bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of T cell hybridomas. III. Distinctions between two types of hapten-specific suppressor factors that affect plaque-forming cell responses.
Authors: Sherr D H , Minami M , Okuda K , Dorf M E
Published: June 2004

The ability of two cloned T cell hybridomas and their products to specifically suppress the in vitro plaque-forming cell (PFC) response to the 4-hydroxy-3-nitrophenyl acetyl hapten (NP) was studied. Supernatant from one hybridoma (TS1) was shown to suppress in the induction but not the effector phase of the immune response. Supernatant from the TS1 hybridoma was capable of inducing second-order (TS2) effector-phase suppressor cells in vitro but did not suppress the response of anti-I-J plus C-treated responder cells. In contrast, supernatant from a second hybridoma (TS3) was capable of suppressing PFC responses when added either in the induction or the effector phase of the response. TS3 supernatant was unable to induce effector-phase suppressor cells but was capable of suppressing the response of anti-I-J plus C-treated responder cells. In addition, specific suppressor factors isolated from supernatants of the TS1 and TS3 hybridomas were shown to bind to NP, bear NPb idiotypic and I-J-encoded but not immunoglobulin-constant region determinants. The factor secreted by the TS3 hybridoma appears to act directly on B cell targets. Mild reduction of this factor results in two separable moieties, only one of which binds NP. Reconstitution experiments suggest that both chains are required for function. The collective data indicate that these hybridomas represent cells from first- and third-order suppressor T cell populations described previously in contact sensitivity and in vitro PFC systems. The implications of the ability of these hybridoma products to affect both T and B cell-mediated immune responses are discussed.
Differential sensitivity of human B cell subsets to activation signals delivered by anti-mu antibody and proliferative signals delivered by a monoclonal B cell growth factor.
Authors: Muraguchi A , Butler J L , Kehrl J H , Fauci A S
Published: June 2004

The present study demonstrates the minimal, optimal, and synergistic signals involved in the activation of normal human peripheral blood and tonsillar B cells to proliferation. Initial activation signals were delivered to B cells by low concentrations of anti-mu antibody which did not induce proliferation by themselves. However, marked synergy was seen when anti-mu antibody was added to cultures in the presence of monoclonal B cell growth factor (BCGF) obtained from a human T-T cell hybrid such that the B cells underwent substantial proliferation. This latter proliferation was seen without maturation into Ig-secreting cells, which indicates that the BCGF is not a differentiation signal but a signal that drives the cell up to but not beyond the proliferative phase. Of note was the fact that B cells reflected differential sensitivity on the basis of size to either the activation signal delivered by anti-mu antibody or the proliferative signal delivered by BCGF. BCGF directly stimulated the larger B cells in the normal tonsillar B cell repertoire to proliferate without the requirement for an in vitro activation signal, which indicates that the cells had already received some form of activation signal in vivo. Indeed, these cells expressed the 4F2 antigen found on activated but not resting lymphocytes. In contrast, the smaller tonsillar B lymphocytes did not express the 4F2 activation antigen and required activation by anti-mu antibody, which did not of itself induce proliferation, but which acted in synergy with BCGF for substantial proliferation of the B cells. These studies thus provide a useful model of human B cell activation, proliferation, and differentiation and allow a more precise delineation of each phase in this cascade.
Experimental IgA nephropathy induced by oral immunization.
Authors: Emancipator S N , Gallo G R , Lamm M E
Published: June 2004

To test the hypothesis that IgA nephropathy can result from a mucosal immune response, mice were orally immunized with one of three protein antigens for 14 wk. Such mice exhibited an essentially pure mucosal antibody response characterized by specific IgA-producing plasma cells in exocrine sites and specific IgA antibodies in serum. Furthermore, 73% of immunized mice had IgA and 88% had immunogen deposited in the glomerular mesangium, and 64% of immunized mice examined ultrastructurally had electron-dense mesangial deposits. All three were present concurrently in 57% of the immunized mice. No differences in regard to IgG or IgM were observed between immunized and control mice for any of these parameters. Mucosal immunization therefore can result in a specific immune response that leads to mesangial deposition of immune complexes containing IgA antibody. In its fundamental features the experimental renal lesion resembles that seen in the human disease IgA nephropathy.
T cell-derived B cell growth and differentiation factors. Dichotomy between the responsiveness of B cells from adult and neonatal mice.
Authors: Pure E , Isakson P C , Kappler J W , Marrack P , Krammer P H , Vitetta E S
Published: June 2004

In these studies we have determined the molecular weights of B cell growth factor (BCGF) (less than 20,000), and B cell differentiation factors (BCDF) that induce immunoglobulin M (IgM) secretion (BCDF mu) (30-60,000) and IgG secretion (BCDF gamma) (less than 20,000). Thus, the molecular weight of BCDF mu is distinct from that of BCGF and BCDF gamma; BCGF and BCDF gamma cannot be distinguished. In addition, BCGF, BCDF mu, and BCDF gamma are distinguishable by their presence or absence in different supernatants from a panel of mitogen-induced T cell clones. These results suggest that the three lymphokines are different. This conclusion is supported by their differential biological effect on B cells from adult and neonatal mice. Thus, treatment with anti-Ig induces B cells from adult mice to proliferate and this proliferation is sustained by BCGF. In contrast, even in the presence of BCGF, anti-Ig does not induce B cells from neonatal mice to proliferate. However, BCDF mu and BCDF gamma induce IgM and IgG secretion in B cells, respectively, from both adult and neonatal mice. Thus, mature B cells can both clonally expand and differentiate in response to anti-Ig, BCGF, and BCDF, whereas immature B cells can only differentiate. The poor response of neonatal B cells to anti-Ig and BCGF may partially explain the relative immunoincompetence of immature B cells.
Generation of antibody diversity in the immune response of BALB/c mice to influenza virus hemagglutinin. I. Significant variation in repertoire expression between individual mice
Authors: Staudt LM , Gerhard W
Published: June 2004

The paratypic and idiotypic diversity of the BALB/c antibody response to the hemagglutinin (HA) of the influenza A/PR/8/34 virus (PR8) was investigated using a panel of 125 anti-HA hybridoma antibodies derived from 14 BALB/c mice. The paratypic diversity, as assessed by a fine specificity analysis using 51 related influenza viruses, was extensive: 104 distinct paratopes were observed. In three instances, antibodies with indistinguishable paratopes were isolated from two individual mice. A minimum estimate of the size of the adult BALB/c anti-HA paratypic repertoire, calculated from these data, is 1,500.

The generation of this diverse repertoire was studied by screening the anti-HA hybridoma panel for the presence of idiotypes (Id) that are markers for variable (V) region sequences derived from related germ line V genes. Three cross-reactive Id (IdX) that are markers for the V(k)21C, V(k)21B, and V(k)21A, D, E, or F L chain subgroups were found, respectively on 16, 1, and 10 anti-HA hybridoma antibodies derived from seven individual BALB/c mice. Thus, the V(k)21 IdX(+) hybridomas constitute 22 percent of the anti-HA hybridoma panel. The V(k)21 IdX are also present on 8.6 percent of K-bearing immunoglobulin in normal BALB/c serum. This suggests that the V(k)21 group is used preferentially in the BALB/c anti-HA immune response.

The generation of the anti-HA repertoire was further studied using large panels of anti-HA hybridomas derived from two individual adult BALB/c mice. Anti-idiotypic antisera were raised in rabbits against individual hybridomas from each mouse. One anti-Id serum defined a family of four idiotypically and paratypically related, but not identical, antibodies from mouse 36, which represented 31 percent of the hybridoma antibodies isolated from this mouse. None of the 112 anti-HA hybridoma antibodies derived from 13 other individual mice showed idiotypic cross-reactivity. Furthermore, this Id could not be detected in anti-PR8 antisera from 75 individual BALB/c mice. Another anti-Id serum defined a family of 27 idiotypically related antibodies from mouse 37, which represented 50 percent of the hybridoma antibodies isolated from this mouse. Only 1 of the 71 hybridoma antibodies isolated from 13 other individuals was idiotypically cross-reactive.

These results demonstrate that individual adult BALB/c mice express paratypically and idiotypically distinct antibody repertoires to the HA of influenza virus PR8. Based on these observations, we suggest that somatic mutation plays an important role in the generation of the adult anti-HA repertoire. Mechanisms that could account for differences in repertoire expression among individual mice are discussed.
Xenogeneic human anti-mouse T cell responses are due to the activity of the same functional T cell subsets responsible for allospecific and major histocompatibility complex-restricted responses.
Authors: Swain S L , Dutton R W , Schwab R , Yamamoto J
Published: June 2004

Human T cells respond strongly to mouse major histocompatibility complex (MHC) antigens. The response is directed predominantly to the polymorphic determinants of the MHC antigens and there is little or no response to the nonpolymorphic determinants or to non-MHC antigens. Human cytotoxic T lymphocytes (CTL) are generated specific for the mouse class I MHC antigens and the CTL effectors are blocked by anti-Leu-2a antisera. Human interleukin 2-producing T cells are generated specific for mouse class II antigens and their induction is blocked by anti-Leu-3a antisera. These and other considerations lead us to propose a model for the T cell receptor that provides an explanation for several of the features of T cell recognition. In this model, the recognition of the "class" (I or II) of MHC antigen is separate from the recognition of the polymorphic determinants. We suggest that the initial recognition of the conserved "class" determinants positions another domain of the receptor so that it can only engage with the part of the MHC molecule carrying the polymorphic determinants.
Allosuppressor and allohelper T cells in acute and chronic graft-vs.-host disease. II. F1 recipients carrying mutations at H-2K and/or I-A.
Authors: Rolink A G , Pals S T , Gleichmann E
Published: June 2004

By induction of a graft-vs.-host reaction (GVHR) in nonirradiated H-2-different F1 mice, one can induce stimulatory pathological symptoms, such as lymphadenopathy and hypergammaglobulinemia, combined with the production of autoantibodies characteristic of systemic lupus erythematosus (SLE). Alternatively, the GVHR can lead to the suppressive pathological symptoms, such as pancytopenia and hypogammaglobulinemia, characteristic of acute GVH disease (GVHD). Whether stimulatory or suppressive symptoms are induced by a GVHR depends, in our view (2-4), on the functional subset of donor T cells activated in the F1 host. The purpose of the present study was to investigate whether class I and/or class II H-2 alloantigens can selectively trigger, out of a pool of unselected donor T cells, those subpopulations of T cells responsible for the stimulatory and suppressive GVH symptoms, respectively. For the induction of the GVHR, 10(8) lymphoid cells from C57BL/6 (B6) donors were injected into three kinds of F1 hybrid mice, which had been bred from H-2 mutant strains on a B6 background. Whereas the I-A-disparate (B6 X bm12)F1 recipients exclusively developed stimulatory GVH symptoms, including SLE-like autoantibodies and immune complex glomerulonephritis, the K locus-disparate (B6 X bm1)F1 recipients showed neither clearly stimulatory nor clearly suppressive GVH symptoms. In marked contrast, the (bm1 X bm12)F1 recipients, which differ from the B6 donor strain by mutations at both K and I-A locus, initially developed stimulatory GVH symptoms, but rapidly thereafter showed the suppressive pathological symptoms of acute GVHD and died. Moreover, spleen cells obtained from (B6 X bm12)F1 mice injected with B6 donor cells helped the primary anti-sheep erythrocyte (SRBC) response of normal (B6 X bm12)F1 spleen cells in vitro, whereas spleen cells (bm1 X bm12)F1 mice injected with B6 donor cells strongly suppressed the primary anti-SRBC response of normal (bm1 X bm12)F1 spleen cells. Spleen cells from the K locus-disparate (B6 X bm1)F1 recipients also suppressed the primary anti-SRBC of normal (B6 X bm1)F1 spleen cells; this suppression, however, was weak when compared with the suppression induced by spleen cells from GVH (bm1 X bm12)F1 mice. Taken together, these findings indicate that a small class II (I-A) antigenic difference suffices to trigger the alloreactive donor T helper cells causing SLE-like GVHD. In contrast, both class I (H-2K) and class II (I-A) differences are required to trigger the subsets of donor T cells responsible for acute GVHD. It appears that alloreactive donor T helper cells induce the alloreactive T suppressor cells, which then act as the suppressor effector cells causing the pancytopenia of acute GVHD. These findings may help to understand the variability of GVH-like diseases caused by a given etiologic agent, their cellular pathogenesis, and association with certain HLA loci.
Germinal center B cells lack homing receptors necessary for normal lymphocyte recirculation.
Authors: Reichert R A , Gallatin W M , Weissman I L , Butcher E C
Published: June 2004

Germinal center B cells (GCLC) are a discrete population of antigen-activated lymphoblasts that lack surface IgD and express abundant cell surface binding sites for peanut agglutinin (PNA). These phenotypic features render GCLC easily distinguishable from nearly all plasma cells, T cells, and unstimulated B cells, and have enabled us to identify and isolate GCLC from antigen-stimulated murine lymphoid organs. We have examined the migratory properties of these lymphoblasts in (a) short-term in vivo homing studies, and (b) an in vitro assay of lymphocyte binding to post-capillary, high endothelial venules (HEV) in frozen sections of Peyer's patches and peripheral lymph nodes. In the in vivo experiments, intravenously injected GCLC failed to migrate in significant numbers to peripheral lymphoid organs in comparison with T cells or IgD+ B cells. In the in vitro binding assay, GCLC did not adhere to HEV in either Peyer's patch or peripheral node sections. A variety of factors, such as preferential sequestration in the liver, may operate in vivo to influence the localization of these cells. However, their nearly total failure to migrate into lymphoid organs can best be explained by their inability to recognize and adhere to the specialized HEV which normally mediate the emigration of recirculating lymphocytes from the blood into these sites. The concept that GCLC fail to express functional homing receptors for HEV has been further supported by studies using MEL-14, a monoclonal antibody that appears to recognize the lymphocyte surface receptor for peripheral node HEV: In contrast to most peripheral lymphocytes, GCLC fail to bind MEL-14. These migratory and endothelial-recognition properties of GCLC, when viewed in the context of the possible role of these cells as precursors of plasma cells and/or memory B cells, have led us to propose that the inability of GCLC to recognize HEV may be transient and related to a phase of sessile B cell differentiation.
Cloned mouse cells with natural killer function and cloned suppressor T cells express ultrastructural and biochemical features not shared by cloned inducer T cells.
Authors: Dvorak A M , Galli S J , Marcum J A , Nabel G , der Simonian H , Goldin J , Monahan R A , Pyne K , Cantor H , Rosenberg R D , Dvorak H F
Published: June 2004

We have examined the morphology, cytochemistry, and biochemistry of mouse leukocyte subsets by analyzing cloned leukocyte populations specialized to perform different immunologic functions. Cloned cells expressing high-affinity plasma membrane receptors for IgE and mediating natural killer (NK) lysis and cloned antigen-specific suppressor T cells contained prominent osmiophilic cytoplasmic granules similar by ultrastructure to those of mouse basophils. Both clones also incorporated 35SO4 into granule-associated sulfated glycosaminoglycans, expressed a characteristic ultrastructural pattern of nonspecific esterase activity, incorporated exogenous [3H]5-hydroxytryptamine, and contained cytoplasmic deposits of particulate glycogen. By contrast, cloned inducer T cells lacked cytoplasmic granules and glycogen, incorporated neither 35SO4 nor [3H]5-hydroxytryptamine, and differed from the other clones in pattern of nonspecific esterase activity. These findings establish that certain cloned cells with NK activity and cloned suppressor T cells express morphologic and biochemical characteristics heretofore associated with basophilic granulocytes. However, these clones differ in surface glycoprotein expression and immunologic function, and the full extent of the similarities and differences among these populations and basophils remains to be determined.
Dendritic cells initiate a two-stage mechanism for T lymphocyte proliferation.
Authors: Austyn J M , Steinman R M , Weinstein D E , Granelli-Piperno A , Palladino M A
Published: June 2004

T cells oxidized with sodium periodate proliferate polyclonally in response to accessory cells. We confirmed previous work showing that DC are potent stimulators of this response. In addition, the accessory function of unfractionated mouse spleen and spleen adherent cells was markedly reduced after elimination of DC with a specific monoclonal antibody and complement. Therefore oxidative mitogenesis was used as a model to study the mechanism by which DC stimulate T cell proliferative responses. A two-stage mechanism was identified. The first stage occurred during the first 20 h of culture, required live DC, and involved the progressive release of interleukin 2 (IL-2) into the medium and acquisition of responsiveness to this growth factor. The second stage occurred between 20 and 40 h, did not require live DC, and involved DNA synthesis in response to IL-2. Similar events occurred during culture of DC with unmodified T cells (syngeneic MLR) but were quantitatively reduced. The experimental approach was to co-culture DC and T cells for up to 20 h and then kill the DC with specific antibody, or anti-Ia antibody, and complement. Subsequent proliferation was inhibited if the T cells were cultured in fresh medium. However, proliferation was restored when the lymphocytes were cultured in the original DC-T cell medium, or with a crude or a purified preparation of IL-2. IL-2 did not induce the proliferation of T cells that had been cultured in the absence of DC, and did not synergize with viable DC. We conclude that DC induce proliferation by tightly coordinating the release of, and responsiveness to, T cell growth factor or IL-2.
Selective proteolysis of immunoglobulins by mouse macrophage elastase.
Authors: Banda M J , Clark E J , Werb Z
Published: June 2004

Mouse macrophage elastase, a metalloproteinase secreted by inflammatory macrophages, catalyzed the limited proteolysis of selected subclasses of mouse immunoglobulins, including monomeric IgG2a, IgG3, and some forms of IgG2b. Mouse IgG1 was resistant to elastase degradation; however, human IgG1 was degraded. IgG3 in immune complexes was cleaved in a manner similar to that of monomeric IgG3. Degradation by macrophage elastase was limited to the heavy chain, resulting in products that did not compete for binding to the macrophage Fc receptor. Macrophage elastase usually produced a pepsin-like rather than a papain-like pattern of proteolysis, resulting in the release of F(ab')2 and Fc' subfragments. This degradation of IgG differed from the papain-like cleavage of IgG by granulocyte elastase. Macrophage elastase degraded papain-generated Fc fragments of IgG2a into multiple fragments. Therefore, macrophage elastase at concentrations found in culture medium has the potential to regulate some aspects of cellular events associated with immunoglobulins.
Antibody response of immunodeficient (xid) CBA/N mice to Escherichia coli 0113 lipopolysaccharide, a thymus-independent antigen.
Authors: Hiernaux J R , Jones J M , Rudbach J A , Rollwagen F , Baker P J
Published: June 2004

CBA/N mice, which possess an X-linked immunodeficiency (xid), produce a convincing antibody response to lipopolysaccharide derived from Escherichia coli 0113 (LPS 0113), a thymus-independent antigen. The antibody response produced was shown to be specific for the O-polysaccharide moiety of LPS 0113, rather than lipid A or lipid-A-associated protein. The relevance of this finding to the nature of the genetic defect of xid-mice is discussed.
Analytical subcellular fractionation of cultivated mouse resident peritoneal macrophages
Authors: Darte C , Beaufay H
Published: June 2004

Resident peritoneal macrophages of the mouse, cultivated for 3 d, have been studied by quantitative subcellular fractionation using differential centrifugation and density equilibration in linear gradients of sucrose. Density equilibration experiments were carried out on untreated cytoplasmic extracts, on cytoplasmic extracts treated with digitonin or sodium pyrophosphate, and on cytoplasmic extracts derived from cells cultivated for 24 h in the presence of Triton WR-1339. The enzyme distributions obtained distinguished six typical behaviors characteristic of distinct subcellular entities. Acid α-galactosidase and other acid hydrolases displayed the highest average velocity of sedimentation and equilibrium density. Culturing in a medium that contained Triton WR-1339 markedly decreased their density, most likely as a result of Triton WR-1339 accumulation within lysosomes. Cytochrome c oxidase and the sedimentable activity of malate dehydrogenase showed a narrow density distribution centered around 1.17, very similar under all the experimental situations; their rate of sedimentation fell within the range expected for mitochondria. Catalase was particle-bound and exhibited structure-linked latency (80 percent); it was released in soluble and fully active form by digitonin, but this required a much higher concentration than in the case of lysosomal enzymes. Differences relative to all the other enzymes studied suggest the existence of a particular species of organelles, distinctly smaller than mitochondria, and possibly related to peroxisomes. Many enzymes were microsomal in the sense that the specific activities, but not the yields, were greater in microsomes than in other fractions obtained by differential centrifugation. These enzymes were distinguished in three groups by their properties in density equilibration experiments. NAD glycohydrolase, alkaline phosphodiesterase I, and 5'-nucleotidase had low equilibrium densities but became noticeably more dense after addition of digitonin. The other microsomal enzymes were not shifted by digitonin, in particular N-acetylglucosaminyltransferase and galactosyltransferase, which otherwise equilibrated at the same position in the gradient. We assign the digitonin-sensitive enzymes to plasma membranes and possibly to related endomembranes of the cells, and the two glycosyltransferases to elements derived from the Golgi apparatus. Finally, α-glucosidase, sulphatase C, NADH cytochrome c reductase, NADPH cytochrome c reductase, and mannosyltransferase, equilibrated at a relatively high density but were shifted to lower density values after addition of sodium pyrophosphate. These properties support their association with elements derived from the endoplasmic reticulum.
Fever and immunoregulation. III. Hyperthermia augments the primary in vitro humoral immune response.
Authors: Jampel H D , Duff G W , Gershon R K , Atkins E , Durum S K
Published: June 2004

We have examined the possibility that hyperthermia, such as that occurring during fever, may benefit the immune response. The effect of temperature on the in vitro immune response of unprimed murine spleen cells against the antigen sheep erythrocytes was tested. Hyperthermia potently augmented the plaque-forming cell response. Temperature-sensitive events occurred early in the culture period. Subsets of lymphocytes were independently assessed for effects of temperature on their activation and function. We showed that the beneficial effect of elevated temperature on the plaque-forming cell response probably occurs during the priming stage of T helper cells, and neither improves the delivery of help or the activation of B cells, nor impairs suppressor T cell generation or function. We propose that this powerful immunopotentiating effect of hyperthermia may account for the selective value of the fever response. This suggests taht the monokine interleukin 1, which is the endogenous mediator of fever, may promote immune responses both through a direct action on lymphocytes, and indirectly by an action on the central nervous system resulting in fever.
Characterization of the killer cell generated in the autologous mixed leukocyte reaction.
Authors: Goto M , Zvaifler N J
Published: June 2004

Cytotoxic cells are produced in an autologous mixed leukocyte reaction (AMLR). At 1 wk in culture the AMLR killers are mainly IgG Fc- cells and can kill autologous lymphoblastoid cell lines and Raji and Daudi targets that are usually resistant to natural killer cell (NK) lysis. To define the phenotype of these cells, we have used complement (C')-mediated lysis with monoclonal antibodies (MAb). AMLR killer activity was virtually eliminated by treatment with C' and 9.6 or 4F2, but the cytotoxic cells did not express NK-specific antigens, OKM1 and Leu-7, nor cytolytic T lymphocyte-specific antigens, 9.3 and OKT8. None of the 10 MAb used could significantly block cytotoxicity at the final concentration of 1.5 mcg/ml which is generally sufficient to inhibit CTL. The majority of cells at 1 wk in AMLR cultures stained with T cell activation antigens Ia and 4F2; AMLR killing was proportional to the percentage of 4F2+ cells but unrelated to the expression of Ia antigen.
Neonatal tolerance of major histocompatibility complex antigens alters Ir gene control of the cytotoxic T cell response to vaccinia virus.
Authors: Müllbacher A , Blanden R V , Brenan M
Published: June 2004

The K region of H-2 controls the Tc cell response to vaccinia-Db. The Kb, Kd, and Kq alleles allow good Tc cell responses against vaccinia-Db. In contrast, the presence of Kk in H-2 recombinants 2R (Kk,Db) and 4R (Kk,Db) or in F1 hybrids greatly reduces the anti-vaccinia-Db response. The defect does not lie in antigen presentation, as infected 4R cells can stimulate anti-vaccinia-Db Tc cells in vitro. Furthermore, nonresponder animals possess Tc cell precursors for vaccinia-Db, as transfer of F1 nonresponder spleen cells into infected, lethally irradiated responder recipients allowed generation of anti-vaccinia-Db effector Tc cells. Secondary responses to vaccinia-Db can also be obtained in vitro from T cells of 4R animals. Feedback inhibition was excluded in experiments with mixed chimeras in which Kk and Db were expressed on separate cell populations. Neonatal tolerance of B10 animals to Kk suppressed the anti-vaccinia-Db response but did not affect anti-vaccinia-Kb, anti-lymphocytic choriomeningitis virus, or anti-H-2d responses. In cold target competition experiments, H-2k competitors inhibited vaccinia-Db-specific target cell lysis by Tc cells, which suggests that anti-vaccinia-Db and anti-H-2Kk Tc cells may cross-react. Therefore, we propose that the suppressive influence of Kk on anti-vaccinia-Db Tc cell responses is a consequence of self-tolerance and that suppression of anti-Kk Tc cells results in cross-reactive suppression of anti-vaccinia-Db Tc cells.
Cyclical antiidiotypic response to anti-hormone antibodies due to neutralization by autologous anti-antiidiotype antibodies that bind hormone.
Authors: Couraud P O , Lü B Z , Strosberg A D
Published: June 2004

Antiidiotype antibodies were raised against anti-catecholamine ligand antibodies. The antiidiotype response was shown to be cyclical and to correspond to the production of antibodies that could bind to catecholamine beta-adrenergic receptors and stimulate adenylate cyclase. Disappearance of these antibodies from the serum could be correlated with the appearance of a catecholamine ligand-binding activity corresponding to the synthesis of autologous anti-antiidiotype antibodies directed against the induced antiidiotypic molecules. Comparison of the injected versus the induced anti-ligand antibodies reveals striking differences in affinities but similarities in the ability to bind to the antiidiotype antibodies and to the ligand-containing affinity gel. The results support the existence of a functional network of idiotype antiidiotype interactions involving external as well as internal antigens, antibodies, and possibly other types of molecules involved in recognition phenomena, such as hormone receptors.
The I-Ab mutant B6.C-H-2bm12 allows definition of multiple T cell epitopes on I-A molecules.
Authors: Beck B N , Nelson P A , Fathman C G
Published: June 2004

The experiments presented in this study demonstrate that there exist at least two functional epitopes on an I-A molecule that can be recognized by T cell clones. By comparing the abilities of spleen cells from C57BL/6 mice and the congenic I-A mutant line B6.C-H-2bm12 to stimulate alloreactive T cell clones specific for the I-Ab molecule, we have discriminated two sets of clones, those recognizing the I-Ab and I-Abm12 molecule equally well and those able to recognize only the I-Ab molecule. These results imply that the two sets of clones have different receptors for I-A and that they therefore recognize separate epitopes on the I-A molecule. We have similarly been able to separate T cell clones, both alloreactive and L-glutamic acid60-L-alanine30-L-tyrosine10-reactive, specific for the Ab alpha Ak beta hybrid molecule into two groups based on their ability to recognize bm 12 spleen cells. Although the recognition of bm 12 spleen cells by these clones was unexpected since none of them responds to B6 spleen cells, these data again allow us to conclude that these groups of clones have different receptors for the same I-A molecule and therefore that they recognize distinct epitopes on the molecule. Additional studies, in which monoclonal anti-I-A antibodies were used to block the stimulation of T cells by stimulator or antigen-presenting cells, have demonstrated that this blockade can be a steric effect and therefore is not necessarily indicative of direct competition between the antibody and the T cell for the same site on an I-A molecule. Although this study does not reveal the physical nature of an I region-controlled "antigen-restriction site," we can suggest that increasing the number of possible functional Ia restriction sites either through combinatorial association of alpha and beta chains or by using more than one site per molecule will increase the number of configurations the ternary complex of Ia, antigen and T cell receptor(s) can form.
Expression of passively transferred immunity against an established tumor depends on generation of cytolytic T cells in recipient. Inhibition by suppressor T cells.
Authors: Mills C D , North R J
Published: June 2004

The results of this study with the P815 mastocytoma confirm the results of previous studies that showed that the passive transfer of tumor-sensitized T cells from immunized donors can cause the regression of tumors growing in T cell-deficient (TXB) recipients, but not in normal recipients. The key additional finding was that the expression of adoptive immunity against tumors growing in TXB recipients is immediately preceded by a substantial production of cytolytic T cells in the recipients' draining lymph node. On the other hand, failure of adoptive immunity to be expressed against tumors growing in normal recipients was associated with a cytolytic T cell response of much lower magnitude, and a similar low magnitude response was generated in TXB recipients infused with normal spleen cells and in tumor-bearing control mice. Because the passively transferred sensitized T cells possessed no cytolytic activity of their own, the results indicate that the 6-8-d delay before adoptive immunity is expressed represents the time needed for passively transferred helper or memory T cells to give rise to a cytolytic T cell response of sufficient magnitude to destroy the recipient's tumor. In support of this interpretation was the additional finding that inhibition of the expression of adoptive immunity by the passive transfer of suppressor T cells from tumor-bearing donors was associated with a substantially reduced cytolytic T cell response in the recipient's draining lymph node. The results serve to illustrate that interpretation of the results of adoptive immunization experiments requires a knowledge of the events that take place in the adoptively immunized recipient. They support the interpretation that suppressor T cells function in this model to "down-regulate" the production of cytolytic effector T cells.
Cytolysis by H-2-specific T killer cells. Assembly of tubular complexes on target membranes.
Authors: Dennert G , Podack E R
Published: June 2004

Cloned T killer cells derived from one-way mixed lymphocyte reactions were characterized with regard to their Lyt phenotype and specificity. Two clones of Lyt-1-2+ phenotype that recognized H-2Dd were selected and examined for their cytolytic function by negative staining and thin section electron microscopy. When incubated with the H-2d target S194, they assemble two types of tubular complexes, polyperforin 1 and 2. Both structures appear to arise by polymerization of precursors that may originate in dense granules and/or Golgi of T killer cells. Polyperforins appear to be associated with vesicles that are released during the lytic reaction and transferred to target membranes as shown by immunoelectron microscopy. Since there is a close correlation between target lysis and the appearance of polyperforins on target membranes, it is suggested that polyperforins take part in the cell-mediated killing reaction. Although polyperforins are different in size and several molecular properties from complement, there are striking similarities between these circular complexes and polyperforin (C9). It is therefore possible that they belong to a closely related family of cytolytic effector molecules.
Long-term erythropoietic repopulating ability of old, young, and fetal stem cells.
Authors: Harrison D E
Published: June 2004

It is possible that erythropoietic stem cells do not age. This would mean that stem cells from old donors can function as well as those from young or fetal donors. The competitive repopulation assay has been used to test long-term stem cell function by directly comparing how well competing stem cells repopulate a recipient and produce differentiated cell types. C57BL/6J (B6) mice were used as donors, while recipients and competitors were WBB6F1 hybrids with genetically distinguishable hemoglobin. Lethally irradiated young WBB6F1 recipients were given a mixture of 2.5 X 10(6) cells from B6 old marrow, young marrow, or fetal liver donors; each recipient also received a standard dose of 1 X 10(6) marrow cells from a pool of young WBB6F1 competitors. Surprisingly, the old marrow cells competed the best in repopulating the recipients. This pattern was maintained even after recovery from sublethal irradiation, a treatment that severely stresses stem cells. This stress was demonstrated when sublethal irradiation caused a 20-fold decline in repopulating ability measured using hemoglobin markers, and a 3- to 7-fold decline using chromosome markers. Stem cells from old marrow competed better than young or fetal cells in similar experiments using immunologically crippled recipients or using unirradiated W/Wv recipients that are immunologically intact. In both types of recipients, the advantage of old marrow cells again persisted after recovery from sublethal irradiation. Other genotypes were tested, and marrow cells from old B6CBAF1 donors competed better than those from young donors of that genotype. However, marrow cells from young CBA donors completed better than those from old CBA donors. These results support the hypothesis that stem cells do not age, and suggest that regulatory changes with age promote rapid stem cell repopulation in B6 and B6CBAF1 mice, but inhibit it in CBA mice.
Induction of idiotype-specific suppressor T cells with antigen/antibody complexes.
Authors: Caulfield M J , Luce K J , Proffitt M R , Cerny J
Published: June 2004

The effects of immune complexes on the antibody response of BALB/c mice to Streptococcus pneumoniae R36a (Pn) were investigated. The cell wall polysaccharide (PnC) extracted from Pn was used to form complexes with TEPC-15, a myeloma protein that binds to phosphorylcholine determinants on the PnC. Complexes formed at equivalence were cultured with splenic T cells from BALB/c mice for 2 d, and then the cells were added to fresh BALB/c spleen cell cultures to test their effect on the antibody response to Pn, a response dominated by the T15 idiotype family. The results indicate that TEPC-15/PnC complexes induced potent suppressor T cells (Ts) whereas cells cultured with free antigen or free antibody alone had no effect on the plaque-forming cell response to Pn. The suppression was specific since the response to control antigens such as sheep erythrocytes was unaffected. The suppression appears to be idiotype-specific since the Ts had a relatively weak (and in some cases no) effect on the anti-Pn response of BALB/c mice that had been suppressed for T15 idiotopes by neonatal injection of a monoclonal anti-T15 antibody, MaId 5-4. Furthermore, cells cultured with TEPC-15/PnC complexes were shown to express specific receptors for TEPC-15 idiotopes. The results indicate that antigen/antibody complexes may have important immunoregulatory effects because they are potent inducers of idiotype-specific Ts.
Interferonlike factors from antigen- and mitogen-stimulated human leukocytes with antirickettsial and cytolytic actions on Rickettsia prowazekii. Infected human endothelial cells, fibroblasts, and macrophages.
Authors: Wisseman C L , Waddell A
Published: June 2004

Unique features of the primary site of rickettsial replication in typhus fevers, i.e., within the endothelial cells of small blood vessels in tissues, suggest that effector mechanisms, other than those dependent on phagocytosis by activated macrophages with enhanced microbicidal properties, most likely are necessary to explain the cell-mediated immune control of intracellular rickettsial replication in these sites. Theoretically, such mechanisms might involve contact between infected endothelial cells and activated T lymphocyte subpopulations or macrophages or immunologically induced soluble factors or lymphokines. Support for the existence of at least one of these alternative effector mechanisms is presented here for Rickettsia prowazekii. Cultures of human blood leukocytes, upon immunologically specific stimulation with R. prowazekii antigen or nonspecific stimulation with the mitogen phytohemagglutinin, produce soluble factor(s) in the supernatant fluid which, in culture, have (a) an intracellular antirickettsial action on R. prowazekii-infected human endothelial cells, fibroblasts, and macrophages, and (b) a specific cytolytic action on R. prowazekii-infected, but not uninfected bystander, human fibroblasts. Neither action is demonstrable in R. prowazekii-infected chicken embryo fibroblasts. The factor(s) has no direct antimicrobial action on extracellular rickettsiae and is inactivated by heating at 56 degree C for 1 h or by acid treatment at pH 2. Expression of the antirickettsial action requires new host cell messenger transcription and protein synthesis, whereas the cytolytic action does not. The circumstances of production and action and the properties of the factor(s) responsible for the intracellular antirickettsial, and perhaps also the cytolytic action are consistent with those of immune interferon (IFN-gamma).
Frequencies of the separate human B cell subsets activatable to Ig secretion by Epstein-Barr virus and pokeweed mitogen.
Authors: Martínez-Maza O , Britton S
Published: June 2004

We have developed a microculture system suitable for limiting dilution analysis of Epstein-Barr virus (EBV)- and pokeweed mitogen (PWM)-induced activation of immunoglobulin secretion by human B cells. It was found that exogenous filler cells were not required to obtain optimal EBV-induced B cell precursor frequency (PF) estimates, although filler T cells were required for optimal PWM activation. In fact, when autologous T cells were used as filler cells, a marked decrease in the EBV-induced IgM PF was noted. Treatment of the T cells with cyclosporin A partially eliminated, and irradiation of the T cells completely eliminated, this decrease. The calculated PF of B cells activated by EBV was from 1/290 to 1/3,700 for IgM, and from 1/920 to 1/3,250 for IgG secretion. PWM activated from 1/140 to 1/3,200 B cells to IgM secretion. The results of experiments in which EBV and PWM were mixed, indicated that these two polyclonal activators operated on different B cell subpopulations. Therefore, both these agents seem to activate small, discrete subpopulations of human peripheral blood B cells to Ig secretion.
Plasma fibronectin enhances phagocytosis of opsonized particles by human peripheral blood monocytes.
Authors: Pommier C G , Inada S , Fries L F , Takahashi T , Frank M M , Brown E J
Published: June 2004

We have investigated the effect of plasma fibronectin (Fn) on binding and phagocytosis of sheep erythrocytes (E) by human peripheral blood monocytes. Unopsonized E were not phagocytosed in the absence or presence of Fn, but Fn enhanced the phagocytosis of E bearing IgG. Sheep erythrocytes sensitized with IgM and C3b were ingested only when monocytes were exposed to Fn. The Fn enhancement of phagocytosis occurred for both fluid-phase and glass-adherent monocytes. Experiments in which Fn was washed out before mixing monocytes with opsonized E demonstrated that the Fn effect occurred because of interaction with the monocytes and not the opsonized particles. Chromatography of the Fn on Biogel A 1.5m showed that the phagocytosis-enhancing activity exactly co-chromatographed with the Fn protein. Fn did not increase the number of monocyte membrane receptors for the Fc fragment of monomeric IgG. We conclude that Fn enhances monocyte phagocytosis, not by binding to particles as a conventional opsonin, but by stimulating monocytes to ingest already opsonized particles more avidly.
Protection against two spontaneous mouse leukemias conferred by immunogenic variants obtained by mutagenesis.
Authors: Van Pel A , Vessière F , Boon T
Published: June 2004

Two spontaneous mouse leukemias were adapted to culture. In agreement with most reported observations on spontaneous tumors, injection of irradiated cells of the malignant culture cell lines failed to protect mice against these leukemias. These cell lines were treated in vitro with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine and stable immunogenic variants (tum-) were obtained, that failed to form progressive tumors in syngeneic CBA/Ht mice. Mice that had rejected tum- variants showed a significant degree of resistance to challenge not only with the original malignant cell line but also with the original transplantable tumor. No protection was observed against syngeneic tumor cells other than those of the parental tumor. These results indicate that these two spontaneous leukemias carry a specific transplantation antigen that can be the target of a rejection response by syngeneic mice. In confirmation of this, we found that lymphocytes of CBA/Ht mice that had rejected tum- variants could be restimulated in vitro so as to develop a cytolytic activity directed against an antigen that was specific for the original tumor cell line.
Isolation of a high molecular weight polyphosphate from Neisseria gonorrhoeae.
Authors: Noegel A , Gotschlich E C
Published: June 2004

Neisseria gonorrhoeae, as well as other Neisseriae, produce polyphosphate. This polyphosphate exists in two forms. Approximately half of it is loosely associated with the cells and can be recovered by washing in neutral buffers under conditions in which no significant lysis of the cells is observed. The other half is either intracellular or tightly associated, because it requires digestion of the cells with perchloric acid or sodium hypochlorite. Polyphosphate obtained by both methods was purified by column chromatography and chemically characterized. In contrast to other organisms, gonococci do not respond with increased polyphosphate synthesis when shifted from phosphate starvation to a phosphate-rich medium. In addition, gonococcal polyphosphate does not serve as a depletable phosphate source during phosphate starvation. All strains of Neisseriae examined produce substantial amounts of polyphosphate.
Interferon-induced 2'-5' adenylate synthetase in vivo and interferon production in vitro by lymphocytes from systemic lupus erythematosus patients with and without circulating interferon.
Authors: Preble O T , Rothko K , Klippel J H , Friedman R M , Johnston M I
Published: June 2004

The interferon (IFN)-induced enzyme 2-5A synthetase was elevated in mononuclear cells from both serum IFN-positive and -negative systemic lupus erythematosus (SLE) patients. This suggests that a much higher percentage of patients than previously thought produce endogenous IFN. These results may partly explain findings that mononuclear cells from SLE patients are deficient in IFN production in vitro in response to certain IFN inducers. Although normal lymphocytes can produce an acid-labile alpha IFN after stimulation with C. parvum in vitro, the reason for endogenous production of this unusual alpha IFN by SLE patients remains unknown.
Restricted adult clonal profiles induced by neonatal immunization. Influence of suppressor T cells.
Authors: Thompson M A , Raychaudhuri S , Cancro M P
Published: June 2004

The effects of neonatal antigen exposure on the adult B cell repertoire have been examined by characterizing the influenza hemagglutinin (HA)-specific response of adult BALB/c mice given antigen soon after birth. Ligand exposure during early life exerts a profound and lasting effect upon the B cell repertoire, characterized by the expansion and preservation of particular antigen-reactive clones and the apparent loss of others. The precise subset of clonotypes selectively preserved depends upon the age at which antigen is first encountered; and is predictable given a knowledge of the emerging primary pool's dynamics and composition. The preserved (secondary) B cells differ from their unprimed precursors with respect to (a) expression of the surface marker detected by the monoclonal antibody J11d, and (b) susceptibility to T cell-mediated suppression. These studies thus demonstrate a strong relationship between the heritable dynamics of the emerging primary B cell repertoire and the effect of ligand-driven events upon repertoire phenotype. In addition, they provide a mechanistic model for certain forms of antigen-induced oligoclonal dominance, especially the phenomenon of original antigenic sin.