bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of bacterial toxins on human B cell activation. II. Mitogenic activity of the B subunit of cholera toxin
Authors: Dugas Bernard , Paul‐Eugène Nathalie , Génot Elisabeth , Mencia‐Huerta Jean Michel , Braquet Pierre , Kolb Jean Pierre
Published: March 2007

The B subunit of cholera toxin (CT) but not the entire CT was found to induce the proliferation of resting human B lymphocytes. A significant mitogenic effect was observed for B subunit concentrations > 1 μg/ml and reached a maximum of stimulation at 10 μg/ml. As already described for B lymphocytes preactivated with Staphylococcus aureus Cowan Strain I (SAC), B lymphocytes preactivated with the B subunit of CT, but not with the entire CT, were able to proliferate in response to exogenous interleukin 2 (IL 2) and to the low‐molecular weight B cell growth factor (BCGF).

To determine the transmembrane signaling system used by the B subunit of CT to mediate its biological effects, we compared the transmembrane signals used by the entire CT, its B subunit and SAC. In comparison to the entire CT, which directly activates adenylate cyclase and increases intracellular cAMP levels, neither the B subunit nor SAC modified the cAMP content. In contrast, although SAC induced inositol phosphate generation neither CT nor the separate subunits were able to induce such a production. Moreover, changes in the fluorescence of indo‐1‐loaded B lymphocytes revealed that mitogenic doses of either the B subunit or SAC induced a rapid and sustained increase in cytoplasmic free Ca2+ concentration ([Ca2+]i). The effect of the B subunit appeared to be largely dependent on the presence of extracellular Ca2+, because in Ca2+‐free medium no [Ca2+]i uptake was observed. In contrast, the SAC‐induced [Ca2+]i uptake is substantially, but not totally, inhibited in Ca2+‐free medium, suggesting that part of the rise in [Ca2+]i was due to the release from internal stores. Moreover, fluorimetric measurements on loaded cells with 2′,7′‐bis(carboxyethyl)‐5(6′)‐carboxyfluorescein revealed that SAC induced a rapid cytoplasmic alkalinization via activation of Na+/H+ exchange, whereas the entire CT and its B subunit had no effect on intracellular pH. Taken together, these data suggest that, in comparison to SAC, the mitogenic effect of the B subunit of CT was mediated through different intracellular biochemical pathways.
Expression of a novel type of immunoglobulin Cλ transcripts in human mature B lymphocytes producing χ light chains
Authors: Guglielmi Paul , Davi Frédéric
Published: March 2007

Ordered rearrangement of immunoglobulin genes (heavy chain then χ and eventually λ genes) is observed during B lymphocyte ontogeny. Unexpectedly, we found that human mature B cells producing χ chains and having germ‐line λ genes contain λ mRNA consisting of an invariant 5′ region (herein termed X) and of one of the classical Cλ exons. The X region of these transcripts originates from a unique exon located 5 kb upstream of the J‐Cλ1 gene segment. X‐Cλ mRNA expression occurs without somatic DNA rearrangement. The use of the X DNA fragment as a probe allows definition of a family of human genes that comprises at least four members and includes the first exon of the λ14.1 gene. The latter is selectively transcribed in pre‐B lymphocytes and directs the synthesis of a λ‐like chain. In contrast, the X‐Cλ transcripts do not appear to encode a Cλ‐related polypeptide in mature B cells. Thus, despite a 73% homology extending far beyond the exon sequences, the X and λ14.1 genes are expressed at different stages of B cell development and might serve different functions.
Reticular cells in peripheral lymphoid tissues express the phosphatidylinositol‐linked BP‐3 antigen
Authors: McNagny Kelly M. , Bucy R. Pat , Cooper Max D.
Published: March 2007

The murine BP‐3 antigen was initially described as a variably glycosylated cell surface protein of Mr 38000 to 48000 on lymphoid and myeloid cells. In the present experiments we found that this antigen is released from the surface of pre‐B cells and macrophages by treatment with phosphatidylinositol‐specific phospholipase C (PI‐PLC), suggesting a glycosyl‐phosphatidylinositol (GPI) linkage with the plasma membrane. When the tissue distribution of the BP‐3‐reactive cells was examined by immunohistology, high levels of the antigen were observed on brush borders of the intestinal epithelial cells, within collecting tubules of the kidney and on a subpopulation of reticular cells located in lymph nodes, Peyer's patches and the white pulp areas of the spleen. In contrast, reticular cells located in the thymus, bone marrow and splenic red pulp did not express the BP‐3 antigen. Ontogenic studies revealed that BP‐3 was expressed by the reticular cells in peripheral lymphoid tissues in the neonatal period near the time of lymphocyte immigration into these organs. BP‐3+ reticular cells were observed in the collapsed periarterial lymphatic sheaths of adult mice depleted of T and B cells by cyclophosphamide treatment and in mice with severe combined immunodeficiency (scid), indicating that development of this reticular network is lymphocyte independent. The BP‐3 antigen on the splenic reticular cells was also GPI anchored but its glycosylation pattern differed from that of the BP‐3 molecules on pre‐B cells. A special subpopulation of reticular cells is thus marked by the BP‐3 antigen, and the distribution and biochemical properties of the molecule make it an attractive candidate for a role in lymphocyte‐stromal interactions in the peripheral lymphoid tissues.
CD3+ T cells in severe combined immune deficiency (scid) mice. I. Transferred purified CD4+ T cells, but not CD8+ T cells are engrafted in the spleen of congenic scid mice
Authors: Rudolphi Angelika , Spieß Sibylle , Conradt Peter , Claësson Mogens H. , Reimann Jörg
Published: March 2007

Young (< 3 months of age) and old (> 1 year of age) C.B‐17 scid/scid mice were tested for the presence of immunoglobulin in serum and CD3+ T cells in spleen and peritoneal cavity. In all old severe combined immune deficiency (scid) mice tested we found detectable, but very variable levels of serum immunoglobulin as well as splenic and peritoneal CD3+ T cells comprising 3% to 10% of the nonfractionated cell populations of these organs (n = 10). In contrast, none of the analyzed young scid mice showed any evidence of peripheral lymphocytes. Low numbers (2 × 105 to 5 × 105 cells/mouse) of highly purified CD4+ cells from congenic C.B‐17 or BALB/c donor mice were injected intravenously into young scid recipient mice. A CD4+ T cell population was clearly engrafted when transplanted scid mice were analyzed 8 to 13 weeks after T cell transfer: (a) a CD3+CD4+CD8− T cell population was detectable in the spleens of all recipient scid mice by flow microfluorometry analyses; (b) CD3+CD4+CD8− T cell lines could be grown out of these spleens in vitro; (c) the histological examination revealed evidence of lymphoid cell repopulation in the spleens of all transplanted scid mice and (d) transplanted CD4+ T cell populations could be serially transferred into secondary and tertiary recipient scid mice. These data indicate that scid mice can be constructed in which only the CD4+ T cell compartment is selectively reconstituted. In contrast to the successful engraftment of CD4+ T cell, highly purified congenic CD8+ T cells could not be engrafted into the spleen of scid mice.
Exacerbation of experimental murine cutaneous leishmaniasis with CD4+Leishmania major‐specific T cell lines or clones which secrete interferon‐γ and mediate parasite‐specific delayed‐type hypersensitivity
Authors: Titus Richard G. , Müller Ingrid , Kimsey Paul , Cerny Andreas , Behin Reza , Zinkernagel Rolf M. , Louis Jacques A.
Published: March 2007

Leishmania major‐specific T cell lines were derived from mice sensitized to the parasite. The cells were of the CD4+ T cell lineage and, upon adoptive transfer, were found to be capable of inducing parasite‐specific delayed‐type hypersensitivity. Adoptive transfer of these L. major‐specific T cells to syngeneic recipients which were either normal, T cell deficient or B cell and antibody deficient led to exacerbation of infection upon subsequent challenge with L. major. This suggested that host T cells, B cells and antibody were not required for the L. major‐specific T cells to exert their exacerbative effect on the course of cutaneous leishmaniasis. Additional studies revealed that the adoptive transfer of graded doses of these L. major‐specific T cells always resulted in exacerbation of infection. Study of the localization pattern of the cells following transfer showed that they migrate preferentially to the site of the lesions. Furthermore, although the induction phase of this phenomenon was immunologically specific, its effector phase was not.

Finally, T cell clones were derived from the L. major‐specific T cell lines. The Tcell clones were phenotypically and functionally identical to the T cell lines from which they were derived. Adoptive transfer of these parasite‐specific Tcell clones to normal syngeneic recipients induced an exacerbated course of infection with L. major. Interestingly, when these cloned T cells were specifically activated in vitro, the cells produced interleukin 2 and interferon‐γ, but no interleukin 4, indicating that they belong to the murine Th1 subset of CD4+ T cells.
Cloning of murine splenic T lymphocytes and natural killer (NK) cells on filter paper discs: detection of a novel NK/T phenotype
Authors: Sarzotti Marcella , Kumar Vinay , Bennett Michael , Kelsoe Garnett
Published: March 2007

Discrete colonies of splenocytes were grown on filter paper discs in the presence of concanavalin A and interleukin 2. Phenotypic analysis of the colonies indicated that the majority expressed the Thy‐1.2 marker and 72% of these co‐expressed the CD3 molecule. Of the colonies 20%–25% were NK 1.1+ and they developed regardless of the presence of Con A in the culture medium, a property of the NK lineage. In addition, Thy‐1.2+ colonies developed when splenocytes from scid mice, which lack mature T and B cells, were grown both in the presence and absence of concanavalin A. These results demonstrate that colonies of murine splenic T lymphocytes and NK cells could be successfully grown on filter paper discs and phenotypically characterized. With this colonies technique, it was possible to identify a novel subset of NK 1.1+ colonies that co‐expresses CD3 and shares growth properties with T cell colonies.
Rescue of thymocytes and T cell hybridomas from glucocorticoid‐induced apoptosis by stimulation via the T cell receptor/CD3 complex: a possible in vitro model for positive selection of the T cell repertoire
Authors: Iwata M. , Hanaoka S. , Sato Kazuki
Published: March 2007

Positive and negative selection events are involved in determining useful T cell clones to mature in the thymus. Accumulating evidence suggests that immature self‐reactive thymocytes undergo apoptotic death (negative selection) upon stimulation via the T cell receptors (TcR). A similar phenomenon of activation‐induced death has been reported in T cell hybridomas. On the other hand, little is known about the mechanism of the positive selection. Apoptosis in rodent thymocytes or T cell hybridomas is also known to be induced by glucocorticoids in vitro at concentrations within the physiologic range. We report here that the TcR/CD3‐mediated stimulation and glucocorticoids mutually inhibit the apoptosis in T cell hybridomas. The production of interleukin 2 by the rescued cells indicated that the TcR/CD3‐mediated signal was transduced into the cells. Thymocytes were also rescued from glucocorticoid‐induced apoptosis by the stimulation with antibodies to TcR/CD3 molecules. The rescue of thymocytes, however, was observed only at a narrow concentration range of each of the antibodies, suggesting that the proper stimulation via the TcR/CD3 is required for the rescue. If thymocytes in situ are differentially stimulated according to the affinity of the TcR towards self, only the thymocytes whose TcR have proper affinity towards self may be rescued from glucocorticoid‐induced apoptosis. Therefore, we propose a hypothesis that the positive selection of the T cell repertoire is based on the inhibition of glucocorticoid‐induced apoptosis in immature thymocytes bearing TcR with proper affinity for self by the TcR‐mediated signals in situ. Furthermore, the selection may be influenced by the peak level of glucocorticoid concentration, since the proper concentration range of the anti‐TcR/CD3 antibody for the rescue was variable depending on the glucocorticoid concentration.
The “adjuvant effect” of the polymorphic B‐G antigens of the chicken major histocompatibility complex analyzed using purified molecules incorporated in liposomes
Authors: Salomonsen Jan , Eriksson Håkan , Skj⊘dt Karsten , Lundgreen Tina , Simonsen Morten , Kaufman Jim
Published: March 2007

The polymorphic B‐G region of the chicken major histocompatibility complex has previously been shown to mediate an “adjuvant effect” on the humoral response to other erythrocyte alloantigens. We demonstrate here that B‐G molecules purified with monoclonal antibodies exert this adjuvant effect on the production of alloantibodies to chicken class I (B‐F) molecules, when the two are in the same liposome. The adjuvant effect may in part be mediated by antibodies, since the antibody response to B‐G molecules occurs much faster than the response to B‐F molecules, and conditions in which antibodies to B‐G are present increase the speed of the response to B‐F molecules. We also found that the presence of B‐G molecules in separate liposomes results in a lack of response to B‐F molecules. In the light of this and other data, we consider the possible roles for the polymorphic B‐G molecules, particularly for the generation of B cell diversity, in the immune systems of birds and other animals.
Functional dichotomy of CD4+ T helper lymphocytes in asymptomatic human immunodeficiency virus infection
Authors: Clerici Mario , Shearer Gene M. , Via Charles S. , Lucey Daniel R. , Roilides Emmanuel , Pizzo Philip A.
Published: March 2007

The majority of asymptomatic, human immune deficiency virus seropositive (HIV+) individuals exhibit a defect in CD4+ T helper cell (Th) function that is selective for responses to recall antigens, but not to HLA alloantigens. The CD4‐dependent Th response to HLA alloantigens (Allo) can be mediated by two distinct Th pathways: self‐restricted CD4+ Th that recognize allogeneic determinants processed and presented by autologous or self accessory or antigen‐presenting cells (sAC); and allo‐restricted, CD4+ Th that recognize allogeneic determinants directly on allogeneic accessory or antigen‐presenting cells (aAC). In contrast, the Th response to recall antigens requires CD4+ Th and sAC and is therefore limited to the major histocompatibility complex (MHC) self‐restricted pathway. Peripheral blood leukocytes from 56 asymptomatic HIV+ patients that exhibited a selective defect in CD4+ Th function were analyzed to determine whether the Th response to Allo was entirely functional, or whether one of the CD4‐mediated components of the Allo Th response was also defective. By depletion of AC and/or CD8+ Th subsets (to analyze CD4+ Th function), we demonstrated that HIV+ patients who were selectively deficient in Th function to recall antigens were also unresponsive to Allo presented by autologous AC (HLA self‐restricted Th pathway), but retained Allo Th activity presented by allogeneic AC (allo‐restricted CD4+ Th pathway). These findings indicate that the CD4+ Th defect seen in the majority of asymptomatic, HIV+ individuals is not limited to recall antigens, but also extends to the component of the response to HLA alloantigens that involves the self‐restricted, CD4+ Th pathway. Thus, the Th defect observed in asymptomatic, HIV+ patients does not involve a CD4+ Th defect per se, but is limited to the HLA self‐restricted component of Th function.
Human interleukin 7 is a B cell growth factor for activated B cells
Authors: Joshi Pratibha C. , Choi Yong Sung
Published: March 2007

We investigated the capacity of human interleukin (IL) 7 to induce proliferation of B cells. Purified tonsillar B cells were cultured in the presence of IL7 with Staphylococcus aureus Cowan I (SAC) or anti‐μ beads as co‐mitogens. IL 7 supported a dose‐dependent proliferation of anti‐μ‐activated B cells but did not significantly support proliferation of SAC‐activated B cells. When B cells were separated on Percoll gradient into small (60%‐80%) and large (50%–60%) B cells and then cultured with anti‐μ beads, IL7 acted on both cell populations equally well. IL7 and BCGF (low molecular weight) were synergistic in their proliferative action on anti‐μ‐activated B cells in a 5‐day culture. On the other hand, synergistic effect of IL 7 on activated B cells was not evident in the presence of any other factor recombinant [(r)IL 1β, rIL2, rIL3, rIL4, rIL5, rIL6, recombinant tumor necrosis factor‐α, recombinant lymphotoxin, recombinant granulocyte‐monocyte colony‐stimulating factor and recombinant interferon‐γ] we tested. IL7 did not induce IgG secretion by activated B cells.
Granzyme A and perforin as markers for rejection in cardiac transplantation
Authors: Griffiths Gillian M. , Namikawa Reiko , Billingham Margaret , Weissman Irving , Mueller Christoph , Liu Chau‐Ching , Young John Ding‐E
Published: March 2007

The use of granzyme A and perforin as markers for rejection after cardiac transplantation has been investigated. Using in situ hybridization we have detected lymphocytes expressing granzyme A and perforin RNA that are infiltrating the donor heart after transplantation.

A total of 29 different biopsies from 17 different patients who had undergone cardiac transplantation were examined. Twelve biopsies classified by conventional histological criteria as showing evidence of rejection were found to contain lymphocytes expressing granzyme A and perforin. Seven biopsies classified as showing no histological evidence of rejection infiltrating lymphocytes were found not to be expressing granzyme A or perforin. However, in 10 other biopsies from 5 different patients that had been classified as showing no evidence of rejection by the conventional grading system, lymphocytes expressing granzyme A and perforin were detected. In six of these cases the patient was found to have undergone a subsequent rejection episode. In the other four cases the biopsies were either taken at a very early stage after transplantation and the high doses of immunosuppression used routinely at that stage are likely to have averted any rejection episodes, or it was not possible to follow subsequent rejection episodes. These results, which are statistically significant (p = 0.06), demonstrate that granzyme A‐ and perforin‐expressing lymphocytes can be identified in rejecting biopsies before histological damage is seen. The identification of perforin and granzyme A expression in vivo suggest a possible role for these proteins in the cytolysis that occurs during transplantation rejection. Furthermore, the data presented here suggest that it may be possible to use granzyme A and perforin as early predictive markers of transplantation rejection.
Chronic experimental autoimmune encephalomyelitis induced by the 89‐101 myelin basic protein peptide in B10RIII (H2r) mice
Authors: Jansson Liselotte , Holmdahl Rikard , Olsson Tomas , Höjeberg Bo
Published: March 2007

Development of experimental allergic encephalomyelitis (EAE) in the SJL (H‐2s) mice is associated with a T cell‐dependent autoimmune response to the C‐terminal part of the myelin basic protein (MBP). In this study the influence of both H‐2 and non‐H‐2 genetic background on EAE induced with the MBP89‐101 peptide is described. Analysis of different H‐2q haplotype strains, B10G, B10Q, SWR and NFR/N, showed that the B10 background is relatively resistant to disease induction. Both SWR and NFR/N were susceptible to EAE showing that the H‐2q haplotype is permissive for EAE development induced with MBP89‐101 and that the T cell receptor (TcR) haplotype or complement C5 deficiency exert no significant influence on disease susceptibility. In a series of H‐2‐congenic strains on the B10 background only B10RIII (H‐2r) mice were susceptible to EAE. The B10RIII mice developed a severe EAE with early onset and chronic progressive or relapsing course of disease. In addition, B10RIII mice treated with Freund's complete adjuvant and pertussis toxin alone showed an early monophasic disease. The clinical observations were confirmed by immunohistopathologic analysis of the central nervous system. In these studies, we also applied antibodies to different TcR Vβ elements which showed no specific limitation of the used TcR among infiltrating T cells in the target tissue in any of the strains. It is concluded that an MBP peptide‐specific disease can be induced in three different haplotypes and it is possible that shared structures between the As, Aq and Ar molecules are of importance for the trigger of encephalitogenic T cells with different TcR Velements. The presently described chronic EAE model induced in the B10RIII mice will be of value as a model for multiple sclerosis.
Phorbol ester responsiveness of murine Ly‐1‐lineage B cells from normal and viable motheaten mutant mice
Authors: Kolber Donna L. , Rothstein Thomas L. , Shultz Leonard D.
Published: March 2007

Simultaneous analysis of stimulated cells for surface phenotype and DNA content by flow cytometry was used to delineate the characteristics of murine lymphocytes that respond to phorbol esters. Peritoneal cells that expressed high‐density sIgM, Ly‐1, Mac‐1 and high‐density Pgp‐1, were preferentially stimulated to enter the S + G2/M phases of the cell cycle by the protein kinase C agonist, phorbol 12‐myristate 13‐acetate (PMA). Since these phenotypic characteristics correspond well with those of Ly‐1‐lineage B cells, non‐peritoneal sources of Ly‐1+ B cells were examined to test the relative role of lineage and environment in determining phorbol ester responsiveness. Splenic sIgM+ lymphocytes from adult mev/mev mice, and Ly‐1+ splenic B cells from neonatal normal mice, were stimulated to enter the S + G2/M phases by PMA, although not to the same extent as peritoneal Ly‐1+ B cells. These results suggest that responsiveness to phorbol ester, acting alone, is characteristic of murine Ly‐1‐lineage B cells regardless of tissue of origin; however, a role for environmental influences has not been completely ruled out.
Unusual phenotype of intestinal intraepithelial lymphocytes in the rat: predominance of T cell receptor α/β+/CD2− cells and high expression of the RT6 alloantigen
Authors: Fangmann Josef , Schwinzer Reinhard , Wonigeit Kurt
Published: March 2007

The phenotype of intraepithelial lymphocytes (IEL) from the small intestine of adult rats was studied by flow cytometry. Using appropriate monoclonal antibodies the expression patterns of the T cell receptor α/β (TcR2), CD2, the alloantigen RT6 and several other T cell antigens were analyzed. The vast majority of rat IEL expressed TcR 2 which is in contrast with data reported for the mouse. The comparison of IEL with lymph node cells revealed major phenotypic differences. Whereas CD2 was present on virtually all lymph node T cells it was found on only < 5% of IEL. The T cell‐specific differentiation antigen RT6 present on only a fraction of lymph node cells was found on about 99% of IEL demonstrating uniform expression with an approximately tenfold higher density. Identity of the detected molecule with RT6 was proven by using congenic controls and by the demonstration of phosphatidylinositol linkage to the IEL membrane. About 86% of IEL expressed CD8 but a substantial proportion of these cells co‐expressed the CD4 molecule (34%). Two‐color analysis revealed that the CD4+CD8+ double‐positive subset completely lacked CD45RB suggesting that they represent memory cells. In the CD4−CD8+TcR2+ subset there was a remarkable heterogeneity of CD5 expression. A substantial number of these cells did not express CD5 despite high density of TcR 2. Phenotypic peculiarities found on all or most IEL such as the lack of CD2 and the increased expression of RT6 indicate that the intestinal epithelial environment exerts strong effects on the development and maturation of these cells.
Staphylococcal enterotoxin B as a potent suppressant of T cell proliferative responses in rats
Authors: Ben‐Nun Avraham
Published: March 2007

The staphylococcal toxins are well known as stimulators of powerful T lymphocyte proliferative responses. Staphylococcal enterotoxin B (SEB) was found, in both humans and mice, to preferentially stimulate T cells bearing particular Vβ gene products as part of their functional T cell receptor α/β. In contrast to this reported stimulatory activity we demonstrate here that SEB is a poor stimulant of T lymphocyte proliferative responses in Lewis rats. Moreover, under appropriate conditions, SEB can serve as a powerful suppressant of Lewis rat T lymphocytes, capable of abolishing their antigen‐specific or mitogen‐stimulated proliferative responses. Suppression of mitogen‐induced proliferative responses of rat T cell clones was effective in the presence of syngeneic or allogeneic accessory cells and similar to its stimulatory characteristics, SEB suppressed high proportions of rat T lymphocyte subsets. These data suggest that in certain circumstances SEB can be considered a “supersuppressogen” as well as a “superantigen”. Whether SEB will be “superantigen” or “supersuppressogen” is likely to depend on the TcR elements of the lymphocytes as well as on the MHC molecules presenting SEB.
Contribution of the VH11 gene family to mitogen‐responsive B cell repertoire in C57BL/6 mice
Authors: Kaushik Azad , Bona Constantin , Reininger Luc , Jaton Jean‐Claude , Kelsoe Garnett
Published: March 2007

The contribution of VH11 gene family to the development of the primary B cell repertoire has been studied by analyzing 1.8 × 104 mitogen induced B lymphocyte colonies. The data demonstrate that VH11 family is predominantly expressed among neonatal splenic as well as adult peritoneal B cell colonies, both rich in Ly‐1+ B cells. VH11 gene family expression among B splenocytes decreases during ontogeny and VH11 family pairs stochastically with different Vx families among mitogen‐activated neonatal B cell colonies, which are representative of an antigen unselected B cell repertoire. Thus, an increased VH11 expression among peritoneal and neonatal B cells points towards its biased expression among Ly‐1+ B lymphocytes. The restricted V gene rearrangements and VH11‐Vx9 pairing observed among anti‐bromelain‐treated mouse red blood cells autoantibodies are likely to be an outcome of both intrinsic gene recombination processes per se as well as selection by an autoantigen and/or local selective environmental factors.
Interleukin 2‐dependent activation of tumor‐specific cytotoxic T lymphocytes in vivo
Authors: Ley Victoria , Langlade‐Demoyen Pierre , Kourilsky Philippe , Larsson‐Sciard Eva‐Lotta
Published: March 2007

We have quantitatively studied the effect of interleukin (IL) 2 on the cytotoxic T lymphocyte (CTL) response to tumor cells in vivo. Mastocytoma P815 was transfected with murine IL 2 cDNA (P815‐IL 2) and injected into syngeneic mice. The anti‐tumor response was analyzed and compared with the response induced by the non‐transfected cells. P815 parental cells are highly tumorigenic, causing death within 20‐30 days. In contrast, IL 2‐transfected cells were totally rejected. Co‐injection of IL 2‐secreting and parental cells resulted in the inhibition of growth of both type of tumors. In addition, the response induced by IL 2‐secreting cells protected the mice against a subsequent challenge with P815. Long‐term memory persisted in treated mice 3 months after tumor rejection. Frequencies of CTL precursors and CTL specific for P815 increased as a result of IL 2 secretion by the target cells. Estimates of CTL frequency at days 8 and 12 after injection were 2 to 3 times higher in mice inoculated with P815‐IL 2 cells, and this correlated with tumor rejection.
Platelet‐induced expression of FcγRIII (CD16) on human monocytes
Authors: Phillips Joseph H. , Chang Chiwen , Lanier Lewis L.
Published: March 2007

Monocytes constitutively express Fc receptor (FcR) for IgG type I (CD64) and type II (CD32), but not type III (CD 16). Prior studies have indicated that in vitro culture of monocytes results in spontaneous induction of CD16, but this phenomenon has been variable and the mechanism unexplained. Here, we demonstrate that activated platelets are responsible for induction of CD16 on monocytes, as a consequence of TGF‐β release. Local release of TGF‐β by activated platelets at sites of tissue damage may induce CD16 on infiltrating or resident monocytes that in turn facilitate the function of these effector cells. The FcR on these CD16+ monocytes is functionally competent, and enables the monocytes to kill murine anti‐CD16 hybridoma cells. CD16 expressed on platelet‐activated monocytes is structurally similar to the transmembraneanchored CD16‐II polypeptide expressed on natural killer (NK) cells. However, whereas CD16‐II on NK cells is co‐associated with CD3ζ, we were unable to detect CD3 ζ transcript or protein in monocytes. Transcripts for the γ subunit of the high‐affinity IgE FcR (FcϵRI‐γ) were detected in monocytes, and presumably γ proteins are co‐associated with CD16‐II in these cells. Nucleotide sequence analysis of FcϵRI‐γ cDNA derived from both NK cells and cultured monocytes indicated identity with the structure previously cloned from basophils. Since CD16+ monocytes can kill anti‐CD16 hybridoma cell targets in the absence of CD3 ζ, these results indicate that CD3 ζ is not essential for signal transduction in CD16‐II‐mediated cytotoxicity.
Studies on the human T cell receptor α/β variable region genes. I. Identification of 7 additional Vα subfamilies and 14 Jα gene segments
Authors: Roman‐Roman Sergio , Ferradini Laurent , Azocar José , Genevée Catherine , Hercend Thierry , Triebel Frédéric
Published: March 2007

The anchored‐polymerase chain reaction has been used to study further the diversity of the human T cell receptor α chain. The analysis of 308 cDNA transcripts from human peripheral lymphocytes hybridizing with a Cα probe led to the identification of a series of additional Vα and Jα gene segments. The sequences of seven Vα gene segments which individually define a novel Vα subfamily (termed Vαw23 to Vαw29) are reported. The sequences of some previously described Vα1, Vα2, Vα5, Vα7 and Vα22 gene segments are also extended. In addition, we report 14 novel Jα gene segment sequences. Taken together, these data indicate that the contribution of the α chain combinatorial diversity to the human T cell receptor α/β variability has not yet been fully appreciated.
Relative frequencies of secondary B cells activated by cognate vs. other mechanisms
Authors: Johnson Julia G. , Jemmerson Ronald
Published: March 2007

Three distinct mechanisms for the activation of secondary B cells to antibody‐forming cells have been examined in splenic fragment cultures. The clonal response to a protein antigen [cytochrome c (cyt)] was quantified in terms of both the number of B cells activated and the amount of antibody produced by each clone. The vast majority of memory B cells required surface immunoglobulin (sIg) receptor‐mediated uptake of antigen followed by cognate interactions with an antigen‐specific T helper cell. Nevertheless, a significant number (as many as 12%) could be activated via soluble factor‐mediated bystander activation, involving occupation of neither the sIg receptor nor class II major histocompatibility complex (MHC) molecules. This pathway, however, was relatively inefficient in that individual clones secreted less than half as much antibody as clones activated as a result of cognate collaboration with a T helper cell. A similar number of secondary B cells were activated following nonspecific uptake of high concentrations of antigen for which splenic fragment T cells had been primed [i. e., hemocyanin (Hy)], independent of sIg receptor occupancy. Antibody levels were similar to those in cultures where B cells were activated in a cognate manner with sIg receptor occupancy. When Hy‐stimulated fragment cultures were supplemented with polymerized cyt, the frequency of activation via this latter pathway increased fourfold, despite the fact that no cyt‐primed T cells were present. This observation supports the idea that receptor‐mediated uptake of antigen serves not just to focus antigen but also provides an important signal in activating B cells. Bystander B cell activation, however, was not enhanced by providing a sIg cross‐linking signal with polymerized cyt. The lower level of antibody production by B cells activated in a bystander fashion and the inability to enhance their frequency of activation with sIg receptor occupancy suggest that there is indeed a fundamental difference between soluble factor‐mediated bystander activation and activation via T cell determinant‐mediated cognate T helper‐B cell interactions, perhaps involving signaling through class II MHC molecules.
Evidence for an active hydrophobic form of factor H that is able to induce secretion of interleukin 1‐β or by human monocytes
Authors: Iferroudjene Djedjiga , Schouft Marie‐Thérèse , Lemercier Claudie , Gilbert Danièle , Fontaine Marc
Published: March 2007

We studied the capacity of human factor H to promote the secretion of a lymphocyte‐activating factor (LAF) by human monocytes cultured under serum‐free conditions. Presence of LAF in the culture supernatants was assessed with the mouse thymocyte assay. Highly purified factor H alone had no effect on thymocyte proliferation. When monocytes were cultured with factor H for 24 h, a significant secretion of LAF was observed. The effect was dose dependent over a range of factor H concentrations from 1 to 15 μg/ml. Polymyxin B did not abrogate the capacity of factor H to induce LAF secretion. Adsorption of factor H preparations onto anti‐factor H‐Sepharose completely suppressed the phenomenon. Conversely, the activity was recovered in the acidic eluate. Furthermore, factor H subpopulation Φ2, that was able to bind to phenyl‐Sepharose, was a stronger inducer of LAF secretion by monocytes than the subpopulation Φ1 (which did not bind to phenyl‐Sepharose). Using a specific radioimmunoassay for interleukin 1‐β (IL 1β), we observed a good correlation between the LAF activity and the amount of IL 1β secreted by human monocytes stimulated with factor H.

We have shown previously that factor H (Φ2) bound specifically on Raji cells whereas factor H (Φ1) did not. These results argue for the participation of the interaction of factor H with its receptor to stimulate the secretion of IL 1 by monocytes and that the Φ2 form of factor H is a ligand for the human factor H receptor.
Presence of CD4 and CD8 determinants on CD4−CD8− murine thymocytes: passive acquisition of CD8 accessory molecules
Authors: Shores Elizabeth W. , Sharrow Susan O. , Singer Alfred
Published: March 2007

In the present study we have examined the possibility that CD4 and CD8 accessory molecules can be passively acquired by thymocytes. We initially observed that most thymocytes contained within the CD4−CD8− subset actually possess low levels of CD4 and CD8 on their cell surface. However, the detection of CD4 and CD8 on CD4−CD8− cells was dependent on the presence of other CD4+/CD8+ thymocytes which were actively synthesizing CD4 and CD8. These initial findings suggested that the appearance of CD4/CD8 on “double‐negative” thymocytes was due to the passive acquisition of these accessory molecules from CD4+/CD8+ cells present within the thymus. To investigate this possibility directly, we made both in vivo and in vitro mixes of thymocytes possessing different alleles of CD8 (Ly‐2.1 and Ly‐2.2). Under these experimental conditions, we detected Ly‐2.2 on the surface of thymocytes that were genetically Ly‐2.1+ and incapable of synthesizing Ly‐2.2. These data indicate that thymocytes can express cell surface CD8 molecules which they have not produced but have acquired from other cells in their environment. Thus, the present study indicates that low‐level surface expression of cell surface CD4/CD8 differentiation molecules does not necessarily identify distinct thymocyte subpopulations.
Oligonucleotide primers for polymerase chain reaction amplification of human immunoglobulin variable genes and design of family‐specific oligonucleotide probes
Authors: Marks James D. , Tristem Michael , Karpas Abraham , Winter Greg
Published: March 2007

In recent work, the polymerase chain reaction (PCR) has been used to amplify rearranged mouse and human immunoglobulin heavy and χ light chain variable (V) genes. Here we have optimized the design of the PCR primers for human V genes and used them to amplify cDNA from human peripheral blood lymphocytes. Cloning and sequencing revealed a diverse repertoire of V genes, and the presence of members of each human V gene family. After alignment of the sequences, we identified a region conserved within V gene families, but differing between families, and used this to design family‐specific oligonucleotide probes.
Immune response to soluble exoantigens of Plasmodium falciparum may contribute to both pathogenesis and protection in clinical malaria: evidence from a longitudinal, prospective study of semi‐immune African children
Authors: Riley Eleanor M. , Jakobsen Palle Hoy , Allen Stephen J. , Wheeler Jeremy G. , Bennett Stephen , Jepsen Soren , Greenwood Brian M.
Published: March 2007

Some soluble exoantigens of Plasmodium have lipopolysaccharide (LPS)‐like properties and are believed to contribute to the pathogenesis of acute malaria. We have studied cellular and humoral immune responses to several purified exoantigens of Plasmodium falciparum in a cohort of children and compared these responses with their subsequent susceptibility to malaria infection and clinical disease. We found no evidence that either lymphoproliferative or interferon‐γ (IFN‐γ) responses to these antigens were associated with protective immunity. On the contrary, children whose cells produced IFN‐γ after in vitro activation with one of the soluble antigens (Ag7) were more likely to experience clinical manifestations of malaria infection (fever and malaise) than were children whose cells did not produce IFN‐γ. It is possible that exoantigen‐induced IFN‐γ may exacerbate the LPS‐like effects of these antigens. However, serum antibodies to another antigen (Ag2) were more prevalent in children with asymptomatic infections or low parasitemia than in children with fever and higher parasitemia (confirmed clinical malaria), suggesting that these antibodies may contribute to the development of protective immunity.
The genes for a mouse hematopoietic differentiation marker called the heat‐stable antigen
Authors: Wenger Roland H. , Ayane Mohamed , Bose Ron , Köhler Georges , Nielsen Peter J.
Published: March 2007

We have isolated a murine cDNA by virtue of its expression in pre‐B cell lines but not in plasmacytomas. In mouse, mRNA is detected by Northern blot analysis exclusively in hematopoietic tissues with the exception of brain. When expressed in bacteria, the encoded protein is specifically recognized by several antibodies against the murine hematopoietic differentiation marker called heat‐stable antigen (HSA). In contrast to previous speculations, these results suggest that the antigenic determinant recognized by anti‐HSA antibodies is proteinaceous. The cDNA sequence is essentially identical to a mouse HSA cDNA recently published (Kay et al., J. Immunol. 1990. 145: 1952). Three HSA genes were isolated, one of which corresponds to the isolated cDNA. The other two appear to be intronless retroposons which, despite numerous sequence changes, maintain an open reading frame. One of these intronless genes could code for an alternative form of HSA with a transmembrane domain and a cytoplasmic tail not encoded by the intron‐containing gene. This gene could be expressed, based on sequence comparisons of the three genes. However, using polymerase chain reaction amplification of first strand cDNA from various cell lines and adult mouse tissues, we could detect expression only of the intron‐containing gene.
Synergistic effect of interleukin 1 and soluble CD23 on the growth of human CD4+ bone marrow‐derived T cells
Authors: Bertho Jean‐Marc , Fourcade Christine , Dalloul Ali H. , Debré Patrice , Mossalayi M. Djavad
Published: March 2007

Low‐affinity Fcϵ receptor (FcϵRII/CD23) is expressed by various human cells and known to be cleaved into soluble fragments (sCD23). Several biological activities were ascribed to these molecules. In this study, we have assessed the effect of recombinant 25‐kDa sCD23 (rsCD23) on human bone marrow‐derived T cells. Our results show that rsCD23 in synergy with recombinant interleukin 1 enhances mitogenic responsiveness of CD4+ T cells but does not affect CD8+ cell growth. Furthermore, rsCD23 synergizes autologous marrow cells in enhancement of CD4+ cell growth while CD23 monoclonal antibodies decrease accessory cell effect. Together, these data confirm cytokine‐like activity of sCD23 on human T cell lineage.
CD2 is functionally linked to the ζ‐natural killer receptor complex
Authors: Vivier Eric , Morin Paul M. , O'Brienm Carmeline , Schlossman Stuart F. , Anderson Paul
Published: March 2007

Natural killer (NK) cells express two distinct surface receptors capable of triggering cytolytic effector function. The first is CD 16, an immunoglobulin Fc receptor that allows NK cells to mediate antibody‐dependent killing (ADCC). NK cells express CD16 in association with ζ, a signal‐transducing subunit that is also a component of the T cell receptor complex. Activation of NK cells via CD16 results in tyrosine phosphorylation of ζ. The second NK cell triggering receptor is CD2, a 50–55‐kDa cell surface molecule that is also expressed on T cells. Here we show that NK cell activation induced by mAb reactive with CD2 (either anti‐T11.1 alone or with anti‐T11.2 in combination) also results in the tyrosine phosphorylation of ζ. Our results indicate that CD2 is functionally linked to the CD16‐ζ complex and suggest that the ζ subunit plays a central role in the signal transduction pathways utilized by NK cells.
Adhesion receptors involved in clustering of blood dendritic cells and T lymphocytes
Authors: Scheeren Robert A. , Koopman Gerrit , van der Baan Sieberen , Meijer Chris J. L. M. , Pals Steven T.
Published: March 2007

The relationship of dendritic cells (DC) isolated from the peripheral blood to those of lymphoid tissue is, in terms of maturation and function, incompletely understood. In our present study, we have explored the molecular basis of adhesion of T cells to blood DC. Analysis of the expression of adhesion receptors on the cell surface of blood DC revealed that these cells express lymphocyte function‐associated antigen (LFA)‐1 (CD11a/18), ICAM‐1 (CD54), LFA‐3 (CD58) and CD44, but are very late antigen (VLA)‐4 (CD49d) and vascular cell‐adhesion molecule (VCAM)‐1 negative. The LFA‐1 pathway was found to play a key role in T cells‐blood DC adhesion; monoclonal antibodies (mAb) against both LFA‐1 and ICAM‐1 strongly inhibited adhesion between those cells. Moreover, a T cell clone from an LFA‐1‐deficient patient showed poor binding to blood DC. The important role of LFA‐1 in T cell‐blood DC adhesion was also supported by the metabolic energy and divalent cation dependence of the interaction. mAb against LFA‐3 and CD2 did not inhibit T cell‐blood DC binding. In contrast to the strong inhibition by antibodies to LFA‐1 and ICAM‐1, antibodies to CD44 enhanced conjugate formation between T cells and blood DC. Together, our results show that the LFA‐1/ICAM‐1 pathway plays a central role in T cell‐blood DC adhesion, a situation like that in T cell adhesion to lymphoid DC. However, unlike lymphoid DC, blood DC do not express VCAM‐1 nor use LFA‐3 for T cell binding.
Antibody specificity and immunoglobulin VH utilization of human monoclonal CD5+ B cell lines
Authors: Schutte Mieke E. M. , Ebeling Saskia B. , Akkermans Karine E. , Gmelig‐Meyling Frits H. J. , Logtenberg Ton
Published: March 2007

Human B lymphocytes that bear the CD5 antigen are relatively abundant in early ontogeny and comprise a small fraction of the B cell population in adults. The CD5 B cell subset has attracted much attention because of its possible involvement in autoimmune disease and certain B cell malignancies. To begin to understand the role of CD5 B cells in disease processes, we have generated a panel of ten human monoclonal B cell lines selected for expression of the CD5 antigen. These cell lines were obtained by Epstein‐Barr virus transformation of B lymphocytes isolated from the spleen, liver and bone marrow of a 19‐week‐old fetus, from cord blood and from peripheral blood of healthy volunteers. In addition, one cell line was isolated from the spleen of a patient with chronic lymphocytic leukemia. Here, we describe the antibody and immunoglobulin VH gene repertoire of this panel of CD5 B cell lines. The results of these experiments show that (a) some but not all CD5 B cell lines secrete polyreactive antibodies that bind to a variety of self‐ and xenoantigens and (b) members of the small VH4, VH5 and VH6 gene families are overrepresented in this panel of cell lines. Nucleotide sequence analysis revealed the expression of VH gene elements that have been previously reported in the preimmune B cell repertoire, in CD5 B cell tumors and in polyreactive antibodies.
Antigen‐induced inhibition of autoimmune response to rat male accessory glands: distinct characteristics of I‐A‐ and I‐E‐positive peritoneal cells
Authors: Rivero Virginia Elena , Ferro Maria Elena , Romero‐Piffiguer Marta , Correa Silvia , Yranzo‐Volonté Nora , Riera Clelia Maria
Published: March 2007

The present report describes different aspects of two populations of peritoneal cells (PC) obtained from rats injected i.p. 2 h or 24 h previously with a suppressor dose of a purified fraction (FI) of rat male accessory glands (RAG) (FI‐PC2h and FI‐PC24h, respectively). The FI‐PC2h, which are mainly I‐E (OX17) positive and can suppress the autoimmune response to RAG autoantigens, have an elevated phagocytic activity against Candida albicans and capacity to reduce the dye nitroblue tetrazolium. In contrast, FI‐PC24h, which are mainly I‐A (OX6) positive and can potentiate the autoimmunity to RAG autoantigens, have a diminished capacity to reduce the dye and a diminished phagocytic activity. Moreover, the Toxoplasma gondii appear to have a different effect on both populations. The parasites can invade FI‐PC2h while FI‐PC24h offer resistance to T. gondii aggression.

FI‐PC2h cultured during 22 h (FI‐PC2‐24h in vitro), or PC obtained from syngeneic recipients injected i.p. 22 h previously with FI‐PC2h (FI‐PC2‐24h in vivo) show, as FI‐PC2h, an increase of the I‐E+ cells and capacity to induce suppression of the delayed‐type hypersensitivity response to RAG autoantigens when they are injected to syngeneic rats 10 and 3 days prior to the immunization with chemically modified (diazotized arsanilic and sulfanilic acid) RAG in complete Freund's adjuvant.

The PC obtained 24 h after injection of irradiated rats with N‐PC plus FI show an increase of I‐E+ cells whereas an enhancement of I‐A+ cells can be observed when the PC are obtained 24 h after injection of irradiated and bone marrow‐reconstituted rats with N‐PC plus FI.

These findings appear to indicate that FI‐PC2h and FI‐PC24h are functionally different and that the population obtained 24 h after injection of FI of RAG could not originate from either the population present 2 h after injection of FI of RAG injection nor from normal PC. They appear to require bone marrow precursors.