bluuebunny/crossref_metadata_2025 huggingface dataset:
Complement receptor mediates enhanced flavivirus replication in macrophages.
Authors: Cardosa M J , Porterfield J S , Gordon S
Published: June 2004

Evidence is presented that M phi complement receptors (CR3) mediate IgM-dependent enhancement of flavivirus replication in the presence of complement. Enhancement is blocked by pretreatment of macrophages with monoclonal antibody Ml/70, which inhibits CR3 binding, but not by pretreatment with monoclonal antibody 2.4G2, which inhibits FcR binding.
Quantitative studies on T cell diversity. IV. Mathematical analysis of multiple limiting populations of effector and suppressor T cells.
Authors: Fey K , Melchers I , Eichmann K
Published: June 2004

Limiting dilution (LD) analyses of polyclonally activated T cells yielded results suggesting the existence of multiple paired populations of effector and suppressor precursors for a number of different T cell functions and specificities analyzed. These populations occur at graded frequencies and suppression occurs within a pair but not between pairs. In this paper, we establish the mathematical basis for the interpretation of these multi-component limiting dilution results. First, we derive equations for a number of mathematical models and identify one model that both makes biological sense and can be used to reproduce experimental data. Second, within this model, we identify parameters such as the frequency of suppressive cells and the number of suppressive cells required for suppression. The results suggest that within each paired population, suppressor precursors are 20 times more frequent that effector precursors. Furthermore, a similar but variable excess of suppressor cells is required for suppression to become effective. Together with the high frequency (1/50-1/500) of most effector T cell precursors previously reported, the results suggest that up to 40% of the T cells can become involved in suppression of an antigen-specific effector T cell population. These studies may provide exact estimates for predictions to be tested in experiments on immune regulation.
c-sis is translocated from chromosome 22 to chromosome 9 in chronic myelocytic leukemia.
Authors: Groffen J , Heisterkamp N , Stephenson J R , van Kessel A G , de Klein A , Grosveld G , Bootsma D
Published: June 2004

By analysis of a series of somatic cell hybrids derived by fusion of either mouse or Chinese hamster cells with leukocytes from different chronic myelocytic leukemia (CML) patients or from normal donors, we have localized the human oncogene, c-sis, on the q11 to qter segment of chromosome 22 and demonstrated its translocation from chromosome 22 to chromosome 9 (q34) in CML.
Specificity of T cell clones for antigen and autologous major histocompatibility complex products determines specificity for foreign major histocompatibility complex products.
Authors: Abromson-Leeman S R , Cantor H
Published: June 2004

We have analyzed a panel of T cell clones that corecognize defined epitopes of the insulin molecule in association with Ia for their patterns of recognition of alloantigens. A striking correlation is observed between recognition of the I-Ab gene product and cow insulin alpha loop and recognition of I-Eu of the PL/J haplotype. These results are consistent with the notion that reactions to foreign major histocompatibility complex (MHC) products reflect molecular mimicry by foreign class II antigens of 'physiologic' complexes formed by autologous class II MHC molecules and antigen.
Idiotype profile of an immune response. II. Reversal of the relative dominance of major and minor cross-reactive idiotypes in arsonate-specific T-independent responses.
Authors: Conger J D , Lamoyi E , Lewis G K , Nisonoff A , Goodman J W
Published: June 2004

Two different cross-reactive idiotype (CRI) groups are distinguishable in the Ab response of A/J mice to the p-azobenzenearsonate (ABA) hapten: CRIA and CRIm. These two groups showed distinct patterns of relative dominance in the ensuing response depending on whether the inducing Ag was a T cell-dependent (TD) form of ABA, such as ABA-KLH or ABA-CGG, or a T-independent type 1 (TI-1) form, such as ABA-Brucella abortus or ABA-lipopolysaccharide (LPS), and on whether the response was elicited in vivo or in vitro. The CRI+ component of primary in vivo plaque-forming cell (PFC) responses to TD ABA Ags was largely (greater than 90%) CRIA+ as was, to a slightly lesser extent (greater than 75%) the CRI+ portion of secondary or hyperimmune serum Ab or PFC responses to the same Ags. In contrast, in vivo primary and hyperimmune PFC responses to ABA-Bru or ABA-LPS showed a significantly lower CRIA/CRI ratio, averaging 0.5-0.6, with some individual mice giving figures as low as 0.2, indicating predominance of CRIm over CRIA. Serological analysis of hyperimmune anti-ABA Abs from a group of 5 A/J mice immunized with ABA-Bru gave a figure of less than 0.5 for the CRIA/CRI ratio. The most striking disparity from the TD pattern was seen in primary in vitro PFC responses to the TI ABA Ags; here ratios of less than 0.2 were generally seen. Since T cell removal did not alter the Id pattern in the TI responses, CRIA-specific Ts cells do not account for the weak expression of CRIA in such responses. We propose a model that explains these results on the basis of differential expression of IdX dominance by two distinct B cell subpopulations--equatable to the Lyb-5+ and Lyb-5- B cell subsets--along with differential relative activation of these subsets in different types of responses. Examination of anti-ABA PFC responses of F1 progeny of CBA/N and A/J mice to ABA-Bru lends support to this hypothesis since CRIA expression was significantly lower in mice with the xid defect.
Chemical inhibitors of phagosome-lysosome fusion in cultured macrophages also inhibit saltatory lysosomal movements. A combined microscopic and computer study.
Authors: Hart P D , Young M R , Jordan M M , Perkins W J , Geisow M J
Published: June 2004

The effects on lysosomal movements produced by the weak base ammonium chloride and by a representative polyanion poly-D-glutamic acid (PGA), previously reported to inhibit phagosome-lysosome (P-L) fusion, have been studied in cultured mouse macrophages using direct visual phase-contrast microscopy, a previously described (1, 3, 7) fluorescence assay of fusion, and computer analysis techniques. Treatment of the macrophages with 5-10 mM NH4Cl for 0.5-2 h or with 100 micrograms PGA/ml for 5 d caused a striking inhibition of saltatory lysosomal movements, as well as the expected inhibition of P-L fusion. Two other anionic fusion inhibitors tested, dextran sulphate and suramin, inhibited movements similarly. Removal of the NH4Cl from the cell medium reversed the lysosomal stasis and restored P-L fusion. Computer analyses of changes in lysosomal positions in treated and untreated macrophages during 2, 10, and 30-s intervals, using data from photomicrographs, computer graphics, and quantitative nearest-neighbour techniques developed for this purpose, supported the qualitative visual observation of the inhibition of lysosomal movements by the fusion inhibitors NH4Cl and PGA. Over the chosen intervals, from 80 to 96% of the lysosomes could be paired within 1 micron of each other in the NH4Cl- and PGA-treated cells in comparison with 50-70% in normal cells. The differences between the drug-treated and normal cells were highly significant. In an analogous system, the lysosomal stasis induced by hypertonic sucrose was examined and it was observed that P-L fusion too was inhibited. Both effects were reversible. We conclude that inhibition of P-L fusion and of lysosomal movement are associated. We suggest a causal relationship between these changes, namely, that the lysosomotropic inhibitors of fusion under study produce their effects largely, though perhaps not exclusively, by reducing saltatory lysosomal motion and consequently periphagosomal assembly, rather than directly and independently on P-L contact or on the fusion process itself. The possibility is raised that microtubules may be involved in the effector mechanism of these modulations.
Identification of an active disaccharide unit of a glycoconjugate receptor for pneumococci attaching to human pharyngeal epithelial cells.
Authors: Andersson B , Dahmén J , Frejd T , Leffler H , Magnusson G , Noori G , Edén C S
Published: June 2004

Glycoconjugates containing the disaccharide unit GlcNAc beta 1 leads to 3Gal beta were suggested as receptors for pneumococci adhering to human pharyngeal epithelial cells. The receptor activity was detected both by inhibition of adhesion by an excess of free oligosaccharide and by induction or increase of adhesion after coating of target cells with glycolipid. Studies with free natural and synthetic oligosaccharides identified the disaccharide GlcNAc beta 1 leads to 3Gal beta as one critical binding site. The specificity of recognition was shown inter alia by the lack of inhibitory activity of GlcNAc beta 1 leads to 4Gal beta, which differs only in the linkage of the two sugars. Specific interference with pneumococcal adhesion by administration of soluble receptor sugar may improve our understanding of the role of adhesion in vivo.
Quantitative assessment of the pool size and subset distribution of cytolytic T lymphocytes within human resting or alloactivated peripheral blood T cell populations.
Authors: Moretta A , Pantaleo G , Moretta L , Mingari M C , Cerottini J C
Published: June 2004

In order to directly assess the distribution of cytolytic T lymphocytes (CTL) and their precursors (CTL-P) in the two major subsets of human T cells, we have used limiting dilution microculture systems to determine their frequencies. The two subsets were defined according to their reactivity (or lack thereof) with B9.4 monoclonal antibody (the specificity of which is similar, if not identical, to that of Leu 2b monoclonal antibody). Both B9+ and B9- cells obtained by sorting peripheral blood resting T cells using the fluorescence-activated cell sorter (FACS) were assayed for total CTL-P frequencies in a microculture system that allows clonal growth of every T cell. As assessed by a lectin-dependent assay, approximately 30% of peripheral blood T cells were CTP-P. In the B9+ subset (which represents 20-30% of all T cells), the CTL-P frequency was close to 100%, whereas the B9- subset had a 25-fold lower CTL-P frequency. It is thus evident that 90% and 10% of the total CTL-P in peripheral blood are confined to the B9+ or B9- T cell subsets, respectively. Analysis of the subset distribution of CTL-P directed against a given set of alloantigens confirmed these findings. CTL-P frequencies were also determined in B9+ and B9- subsets derived from T cells that had been activated in allogenic mixed leucocyte cultures (MLC). Approximately 10% of MLC T cells were CTL-P. This frequency was increased 3.5-fold in the B9+ subset, whereas the B9- subset contained only a small, although detectable number of CTL-P. Moreover, the great majority of the (operationally defined) CTL-P in MLC T cell population were found to be directed against the stimulating alloantigens, thus indicating a dramatic increase in specific CTL-P frequencies following in vitro stimulation in bulk cultures.
Human platelet activation by C3a and C3a des-arg.
Authors: Polley M J , Nachman R L
Published: June 2004

C3a liberated from C3 by treatment with C3 convertase (or by trypsin) induced aggregation of gel-filtered human platelets and stimulated serotonin release. At concentrations of 10(-10) M to 8 X 10(-12) M, C3a induced aggregation when added alone to platelets. However, at lower concentrations (2 X 10(-12) M) C3a did not aggregate platelets directly but exhibited highly significant synergism (two-way analysis of variance P less than 0.0001) with ADP in mediating platelet aggregation and release of serotonin. Removal of the C-terminus arginine from C3a abolished anaphylotoxin activity but did not affect the platelet-stimulating activity of the peptide. C3a and C3a des-arg were equally reactive in mediating platelet aggregation and release of serotonin. Further C3a and C3a des-arg exhibited synergism with ADP of equal significance in both aggregation and the release reaction. The concentrations of C3a required for the platelet-stimulating activity involve relatively small number of molecules per platelet (4,000-10,000 for the synergistic reaction with ADP). These data suggest the possibility of a C3a (C3a des-arg) receptor on human platelets. This premise is strengthened by the demonstration ultrastructurally of C3a on the platelet membrane subsequent to C3a stimulation.
Mechanisms regulating IgA class-specific immunoglobulin production in murine gut-associated lymphoid tissues. II. Terminal differentiation of postswitch sIgA-bearing Peyer's patch B cells.
Authors: Kawanishi H , Saltzman L , Strober W
Published: June 2004

Our previous studies indicated that cloned T cells obtained from Peyer's patches (PP) (Lyt-1+, 2-, Ia+, and H-2K/D+) evoked immunoglobulin (Ig) class switching of PP B cells from sIgM to sIgA cells in vitro; however, these switch T cells could not in themselves provide optimal help for the differentiation of postswitch sIgA-bearing PP B cells to IgA-secreting cells. Thus, in the present report we described studies focused on mechanisms regulating terminal differentiation of the postswitch PP sIgA-bearing B cells. First, to explore the effect of T cell-derived B cell differentiation factor(s) (BCDF) and macrophage factor(s) (MF) on the terminal maturation of PP B cells, LPS-stimulated PP B cells were co-cultured for 7 d with cloned T cells in the presence or absence of the above factors. In the absence of PP cloned T cells the BCDF and MF had only a modest effect on IgA production, whereas in the presence of PP, but not spleen cloned T cells, IgA production was increased. Next, to investigate the effect of T cells derived from a gut-associated lymphoid tissue (GALT), mesenteric lymph nodes (MLN), as well as from spleen on terminal differentiation of postswitch sIgA PP B cells, LPS-driven PP B cells were precultured with the cloned T cells to induce a switch to sIgA, and subsequently cultured with MLN or spleen T cells or a Lyt-2+-depleted T cell subset in the presence of a T-dependent polyclonal mitogen, staphylococcal protein A. Alternatively, in the second culture period BCDF alone was added, instead of T cells and protein A. Here it was found that B cells pre-exposed to switch T cells from PP, but not spleen, were induced to produce greatly increased amounts of IgA in the presence of protein A and T cells or a Lyt-2+-depleted T cell subset as well as in the presence of BCDF alone. Furthermore, in the presence of BCDF alone many B cells expressed cytoplasmic IgA. These observations strongly support the view that the terminal differentiation of postswitch sIgA B cells is governed by helper T cells and macrophages, or factors derived from such cells. Such cells or factors do not affect preswitch B cells.
Selective suppression of an early step in human B cell activation by cyclosporin A.
Authors: Muraguchi A , Butler J L , Kehrl J H , Falkoff R J , Fauci A S
Published: June 2004

The effect of cyclosporin A (CsA), a fungal metabolite with immunosuppressive properties, on the induction of human B cell proliferation and differentiation, has been described. CsA had a selective inhibitory effect on the activation phase of the cell cycle vs. the proliferation phase following preactivation of the cells. Cell enlargement and RNA synthesis of small resting B cells triggered by anti-mu were inhibited by addition of CsA (5-500 ng/ml). The inhibitory effect of CsA was found only when the drug was added within 24 h of initiation of culture. In marked contrast, once small B cells were activated by anti-mu, the resulting large, activated B cells could be induced to initiate DNA synthesis by incubation with B cell growth factor (BCGF), and addition of CsA (1-1,000 ng/ml) to the culture did not suppress this BCGF-induced B cell proliferation. Addition of CsA to cultures of B cells which had been preactivated with Staphylococcus aureus Cowan strain I (SAC) and were already proliferating did not suppress B cell differentiation factor (BCDF)-induced differentiation of these cells. Thus, these data indicate that CsA can be used as a pharmacologic tool to dissect out human B cell responses into two distinct steps: (a) the initial activation step induced by anti-Ig, which is characterized by cell enlargement, RNA synthesis, and expression of receptors for BCGF; and (b) the proliferative step induced by BCGF in these preactivated B cells that undergo DNA synthesis and can then go on to differentiate in the presence of BCDF. In this regard, CsA selectively suppresses an early step of human B cell activation and has little inhibitory effect on the subsequent factor-dependent proliferation and differentiation.
Idiotypic cross-reactions of monoclonal human lupus autoantibodies.
Authors: Shoenfeld Y , Isenberg D A , Rauch J , Madaio M P , Stollar B D , Schwartz R S
Published: June 2004

Idiotypic cross-reactions were evaluated in 60 polynucleotide-binding monoclonal lupus autoantibodies produced by human-human hybridomas that were derived from seven unrelated patients with SLE. Three antiidiotype reagents were prepared by immunization of rabbits or a mouse with monoclonal autoantibodies from two patients. Binding of the three reagents to their corresponding idiotypes was inhibited by one or more polynucleotides, an indication that the antiidiotypes reacted with the variable regions of the autoantibodies. Each antiidiotype appeared to detect a different idiotypic determinant. Of the 60 monoclonal autoantibodies tested, 40 reacted in one or more competitive immunoassays; 15 reacted with one antiidiotype, 10 reacted with two antiidiotypes and 15 reacted with three antiidiotypes. A monoclonal antiidiotype reagent cross-reacted with autoantibodies from six of the seven patients. The idiotypic cross-reactions of immunoglobulins from unrelated patients suggest that the autoantibodies are derived from related families of germ line genes that are expressed by patients with SLE.
An antigen-specific signal is required for the activation of second-order suppressor T cells in the regulation of delayed-type hypersensitivity to 2,4,6-trinitrobenzene sulfonic acid.
Authors: Tsurufuji M , Benacerraf B , Sy M S
Published: June 2004

Suppressor T cells (Ts-1) induced with trinitrophenyl (TNP)-conjugated syngeneic spleen cells (TNP-SC) can be enriched on antigen-coated plates and are afferent suppressors. In addition, these suppressor cells produced soluble suppressor factors (TsF) that were active in vivo. Therefore, the Ts-1 cells in the TNP system are very similar to the Ts-1 cells in other systems we have studied earlier. Further characterization of these TsF-1 revealed that TsF-1 obtained from TNP-SC-induced Ts-1 is major histocompatibility complex restricted in its activity. Injection of TNP-specific TsF-1 into naive mice did not induce Ts-2 unless additional corresponding antigen was provided. Moreover, the Ts-2 cells induced by administration of both TsF-1 and trinitrobenzene sulfonic acid were antigen specific rather than antiidiotypic.
Role of contrasuppression in the adoptive transfer of immunity.
Authors: Iverson M , Ptak W , Green D R , Gershon R K
Published: June 2004

The data presented in this paper show that the population of cells that adoptively transfer contact hypersensitivity are Lyt-1+ 2-, I-J- and nonadherent to V. villosa lectin. However, the adoptive transfer of immunity by this population of cells is successful only when the recipient has been treated in such a way as to impair the host immunosuppression mechanism. This population cannot, on its own, transfer immunity to adult, untreated naive recipients unless an additional population of immunoregulatory cells is present. This immunoregulatory population does not itself adoptively transfer immunity. This latter population is differentiated from the immune cells in that they are Lyt-1+ 2-, I-J+ and are adherent to V. villosa lectin. Both populations are required to adoptively transfer immunity to adult untreated naive recipients.
Idiotype-antiidiotype regulation. V. The requirement for immunization with antigen or monoclonal antiidiotypic antibodies for the activation of beta 2 leads to 6 and beta 2 leads to 1 polyfructosan-reactive clones in BALB/c mice treated at birth with minute amounts of anti-A48 idiotype antibodies.
Authors: Rubinstein L J , Goldberg B , Hiernaux J , Stein K E , Bona C A
Published: June 2004

The anti-beta 2 leads to 6 fructosan antibodies sharing the idiotypes (Id) of ABPC48 (A48) monoclonal protein represent a silent fraction of the anti-beta 2 leads to 6 fructosan repertoire, since these antibodies cannot be detected during a conventional immune response elicited by bacterial levan (BL). However, the administration at birth of minute amounts of anti-A48 Id antibodies causes a long-lasting activation of A48 Id+-bearing clones. This activation is related to direct interaction of anti-A48 Id antibodies with precursors bearing the A48 Id+ immunoglobulin receptor, since an A48 Id+ response can be transferred with highly purified B cells in lethally irradiated mice. The maturation of these precursors into A48 Id+ anti-beta 2 leads to 6 fructosan antibody-secreting cells requires challenge by the antigen. Isoelectric focusing (IEF) data showed that in 1-mo-old mice an UPC10 (U10)-like spectrotype was observed, whereas in 3-mo-old mice, a new spectrotype binding BL rather than inulin (In) was identified. This spectrotype was observed only in CXBJ mice, the single strain in which an A48 Id+ response was observed. The antigenic challenge can be replaced by a monoclonal anti-A48 Id antibody (i.e., 17-38). Interestingly, in 1-mo-old BALB/c mice treated with anti-A48 Id antibodies, the challenge with 17-38 monoclonal antibody led to the activation of A48 Id- anti-beta 2 leads to 6 fructosan-reactive clones with BALB/c type IEF spectrotypes, whereas in 3-mo-old BALB/c mice treated with anti-A48 Id antibodies, the challenge with 17-38 monoclonal antibody led to the activation of W3082 IdX+ anti-beta 2 leads to 6 and beta 2 leads to 1 fructosan-reactive clones. In these animals, inhibition of A48 Id+ anti-beta 2 leads to 6 fructosan clones was observed. This antibody probably represents a homobody carrying the internal image of the antigen, which through its paratope suppresses the A48 Id+ response and through its Id activates an A48 Id- anti-beta 2 leads to 6 fructosan response in 1-mo-old mice and in 3-mo-old mice leads to an anti-beta 2 leads to 6 and beta 2 leads to 1 fructosan response dominated by the W3082 IdX.(ABSTRACT TRUNCATED AT 400 WORDS)
Altered transcription of genes coding for class I histocompatibility antigens in murine tumor cells.
Authors: Baldacci P , Pozo F , Gisselbrecht S , Kourilsky P
Published: June 2004

Three murine tumors induced by Moloney murine leukemia virus (M-MLV) which exhibited loss of some or all H-2 class I antigens at the cell surface were analyzed at the DNA and RNA level with molecular probes specific of H-2 heavy chains and beta 2-microglobulin sequences. No observable difference could be detected at the DNA level between the tumors and the parent animals. However, a decrease in H-2 mRNA was observed, especially in phenotypically H-2 negative tumor, BM5R, where H-2 transcripts were at least 30-fold less abundant. These results show that an H-2-negative character may result from a general alteration in the transcription of H-2 genes, which could reflect some kind of regulatory process.
Human Ia beta chains and the invariant chain share a common antigenic determinant.
Authors: Finn O J , Stackhouse C J , Metzgar R S
Published: June 2004

We have presented evidence that a mouse monoclonal antibody 1,227, which was previously shown to recognize a determinant on the light chains beta 1 and beta 2 of human Ia antigens, also recognizes a determinant on the invariant chain (1) associated with these molecules. Ia-specific proteins were resolved by two-dimensional (2D) PAGE and electrophoretically transferred onto nitrocellulose filters. The presence of a determinant shared between beta 1, beta 2 and I was established using "Western blotting" technique. In addition, we demonstrated that 1,227 can immunoprecipitate isolated beta 1, beta 2, and the invariant chain proteins following their separate elution from SDS-PAGE.
A cloned major histocompatibility complex-restricted trinitrophenyl-reactive human helper T cell line that activates B cell subsets via two distinct pathways.
Authors: Principato M A , Thompson G S , Friedman S M
Published: June 2004

A cloned, trinitrophenyl (TNP)-specific helper T cell line (TCL), termed E-11, has been established in long-term, interleukin 2-dependent culture and used to study human T helper (Th)-B cell collaboration. Co-culture of E-11 with TNP-modified, but not unmodified or FITC-modified, autologous B cells results in a vigorous, polyclonally plaque-forming cell (PFC) response. E-11 helper activity is not constitutive, but requires antigen-specific, major histocompatibility complex-restricted activation of the TCL cells by interaction with TNP-modified autologous or DR 5+ allogeneic macrophages. Using B cell subsets isolated by discontinuous density gradient cengrifugation as responder populations, we determined that E-11 activates B cell subsets via two distinct mechanisms: (a) E-11 polyclonally activates large B cells in an unrestricted and nonspecific manner; and (b) E-11 preferentially induces a PFC response by TNP-modified small B cells. These results suggest that the large B cell subset is activated by helper signals generated during the Th-antigen-presenting cell interaction, while small B cells require an additional stimulus that is provided by antigen-specific Th-B cell contact.
Gonococcal pilus subunit size heterogeneity correlates with transitions in colony piliation phenotype, not with changes in colony opacity.
Authors: Swanson J , Barrera O
Published: June 2004

The apparent subunit sizes for pili of gonococci (Gc) have been visualized by using either Iodogen 125I-labeled whole Gc or immunoblotting with antipilus antiserum. These methods permitted definition of pilus subunit sizes for Gc of a given strain that had undergone changes either in piliation phenotype or in colonial opacity/protein II phenotype. The results indicate that pilus subunit size does not change coincident with changes in colony opacity/protein II phenotypes; but change in pilus subunit size is seen after a change in piliation phenotype (P+ leads to P++, and vice versa). Marked diversity in pilus subunit sizes is found for Gc of individual strains when P+ derivatives of P- colonies are compared. This diversity extends to pilus subunits of Gc found in single colonies; two distinct pilus forms were demonstrated for Gc residing in several single colonies. These findings show that Gc of a given strain are able to express any of a number of different pilus subunit size forms.
The mononuclear phagocyte system of the mouse defined by immunohistochemical localization of antigen F4/80. Relationship between macrophages, Langerhans cells, reticular cells, and dendritic cells in lymphoid and hematopoietic organs.
Authors: Hume D A , Robinson A P , MacPherson G G , Gordon S
Published: June 2004

The macrophage-specific antigen F4/80 has been localized in mouse lymphoid and hematopoietic tissue and skin using immunoperoxidase staining. The antigen permits identification of early mononuclear phagocyte precursors in the bone marrow, and is present also on larger cells forming the center of hematopoietic islands and lining vascular sinuses. In thymus F4/80+ cells are numerous in both cortex and medulla and are particularly concentrated around the corticomedullary region. In spleen, lymph node, and gut-associated lymphoid areas the major F4/80+ populations are in the red pulp, the medulla and subcapsular sinus, and the adjacent lamina propria, respectively. F4/80+ cells are rarely seen in T-dependent areas of lymph nodes, spleen, or Peyer's patch, but are present in large numbers in these areas during bacillus Calmette-Guerin (BCG)-induced inflammation. Macrophage infiltration occurs also in lymph nodes from athymic nu/nu mice and is therefore T cell independent. The interdigitating cell of T-dependent areas is F4/80-, but the Langerhans cell of the epidermis of the skin, which bears some ultrastructural resemblance to the interdigitating cell, is F4/80+. We conclude that the two cell types are probably not related.
B cell activation. III. B cell plasma membrane depolarization and hyper-Ia antigen expression induced by receptor immunoglobulin cross-linking are coupled.
Authors: Monroe J G , Cambier J C
Published: June 2004

We report investigation of the relationship between ligand-induced B cell plasma membrane depolarization and increased expression of membrane-associated, I-A subregion encoded (mI-A) antigens. Results demonstrate that equal frequencies of B cells are stimulated to undergo membrane depolarization and to increase mI-A expression in response to mitogen, anti-Ig, and thymus-independent (TI) or thymus-dependent (TD) antigens. Further, a cause-and-effect relationship between these two events is suggested by results that demonstrate that inhibition of anti-Fab--induced depolarization by valinomycin also inhibits the subsequent increase in mI-A antigen expression and "passive" (non-ligand-mediated) depolarization of murine B cells by K+ results in hyper-mI-A antigen expression. Based upon these results we hypothesize that antigen-mediated receptor cross-linking results in signal transduction via membrane depolarization, which is resultant in increased mI-A antigen synthesis and cell surface expression. This increase in mI-A antigen density may render the B cell more receptive to subsequent interaction with I-region-restricted helper T cells.
Surface antigens of malaria merozoites. A high molecular weight precursor is processed to an 83,000 mol wt form expressed on the surface of Plasmodium falciparum merozoites.
Authors: Freeman R R , Holder A A
Published: June 2004

A technique was developed for obtaining high yields of naturally released Plasmodium falciparum merozoites from synchronous cultures of parasitized erythrocytes. The cultured erythrocytes were treated with trypsin to prevent reinvasion (6), and the released merozoites that accumulated extracellularly were harvested by differential centrifugation. The total biosynthetically labeled proteins of schizonts and merozoites, and those immunoprecipitated by human immune serum were analyzed and compared. The surface antigens of free merozoites, labeled by lactoperoxidase-catalyzed iodination, were also described. A monoclonal antibody, specific for a 195,000 mol wt schizont protein, and processing fragments derived from it (3) were used in immunoprecipitation and Western transfer analyses to determine which of the processing fragments are associated with merozoites and which of them are located on the merozoite surface. It was found that processing of the 195,000 mol wt precursor down to an 83,000 mol wt fragment is complete in free merozoites, and that this fragment is expressed as one of the major surface antigens of P. falciparum merozoites.
Precursors of T cell growth factor producing cells in the thymus: ontogeny, frequency, and quantitative recovery in a subpopulation of phenotypically mature thymocytes defined by monoclonal antibody GK-1.5.
Authors: Ceredig R , Dialynas D P , Fitch F W , MacDonald H R
Published: June 2004

In this report, the ontogeny of precursors of T cell growth factor (TCGF)-producing cells in the mouse thymus was investigated using a recently described limiting dilution microculture system. In agreement with previous studies, in the adult thymus TCGF production by cells stimulated by alloantigens was largely the property of the Lyt-2-negative subpopulation. Furthermore, when Lyt-2-negative cells were stained with monoclonal antibody GK-1.5 and sorted according to fluorescence intensity, all precursors of TCGF-producing cells were quantitatively recovered in the GK-1.5-positive subpopulation. During ontogeny, TCGF production by Lyt-2-negative thymocytes was first detectable on the 19th day of embryonic development at which time the precursor frequency was 1/10th that found in the adult thymus. As in the adult thymus, all precursors of TCGF-producing cells had the GK-1.5-positive, Lyt-2-negative phenotype. In parallel to these functional studies, the ontogeny of GK-1.5+, Lyt-2- cells was investigated. In the adult thymus, 80% of cells expressed both GK-1.5 and Lyt-2 antigens, whereas minor subpopulations of 10% and 5% (corresponding to phenotypically mature thymocytes as defined by cortisone-resistant thymocytes [CRT]) expressed GK-1.5 or Lyt-2 exclusively; 3% of cells expressed neither antigen. During ontogeny, thymocytes expressing both GK-1.5 and Lyt-2 first appeared on the 16th day of embryonic development and their proportion increased rapidly thereafter. Interestingly, the GK-1.5+, Lyt-2- subpopulation first appeared in significant numbers on day 19 in parallel with the appearance of functional TCGF activity. Taken together with our previous studies correlating cytolytic T lymphocyte precursor (CTL-P) activity with the Lyt-2+, GK-1.5- subpopulation, these results further emphasize the strict correlation between functional activity and mature surface phenotype of both embryonic and adult thymocytes.
HNK-1 antibody detects an antigen expressed on neuroectodermal cells.
Authors: Lipinski M , Braham K , Caillaud J M , Carlu C , Tursz T
Published: June 2004

The HNK-1 antibody known to define a subpopulation of human lymphocytes with natural killer and killer cell activities was shown to detect a common neuroectodermal antigen. Most tumor lines and paraffin-embedded tumors and normal tissues of neuroectodermal origin were specifically stained by HNK-1. Lines and tissues of other derivations were negative except a trophoblastic tumor line and a percentage of Ewing's sarcomas, whose histogenesis is poorly understood. These data indicate that HNK-1 antibody could be of interest in clinical histopathology but cannot be considered as specific for a lymphocyte subset.
A novel HLA-D/DR-like antigen specific for human B lymphoid cells. Biochemical evidence for similarity to but nonidentity with known HLA-D/DR antigens.
Authors: Marti G E , Kuo M C , Shaw S , Chang C C , Demars R , Sogn J A , Coligan J E , Kindt T J
Published: June 2004

The polymorphic human B cell-specific antigen, 33.1, detected by a murine monoclonal antibody, was compared by genetics and structural analysis with known human Ia antigens from a panel of DR homozygous Epstein-Barr virus-transformed B lymphoblastoid cell lines. Cells homozygous for DR 1, 2, 4, 5, and w6 were positive, while cells that are DR3,3 or DR7,7 usually failed to express this antigen. Mutant DR null, DC/MB-positive cells were 33.1 positive while DR null, DC/MB-negative cells failed to express this antigen, suggesting the segregation of 33.1 with the DC antigen. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that 33.1 alpha and beta chains were of lower molecular weights than the DR alpha and beta chains isolated from the same cell line. Partial N-terminal amino acid sequence analyses were carried out for the heavy and light chains of the 33.1 antigen radiolabeled with [3H] phenylalanine. The results of these analyses, in conjunction with previous data on tissue distribution, indicate that the 33.1 antigen is a non-DR but Ia-like antigen closely related to the previously defined I-A homologues, DC and DS.
Dendritic cells induce T lymphocytes to release B cell-stimulating factors by an interleukin 2-dependent mechanism.
Authors: Inaba K , Granelli-Piperno A , Steinman R M
Published: June 2004

Dendritic cells (DC) are essential accessory cells for T-dependent antibody responses in culture (1). We have outlined a three-stage mechanism to explain the capacity of DC to stimulate primary antibody responses to heterologous erythrocytes. First, DC induced T cells to produce and to become responsive to interleukin 2 (IL-2). This stage corresponded to the syngeneic mixed leukocyte reaction (2) and involved the clustering of DC and T cells into discrete aggregates. Isolated clusters, representing 5-10% of the culture, were critical for IL-2 release and the production of IL-2-responsive T blasts. In the second stage, IL-2 directly triggered the responsive T cells to release B cell helper factors. This role for IL-2 was documented with a rabbit anti-IL-2 reagent, purified IL-2, and T cells that had been rendered IL-2 responsive by an initial co-culture with DC. T cell growth was not required for IL-2-mediated helper factor release, since irradiated and untreated responders produced similar levels of factor and did so within 3 h of the addition of IL-2. In the final stage, helper factors stimulated the development of antibody-secreting cells from purified B lymphocytes. The helper factors were not H-2 restricted, but for both sheep and horse erythrocytes, the response to factors was antigen dependent and specific. The IL-2 that was present in the DC/T cell-conditioned medium did not act on B cells, since helper activity was neither neutralized nor absorbed by our anti-IL-2 reagent. We conclude that the ability of the DC to induce IL-2 release and responsiveness underlies its capacity to trigger both T and B lymphocyte reactions.
The Legionnaires' disease bacterium (Legionella pneumophila) inhibits phagosome-lysosome fusion in human monocytes.
Authors: Horwitz M A
Published: June 2004

The interactions between the L. pneumophila phagosome and monocyte lysosomes were investigated by prelabeling the lysosomes with thorium dioxide, an electron-opaque colloidal marker, and by acid phosphatase cytochemistry. Phagosomes containing live L. pneumophila did not fuse with secondary lysosomes at 1 h after entry into monocytes or at 4 or 8 h after entry by which time the ribosome-lined L. pneumophila replicative vacuole had formed. In contrast, the majority of phagosomes containing formalin-killed L. pneumophila, live Streptococcus pneumoniae, and live Escherichia coli had fused with secondary lysosomes by 1 h after entry into monocytes. Erythromycin, a potent inhibitor of bacterial protein synthesis, at a concentration that completely inhibits L. pneumophila intracellular multiplication, had no influence on fusion of L. pneumophila phagosomes with secondary lysosomes. However, coating live L. pneumophila with antibody or with antibody and complement partially overcame the inhibition of fusion. Also activating the monocytes promoted fusion of a small proportion of phagosomes containing live L. pneumophila with secondary lysosomes. Acid phosphatase cytochemistry revealed that phagosomes containing live L. pneumophila did not fuse with either primary or secondary lysosomes. In contrast to phagosomes containing live bacteria, the majority of phagosomes containing formalin-killed L. pneumophila were fused with lysosomes by acid phosphatase cytochemistry. The capacity of L. pneumophila to inhibit phagosome-lysosome fusion may be a critical mechanism by which the bacterium resists monocyte microbicidal effects.
Structural analysis of the variable major proteins of Borrelia hermsii.
Authors: Barbour A G , Barrera O , Judd R C
Published: June 2004

Borrelia hermsii undergoes spontaneous antigenic variation in vivo and in vitro. Serotype specificity is associated with expression of one of a family of molecular weight-variable proteins, the pI proteins. We studied the structure of the pI proteins as well as the molecular weight-invariable pII proteins of three serotypes of B. hermsii HS1: C, 7, and 21. The techniques used were one-dimensional (1-D) mapping of Staphylococcus aureus V8 protease-generated peptides and two-dimensional (2-D) mapping of alpha-chymotrypsin-generated peptides. The pI and pII proteins were isolated by excision of polypeptides from stained polyacrylamide gel electropherograms. The 1-D peptide patterns were visualized by fluorography of intrinsically [14C]leucine-labeled proteins or by silver stain. Before 2-D mapping, polypeptides in excised gel fragments were labeled with 125I in the presence of chloramine-T. We also compared the 2-D peptide maps of pI proteins, pI7 and pI21, after their surface-exposed portions were radioiodinated using 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril (Iodogen). The I-D and 2-D peptide maps demonstrated the following: (a) pI proteins of the three serotypes have few V8 protease- or chymotrypsin-generated peptides in common, and (b) pI proteins of each serotype appear to be identical. The findings suggest that pI protein variability derives from extensive differences in the amino acid sequences of these proteins.
Lung injury mediated by antibodies to endothelium. I. In the rabbit a repeated interaction of heterologous anti-angiotensin-converting enzyme antibodies with alveolar endothelium results in resistance to immune injury through antigenic modulation.
Authors: Barba L M , Caldwell P R , Downie G H , Camussi G , Brentjens J R , Andres G
Published: June 2004

To study the effects of relatively long-term interaction of antibodies with surface antigens of lung endothelium, rabbits were intravenously injected for a maximum of 4 d with goat anti-rabbit lung angiotensin-converting enzyme (Gt anti-RbACE) antibodies. On day 1 69%, on day 2 13%, and on days 3 and 4 of injection none of the rabbits developed lethal pulmonary edema. By immunofluorescence microscopy, deposits of GtIgG, frequently in association with RbC3, were found along the endothelium of alveolar capillary walls in all rabbits studied on day 1, in 57% on day 2, in 33% on day 3, and in none of them on day 4. While in vitro anti-ACE antibodies bound in a linear pattern to the lung endothelium, the binding pattern in vivo was distinctly granular. The in vivo interaction of antibodies with ACE also redistributed ACE in a granular pattern along capillary walls. In contrast to the granular deposition of injected anti-ACE IgG and F(ab')2 fragments of anti-ACE IgG, Fab fragments of anti-ACE IgG localized, without fixing C3, in a linear pattern along the endothelium of lung capillaries and did not modify the normal distribution of ACE. However, when the injection of Fab fragments of Gt anti-RbACE IgG was followed by an injection of Rb anti-GtIgG serum, granular deposits of Gt Fab fragments, RbIgG and RbC3 were seen along alveolar capillary walls. Biochemical measurement of ACE activity in lung homogenates provided data in agreement with those obtained by immunofluorescence microscopy, showing diminished activity to none on day 4, with some return of ACE activity on day 5, 24 h after the last injection of antibody, and normal values on day 21. The results obtained indicate that divalent antibodies to an antigen expressed on the plasma membrane of rabbit lung endothelial cells promotes a rapid redistribution of antigenic receptors, fixation of complement and, in surviving rabbits, disappearance of the antigen from the endothelial cells that are no longer susceptible to immune injury. In vivo "immunologic enzymectomy" induced by a ligand-surface antigen interaction is an example of antigenic modulation. These events may have an important role in the pathogenesis of inflammatory lesions induced by antibodies reacting with antigens expressed on the plasma membrane of cells in the lung and in other organs.
T helper cells recognize an idiotope located on peptide 88-114/117 of the light chain variable domain of an isologous myeloma protein (315).
Authors: Jørgensen T , Bogen B , Hannestad K
Published: June 2004

Isolated variable region light chain 315 (VL-315), the VL domain of a myeloma protein of BALB/c origin, induces T cells of BALB/c (H-2d) mice that help the adoptive secondary anti-4-hydroxy-3-iodo-5-nitrophenylacetyl (NIP) antibody response to NIP-Fab315. The location of the epitope recognized by helper cells was examined with two fragments of VL-315, obtained by cleavage with cyanogen bromide at Met 87. Both N-terminal fragment 1-86 and C-terminal fragment 88-114/117 elicited BALB/c antibodies that bound to the respective fragments and to VL-315. By contrast, only fragment 88-114/117, which consists of the third hypervariable region, J region, and 5-7 amino acids of the C region, induced helper cells that augmented the anti-NIP response to NIP-Fab 315.
Induction of tissue transglutaminase in human peripheral blood monocytes.
Authors: Murtaugh M P , Arend W P , Davies P J
Published: June 2004

The levels and activity of tissue transglutaminase were studied in human peripheral blood monocytes during differentiation into macrophages in vitro. The enzyme was present at low levels in freshly isolated monocytes (less than 20 ng/mg cell protein) but increased 50-fold during 10 d of adherent culture in autologous serum, reaching levels of 0.1% of total cellular protein. The rate of appearance of tissue transglutaminase in monocytes was accelerated by low levels of lipopolysaccharide. The half-life of disappearance of transglutaminase from human monocytes was 11 and 7 h in 2-d-old and 10-d-old cells, respectively. Treatment of 1-day-old monocytes with actinomycin D for 24 h blocked the increase in transglutaminase levels. These results indicated that the induction of gene transcription and protein synthesis was responsible for the increased transglutaminase levels and activity observed with cultured human monocytes. The induction of tissue transglutaminase may be a component in the in vivo differentiation of human monocytes into macrophages.
Modulation of apoprotein E secretion in response to receptor-mediated endocytosis in resident and inflammatory macrophages.
Authors: Takemura R , Werb Z
Published: June 2004

We have determined the effect of various endocytic ligands on the secretion of ApoE by macrophages. ApoE was a major secreted protein of resident macrophages, but BCG-activated macrophages secreted little ApoE and periodate-elicited macrophages secreted intermediate amounts of ApoE. Resident, periodate-elicited, and BCG-activated mouse peritoneal macrophages were incubated with AcLDL, EIgG, EIgMC, dextran sulfate, latex, or zymosan, and the resulting protein secretion patterns were analyzed by [35S]methionine labeling and SDS-polyacrylamide gel electrophoresis. AcLDL increased total [35S]methionine incorporation into secreted proteins. Although AcLDL increased the secretion of ApoE by resident macrophages less than or equal to fivefold in a dose-dependent manner, with maximal stimulation at 4.8 micrograms/ml, it decreased the secretion of ApoE by periodate-elicited macrophages to almost nothing and did not affect the low rate of secretion of ApoE by BCG-activated macrophages. However, EIgG, which increases cellular cholesterol content of macrophages as AcLDL does, did not increase ApoE secretion, and dextran sulfate, which is recognized by the same receptor as AcLDL, also did not increase ApoE secretion. The binding and uptake of EIgG, dextran sulfate, zymosan, latex, and EIgMC all decreased the secretion of ApoE. These endocytic ligands also altered the pattern of secreted and cellular proteins other than ApoE. The pattern of response was ligand-specific. However, increased secretion of polypeptides of Mr 62,000 and 68,000 was common to many stimuli. We conclude that receptor-mediated endocytosis modulates the secretion of ApoE and other proteins pleiotypically in resident, inflammatory, and activated macrophages.