bluuebunny/crossref_metadata_2025 huggingface dataset:
Antagonistic effects of gamma interferon and steroids on tissue antigenicity.
Authors: Leszczynski D , Ferry B , Schellekens H , van der Meide P H , Häyry P
Published: June 2004

A single injection of 10(5) U/kg of recombinant rat IFN-gamma increases the amount of tissue dendritic cells up to sixfold, and concomitantly induces the (capillary) endothelial cells to express class II MHC antigens. Both responses peak on the third day after IFN-gamma injection, and the antigen expression returns to basic levels on day 7. Simultaneous administration of 1 mg/kg/d of methylprednisolone entirely abolishes both responses. These observations demonstrate, for the first time, that IFN-gamma and steroids have antagonistic effects on class II MHC antigen presentation in tissue, and suggest that one immunosuppressive mechanism of glucocorticosteroids in organ transplantation is downregulation of graft antigenicity.
Cell surface expression of class II histocompatibility antigens occurs in the absence of the invariant chain.
Authors: Sekaly R P , Tonnelle C , Strubin M , Mach B , Long E O
Published: June 2004

The invariant chain is a glycoprotein transiently associated with the alpha and beta subunits of class II antigens of the major histocompatibility complex during their transport to the cell surface. An expression assay with cDNA clones transfected into simian COS cells was used to test whether the invariant chain is required for assembly and transport of human class II antigens. COS cells do not express detectable levels of RNA from the endogenous invariant chain gene. Cell surface expression of the DP, DQ, and DR antigens was observed in COS cells transfected with the respective alpha and beta chain cDNA clones. Analysis of RNA from the transfected cells showed that the human genes were transcribed in COS cells and that the endogenous simian class II and invariant chain genes were not induced. Cotransfections with an invariant chain cDNA clone did not alter the levels of class II antigens at the cell surface. Biosynthetic labeling and immunoprecipitation demonstrated that the invariant chain cDNA was expressed into a protein which associated with DR alpha and beta chains. Efficient expression of DR antigen in absence of invariant chain was also observed at the surface of a human fibroblast line stably transfected with DR alpha and beta cDNA. This study demonstrates that expression of all three human class II antigens can be achieved with cDNAs cloned in expression vectors. Furthermore, cell surface expression of class II major histocompatibility complex antigens can occur in absence of invariant chain. The postulated role of the invariant chain in class II antigen transport to the cell surface must be reevaluated. The invariant chain may rather be involved in functional properties of class II molecules such as antigen presentation.
Natural killer cell regulation of age-related and type-specific variations in antibody responses to pneumococcal polysaccharides.
Authors: Khater M , Macai J , Genyea C , Kaplan J
Published: June 2004

Pretreatment of mice with anti-asialo GM1, which has been shown to deplete NK cytolytic activity without affecting cytotoxic T cells or macrophages, increased the weak anti-PPS 6 responses of adult mice to levels similar to that of their anti-PPS 3 responses, and increased the weak-to-absent anti-PPS 3 and anti-PPS 6 responses of weanling mice to the same levels as achieved by adult mice. By contrast, pretreatment with poly(IC), which augments NK activity, resulted in a 14-fold reduction in the anti-PPS 3 responses of adult mice. The enhancement of anti-PPS responses in mice treated with anti-asialo GM1 was due to inactivation or depletion of NK cells, and not T suppressor cells, since this enhancement occurred in athymic nude mice as well as in euthymic mice. In addition, strains of mice with low or absent endogenous NK activity were found to have considerably stronger anti-PPS responses than strains of mice with normal NK activity. NK depletion enhanced anti-PPS 6 IgM but not IgG response, and resulted in a true increase in antibody production rather than an alteration in the time course of the response. These findings indicate that NK cells physiologically downregulate anti-PPS responses, and that age-dependent and type-specific variations in these responses are primarily determined by NK regulatory effects.
Identification of a unique tumor antigen as rejection antigen by molecular cloning and gene transfer.
Authors: Stauss H J , Van Waes C , Fink M A , Starr B , Schreiber H
Published: June 2004

Tumor-specific transplantation antigens are antigens that can lead to complete immunological destruction of a transplanted cancer by the syngeneic host. When such antigens are expressed on cancers induced by chemical or physical carcinogens, then they are usually unique, i.e., antigenically different for each independently induced tumor. In this study, we show that the product of a gene encoding a novel MHC class I molecule and isolated from the murine UV light-induced regressor tumor 1591 represents one such unique tumor-specific transplantation antigen that causes tumor rejection. The major evidence comes from our finding that 1591 progressor variants regularly lost the gene encoding this antigen that is expressed in the parental tumor that regresses in normal mice; furthermore, reintroduction of this gene into a 1591 progressor variant by DNA transfection caused the progressor variant to regress in normal immunocompetent mice. Thus, the progressor tumor reverted to the parental regressor phenotype following transfection. Consistent with the conclusion that the expression of the novel MHC class I gene following transfection was responsible for the regressor phenotype is also our finding that a variant of the transfected tumor that had lost expression of the transfected gene resumed its progressive growth behavior. Finally, we show that the molecule encoded by the novel class I gene is specifically recognized by a syngeneic tumor-specific cytolytic T cell clone that we have previously shown to select in vitro for progressor variants from the parental regressor tumor cell line. It remains to be determined to what extent unique tumor-specific rejection antigens of other highly immunogenic regressor tumors are encoded by novel MHC class I genes and whether these genes represent germline mutations or somatic mutations caused by the carcinogen treatment.
Highly malignant tumor variants retain tumor-specific antigens recognized by T helper cells.
Authors: Van Waes C , Urban J L , Rothstein J L , Ward P L , Schreiber H
Published: June 2004

We have studied the components of a complex of tumor-specific antigens to determine if all of the components of the complex were lost during progression from a rather benign regressor tumor to a highly malignant (HM) cancer. We find that the HM tumor cells have lost antigens recognized by CTL but retained antigens recognized by Th cells. Immunization with variants expressing Th-defined antigens induced tumor-specific immunity to challenge with a parental variant that expressed a CTL-recognized target antigen, but did not induce immunity to challenge with the variant that expressed the Th-defined antigen alone. Together, these findings suggested that Th cells fail to exert direct selective pressure upon the tumor, resulting in retention of "lineage-specific," Th-recognized antigens by highly immunoselected variants. Possible advantage could be taken of this fact for the development of specific immunotherapy.
Idiotype variant cell populations in patients with B cell lymphoma.
Authors: Carroll W L , Lowder J N , Streifer R , Warnke R , Levy S , Levy R
Published: June 2004

Using isolated idiotype (Id) protein we generated panels of antibodies in two patients with follicular lymphoma, one of whom had never received prior chemo-or radiotherapy. Flow cytometry and frozen section tissue staining of tumor with these monoclonal antibodies (mAb) revealed multiple subpopulations within each tumor. Individual mAb stained between 7% and 83% of surface Ig+ cells in the tumor samples. These subpopulations were overlapping and no single antibody recognized all the tumor cells. However, combinations of antibodies seemed to capture total tumor in both cases. In some instances, the percentage of tumor stained by a single mAb varied over time, and differed between lymph nodes sampled at the same time. Because a single species of Id protein was used to generate mAb in each case, it appears that the antibodies were directed against idiotopes variably shared by different populations within each tumor, and this was confirmed by crossblocking studies. Tumor cells from one patient were fused to a nonsecreting heteromyeloma line K6H6/B5, and most of the resulting hybrids secreted Id protein. Four mAb were used to screen the Id proteins secreted by these hybrids, and 11 different variants (16 maximal) were found. Southern blot analysis of rearranged Ig genes was done in two hybrids and biopsy material. Identically rearranged light-chain genes were seen but it appeared as though extensive somatic variation had occurred in heavy chain genes. These studies indicate that: striking Id variation can exist at diagnosis in untreated patients, the percentage of tumor represented by an individual variant may change with time and may differ between tumor sampled from different anatomical locations, and somatic variation appears to be responsible for the observed heterogeneity. Although this degree of variation makes anti-Id antibody therapy more difficult, appropriate combinations of mAb should be more efficacious than single antibodies in such cases.
Analysis of a human V beta gene subfamily.
Authors: Siu G , Strauss E C , Lai E , Hood L E
Published: June 2004

We have isolated and sequenced five germline V beta gene segments that are homologous to the V region of the YT35 cDNA encoding the beta chain of the T cell antigen receptor from the tumor MOLT-3. One of these gene segments is identical to the YT35 V segment, and therefore is the corresponding germline V beta gene segment encoding the YT35 cDNA. The other four V beta members exhibit 77-98% homology to the YT35 V gene segment. Two of these V beta gene segments are pseudogenes. Analyses of the coding region sequences reveal that, although the V beta segments are very diverse, they are mutating at a rate comparable to that observed in most eukaryotic genes. Analyses of the genomic clones show that the spacing distance between germline V beta gene segments ranges from 3 kb to greater than 30 kb, and the entire V beta 8 subfamily appears to be linked by a total of no more than 110 kb of DNA.
Cyclosporine-induced autoimmunity. Conditions for expressing disease, requirement for intact thymus, and potency estimates of autoimmune lymphocytes in drug-treated rats.
Authors: Sorokin R , Kimura H , Schroder K , Wilson D H , Wilson D B
Published: June 2004

These studies explore the phenomenon of cyclosporine-induced autoimmunity in irradiated Lewis rats. We show that (a) the presence of a thymus is required, and autoimmune precursors develop in and exit from this organ to the peripheral lymphocyte pool within a 2-wk period after the initiation of cyclosporine treatment; (b) adoptive transfers of drug-induced autoimmunity to irradiated secondary recipients can be accomplished with relatively few cells of the Th subset, and these transfers of autoimmunity can be blocked by cotransfer of normal lymphoid cells; and (c) potency estimates, using popliteal lymph node assays in syngeneic and F1 recipients indicate similar levels of auto- and alloreactivity by cells from drug-induced autoimmune donors. These various findings indicate that this particular animal model may be useful for studies of the onset and control of autoimmunity, and they raise the possibility that the lack of autoimmunity in normal animals and its induction with cyclosporine may involve similar cellular mechanism as have been found to be operative in GVH reactions and specifically induced immunologic resistance to GVHD.
Conversion of an M- group A streptococcus to M+ by transfer of a plasmid containing an M6 gene.
Authors: Scott J R , Guenthner P C , Malone L M , Fischetti V A
Published: June 2004

An M28-derived group A streptococcal strain deleted for the gene encoding M protein was converted to M+ by introduction of a plasmid carrying emm6, the structural gene for type 6 M protein from strain D471. The reconstituted M+ strain, JRS2, resists phagocytosis in human blood and is opsonized by anti-M6 hyperimmune serum, but not by anti-M28 serum. Immunofluorescent microscopy and ELISA demonstrate the presence of M protein on its surface. In addition, JRS2 removes opsonic antibodies from hyperimmune rabbit sera generated by immunization with purified ColiM6 protein and with a synthetic amino-terminal peptide derived from M6. Immunization of rabbits with JRS2 generates opsonic anti-M6 antibodies. These results indicate that the cloned emm6 gene contains the information necessary to convert a phagocytosis-sensitive streptococcus to phagocytosis resistance. Furthermore, it also contains the determinants for M type specificity and those required to elicit opsonic antibodies. It thus appears to determine all the traits associated with M protein.
Production of a cytokine with interleukin 3-like properties and cytokine-dependent proliferation in human autologous mixed lymphocyte reaction.
Authors: Suzuki R , Suzuki S , Takahashi T , Kumagai K
Published: June 2004

The autologous mixed lymphocyte reaction (AMLR) was assayed in a medium containing fresh autologous serum, by using nylon-adherent stimulator cells and nonadherent responder T cells, which were prepared from human peripheral blood mononuclear cells in the absence of fetal calf serum (FCS) to avoid any sensitization to xenogeneic protein antigens. DNA replication without a background proliferative response was induced by stimulator cells in the responder cells. The addition of monoclonal anti-HLA-DR antibody to the culture or treatment of the responder cells with complement plus anti-T4 but not anti-T8 monoclonal antibody suppressed the AMLR, suggesting that this specific AMLR involves an interaction between HLA-DR antigens and helper/inducer T cells. Regardless of this specific DNA replication, the AMLR generated no production of interleukin 2 (IL-2) and interferon gamma (IFN-gamma), both of which could be found in the allogeneic (allo) MLR. In addition, DNA replication in the AMLR was not inhibited by the addition of specific antisera for IL-2 and IFN-gamma, both of which significantly inhibited the DNA replication in allo-MLR. The AMLR was accompanied by production of a soluble factor, which could stimulate the proliferation of murine interleukin 3 (IL-3)-dependent cell line 32Dcl but not the proliferation of IL-2-dependent cell lines. This factor was also found to be responsible for proliferation of responder nonadherent cells in the AMLR. It strongly stimulated bone marrow cells, as did the murine IL-3. The factor had an Mr range, as determined by gel filtration, of 15,000-28,000, but it did not bind to fast protein liquid chromatography (FPLC)-MonoQ column. Thus, the factor is distinguishable from IL-2 in physicochemical or biological properties, but similar to murine IL-3. These results suggest that the human AMLR may be primarily a phenomenon in which non-T cells mediated by the HLA-DR antigens on the cell stimulate helper/inducer T cells to produce a lymphokine with IL-3-like properties, but no IL-2, which in turn stimulates the factor-dependent cells to proliferate.
Anthrax toxin blocks priming of neutrophils by lipopolysaccharide and by muramyl dipeptide.
Authors: Wright G G , Mandell G L
Published: June 2004

We studied the pretreatment of human polymorphonuclear neutrophils (PMN) with purified preparations of the anthrax toxin components--protective antigen (PA), edema factor (EF), and lethal factor (LF)--and their effects on release of superoxide anion (O-2) after stimulation with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). PMN isolated in the absence of lipopolysaccharide (LPS) (less than 0.1 ng/ml) released only small amounts of O-2 after FMLP stimulation; pretreatment with anthrax toxin had little effect. The release of O-2 was increased fivefold by prior treatment with 3 ng/ml LPS for 1 h at 37 degrees C, an effect referred to as priming. PMN were primed to an equivalent extent by treatment with 100 ng/ml N-acetyl-muramyl-L-alanyl-D-isoglutamine (muramyl dipeptide [MDP]). Pretreatment of PMN with anthrax toxin components PA plus EF or PA plus LF inhibited priming by LPS or MDP, as shown by the reduction in the release of O-2 up to 90% relative to controls not treated with toxin; single toxin components were inactive. The inhibition was markedly reduced when priming with LPS or MDP was carried out before exposure to toxin. O-2 release after stimulation by phorbol myristate acetate was not increased by priming, and pretreatment with toxin did not inhibit O-2 release after this stimulus. Evidently, anthrax toxin inhibits the priming that is normally induced in PMN by bacterial products and is necessary for the full expression of antimicrobial effects.
Retroviral activation of interleukin 2 gene in a gibbon ape T cell lymphoma line.
Authors: Durand D B , Kamoun M , Norris C A , Holbrook N J , Greengard J S , Crabtree G R , Kant J A
Published: June 2004

The gibbon ape leukemia virus (GaLVSF)-infected T cell line, MLA 144, was established from the lymphoma of a gibbon ape. The cell line constitutively expresses IL-2 and its receptor, implying that an autocrine mechanism could be responsible for or contribute toward its growth. To explore the mechanism of constitutive IL-2 expression in MLA 144, we have isolated and characterized cosmid clones representing a normal and a doubly inserted IL-2 allele in this cell line. The map of the normal MLA 144 IL-2 allele closely resembles that of the normal human IL-2 gene. The abnormal allele contains a 3' insertion that is a GaLVSF provirus with two long terminal repeats (LTR) and an internal 3.25 kb deletion. At the 5' end of the abnormal allele is a second insertion that DNA sequencing showed to be an isolated GaLVSF LTR with a transcriptional orientation opposing that of the IL-2 gene. We demonstrate by Northern blotting analysis that the vast majority of transcripts are from the abnormal allele, implying that one or both retroviral insertions are responsible for constitutive expression of the allele.
Immunoglobulin G antibodies directed against protein III block killing of serum-resistant Neisseria gonorrhoeae by immune serum.
Authors: Rice P A , Vayo H E , Tam M R , Blake M S
Published: June 2004

Neisseria gonorrhoeae that resist complement-dependent killing by normal human serum (NHS) are sometimes killed by immune convalescent serum from patients recovering from disseminated gonococcal infection (DGI). In these studies, killing by immune serum was prevented or blocked by IgG isolated from NHS. Purified human IgG antibodies directed against gonococcal protein III, an antigenically conserved outer membrane protein, contained most of the blocking activity in IgG. Antibodies specific for gonococcal porin (protein I), the major outer membrane protein, displayed no blocking function. In separate experiments, immune convalescent DGI serum which did not exhibit bactericidal activity was restored to killing by selective depletion of protein III antibodies by immunoabsorption. These studies indicate that protein III antibodies in normal and immune human serum play a role in serum resistance of N. gonorrhoeae.
Antigen-specific, MHC nonrestricted T helper cell-induced B cell activation.
Authors: Friedman S M , Jover J A , Chartash E K , Crow M K
Published: June 2004

We used a cloned, TNP-specific, MHC-restricted, human Th cell line, E-11, and an assay of cognate Th-B cell interaction, BLAST-2 antigen expression on the B cell surface, to investigate the functional nature of the Th cell antigen receptor. We observed that E-11 induces BLAST-2 expression by resting B cells in a hapten-dependent, hapten-specific, but MHC nonrestricted manner. The implication of these results for the Th cell receptor are discussed.
Sequence of myosin-crossreactive epitopes of streptococcal M protein.
Authors: Dale J B , Beachey E H
Published: June 2004

Group A streptococcal M proteins contain epitopes that crossreact with sarcolemmal membrane proteins of human myocardium and myosin. In the present study, synthetic peptide copies spanning the entire 197-residue pepsin extracted fragment of type 5 M protein were used to localize the myosin-crossreactive epitopes of the molecule. Peptide 84-116 inhibited by 75% the binding of myosin-crossreactive antibodies evoked by pep M5, as determined by ELISA. Immunoblot inhibition studies confirmed that peptide 84-116 almost totally inhibited the binding of pep M5 antibodies to the heavy chain of human cardiac myosin. None of the remaining synthetic peptides, including peptide 1-35, which contains protective epitopes, inhibited antibodies binding to myosin. Two of three rabbits immunized with peptide 84-116 developed low but significant levels of antibodies crossreactive with myosin. Identification of the primary structures containing tissue-crossreactive as opposed to protective epitopes should not only allow the development of safe and effective M protein vaccines, but may also provide insights into the pathogenesis of rheumatic heart disease.
Effect of gamma interferon on cachectin expression by mononuclear phagocytes. Reversal of the lpsd (endotoxin resistance) phenotype.
Authors: Beutler B , Tkacenko V , Milsark I , Krochin N , Cerami A
Published: June 2004

IFN-gamma permits the endotoxin-induced production of cachectin by C3H/HeJ (endotoxin resistant) macrophages, apparently by facilitating endotoxin-induced cachectin biosynthesis at both transcriptional and posttranscriptional levels. IFN-gamma cannot induce cachectin biosynthesis by itself, nor does it markedly enhance cachectin production by endotoxin-induced peritoneal macrophages obtained from endotoxin-responsive mice. Elucidation of the precise mechanism through which IFN-gamma influences cachectin biosynthesis may permit a better understanding of the molecular events that follow endotoxin-induced activation of macrophages. Moreover, the permissive effect of IFN-gamma on cachectin biosynthesis might elicit enhanced endotoxin sensitivity in vivo.
An expanded population of natural killer cells in mice with severe combined immunodeficiency (SCID) lack rearrangement and expression of T cell receptor genes.
Authors: Lauzon R J , Siminovitch K A , Fulop G M , Phillips R A , Roder J C
Published: June 2004

Mice with severe combined immunodeficiency syndrome (SCID) exhibit an impairment in both T and B cell maturation, whereas myelopoiesis remains unaffected. We report here that spleens from SCID mice have undergone phenotypic expansion of cells bearing the NK-2 and asialo GM1 markers (70-80%) characteristic of NK cells and this expansion is accompanied by a 3-4-fold enrichment in NK cytolytic activity over their normal C.B-17 littermates. Furthermore, the NK cells from SCID mice do not rearrange or express T cell receptor alpha or beta genes, or a third T cell rearranging gene, gamma. These findings suggest that (a) T cell receptors are not necessary for NK-mediated cytolysis, and (b) either NK cells constitute an entirely distinct lineage or NK cell function is acquired in pre-T cells prior to the expression of T cell receptor genes.
Human rheumatoid factor crossidiotypes. I. WA and BLA are heat-labile conformational antigens requiring both heavy and light chains.
Authors: Agnello V , Barnes J L
Published: June 2004

Evidence was obtained that both the WA and BLA crossidiotype (XId) groups are conformational antigens requiring both L and H chains and that with heat denaturation the antigens that define the XIds and antigen-binding activity are lost in parallel. In contrast, the primary structure-dependent crossreactive idiotype (CRI), PSL2, which is only weakly detected on native Wa and Bla monoclonal rheumatoid factors (mRFs), became prominently detected on the heated Wa and Bla mRFs. Heat denaturation may provide a simple method for distinguishing Ids determined by conformational antigen from primary structure-dependent Ids. In addition to heat denaturation, some acid conditions commonly used for preparation of RFs were also found to cause marked loss of Id antigen. The finding of PSL2-CRI on Bla mRF indicates that this Id is not unique to the WA XId.
Thromboxane generation by human monocytes enhances platelet function.
Authors: Altieri D C , Mannucci P M
Published: June 2004

Human monocytes potentiate the ADP-stimulated aggregation of autologous platelets through a fourfold increased binding of 125I-fibrinogen to the platelet surface. The enhancement of platelet function is rapid, relatively transient and is due to thromboxane (Tx) synthesized by monocytes under these conditions. Tx generation by monocytes is triggered by the interaction between fibrinogen and the specific monocyte membrane receptor. These data suggest that the monocyte enhancement of platelet function combined with the clot-promoting activity of these cells might unbalance normal hemostasis.
Helodermatine, a kallikrein-like, hypotensive enzyme from the venom of Heloderma horridum horridum (Mexican beaded lizard).
Authors: Alagon A , Possani L D , Smart J , Schleuning W D
Published: June 2004

We have purified and characterized the major N-benzoyl-L-arginine ethyl ester hydrolase from the venom of Heloderma horridum horridum. The enzyme belongs to the serine proteinase family, and its activity vs. peptide amide substrates and human high-molecular-weight kininogen suggests a similarity to the family of kallikreins. This interpretation is corroborated by its reactivity with the natural inhibitors soybean trypsin inhibitor and Kunitz-type bovine pancreatic trypsin inhibitor (aprotinin). Injection of the enzyme (2-16 micrograms/kg) into anesthetized rabbits leads to a rapid dose-dependent transient decrease of the arterial blood pressure. Like glandular kallikrein it specifically converts single-chain tissue type plasminogen activator into its double chain form. In contrast to other kallikrein-like enzymes from snake venoms it shows no thrombin-like or plasminogen activator activity. The enzyme is a single-chain glycoprotein (Mr 63,000). The N-terminal sequence revealed significant homology to pig pancreatic kallikrein and to kallikrein like enzymes from Crotalus atrox and Crotalus adamanteus venom. This enzyme, which we name Helodermatine, is the first purified from Sauria with kallikrein-like properties.
Changes in the expression of potassium channels during mouse T cell development.
Authors: McKinnon D , Ceredig R
Published: June 2004

In this report we have combined the whole-cell electrophysiological recording technique with flow microfluorometry to isolate phenotypically defined thymocytes and T lymphocytes. Results obtained showed that J11d-/Lyt-2-/L3T4- cells express none or very few delayed rectifier K+ channels, whereas most other Lyt-2-/L3T4- cells, as well as typical cortical thymocytes (Lyt-2+/L3T4+), do express K+ channels. Mature (Lyt-2+/L3T4- or Lyt-2-/L3T4+) thymocytes, which are heterogeneous for J11d expression, were also found to be heterogeneous for K+ channel expression. Consistent with this finding was the observation that the cortisone-resistant subpopulation of thymocytes, which express low levels of J11d, were enriched for cells expressing low levels of K+ channels. Mature phenotype peripheral T lymphocytes expressed very low levels of K+ channels, but upon activation with Con A were found to express high levels of K+ channels. The results suggest that K+ channel expression in T cells is developmentally regulated. Increased expression of the channel is induced in response to mitogenic signals throughout the T cell lineage. Expression of the channel, therefore, serves as a useful marker in defining steps in the T cell differentiation pathway.
Adhesion-promoting receptors on human macrophages recognize Escherichia coli by binding to lipopolysaccharide.
Authors: Wright S D , Jong M T
Published: June 2004

We report here that human macrophages bind Escherichia coli by recognizing bacterial lipopolysaccharide (LPS). Purified LPS was inserted into erythrocyte membranes, and the resulting LPS-coated red cells were bound by macrophages with the same temperature and cation dependence as observed for E. coli. When receptors for LPS were withdrawn from the plasma membrane by spreading the macrophages on LPS-coated surfaces, the binding of E. coli was blocked. We have also identified the receptors on macrophages that recognize LPS. Macrophages express three structurally homologous cell surface proteins, CR3, lymphocyte function-associated antigen (LFA-1), and p150,95. We used surface-bound monoclonal antireceptor antibodies to selectively remove these proteins from the apical surface of macrophages. We found that each of these proteins mediated the binding of E. coli to macrophages.
Synthetic peptides from the circumsporozoite proteins of Plasmodium falciparum and Plasmodium knowlesi recognize the human hepatoma cell line HepG2-A16 in vitro.
Authors: Aley S B , Bates M D , Tam J P , Hollingdale M R
Published: June 2004

Several lines of evidence have emphasized the importance of the malaria circumsporozoite (CS) protein as a factor in sporozoite invasion of the hepatocyte; however, the specific mechanism of cell recognition and invasion has not been explained. In this study we present evidence that a highly conserved region of the CS protein immediately adjacent to the repeat region, the N1 region, specifically recognizes receptors on the human hepatoma cell line HepG2-A16 under conditions where invasion by sporozoites can occur. Peptides consisting of sequences from the repeat region or of the more extensive N2 region showed no such specific association. Antibody against the N1 peptide could inhibit sporozoite invasion in vitro. Covalent coupling of radiolabeled N1 peptide to HepG2-A16 cells identified two hepatic cell proteins to be closely associated with the peptide. We suggest that these proteins could act as receptors or mediators, via the N1 region of the CS protein, for the P. falciparum sporozoite in the process of invasion of the hepatocyte.
Expression of T cell receptor genes in human B cells.
Authors: Calman A F , Peterlin B M
Published: June 2004

We analyzed the transcription and rearrangement of the T cell antigen receptor (Ti) genes Ti alpha and Ti beta in human B cell, T cell, and myeloid cell lines, as well as in purified tonsillar B and T cells. All four B cell lines examined, as well as one of two myeloid cell lines, expressed low levels of truncated Ti beta transcripts, as did freshly purified tonsillar B cells. Two of the B cell lines and one of the myeloid lines also expressed truncated Ti alpha transcripts, while tonsillar B cells did not. Sequence analysis of cDNA clones from a B cell line demonstrated that these truncated Ti alpha and Ti beta transcripts were composed of unrearranged J and C gene segments. Comparison of cDNA clones from T and B cells suggests that D alpha genes or N regions contribute to the formation of Ti alpha transcripts in T cells but not in B cells. None of the B cell or myeloid cell lines in this study showed evidence of Ti beta gene rearrangements by Southern blotting. Our data, and other studies of gene rearrangements in human tumors, demonstrate that the level of Ti beta transcriptional activity and the frequency of Ti beta gene rearrangements are correlated in all cell types examined. Thus, our data support the accessibility model of antigen receptor gene rearrangement, whereby the susceptibility of gene segments to recombination enzymes is correlated with their transcriptional activity.
Proteolytic enzyme treatment reduces glomerular immune deposits and proteinuria in passive Heymann nephritis.
Authors: Nakazawa M , Emancipator S N , Lamm M E
Published: June 2004

We investigated the effect of proteolytic enzyme treatment on the course of passive Heymann nephritis (PHN). PHN was induced by intravenous injection of Heymann antibody into Sprague Dawley rats. Protease-treated rats received intraperitoneal chymopapain and subtilisin. In rats given subnephritogenic doses of Heymann antibody (5 or 10 mg, insufficient to cause proteinuria), glomerular immune deposits were assessed by immunofluorescence and electron microscopy. In rats given 5 mg Heymann antibody and treated with protease in the heterologous phase of the disease (days 1-7), fewer animals were positive for rabbit IgG and rat IgG, as determined by immunofluorescence on day 12, compared with controls (p less than 0.01). Rats given 10 mg Heymann antibody and treated on days 1-5 were less frequently positive for rabbit IgG on day 5 than controls (p less than 0.05). When treatment was given on days 6-12 (autologous phase), fewer rats had glomerular rabbit and rat IgG compared with controls (p less than 0.025). Protease treatment of rats given nephritogenic doses of Heymann antibody (greater than or equal to 40 mg, causing proteinuria) did not result in significant differences in immunofluorescence deposits. However, protease treatment significantly reduced the number of electron dense deposits at all doses of antibody (p less than 0.01). Furthermore, rats given 60 mg Heymann antibody followed by enzyme treatment in the heterologous phase (days 1-7) or throughout the autologous phase (days 6-18) had significantly reduced protein excretion during the autologous phase compared with control rats (p less than 0.05). After onset of significant proteinuria on day 15 in rats given 40 mg Heymann antibody and treated from day 15 until day 25, there was significantly less (p less than 0.05) proteinuria on days 21-22 and 24-25 than in control rats; thus, enzymes could reverse proteinuria. In normal rats, administration of proteases did not have significant effects on urinary protein excretion, serum creatinine, or renal morphology, nor did protease affect anti-rabbit IgG antibody production in rats injected with Heymann antibody. The overall results indicate that proteolytic enzyme treatment can prevent or remove glomerular immune deposits and can prevent or reverse proteinuria.
Human T cell activation. III. Rapid induction of a phosphorylated 28 kD/32 kD disulfide-linked early activation antigen (EA 1) by 12-o-tetradecanoyl phorbol-13-acetate, mitogens, and antigens.
Authors: Hara T , Jung L K , Bjorndahl J M , Fu S M
Published: June 2004

With human T cells activated by 12-o-tetradecanoyl phorbol-13-acetate (TPA) as immunogen, an IgG2a mAb, early activation antigen 1 (EA 1), was generated against a 60-kD protein with disulfide-linked 28-kD and 32-kD subunits. Both subunits were phosphorylated. The antigen, EA 1, was readily detected on approximately 60% of isolated and cryopreserved thymocytes, as determined by indirect immunofluorescence. A low level of EA 1 expression was detectable on 6-7% of blood lymphocytes. TPA-activated T cells expressed EA 1 as early as 30 min after activation. By 1 h, 85-90% of the T cells stained with mAb EA 1. By 3-4 h, the expression of EA 1 was detected in greater than 95% of the T cells. Although the percentages of EA 1+ T cells did not change, the intensity of staining increased slightly. After 18-24 h, both the percentage of EA 1+ cells and the intensity of staining decreased gradually. TPA-induced EA 1 expression was independent of monocytes. EA 1 expression was slightly delayed in T cells that were isolated without the rosette selection and treated with TPA. Nevertheless, greater than 85% of these T cells expressed EA 1 within 1 h, and the maximal number of EA 1+ T cells was also detected at 3-4 h. In T cell populations with 1-2% monocytes, about 50-90% of the PHA- or Con A-activated T cells expressed EA 1 with a slower kinetics. EA 1 expression preceded that of IL-2-R in these activation processes. Similarly, T cells activated by soluble antigens (tetanus toxoid and PPD) and alloantigens in MLR also expressed EA 1 after a longer incubation. Approximately 20% of the T cells stained for EA 1 at day 6. EA 1 expression was not limited to activated T cells. B cells activated by TPA or anti-IgM antibody plus B cell growth factor expressed EA 1. The kinetics of EA 1 expression was markedly slower and the staining was less intense. Repeated attempts to detect EA 1 on resting and TPA-activated monocytes and granulocytes have not been successful. However, the detection of EA 1 in nonlymphoid cell lines would indicate that EA 1 may have a broader cell distribution. EA 1 expression was due to de novo synthesis, as the induction of EA 1 was blocked by cycloheximide and actinomycin D.(ABSTRACT TRUNCATED AT 400 WORDS)
Amyloid A gene family expression in different mouse tissues.
Authors: Meek R L , Benditt E P
Published: June 2004

Serum amyloid A (SAA) is a major acute-phase reactant and apoprotein of high density lipoprotein (HDL). SAA is encoded by a family of three active genes. We examined hepatic expression and searched for extrahepatic expression of the three SAA mRNAs after injection with casein or LPS. Studies using an SAA cDNA, which detects all three SAA mRNAs, revealed that after casein injection liver SAA mRNA was elevated approximately 1,000-fold. Adrenal gland expressed SAA mRNA at a low level (0.5% of hepatic level), and was the only extrahepatic tissue with elevated SAA mRNA after casein injection. The small intestine, primarily the ileum, and the large intestine of unstimulated control animals contained 5- and 15-fold higher SAA mRNA levels than control liver. LPS also elevated liver SAA mRNA approximately 1,000-fold. However, in contrast to casein injection, every extrahepatic tissue examined expressed SAA mRNA. Lung and kidney contained 2-5% and large intestine contained nearly 10% of SAA mRNA levels found in liver RNA. SAA mRNA levels were lower in the remaining tissues and ranged from 0.1% in the brain and pancreas to 1.0% in the small intestine, with the ileum containing 50-fold more than the duodenum. Analysis of liver with SAA1, SAA2, and SAA3 mRNA-specific oligonucleotide probes revealed that SAA1 and SAA2 mRNA were elevated approximately 50-fold higher than SAA3 mRNA after casein administration. LPS, however, induced all three SAA mRNAs equally. In extrahepatic tissues, SAA1, SAA2, and SAA3 mRNAs were expressed differentially and can be grouped into three general classes: tissues expressing all three genes, tissues expressing SAA1 and SAA3, and tissues expressing predominantly or only SAA3.
Major histocompatibility complex (MHC) restriction of foreign transplantation antigens in rats rendered tolerant at birth.
Authors: Kimura H , Desquenne-Clark L , Miyamoto M , Silvers W K
Published: June 2004

Evidence is presented that MHC restriction of foreign transplantation antigens occurs when tolerance is induced. Whereas PVG and F344 rats rendered tolerant at birth with (DA X PVG)F1 and (DA X F344)F1 hybrid bone marrow cells (BMC), respectively, accept ACI skin grafts, presumably because the foreign transplantation antigens of these third party grafts, which are MHC-compatible with DA, are recognized only in association with the MHC of the hosts, DA rats rendered tolerant with (DA X PVG)F1 or (DA X F344)F1 hybrid BMC usually reject ACI skin. Further support that MHC restriction accompanies the induction of tolerance is provided by the observation that Lewis.1N rats rendered tolerant at birth with athymic (nude) Wag BMC are much more likely to accept BN.B2 (MHC-compatible with Wag) skin grafts, than BN (MHC-compatible with Lewis.1N) grafts.
Adult-onset cyclic neutropenia is a benign neoplasm associated with clonal proliferation of large granular lymphocytes.
Authors: Loughran T P , Hammond W P
Published: June 2004

Human cyclic neutropenia occurs in children and adults. Adult-onset cyclic neutropenia is an acquired disease characterized by increased numbers of large granular lymphocytes (LGL), in contrast to childhood-onset cyclic neutropenia in which LGL counts are normal. We investigated the clonality of lymphocytes in these two groups of patients by assessing the rearrangement status of the T cell receptor beta chain gene. Patients with adult-onset cyclic neutropenia showed clonal rearrangement of the T beta gene whereas the children did not. Since LGL are known to have multiple regulatory effects on normal hematopoiesis, the finding of a clonal proliferation of this lymphocyte population implicates these cells in the pathogenesis of cyclic neutropenia.
Human keratinocytes contain mRNA indistinguishable from monocyte interleukin 1 alpha and beta mRNA. Keratinocyte epidermal cell-derived thymocyte-activating factor is identical to interleukin 1.
Authors: Kupper T S , Ballard D W , Chua A O , McGuire J S , Flood P M , Horowitz M C , Langdon R , Lightfoot L , Gubler U
Published: June 2004

Keratinocytes produce an IL-1 like factor termed epidermal cell-derived thymocyte-activating factor (ETAF). In this study, we show that ETAF and IL-1 are identical by the following criteria: Both normal and malignant human keratinocytes contain mRNAs identical to monocytic IL-1 alpha and IL-1 beta mRNA, as determined by an S1 nuclease protection assay; and IL-1 activity in medium conditioned by these cells can be neutralized by antibodies specific for human IL-1. The IL-1 alpha and IL-1 beta mRNAs can be identified in cultured human keratinocytes in the absence of identifiable stimulation; this basal level of mRNA can be further induced to accumulate with certain defined stimuli. Cultured normal human keratinocytes (HFKs) contain 2-4 times more IL-1 alpha than IL-1 beta mRNA; in contrast, human peripheral blood monocytes contain 10-20 times more IL-1 beta than IL-1 alpha mRNA. The IL-1 activity released by these HFK can be neutralized by an antibody that neutralizes both alpha and beta IL-1, but not by an antibody that neutralizes only IL-1 beta. While human monocytes produce a large excess of IL-1 beta after appropriate stimulation, these data suggest that IL-1 alpha is a major (and may be the predominant) form of IL-1 produced by human keratinocytes.
Role of envelope glycoprotein carbohydrate in human immunodeficiency virus (HIV) infectivity and virus-induced cell fusion.
Authors: Lifson J , Coutré S , Huang E , Engleman E
Published: June 2004

Human immunodeficiency virus (HIV) envelope glycoprotein interactions with cell surface CD4 are involved in both virion infectivity and virally mediated cell fusion. D-mannose-specific lectins such as Con A specifically blocked virion infectivity and cell fusion. Studies with a recombinant vaccinia virus containing the HIV envelope gene demonstrated that Con A-mediated inhibition of HIV-induced fusion involved lectin binding to the viral envelope glycoprotein. These results indicate the importance of envelope glycosylation in the pathobiology of HIV infection, and suggest potential mechanisms for interfering with HIV infectivity and cytopathology.
Paucity of phosphorylcholine-specific clones in B cells expressing the VHT15 gene product.
Authors: Primi D , Barbier E , Drapier A M , Cazenave P A
Published: June 2004

The aim of this work was to study the cellular basis of the phenomenon of clonal dominance. To this end we analyzed two collections of BALB/c and C.B20 hybridomas that we selected on the basis of the expression of the VHT15 gene product independently from their antigen specificity. Our study demonstrates that none of the 28 BALB/c and only 2 of the 29 C.B20 hybridomas obtained have variable regions that bind PC. We conclude therefore that the domination of the immune response to PC by particular variable regions cannot be due to the establishment of clonal dominance prior to immunization.
Gamma interferon enhances macrophage transcription of the tumor necrosis factor/cachectin, interleukin 1, and urokinase genes, which are controlled by short-lived repressors.
Authors: Collart M A , Belin D , Vassalli J D , de Kossodo S , Vassalli P
Published: June 2004

Exposure of mouse resident and thioglycollate-elicited peritoneal macrophages to IFN-gamma leads to a marked increase in the TNF-alpha (tumor necrosis factor/cachectin), IL-1 and u-PA (urokinase-type plasminogen activator) mRNA levels. Nuclear run-on experiments show that IFN-gamma acts by enhancing the transcription of these three genes. Transcription of these three genes is also rapidly and transiently induced by cycloheximide, an inhibitor of protein synthesis, indicating that they are under the control of short-lived repressors.
A conserved human germline V kappa gene directly encodes rheumatoid factor light chains.
Authors: Radoux V , Chen P P , Sorge J A , Carson D A
Published: June 2004

The full-length gene that encodes the light chain variable regions of an idiotypically related group of human IgM kappa rheumatoid factors (RFs) has been cloned and sequenced. The deduced amino acid sequence is identical to four separate RF proteins. These results prove that genes capable of encoding human anti-IgG autoantibody light chains without any somatic mutation are present in the kappa gene repertoire of normal people.
Regional variations in antigenic properties of skin. A possible cause for disease-specific distribution of skin lesions.
Authors: Sison-Fonacier L , Bystryn J C
Published: June 2004

The possibility that the distribution of skin lesions in some cutaneous diseases is due to variations in the antigenic properties of skin was investigated by mapping the expression of the skin-specific pemphigus vulgaris and bullous pemphigoid antigens in different regions of the body. The expression of both antigens was relatively stable within the same region, but varied between regions in a pattern that was distinct for each antigen. For each antigen there was a correlation between regions of high expression and location of skin lesions in autoimmune diseases involving the antigen. The results indicate that there are marked regional differences in the antigenic properties of skin and suggest this may influence the distribution of cutaneous lesions in some skin diseases.
The MRC OX-44 antigen marks a functionally relevant subset among rat thymocytes.
Authors: Paterson D J , Green J R , Jefferies W A , Puklavec M , Williams A F
Published: June 2004

A monoclonal antibody called MRC OX-44 is described that labels all myeloid cells and peripheral lymphoid cells but only 12% of thymocytes. The OX-44+ thymic cells include most if not all cells found in the medulla but only a small fraction of the cortical cells. Together with CD4 and CD8 antigens, seven subsets of thymic cell were defined and it was notable that most CD4- CD8- cells were OX-44+ whereas almost all CD4+ CD8+ cells were OX-44-. In functional tests, the OX-44+ cells accounted for all proliferation by thymocytes when stimulated by allogeneic spleen cells or concanavalin A plus growth factors and OX-44- cells were completely negative in these assays. Also, in tests for thymopoiesis after intra-thymic injection of cells, all activity was OX-44+. It seems possible that the OX-44+ set may include all functionally relevant cells in the rat thymus.