bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myasthenogenicity of human acetylcholine receptor synthetic alpha-subunit peptide 125-147 does not require intramolecular disulfide cyclization.
Authors: McCormick D J , Griesmann G E , Huang Z X , Lambert E H , Lennon V A 
Published: December 2022

Abstract
This study reports the synthesis of a disulfide-looped peptide corresponding to residues 125-147 (Cys 128-Cys 142) of the nicotinic acetylcholine receptor (AChR) of human skeletal muscle, H alpha 125-147 (Lys-Ser-Tyr-Cys-Glu-Ile-Ile-Val-Thr-His-Phe-Pro-Phe-Asp-Glu-Gln- Asn-Cys-Ser-Nle-Lys Leu-Gly), and a nondisulfide-looped analogue, H alpha 125-147(S) (Lys-Ser-Tyr-Ser-Glu-Ile-Ile-Val-Thr-His-Phe-Pro-Phe-Asp-Glu- Gln-Asn-Cys-Ser-Nle-Lys-Leu-Gly), in which the amino acid Cys 128 was replaced with serine. Both peptides induced antigen-specific helper T cell responses, as evidenced in vitro by lymph node cell proliferation and in vivo by production of anti-AChR antibodies. Rats immunized with 100 micrograms of either synthetic peptide, without conjugation to a carrier, produced anti-peptide antibodies which bound to native AChR in immunoprecipitation assays and induced modulation of membrane-bound AChR from cultured human myotubes. Both peptides also induced electrophysiologic and biochemical signs of experimental autoimmune myasthenia gravis. Thus, region 125-147 of the AChR alpha-subunit is at least partly exposed extracellularly in human muscle and contains one or more autoantigenic sites capable of stimulating T cells and B cells. Disulfide-linkage between residues Cys 128 and Cys 142 is not essential for myasthenogenicity.
Immunity to herpes simplex virus type 2. Suppression of virus-induced immune responses in ultraviolet B-irradiated mice.
Authors: Yasumoto S , Hayashi Y , Aurelian L 
Published: December 2022

Abstract
Ultraviolet B irradiation (280 to 320 nm) of mice at the site of intradermal infection with herpes simplex virus type 2 increased the severity of the herpes simplex virus type 2 disease and decreased delayed-type hypersensitivity (DTH) responses to viral antigen. Decrease in DTH resulted from the induction of suppressor T cells, as evidenced by the ability of spleen cells from UV-irradiated mice to inhibit DTH and proliferative responses after adoptive transfer. Lymph node cells from UV-irradiated animals did not transfer suppression. DTH was suppressed at the induction but not the expression phase. Suppressor T cells were Lyt-1+, L3T4+, and their activity was antigen-specific. However, after in vitro culture of spleen cells from UV-irradiated mice with herpes simplex virus type 2 antigen, suppressor activity was mediated by Lyt-2+ cells. Culture supernatants contained soluble nonantigen-specific suppressive factors.
The expression and regulation of c-myb transcription in B6/lpr Lyt-2-, L3T4-T lymphocytes.
Authors: Yokota S , Yuan D , Katagiri T , Eisenberg R A , Cohen P L , Ting J P 
Published: December 2022

Abstract
Mice homozygous for the lpr gene spontaneously develop massive lymphoproliferation and an associated lupus-like autoimmune disease. In addition, the total lymphoid organs from these mice express high levels of mRNA for the c-myb proto-oncogene. Since enhanced c-myb mRNA is normally observed in immature thymic lymphocytes but not normal peripheral T cells, this may be indicative of the abnormal maturation state of lpr T lymphocytes. To determine whether the abnormal Lyt-2-, L3T4- (double negative) T lymphocytes in lpr mice express high c-myb, we purified this population by complement-mediated lysis with anti-L3T4 and Lyt-2 antibody from B6/lpr lymph nodes. We found that increased c-myb mRNA is expressed by this double-negative subset. To assess whether the high level of c-myb correlated with the aberrant undifferentiated state of these cells, we examined the effects of T cell differentiation inducers, phorbol ester and calcium ionophore, on c-myb expression. We found that c-myb levels were depressed after phorbol ester and calcium ionophore treatment. Concomitantly, transcriptional activation of the interleukin 2 receptor gene and progression of these cells through the cell cycle were observed. Thus, in B6/lpr double-negative T cells, the regulation of c-myb, interleukin 2 receptor, and cell proliferation may be interrelated. A combination of Northern hybridization and nuclear run-on transcription assays revealed two levels at which c-myb can be regulated in the double-negative T cell subset. The gene is transcriptionally regulated in untreated cells, but on induction with phorbol ester and calcium ionophore, the gene is negatively regulated via post-transcriptional mechanisms.
Murine trophoblast resists cell-mediated lysis. I. Resistance to allospecific cytotoxic T lymphocytes.
Authors: Zuckermann F A , Head J R 
Published: December 2022

Abstract
Research on the mechanisms of nonrejection of the fetoplacental allograft has focused on the tissues composing the fetomaternal interface, of which the placental trophoblast, the tissue directly confronting the maternal environment, is considered a prime candidate responsible for the survival of the fetus. We recently developed a method for isolating murine trophoblast, and found that a proportion of trophoblast cells from mature placentas, cultured for 2 days, express class I antigens on their surface, and this expression can be enhanced in vitro by interferon-alpha/beta (IFN-alpha/beta). In the present study, it was determined that cultured trophoblast cells from day 14 placentas were resistant to allospecific cytotoxic T lymphocytes (allo-CTL), while being susceptible to alloantibody and complement-mediated lysis. The trophoblast cells remained resistant to allo-CTL-mediated lysis despite IFN-mediated enhanced expression of class I H-2 antigens on their surface and the addition of phytohemagglutinin into the assay. Inhibition of protein synthesis also had no effect. In contrast, fetal fibroblasts, isolated from the same conceptuses, were readily susceptible to allo-CTL-mediated lysis. That the trophoblast cells do interact with the effector cells was shown by their ability to specifically inhibit the lysis of tumor target cells in a dose-dependent manner. Additionally, trophoblast culture supernatants did not inhibit the lytic activity of allo-CTL, even when concentrated 10- to 25-fold, indicating that a soluble suppressor factor was not inactivating the effector cells. These results suggest that trophoblast cells have a protein synthesis-independent mechanism of resistance to lysis by allo-CTL, which could play an important role in protecting the fetoplacental allograft from maternal immune rejection.
Functional studies with anti-CD3 heavy chain isotype switch-variant monoclonal antibodies. Accessory cell-independent induction of interleukin 2 responsiveness in T cells by epsilon-anti-CD3.
Authors: van Lier R A , Boot J H , Verhoeven A J , de Groot E R , Brouwer M , Aarden L A 
Published: December 2022

Abstract
A series of heavy chain isotype switch-variant anti-CD3 monoclonal antibodies (mAb) was used to study the proliferation requirements of purified T cells. None of the variant antibodies was able by itself to induce proliferation. In the presence of exogenous interleukin 2 (IL-2) strong mitogenesis was observed upon stimulation with epsilon-anti-CD3, whereas gamma 1, gamma 2b, gamma 2a, and alpha-anti-CD3 failed to induce T cell proliferation. All variant antibodies induced vigorous proliferation in combination with phorbol myristate acetate. Purified T cells, cultured in the presence of epsilon-anti-CD3, in the absence of IL-2, did not express detectable amounts of TAC-antigen (CD25). The binding of the variant antibodies to the CD3 antigen was evaluated in cross-blocking experiments. It was demonstrated that the epsilon-anti-CD3 antibody, in comparison with the other variant mAb, has a relatively low avidity for the CD3 antigen. In modulation experiments, the IgE variant antibody was unable to induce a substantial loss of CD3 antigen. T cell triggering was investigated at the level of Ca2+ mobilization by means of the dye Indo-1. In contrast to the gamma 1, gamma 2b, gamma 2a, and alpha mAb, which induced a rapid and high rise in the free intracellular calcium level, epsilon-anti-CD3 caused a slow and low rise. These studies indicate that the epsilon-anti-CD3 antibody has a low avidity for the CD3 antigen, compared with the other variant mAb, possibly as a result of monovalent binding. Apparently, the avidity and/or valency of CD3 antigen binding not only has a major influence on CD3 modulation and anti-CD3-induced Ca2+ mobilization, but also sets T cell requirements for IL-2 responsiveness.
Lyt-2+ cells. Requirements for concanavalin A-induced proliferation and interleukin 2 production.
Authors: Kern D E , Lachmann L B , Greenberg P D 
Published: December 2022

Abstract
The requirements for inducing Lyt-2+ T cell proliferation in response to concanavalin A (Con A) were examined. Purified Lyt-2+ or L3T4+ spleen cells of C57BL/6 origin were stimulated with Con A and syngeneic macrophages (MO) in the presence of monoclonal antibodies to T cell markers or to polymorphic determinants on major histocompatibility complex molecules, and assessed for the ability to proliferate and to produce interleukin (IL) 2. alpha I-Ab failed to inhibit the Con A response of Lyt-2+ cells at dilutions that significantly inhibited the response of L3T4+ cells. In contrast, alphaKb/Db or alpha Lyt-2.2 specifically inhibited the response of Lyt-2+ cells, but not L3T4+ cells. The ability of alpha Kb/Db and of alpha Lyt-2.2 to inhibit the response of Lyt-2+ cells was dependent upon the concentration of Con A. These data demonstrate that optimal triggering of T cell subsets to proliferate and to produce IL-2 in response to Con A requires interactions with the appropriate restricting major histocompatibility complex molecule. The role of accessory cells in Lyt-2+ Con A-induced proliferation and IL-2 production was also investigated. Purified Lyt-2+ cells and purified L3T4+ cells failed to respond to Con A in the absence of MO. IL-1 reconstituted the response when MO were limiting, but failed to restore the response of either Lyt-2+ or L3T4+ cells when T cells were rigorously purified to remove all MO. These results demonstrate that triggering Lyt-2+ T cells, like L3T4+ T cells, requires accessory cells, and that this does not merely reflect a requirement for IL-1 production. Thus, Con A-induced proliferation and IL-2 production by Lyt-2+ T cells requires intimate contact with accessory cells and interactions dependent upon the class I-restricting element.
Purification and characterization of human skin mast cells. Evidence for human mast cell heterogeneity.
Authors: Lawrence I D , Warner J A , Cohan V L , Hubbard W C , Kagey-Sobotka A , Lichtenstein L M 
Published: December 2022

Abstract
Our previous studies of human lung and intestinal mast cells failed to show the heterogeneity found among mast cells in murine species. Recently, we and others have developed techniques for the enzymatic dispersion of human neonatal skin mast cells. In addition, we are now able to make single cell suspensions of mast cells from adult skin and to purify these cells to near homogeneity. Comparative studies of mast cells from these several sources have uncovered several major differences among them. Adult and neonatal skin mast cells themselves differ in that the former are 10-fold less sensitive to goat anti-human IgE, with maximal release occurring at 3.0 and 0.3 microgram/ml, respectively. Skin mast cells also differ in optimal temperature for release: adult mast cells respond maximally at 23 to 30 degrees C and neonatal cells at 37 degrees C. Skin mast cells from both sources are dramatically different from lung and intestinal mast cells in two aspects. First, skin mast cells are quite responsive to several stimuli--morphine sulfate (10(-4) to 10(-6) M), substance P (10(-5) to 10(-7) M), compound 48/80 (10 to 0.1 microgram/ml), f-Met peptide (10(-6) M), and C5a (10(-8) M)--to which the other mast cells fail to respond. Second, although stimulated skin mast cells produce prostaglandin D2, little leikotriene C4, if any, is generated, unlike lung or intestinal mast cells. These differences in inflammatory potential among human mast cells from various sites have important implications for the management of allergic and inflammatory responses.
Effects of differentiation of human macrophage-like U937 cells on intrinsic resistance to herpes simplex virus type 1.
Authors: Tenney D J , Morahan P S 
Published: December 2022

Abstract
We have characterized the effect of differentiation on the resistance of the mononuclear phagocyte to herpes simplex virus type 1 (HSV-1) by using the human mononuclear phagocyte cell line, U937. The replication of HSV-1 was compared in undifferentiated U937 cells and U937 cells induced to undergo differentiation. Undifferentiated U937 cells were highly resistant to HSV-1 infection. Infectious virus levels declined rapidly to less than 0.1 plaque-forming units (PFU) per cell by 24 hr postinfection and the cells were completely resistant to HSV-1-induced cytopathic effect. Differentiation of U937 cells by treatment with phorbol 12-myristate 13-acetate (PMA) was accompanied by a decrease in the resistance to HSV-1 infection. Infectious virus yields were increased greater than 75-fold at 24 hr postinfection, as compared with the undifferentiated U937 cells. PMA-differentiated U937 cells also acquired full susceptibility to HSV-1-induced cytopathic effect. Infectious center assay revealed that the percent of productively infected cells increased from approximately 3% in undifferentiated U937 to greater than 50% in PMA-differentiated cells. U937 cells were also induced to differentiate by treatment with all-trans-retinoic acid, dimethyl sulfoxide, and lymphokine as shown by differentiation-associated changes in morphology and cytochemical enzymes. These cells, however, failed to display increased permissiveness for HSV-1, indicating that the change in permissiveness was uniquely associated with PMA treatment. Undifferentiated U937 cells adsorbed as much virus as PMA-differentiated cells, but immunofluorescence assays, as well as DNA hybridization analysis demonstrated that an early block in HSV-1 replication occurred in undifferentiated U937 cells, before synthesis of viral protein and DNA. PMA-induced differentiation of U937 cells appears to release an early block in HSV-1 replication that is present in undifferentiated U937 cells.
Natural killer cell inhibition of young spherules and endospores of Coccidioides immitis.
Authors: Petkus A F , Baum L L 
Published: December 2022

Abstract
The recent development of a method for culturing the parasitic form of Coccidioides immitis by using conditions compatible with the growth of lymphoid cells has enabled us to investigate the role of natural killer (NK) cells in defense against this pathogenic fungus. Pure cultures of spherules and endospores were grown in RPMI 1640 which contained 10% calf serum. Single cell suspensions of young spherules and endospores were incubated in the presence of freshly isolated human peripheral blood lymphocytes (PBL). After a 4-hr incubation, the colony-forming ability of the fungus was significantly reduced. Leu-11 is a monoclonal antibody that binds to the Fc receptor of NK cells. When PBL were incubated in the presence of this monoclonal antibody and complement, the colony-forming ability of C. immitis was not reduced, indicating that the effector cell involved in reduction of colony-forming units is also recognized by the Leu-11 monoclonal antibody. Classical NK activity can be enhanced by preincubation with interferon; the inhibitory activity of the PBL which are responsible for the reduction in colony-forming units of C. immitis is similarly enhanced by pretreatment with interferon. When PBL are incubated in the presence of young spherules and endospores for 24 hr, the cellfree supernatants will kill U937 target cells. In addition to stimulating the release of NK cytotoxic factor, C. immitis is susceptible to inactivation when incubated in the presence of factors released by PBL which have been incubated in the presence of either K562 or C. immitis. Other evidence reported by this laboratory demonstrates that C-reactive protein is present on the surface of NK cells and that antibody to this molecule blocks NK-mediated killing of standard tumor cell targets. Pretreatment with anti-C-reactive protein also blocks the ability of PBL to inhibit the colony-forming capacity of this fungus. These data suggest that the cell that inhibits the in vitro growth of the pathogenic fungus, C. immitis, is an NK cell.
The heavy chain genes of a lupus anti-DNA autoantibody are encoded in the germ line of a nonautoimmune strain of mouse and conserved in strains of mice polymorphic for this gene locus.
Authors: Trepicchio W , Maruya A , Barrett K J 
Published: December 2022

Abstract
The variable region of the heavy chain of a prototypic anti-DNA autoantibody from the lupus-prone mouse, MRL-lpr/lpr, was cloned and sequenced. The VH and JH genes expressed by this antoantibody were found to be identical to germ line genes from the nonautoimmune mouse strain, BALB/c. The D gene of this autoantibody differed by one nucleotide from several members of the germ line SP2 family, but has been found in expressed D genes from several strains of mice. These results show that a normal mouse strain contains all of the structural information necessary for the expression of the heavy chain variable region of a lupus autoantibody. A fragment that is present in both BALB/c and MRL mice is highly homologous in both coding and flanking sequences to the autoantibody VH gene (VH130) and is the same size as the BALB/c germ line gene. This suggests that these two strains may share the same allele of this VH gene, despite the fact that they are polymorphic for this VH gene family. Other mouse strains that are polymorphic for this locus contained one to three VH genes that were highly related to VH130 in both coding and flanking regions. Thus, VH genes that may be allelic to the antibody VH gene or that may have arisen by gene conversion, unequal crossing over or gene duplication, are conserved in many mouse strains.
Analysis of rat natural killer cytotoxic factor (NKCF) produced by rat NK cell lines and the production of a murine monoclonal antibody that neutralizes NKCF.
Authors: Ortaldo J R , Winkler-Pickett R , Morgan A C , Woodhouse C , Kantor R , Reynolds C W 
Published: December 2022

Abstract
Natural killer cytotoxic factor (NKCF) is produced as a result of the interaction of murine, rat, or human natural killer (NK) cells with NK-susceptible targets. This factor has been linked to the target cell lysis mediated by the NK effector cell. In the present results, culture supernatants from rat large granular lymphocyte (LGL) tumors exhibited NKCF activity which lysed the susceptible targets, MBL-2 and YAC-1. NKCF production from these rat tumor lines was spontaneous and was not significantly increased by co-incubation of the LGL tumors with target cells, target cell membranes, or by preincubation of the LGL tumor cells with interferon or interleukin 2. In addition to NKCF activity, the supernatants lysed L929, indicating the presence of tumor necrosis factor (TNF) in these preparations. The presence of this latter cytokine was verified using specific antibodies to recombinant murine TNF which neutralized the L929 activity while not affecting the NKCF activity against MBL-2 or YAC-1. Mouse monoclonal antibodies (mAb) A0287, A0462, and A0316) which significantly inhibit the NKCF cytolytic activity of these LGL-derived supernatants were also produced. These antibodies were shown to cross-react with human NKCF in a manner similar to that seen in the rat. Interestingly these same mAb demonstrated no inhibition of L929 cytotoxicity from either LGL-derived supernatants or by recombinant murine or human TNF. To examine further the specificity of these antibodies, they were chemically linked to Sepharose 4B and found to remove a significant proportion of the NKCF cytolytic activity from LGL supernatants, while not affecting the TNF reactivities in these preparations. In addition, these antibodies demonstrated significant inhibition of cell-mediated cytotoxicity by rat LGL against YAC-1 target cells. Biochemical analysis of labeled NKCF-containing supernatants indicated the major protein recognized by these anti-NKCF mAb to be approximately 12,000 m.w. The use of these mAb against NKCF should be very useful in further purification and biochemical characterization of NKCF and in studying its role in a variety of cell-mediated cytotoxicity assays.
Adoptive chemoimmunotherapy of murine leukemia with helper T lymphocyte clones.
Authors: Bookman M A , Swerdlow R , Matis L A 
Published: December 2022

Abstract
Antigen-specific syngeneic noncytolytic helper T lymphocyte clones were investigated for their ability to mediate successful adoptive chemoimmunotherapy (ACIT) of mice with established RBL5 tumors. Clone B10, specific for the viral coat m.w. 70,000 glycoprotein, could be rapidly activated in situ after local transfer with intact tumor cells in syngeneic hosts to produce a delayed-type hypersensitivity reaction. For ACIT, mice bearing 5-day-old tumors received cyclophosphamide followed by transfer of resting helper T lymphocyte clones with or without exogenous interleukin 2 (rIL-2). A single injection of clone B10 was effective in ACIT when followed by a short course of exogenous rIL-2. Alternatively, repeated injections of resting clone were also effective without exogenous rIL-2, suggesting that the major role for rIL-2 was prolongation of clone survival in vivo rather than activation of other effector cells. Clone F12, specific for a component of fetal calf serum, was not effective in ACIT either with or without rIL-2, even when administered under conditions known to result in clone activation. Thus, antigen-specific helper T lymphocyte clones are capable of activation and promotion of antitumor responses after adoptive transfer.
Density-dependent recognition of cell surface GM3 by a certain anti-melanoma antibody, and GM3 lactone as a possible immunogen: requirements for tumor-associated antigen and immunogen.
Authors: Nores G A , Dohi T , Taniguchi M , Hakomori S 
Published: December 2022

Abstract
A mouse monoclonal antibody M2590, previously established after immunization of mice (C57BL/6) with syngeneic melanoma B16 cells and showing preferential reactivity with various types of melanoma over other tumor and normal cells or tissues, was shown to be directed to GM3 ganglioside. Since GM3 is widely distributed in essentially all types of animal cells, there is a conflict with the concept of a tumor-associated antigen and immunogen. Studies on the reactivity of M2590 antibody with various cells having different GM3 density at their cell surface, including cells treated with sialidase, liposomes, and solid-phase lipid layer containing different GM3 concentrations, have indicated that 1) reactivity of the antibody M2590 depends greatly on the density of GM3 exposed at the cell surface, on liposomes, or on solid phase; and 2) there is a threshold density that is recognized by the antibody in all-or-none fashion. In addition, the antibody M2590 reacts not only with GM3 but also with GM3 lactone, and the binding affinity of the antibody to GM3 lactone is strikingly higher than to GM3; however, the antibody does not react with GM3 ethyl ester. GM3 lactone was detected in melanoma as 3H-labeled GM3 gangliosidol after melanoma cells were directly treated with NaB[3H]4. A comparative immunization of BALB/c mice with GM3 and GM3 lactone showed that GM3 lactone is a much stronger immunogen than GM3, although the antibody elicited reacts with both GM3 and its lactone. Thus, the real immunogen could be GM3 lactone, although it is a minor membrane component.