppression
Authors: Fridman W.H. , Fradelizi D. , Guimezanes A. , Plater Christine , Leclerc J.C. 
Published: February 2007

AbstractAlloantigen‐activated T cells (ATC) were prepared by injecting C3H/He thymocytes into host‐irradiated BALB/c mice. ATC were taken from the spleen of the recipients at day 5 and tested for their activity on “In vitro” primary antibody production to sheep red blood cells (SRBC) induced in splenic C3H/He lymphocytes. ATC added 24 h after antigen were found to be suppressive. Separation of ATC by velocity sedimentation, according to cell size showed that suppressor cells were found in each population, medium and large lymphocytes, however, being more active. Separation of ATC, according to the presence of Fc receptor (FcR) at their membrane was achieved by velocity sedimentation after rosetting with IgG‐sensitized SRBC (EA). Suppressor cells were then found in FcR+ and not in FcR− fractions, the degree of suppression being parallel to the ratio of FcR+ cells. At both extremes, pure populations of FcR+ cells were highly suppressive, while populations of ATC, completely devoid of FcR+ cells, were inactive. Since FcR is a very labile molecule at the T cell surface and shed within 3 h at 37°C, but not at 4°C, ATC were pre‐incubated at each temperature and added 24 h after antigen to the spleen cell cultures. In these cases, ATC having released their FcR, were much less suppressive than control ATC, and in previous work we have shown that the suppressive activity was found in the cell supernatant associated with an FcR‐like molecule (immunoglobulin‐binding factor). The data therefore allow the conclusion that FcR may be a marker of nonantigen‐specific suppressor T cells and seems to be involved itself in the suppression phenomenon.
Idiotype suppression by maternal influence
Authors: Weiler Ivan Jeanne , Weiler E. , Sprenger Renate , Cosenza H. 
Published: February 2007

AbstractIn BALB/c mice, antibodies to the α‐(1–3) glucosidic linkage of some dex‐trans (Dex) carry the idiotype of the BALB/c myeloma protein J558. Both specific antibody and idiotype are inherited in a dominant fashion, linked to the immunoglobulin (Ig) (heavy chain) allotype Igla of BALB/c mice (Eur. J. Immunol. 1975.5: 775). In F1 hybrid mice from the parent strains SJL and BALB/c, we were able to suppress the expression of anti‐Dex antibodies by immunizing prospective SJL mothers to the J558 idiotype. The state of suppression in the progeny was ascertained by immunization with Dex, and tests for the following were carried out: (a) antibodies specific for Dex; (b) inhibition of such antibodies (if present) by anti‐idiotypic serum to protein J558; (c) presence of the J558 idiotype; and (d) concentration of λ1 chains (which are associated with the 558 idiotype) in the serum.SJL mothers, once immunized, conferred suppression upon several successive litters, spanning a period of 4–5 months. Suppression in F1 progeny animals lasted for 16 weeks or more. Spleen cells from suppressed F1 mice which had neither been treated with Dex nor with J558 protein, were able to confer suppression to further F1 newborn mice.
T cells which proliferate in response to concanavalin A include cells which proliferate in mixed leukocyte reactions
Authors: Watanabe T. , Fathman C.G. , Coutinho A. 
Published: February 2007

AbstractSelection in long‐term culture of alloreactive T cells, by successive in vitro restimulation with semi‐allogeneic cells, results in primed responder cell populations which maintain full proliferative reactivity to allogeneic cells as well as to the T cell mitogens concanavalin A (Con A) and phytohemagglutinin (PHA) but are depleted of cells which can effect target cell destruction in either a specific or nonspecific manner.Con A‐induced T cell blasts (selected by velocity sedimentation) can revert to small resting lymphocytes in the presence of inert “filler” cells. Con A blasts which have reverted, readily proliferate in response to Con A or allogeneic stimulator cells but are largely depleted of effector killer cells and PHA‐re‐sponsive cells.
Mechanism of lymphocyte activation: the binding of phytohemagglutinin to the lymphocyte surface
Authors: Perlés Brigitte , Flanagan M.T. , Auger Judy , Crumpton M.J. 
Published: February 2007

AbstractThe dynamics of phytohemagglutinin (PHA)‐lymphocyte interaction was studied using 125I‐labeled PHA (leucoagglutinin) and pig mesenteric lymph node lymphocytes that had been depleted of erythrocytes, dead cells, adherent cells and immunoglobulin‐bearing cells. Evidence was obtained that PHA stimulated the majority of the lymphocytes to transform. Binding of PHA at 37°C was fairly rapid (rate constant for association: 2.6 x 105 M−1 sec−1), saturable, reversible and specifically inhibited by N‐acetylgalactosamine (Kdiss: 3 x 10−4 M) and unlabeled PHA. A Scatchard plot was curvilinear and gave evidence for 3.6 x 105 binding sites per cell comprising 8.7 % of high affinity sites (Kdiss: 3.7 x 10−9 M) and 91.3 % of lower affinity (Kdiss: 1.4 x 10−7 M). About 20 % of the sites were occupied under culture conditions giving maximal transformation. Alternative explanations for the curvilinear plot included negative cooperative interactions and/or increase in affinity through multivalent interaction. Negative cooperativity was supported by the demonstration that free PHA promoted the dissociation of bound PHA. Binding was not affected by metabolic inhibitors, and binding to purified lymphocyte plasma membrane resembled that to whole cells. These results suggested that PHA binding to whole lymphocytes was not grossly influenced by “capping”, endocytosis and shedding.
Enhancing effect of low dose cyclophosphamide treatment on the in vitro antibody response
Authors: Duclos HéLène , Galanaud P. , Devinsky O. , Maillot Marie‐Christine , Dormont J. 
Published: February 2007

AbstractWe have studied the effect of cyclophosphamide (CY) administration on the subsequent in vitro antibody response in the mouse. Treatment with a low dose (20 mg/kg) of CY four days before culture results in an increased IgM response to the T‐independent antigen trinitrophenylated polyacrylamide (TNP‐PAA), without affecting the background response of unstimulated cultures. This suggests that CY treatment eliminates a short‐lived suppressor cell, involved in the regulation of the in vitro B cell response. In contrast, the same regimen decreases the ability of nude mouse spleen cells to respond to TNP‐PAA, showing that the target of CY‐enhancing effect is a mature T cell. The increased response observed in conventional mice should be the result of a balance between the direct suppressive effect of CY on B cells and the elimination of a suppressor T cell, the latter phenomenon being of predominant significance in our conditions. The target of CY‐enhancing effect is nonadherent to plastic, but adherent to Sephadx G‐10 columns.
Structure of mouse Fc receptor
Authors: Burgois A. , Abney Erika R. , Parkhouse R.M.E. 
Published: February 2007

AbstractA variety of mouse cell types were externally labeled with radioactive iodine and solubilized in detergent. A single chain radioactive molecule of mol. wt. 120 000 was precipitated from lysates of surface‐labeled lymphocytes, macrophages and fibroblasts by complexes between pneumococcal type 3 poly‐saccharide and its homologous rabbit antibody in the IgG form, but not as F(ab'Iz or Facb. The same results were obtained using an alternative precipitating system, namely ovalbumin and IgG and F(ab'Iz forms of rabbit antiovalbumin. The 120 000 mol. wt. compound could not be detected on a thymoma cell line (5 178) previously known to lack the Fc receptor. On the basis of these criteria the material was therefore identified as mouse Fc receptor.Although very susceptible t o proteolysis, the fragments resulting from digestion remain associated by disulfide bonds in such a way as t o still bind to the anti‐body‐antigen precipitate. The proteolytic fragmentation products (mol. wts. 75 000,45 000,20 000 and 10 000) only become apparent upon chemical reduction, but the ease with which the molecule is degraded explains the wide variation in mol. wts. reported for the Fc receptor, and is perhaps a clue to explain the biological role of the molecule.
Organ culture studies of nude mouse thymus
Authors: Jordan R. K. , Owen J.J.T. , Raff M.C. 
Published: February 2007

AbstractThere is evidence that peripheral lymphoid organs of nude mice, born from homozygous matings, contain a small proportion of θ‐positive lymphocytes indicating that nude mice may not be totally devoid of T cell function. It has been suggested that such lymphocytes may develop within the dysplastic nude thymus itself. While this suggestion receives no support from morphological studies, it has been claimed that on explantation to organ culture the developing nude thymus becomes lymphoid.In this present study we confirm the presence of θ‐positive lymphocytes in peripheral lymphoid tissues of homozygous nude mice born of nude parents. However, when we have organ‐cultured nude thymus, explanted from homozygous nudeembryos at days 13, 14, 16 and 18 of gestation, we have found no histologica sign of lymphopoiesis nor have we detected any θ‐positive cells in such cultured material. On the contrary, the nude thymus in vitro develops into the polycystic structure characteristic of the adult nude thymus.We conclude that the small number of θ‐positive cells present in the periphery result from extrathymic differentiation.
T lymphocyte tissue culture lines produced by cell hybridization
Authors: Hämmerling G.J. 
Published: February 2007

AbstractThis study describes the generation of permanent T cell tissue culture lines by cell fusion techniques. The AKR strain‐derived T cell tumor BW 5147 was hybridized in the presence of polyethylene glycol with various T cell populations isolated from antigen‐sensitized mice. Surface analysis of resulting hybrid cell lines showed expression of both Thy‐1.2 and H‐2 antigens which are characteristic for the lymphocyte used for fusion. In contrast, in hybrids derived from spleen cells neither expression of Ig nor of B cell‐typicyl Ia determinants was found suggesting either preferential hybridization of BW 5147 cells with T lymphocytes or extinction of B cell markers in hybrid cells. These hybrid lines which may display the immunological properties of the T cell population chosen are presently investigated for their antigen reactivity.
Identification of the effector cells in human blood displaying spontaneous cytotoxicity to chicken erythrocytes
Authors: Saksela E. , Häyry P. , Anderrson L. C. 
Published: February 2007

AbstractBy combining velocity and linear density fractionations as well as target cell rosetting techniques we have isolated and morphologically identified the human effector cell type responsible for spontaneous, trypsin‐augmentable cytotoxicity against chicken red cells and human myeloma cell line targets. This cell is a large lymphoid cell with strong α‐naphthyl esterase activity concentrated in a limited area in the cytoplasm usually at the indentation site of a slightly reniform nucleus. Cells with this morphology also formed plaques on chicken erythrocyte monolayers. The cell is nonphagocytic and nonadherent, it carries Fc receptors but no complement receptors on its surface, and shows a weak affinity t o sheep red blood cells (SRBC). The frequency of these cells based on morphological analysis is 3 × 104‐ 6 × 104/ml in normal human blood. This cell shows similarities (surface Ig‐, Fc+, C3‐) with the human natural killer (NK) cells lytic to hematopoetic target cell lines but differs in that the cytotoxicity is augmentable by trypsin and the affinity to SRBC is lower. Therefore, we postulate that these two killer populations represent different subpopulations of human NK cells.
Suppressor T cells in low zone tolerance II. Characterization of suppressor T and amplifier cells by physical and serological methods
Authors: Heuer J. , Stumpf R. , Kölsch E. , Shen F.W. , Hämmerling G.J. 
Published: February 2007

AbstractSuppressor cells involved in low zone tolerance to bacteriophage fd have been characterized by serological and physical methods. Suppressor T cells are peripheral T2 cells which are Ly‐1‐, Ly‐2+ and Ia+. They are of high electrophoretic mobility, sediment 5 mm/h at 1 × g in a linear Ficoll 70 gradient, but are not restricted to a distinct band in a discontinuous bovine serum albumin gradient. Adherent phagocytic cells of low electrophoretic mobility can act as amplifier cells with a much shorter half‐life than suppressor T cells.
Cytoplasmic levels of IgE(Δ) in human myeloma cells in the different phases of the cell cycle
Authors: Killander D. , Nilsson K. , Lundin Lena , Fabricius H.Å. 
Published: February 2007

AbstractThe cytoplasmic levels of IgE (λ and e chains) of human myeloma cells in vitro in different stages of the cell cycle were determined by cytophotometric techniques. Asynchronously proliferating cells were pulsed with 3H or 14C‐labeled thymidine. After fixation the cells were “stained” with fluorescein‐conjugated anti‐λ or anti‐λ sera. Fluorescence intensities, representing the amounts of λ and ε chains respectively, were determined by microspectrofluorometry. The same individual cells were then analyzed by dry mass and Feulgen DNA determinations using microinterferometry and microspectrophotometry, respectively. S cells were identified by autoradiography. This methodology thus enabled cell cycle analyses without using synchronization procedures.The amounts of λ and ε chains correlated well indicating a balanced relationship between them during the cell cycle. In 4 out of 7 experiments the IgE concentration ( = amount of IgE in relation to the cellular mass) fluctuated during interphase: it mostly increased during G1 followed by a decrease in S, sometimes with a recovery during G2. In the other 3 experiments no periodicity was found during the cell cycle, i.e. the cytoplasmic IgE accumulated at the same rate as the overall cellular proteins. Thus, previous published assumptions that Ig synthesis is always restricted to certain periods of the cell cycle, could not be confirmed. Instead, our data indicate that the cell cycle expression of IgE(λ) may be variable in a clonal cell population during in vitro conditions. The explanation for this variability has ot been found. Using the same methodology, surface‐bound Ig however, always shows a noncyclic expression.A nonproliferating fraction of cells (9 %) was found. These cells, predominantly G1 cells, did not differ from proliferating G1 cells with respect to IgE content. Neither was there any relationship between morphology (immature or mature plasma cells) and IgE levels.
Thymocyte subpopulations in youn and adult mice 1. separtion by density tradient and steroid treatment
Authors: Papiernik Martine , Laroche Liliane , Bach J.F. 
Published: February 2007

AbstractThymocyte subpopulations obtained after centrifugation on Ficoll density gradients have been studied in youn and 6‐week‐old mice. Whereas the totality of the thymocytes appeared Θpositive, gradient fractionaton showed the existence of a subpopulation of immunoglobulin and Θnegative lymphocytes among the lightest cells. Similar separation was obtained in both age groups in terms of the distribution of such Θnegative cells as well as of phytomitogen responses. However, cell pools with characteristics of cortical cells were less well represented in 2 to 10‐day‐old mice than in adult mice, indicating that post‐ natal thymic development is essentially associated with the appearance of cortical cell. The gradient did not however, provide a clear separation assessed on other parameterws such as Θantigen, concanavalin A and phytohemagglutinin responses and steroid sensitivity. Cellular heterogeneity for a given cell density is discussed in relation to the hypothesis of two separate maturation pathways of thyocytes.
Clones of cytotoxic lymphocytes in culture: the difference in specificity between stimulated and nonstimulated cytotoxic lymphocytes
Authors: Ching Lai‐Ming , Walker Karen Zell , Marbrook J. 
Published: February 2007

AbstractThe specificity of individual clones of cytotoxic lymphocytes (CL) which develop upon stimulation by semi‐allogeneic cells, have been examined and compared with the specificity of CL clones which develop spontaneously when normal spleen cells are cultured without stimulator cells. It was found that the specificity of stimulated clones was different from the specificity of ‘spontaneous’ clones. Specifically stimulated clones from CBA cells cultured with (CBA × DBA)F1 stimulator cells, did not discriminate between the H2d P81 5 and H2d DBA splenic blasts, and lysed both targets. In contrast, spontaneous CL clones from cultures of CBA or (CBA × DBA)Fi spleen cells were found to lyse either P8 15 or DBA blasts, but not both. The results indicated that the spontaneous CL clones were not a representative sample of the total pool of CL.
Spontaneous clones of cytotoxic T cells in culture III. Discriminatory lysis of pairs of syngeneic blasts induced by different mitogens
Authors: Ching Lai‐Ming , Walker Karen Zell , Marbrook J. 
Published: February 2007

AbstractWhen normal spleen cells are cultured for 4 days in polyacrylamide vessels, individual clones of cytotoxic lymphocytes (CL) can be detected. The specificity of these ‘spontaneous’ CL was investigated by assaying the cytotoxic activity of cells from individual clones against pairs of different targets. Target cells used were syngeneic blast cells induced by dextran sulfate, lipopolysaccharide (LPS), concanavalin A (ConA) and phytohemagglutinin (PHA). It was found that LPS blasts were lysed by a separate set of CL clones from those which lysed PHA blasts of the same H‐2 haplotype, and the clones of CL which lysed PHA blasts were a subset of all the clones which lysed ConA blasts. When individual clones of spontaneous CL were assayed against LPS and DS blasts, there were clones which lysed both types of blasts as well as clones which were specific for either LPS or DS blasts. These results have been interpreted as demonstrating that spontaneous CL can recognize and kill subsets of cells which are stimulated by different mitogens.
Reconstitution of natural cell‐mediated cytotoxicity with specific antibodies
Authors: Takasugi Julie , Koide Y. , Takasugi M. 
Published: February 2007

AbstractThe apparent nonselective reactions of natural cell‐mediated cytotoxicity (NCMC) are selective when tested by inhibition of cytotoxicity with competitor cells indicating a recognition of specificities by the effector cell. N cells that mediate this NCMC in humans have most of the characteristics of K cells that mediate antibody‐dependent, cell‐mediated cytotoxicity (ADCC) and possess Fc receptors. IgG antibodies attached loosely to N cells through their Fc region, form part of the class of lymphocytes with surface immunoglobulin. We hypothesized that ADCC and NCMS involved similar mechanisms but with the specificity of NCMC directed by the natural IgG antibodies already attached to N cells. Removal of the antibodies with trypsin and reconstitution with specific anti‐HLA antibodies produced specific effector cells supporting the role of antibodies on N cells as directors of specificity in NCMC.
Cellular and genetic control of antibody responses in vitro 1.cellular requirements for the generation of genetically controlled primary IgM responses to soluble antigens
Authors: Hodes R.J. , Singer A. 
Published: February 2007

AbstractThrinitropheny1 (TNP)‐specific primary IgM plaque‐forming cell responses were generated in vitro by unprimed spleen cells to the soluble antigens TNP‐keyhole limpet hemocyanin, trinitrophenylated poly‐L(Tyr‐Glu)‐poly‐D,L‐Ala–poly‐L‐Lys[T,G)‐A–L] and poly‐L(His,Glu)‐poly‐D,L‐Ala–poly‐L‐Lys[(H,G)‐A–L].The T cell dependence of these primary lgm responses was esablished by (a) abrogation of responses after pretreatment of cells with a T cell‐specific rabbit anti‐mouse brain serum (RaMB)and C‐treated spleen cells (B cells); and (c) absence of significant responses by spleen cells from congenic nude mice. A requirement for macrophages in these same antibody responses was also demonstrated:(a) responses were abrogated or strongly diminished in spleen cell populations depleted of macrophages by passage over Sephadex G‐10 columns; and (b) these responses were fully reconstituted by the addition of small numbers of adherent, radioresistant, anti‐Thy‐1.2‐treated spleen cells (macrophages) to the Sephadex G‐10‐depleted populations. In addition, H‐2‐linked Ir gene control has been demonstrated for the primary IgM responses to TNP conjugates of (T,G)‐A–L and (H,G)‐A–L. A system has thus been characterized which permits in vitro analysis of the cellular and genetic requirements involved in primary IgM responses to soluble antigens, including those under Ir gene control.
Presence of “la‐like” antigens on human T lymphocytes bearing receptors for IgG
Authors: Samarut Christiane , Gebuhrer Lucette , Brochier J. , Betuel H. , Revillard J.‐P. 
Published: February 2007

AbstractHuman peripheral blood T cells bearing receptors for the Fc portion of immunoglobulins were characterized by the formation of double rosettes with sheep red blood cells and IgG‐coated chicken erythrocytes (EA). Treatment of cells by anti‐“Ia‐like” antisera inhibits the binding of EA. Inhibition appeared to be specific since anti‐HLA‐A and VLA‐B antibodies did not inhibit the formation of EA rosettes, whereas F(ab )2 fragments of anti‐Ia‐like IgC were found to be as potent inhibitors as the whole IgG. This result shows that in humans and in mice, Ia‐like determinants are present, close to Fc7 receptors, on the surface of the T lymphocytes bearing such receptors.