bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstration by class I gene transfer that reduced susceptibility of human cells to natural killer cell‐mediated lysis is inversely correlated with HLA class I antigen expression
Authors: Shimizu Yoji , Demars Robert
Published: March 2007

HLA antigen‐loss mutants and class I gene transferents were used to analyze the influence of class I expression on natural killer (NK) cell‐mediated lysis. Only HLA antigen‐loss mutants that had lost expression of either HLA‐A and HLA‐B antigens (mutant .184) or of HLA‐A, B and C antigens (mutant .221) were distinctly susceptible to NK‐mediated lysis. Mutants with reduced expression of class II antigens but unaltered expression of class I antigens remained resistant to NK lysis. A direct demonstration of the effect of class I antigen expression on human cells was made by analyzing a variety of gene transferents of the HLA‐A, B, C null mutant .221 expressing only one transferred HLA‐A, B or C gene. These results specifically show that expression of class I antigens, with a possible preferential effect of HLA‐B expression, reduces the susceptibility of mutant .221 to NK‐mediated lysis.
In vitro and in vivo effects of interleukin 2 on the protozoan parasite leishmania
Authors: Mazingue Christine , Cottrez‐Detoeuf Françoise , Louis Jacques , Kweider Mahmud , Auriault Claude , Capron André
Published: March 2007

T cells can have either resistance‐promoting or disease‐promoting effects in murine cutaneous leishmaniasis. It is known that the adoptive transfer of parasite‐specific helper T cells led to an exacerbation of Leishmania‐induced lesions. This work presents evidence that lymphokines produced by activated T cells could be involved in this exacerbating process by directly stimulating the parasite growth. In the presence of activated T cell supernatants, the in vitro growth of Leishmania mexicana amazonensis promastigotes was greatly enhanced. This effect was reproduced by addition of recombinant interleukin 2 (IL 2). An anti‐IL 2 antibody partially reversed the stimulatory effect of IL. An in vivo in situ treatment of infected mice with IL 2 led to an exacerbation of the lesions. The increase in footpad swelling after IL 2 treatment was correlated with a higher number of parasites per lesion. The protective effect of cyclosporin A against the development of Leishmania infection was abolished by IL 2 treatment. As we observed that IL 2 has a stimulatory effect on the in vitro Leishmania growth, we speculate that exacerbation of the lesions observed in vivo after IL 2 treatment could be partially related with a direct effect of IL 2 on the parasite growth.
Terminal deoxynucleotidyl transferase‐positive B cell precursors in fetal lymph nodes and extrahemopoietic tissues
Authors: Cattoretti Giorgio , Parravicini Carlo , Bonati Antonio , Buscaglia Mauro , Zuliani Guglielmo , Plebani Anna , Delia Domenico , Rilke Franco
Published: March 2007

Terminal deoxynucleotidyl transferase (TdT)‐positive B cell precursors populate fetal lymph nodes (LN) of mid‐term (16th–22th week) fetuses. These cells have a B cell phenotype (HLA‐DR, CD45R, CD22, μ) and lack mature differentiation antigens (CD1c, CD20, L26). TdT cells are also present in the extranodal mesenteric mesenchyme, pancreas and LN primordia. Extranodal TdT cells are found among proliferating (i.e. Ki‐67) B cells and lack leukocyte function‐associated antigen (LFA‐1) and HLA‐DQ; these latter molecules are acquired by nodal TdT elements. Adult LN, adult and fetal spleen contain less TdT cells than fetal LN. The fetal LN contains the full range of the B cell differentiation compartment, from the TdT precursor cell to the mature B lymphocyte.
Specific immune responses restored by alteration in carbohydrate chains of surface molecules on antigen‐presenting cells
Authors: Boog Claire J. P. , Neefjes Jacques J. , Boes Jolande , Ploegh Hidde L. , Melief Cornelis J. M.
Published: March 2007

Two class I major histocompatibility (MHC) mutant mouse strains, H‐2bm14 and H‐2bm6, differ from the strain of origin C57BL/6 (B6, H‐2b) in one and two amino acids of the H‐2Db and H‐2Kb molecule, respectively. The bm14 Db mutation results in specific failure of female bm14 mice to generate a cytotoxic T lymphocyte (Tc) response to the male‐specific antigen H‐Y. The allospecific Tc response of CD8 B6 T cells against bm6 Kb mutant spleen cells, in contrast to that against other Kb mutants, is absolutely CD4 T helper cell dependent. Purified CD8 T cells completely fail to respond. We now report that the inability to mount these specific immune responses is restored by the use of dendritic cells (DC) as antigen‐presenting cells (APC). Comparison of MHC expression on various types of APC by cytofluorimetry and quantitative immunoprecipitation showed very high expression of class I and class II MHC molecules on DC. Strikingly, examination of class I and class II molecules by isoelectric focusing revealed qualitative differences as well. We show that the surface MHC class I molecules of DC are present in greater quantity and carry on average fewer sialic acids than the same molecules isolated from other APC types such as spleen cells, lipopolysaccharide blasts or concanavalin A blasts. That sialic acids on cell surface molecules, including MHC, may play a role in antigen presentation is suggested by our finding that removal of sialic acids, by neuraminidase, can restore specific responses to nonresponder APC as well.
Molecular control of tissue‐specific expression at the mouse TNF locus
Authors: Victor Jongeneel C. , Shakhov Alexander N. , Nedospasov Sergei A. , Cerottini Jean‐Charles
Published: March 2007

We have examined the patterns of mRNA accumulation and transcription of the tandemly linked genes for tumor necrosis factor (TNF)‐β and TNF‐α. In spite of their tandem arrangement and close linkage, the two TNF genes utilize separate promoters. Our results show that, while levels of mRNA correlate with patterns of TNF‐α and TNF‐β secretion by lymphocytes and macrophages, the transcriptional levels of the corresponding genes do not. The TNF‐α gene is transcribed much more heavily than the TNF‐β gene in T lymphocytes, even though the TNF‐β mRNA is more abundant. Resting T lymphocytes and macrophages, which do not accumulate any TNF mRNA, nevertheless transcribe the TNF‐α gene actively. On the other hand, the TNF‐β gene is transcriptionally silent in macrophages. Our results are consistent with a model where tissue specificity is controlled transcriptionally, whereas post‐transcriptional events differentially control mRNA abundance.
T cells recognize both conformational and cryptic determinants on the insulin molecule
Authors: Thomas James W. , George‐Gattner Hans , Danho Waleed
Published: March 2007

T lymphocytes from strain 2 guinea pigs were studied for recognition of isolated insulin A and B chains. Insulin‐immune T cells require intact conformation of the interchain disulfide bond that forms the A chain loop but do not require the B chain. In addition, strain 2 T cells were unexpectedly found to recognize unique epitopes on isolated insulin B chain that are not generated by presentation of native insulin. These data show that the T cell repertoire of strain 2 guinea pig for insulin includes both conformational and cryptic determinants.
Granzyme A expression by normal rat natural killer (NK) cells in vivo and by interleukin 2‐activated NK cells in vitro
Authors: Velotti Francesca , Palmieri Gabriella , Morrone Stefania , Piccoli Mario , Frati Luigi , Santoni Angela
Published: March 2007

Granzyme A (TSP‐1) is a serine esterase expressed in cytotoxic T and natural killer (NK) cell lines. Its presence in in vivo primed T cells is disputed at present. Here we show that normal rat NK cells contain granzyme A in vivo and that its expression is augmented by their short‐term in vitro treatment with IL2. Granzyme A expression in a NK cell population with LAK activity has also been examined.
Neonatal induction of allogeneic tolerance prevents T cell‐mediated autoimmunity in NOD mice
Authors: Bendelac Albert , Boitard Christian , Bach Jean‐François , Carnaud Claude
Published: March 2007

Diabetes in the NOD mouse strain is a genetically programmed T cell‐mediated autoimmune process that is directed against an as yet unknown antigen target(s) on pancreatic β cells. To investigate whether the course of the autoimmune disease could be altered by immune manipulations of the T cell repertoire, we have induced allogeneic tolerance by injecting F1 semiallogeneic spleen cells into NOD neonates. This procedure resulted in a significant protection against both insulitis and diabetes. However, although it requires the induction of tolerance, as shown by the failure of non‐tolerizing irradiated cells to prevent autoimmunity, protection appeared to be independent of the major histocompatibility complex haplotypes of the F1 spleen cells injected at birth, e.g. (C57BL/6 x NOD)F1, (CBA/Ca x NOD)F1 or (BALB/c x NOD)F1 cells. In addition, a similar degree of protection was induced, whether the tolerant state, as assessed by mixed lymphocyte reaction studies in vitro, was of short duration, ∼6 weeks, or lasted for more than 12 weeks. Putative veto or suppressor functions of chimeric T cells were ruled out, since mice tolerized with T cell‐depleted F1 spleen cells were equally protected.

We conclude that the expression of spontaneous T cell‐mediated autoimmunity can be modulated by immune manipulations at birth. Whether the protection observed in the present experiments resulted from the production of one or several specific holes in the autoimmune T cell repertoire, i.e. cross‐tolerance, or whether it resulted from nonspecific disturbances of the emerging T cell repertoire remains to be elucidated.
Rearranging sequence located in the intron of the human T cell receptor γ chain gene constant region
Authors: Chen Zhu , Loiseau Pascale , Bories Jean Christophe , Bensussan Armand , Sigaux FrançOis
Published: March 2007

Human T cell rearranging γ genes encode membrane proteins which are expressed by a minor subset of T cells. Extensive studies have shown that TcR γ gene rearrangements result from Vγ‐Jγ recombinations. Here we analyze an unusual rearrangement involving a non‐translatable sequence flanked by heptamer and nonamer signals in a Ti α/β‐positive T cell clone (JF1). This sequence, designated here as IγRS, is distinct from V, D or J elements. It is located in the first intron of the first constant region (Cγ1) and homologous sequences are conserved in Cγ2 introns. In JF1 cells the IγRS is juxtaposed to the Jγ2 segment downstream to a Vγ10‐Jγ1 rearrangement. The use of a cryptic splicing site induced JF1 cells to produce an aberrant large‐sized transcript containing the IγRS 3′ to the first exon of Cγ1. Such a rearrangement occurring downstram to an inframe Vγ‐Jγ junction may induce premature arrest of translation and lack of the C‐terminal part of Cγ involved in γ‐protein assembly.
Masking of veto function in vivo by activated CD4+ T lymphocytes
Authors: Rammensee Hans‐Georg , Hügin Daniela
Published: March 2007

Donor CD8+ T lymphocytes injected into recipient mice incompatible at major histocompatibility complex (MHC) class I genes induce donor‐specific CTL nonresponsiveness, attributed to the veto function of donor cells. Here we show that conditions leading to strong activation of CD4+ T cells, namely the presence in the recipient of foreign MHC class II determinants, lead to the apparent loss of veto function of donor cells. This ‘masking’ of veto function is dependent on the dose of foreign MHC class II present. Veto function can be partially restored by treatment of recipients in vivo with CD4‐specific antibody, a measure which has been shown to eliminate the function of CD4+ T cells in vivo. We conclude that CD4+ T cells activated by contact with antigen can interfere with the veto function of CD8+ T cells. Consequences of this finding are: (a) veto function of a sample cell population can be overlooked when activation of CD4+ T cells occurs simultaneously. (b) The balance between veto function of recipient cells and its abrogation might be responsible for the kind of graft‐vs.‐host reaction generated (CD8+ T cell‐mediated and frequently lethal or CD4+ T cell‐mediated and not lethal) when parental T cells are injected into recipients incompatible at MHC class I and class II genes, (c) A possible contribution of veto cells should be considered in several protocols in which donor hemopoetic cells were used in conjunction with CD4‐specific antibodies to induce transplantation tolerance, (d) Veto function in vivo does not require a contribution of CD4+ T cells.
Marginal zone macrophages and their role in the immune response against T‐independent type 2 antigens: modulation of the cells with specific antibody
Authors: Kraal Georg , Hart Hennie Ter , Meelhuizen Constantijn , Venneker Gerard , Claassen Eric
Published: March 2007

Marginal zone macrophages are strategically positioned in the marginal zone of the spleen and are thought to play an important role in the initiation of the immune response to T‐independent type 2 responses. The cells are characterized by high phagocytic activity and by the selective uptake of neutral polysaccharides. In the mouse marginal zone macrophages react specifically with the monoclonal antibody ER‐TR9. Injection of the antibody resulted in a complete abrogation of the uptake of neutral polysaccharides by the cells in vivo, although the cells were still capable of taking up latex and carbon particles. The complete blockade of the polysaccharide uptake did not result in an altered humoral immune response against this antigen. When the antibody ER‐TR9 was coupled to the toxin gelonin a complete elimination of the marginal zone macrophages could be established in vivo. However, complete elimination did not result in changes of the immune responses against 2,4,6‐trinitrophenylated Ficoll, suggesting that the marginal zone macrophages are either not involved in this type of response, or that their function can be taken over by other cells. The possible role of these cells and the importance of the spleen in the immune response against bacterial antigens is discussed.
Identification of a human monocyte antigen (Mo3e) associated with cellular activation and lymphokine responsiveness
Authors: Liu David Y. , Ree Joy Y. , Douglas Trochelman R. , Todd, Iii Robert F.
Published: March 2007

A murine monoclonal IgM antibody recognizes an antigen (Mo3e) found on the surface of human peripheral blood monocytes stimulated with phorbol 12‐myristate 13‐acetate (PMA), lipopolysaccharide and muramyl dipeptide and blocks the monocyte response to migration inhibitory factor (MIF). We utilized Western blot and immunoprecipitation analyses of whole cell lysates to investigate the biochemical nature of this monocyte antigen. Two distinct bands (75 kDa and 50 kDa) were detected by anti‐Mo3e after monocyte lysates were resolved by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and transblotted onto nitrocellulose paper. Stimulation of monocytes with PMA resulted in a marked increase in the amount of the 50‐kDa species. Immunoprecipitation of Mo3e from lysates of surface‐iodinated cells demonstrated one broad band at 55–80 kDa which increased after PMA stimulation. The epitope identified by anti‐Mo3e was resistant to 2‐mercaptoethanol and heat treatment (100°C/5 min) and was sensitive to trypsin or papain treatment. Two‐dimensional SDS‐PAGE analysis revealed that the 75‐kDa species has an isoelectric point of 7.0 and the 50‐kDa species is more acidic with an isoelectric point of 5.3. These results indicate that anti‐Mo3e antibody defines unique monocyte proteins that may play a role as suggested by previous studies, in monocyte activation and responsiveness to MIF.
Most human CD3+WT31− clones with T cell receptor Cγ1 rearrangements show strong non‐MHC‐restricted cytotoxic activity in contrast to those with Cγ2 rearrangements
Authors: Christmas Stephen E.
Published: March 2007

Clones expressing CD3 in the absence of WT31 expression were obtained by growing highly purified WT31− cells in the presence of interleukin 2 and phytohemagglutinin. Most clones showed rearrangements of T cell receptor (TcR) γ genes on both chromosomes involving all five currently identified Jγ segments. About a third of these clones had a rearranged 12 kb Kpn I band with the Jγ probe, consistent with a V9JPCγ1 rearrangement. All clones with both chromosomes rearranged to Cγ2 had low or intermediate cytotoxic activity while most of those with at least one chromosome rearranged to Cγ1 had high cytotoxic activity against both natural killer‐sensitive and natural killer‐resistant targets. This applied both to clones with and without the V9JPCγ1 rearrangement. Of three clones with both Cγ1 and Cγ2 rearrangements two had high activity and the other was only weakly cytotoxic. In addition, most clones showed rearrangement of TcR β genes. Some clones were capable of secreting levels of interferon‐γ and tumor necrosis factor‐α which were as high as those produced by CD3+4+WT31+ T cell clones. The results suggest that most human CD3+WT31− clones expressing a disulfide‐linked Cγ1/δ heterodimer are capable of mediating strong non‐major histocompatibility complex‐restricted cytotoxicity whereas those expressing non‐disulfide‐linked Cγ2/δ heterodimers are not.
Functional characterization of the CD45R (2H4) molecule on CD8 (T8) cells in the autologous mixed lymphocyte reaction system
Authors: Takeuchi Tsutomu , Rudd Christopher E. , Tanaka Shinsuke , Rothstein David M. , Schlossman Stuart F. , Morimoto Chikao
Published: March 2007

In the present study, we have investigated the molecular basis for the immunoregulatory function of CD8 cells after autologous mixed lymphocyte reaction (AMLR) activation. We demonstrated that the CD8+CD45R+, but not the CD8+CD45R− subset of cells effected suppression following AMLR activation. In contrast, cytotoxic activity against alloantigens resided in both the CD8+CD45R+ and CD8+CD45R− subsets of cells. Biochemical analysis showed that on CD8 cells, the 220‐kDa isoform of the LCA/T200 antigen family was better represented than the 200‐kDa isoform, when compared to CD4 cells. The density of the CD45R antigen increased on CD8 cells following activation in AMLR and treatment of AMLR‐activated CD8 cells with either anti‐CD45R antibody or anti‐CD3 antibody abolished the suppressor function of these cells. In contrast, treatment of AMLR‐activated CD4 cells with anti‐CD45R, but not anti‐CD3 antibody, abolished the suppressor/inducer function of these cells. The results suggest that the CD45R antigen as well as CD3 T cell receptor complex have an important role in the suppressor function of AMLR‐activated CD8 cells.
In vivo depletion of BoT4 (CD4) and of non‐T4/T8 lymphocyte subsets in cattle with monoclonal antibodies
Authors: Howard Christopher J. , Sopp Paul , Parsons Keith R. , Finch Julie
Published: March 2007

The effect on certain immune responses of depleting two distinct lymphocyte subpopulations in vivo by inoculating calves with monoclonal antibodies (mAb) was examined. An mAb directed against the BoT4 antigen (the bovine homologue of CD4) effectively removed the BoT4+ lymphocytes from peripheral blood mononuclear cells (PBM). Compared to controls, treated calves showed a reduced antibody response to human O red blood cells and to ovalbumin. PBM prepared from BoT4‐depleted animals also had a significantly reduced ability to respond in vitro to the mitogens phytohemagglutinin, concanavalin A and pokeweed mitogen. An mAb directed against a second numerically large bovine lymphocyte subpopulation i.e. BoT2−, BoT4−, BoT8− (CD2−, CD4−, CD8−), that may be homologous to the CD4−, CD8− cells in man and rodents that synthesize the γ/δ+ T cell receptor, was also used for in vivo depletion. Compared to controls, calves depleted of this subpopulation showed an enhanced antibody response. The proliferative response of PBM to pokeweed mitogen was also significantly increased but responses to concanavalin A and phytohemagglutinin remained unchanged. The results suggest this lymphocyte subpopulation has a nonspecific suppressor activity acting on B cell responses either directly or through an effect on T helper cells. The non‐T4/T8 cells are found extensively in the epithelium and lamina propria of the mucosa of the alimentary tract but not in T cell areas of the lymph nodes, tonsil and spleen. These non‐T4/T8 cells may thus be, or contain, an intraepithelial lymphocyte population with a suppressor function.
Ontogeny of expression of UCHL1 antigen on TcR‐1+ (CD4/8) and TcRδ+ T cells
Authors: Hayward Anthony R. , Lee Jane , Beverley Peter C. L.
Published: March 2007

The frequency of blood mononuclear cells expressing the 180‐kDa splice variant of the common leukocyte antigen identified by the UCHL1 monoclonal antibody (a characteristic of post‐thymic cells which have been through a cycle of stimulation) rose in a logarithmic relationship to age between birth and 16 years. At birth only a low frequency of CD4+ (negative for CD 25) and no CD8+ T cells expressed UCHL1. The subsequent increase in UCHL1 expression occurred in parallel on T cells expressing α/β receptors and γ/δ receptors, suggesting that these subsets participated in postthymic proliferation in proportion to their numbers in blood. The frequency of UCHL1 expression on CD8 cells was 5–15% less than on CD4 cells.
Interleukin 7 (murine pre‐B cell growth factor/lymphopoietin 1) stimulates thymocyte growth: regulation by transforming growth factor beta
Authors: Chantry David , Turner Martin , Feldmann Marc
Published: March 2007

The effects of interleukin 7 (IL 7) previously known as murine pre‐B cell growth factor/lymphopoietin 1 on the growth of murine thymocytes was investigated. In the presence of a suboptimal dose of phytohemagglutinin, IL 7 induced a dose‐dependent increase in thymocyte proliferation which was comparable to that induced by IL 1. Additionally IL 7 was shown to synergize with a suboptimal dose of IL 1 to enhance thymocyte proliferation. Thymocyte proliferation induced by IL 7, like that induced by IL 1, was inhibited when either recombinant transforming growth factor (TGF) β1 or β2 were added at the initiation of culture. Interestingly, IL 7‐driven thymocyte proliferation was considerably less susceptible to inhibition by TGF‐β1 or TGF‐β2 than that induced by IL 1. Taken together these results suggest IL 7 may activate distinct populations of thymocytes and/or act through a pathway distinct from that utilized by IL 1.
Antibodies against the T cell receptor/CD3 complex interfere with distinct intra‐thymic cell‐cell interactions in vivo: correlation with arrest of T cell differentiation
Authors: Kyewski Bruno A. , Schirrmacher Volker , Allison James P.
Published: March 2007

Postnatal treatment of mice with antibodies against the T cell receptor complex (TcR) prevents the differentiation of mature T cells in the thymic medulla without affecting the generation of most immature cortical thymocytes, thus interfering with a discrete stage of intra‐thymic T cell differentiation at the cortex/medulla transition. This result has been interpreted as indicating a direct role of the TcR in the differentiation of immature to mature T cells, possibly via TcR‐ligand interactions during direct cell‐cell contact. Here we analyze the effect of anti‐TcR (Vβ8 family) and anti‐CD3 (ε chain) antibodies on distinct intra‐thymic cell‐cell interactions in vivo. We find that the maturation arrest of thymocytes correlates with a nearly complete abrogation of interactions of corresponding immature thymocyte with I‐A/E+ cortical epithelial cells and I‐A/E+ medullary dendritic cells, while preserving interactions with adherent I‐A/E− macrophages. It is proposed that the blockade of thymocyte‐epithelial cell recognition in the cortex by anti‐TcR antibodies prevents the translocation of thymocytes into the medulla and their subsequent differentiation and selection, including interactions with dendritic cells. Interestingly, the anti‐CD3 mAb treatment seems to spare the intra‐thymic development of the CD3+, CD4−/CD8− T cell lineage.
Human T cell activation: differential response to anti‐CD28 as compared to anti‐CD3 monoclonal antibodies
Authors: Bjorndahl Jay M. , Sung Sun‐Sang J. , Hansen John A. , Fu Shu Man
Published: March 2007

Monoclonal antibodies (mAb) against CD3 or CD28 in conjunction with the tumor promoter phorbol 12‐myristate 13‐acetate (PMA) induce interleukin 2 receptor (IL 2R) expression, IL 2 production and proliferation in resting T cells. Recent studies indicate that these two pathways are biochemically distinct. In this study T cell activation induced by PMA and anti‐CD28 mAb 9.3 is compared to the effects of PMA plus anti‐CD3 mAb (T3‐II and 235) in the presence or absence of cyclosporin A (CsA), dibutyryladenosine 3′ : 5′ cyclic monophosphate (db‐cAMP) or cholera toxin (CT). Proliferation of T cells stimulated with PMA plus mAb 9.3 is resistant to the inhibitory effects of CsA, db‐cAMP and CT. Only at the highest dose did CsA have any effect on PMA plus mAb 9.3‐induced T cell proliferation. Conversely, CsA, db‐cAMP and CT inhibit PMA plus T3‐II‐induced T cell proliferation. mRNA analysis further demonstrates the similarities and the differences between the CD28 and CD3 activation pathways. Recently, T3‐II was reported to induce tumor necrosis factor (TNF) and lymphotoxin (LT) mRNA synthesis in PMA‐treated T cells. In this study mAb 9.3 is shown to substitute for T3‐II in the induction of TNF and mRNA. However, the production of TNF and LT mRNA in PMA plus mAb 9.3‐treated T cells is greater than that seen in PMA plus T3‐II‐treated cells. mRNA synthesis included by PMA plus T3‐II is blocked by CsA. mRNA production in T cells activated with PMA plus mAb 9.3 is resistant to CsA. Similar results are noted with IL 2 and IL 2R mRNA. Flow cytometric analysis of the IL 2R confirms the mRNA data. CsA blocks the T3‐II‐induced potentiation of PMA‐induced IL 2R expression but not the mAb 9.3‐induced potentiation. This differential inhibitory effect of CsA on IL 2R expression is also seen with db‐cAMP and CT. We examined the effects of these two pathways on the expression of the early activation antigen EA 1 and cytoplasmic free calcium. Recently, we have shown anti‐CD3 mAb potentiate EA 1 expression induced by 1,2‐sn‐dioctanoylglycerol and this potentiation is calcium dependent, dp‐cAMP blocks T3‐II‐ and 235‐induced potentiation of EA 1 expression and inhibits the T3‐II‐ and 235‐mediated rise in intracellular free calcium ([Ca2+]i). Conversely, 9.3 does not potentiate EA 1 expression or induce a rise in [Ca2+]i. These results provide further evidence that the CD28 and CD3 activation pathways utilize distinct signal transduction pathways.
Peripheral T lymphocytes: expansion potential and homeostatic regulation of pool sizes and CD4/CD8 ratios in vivo
Authors: Rocha Benedita , Dautigny Nicole , Pereira Pablo
Published: March 2007

Peripheral T lymphocytes are self‐renewable cell populations since, when transferred into syngeneic T cell‐deficient athymic mice, they expand in the absence of exogenous antigen stimulation. Quantification of the expansion potential of CD4+ cells by transfer of the same population into successive host mice shows that these cells are able to divide up to 56 times in vivo. Therefore, as a population, CD4+ cells can increase in size 8 × 105‐fold, an expansion potential of similar magnitude to that previously reported for colony‐forming units. Injection of different numbers of T cells at different CD4/CD8 ratios is followed by T cell accumulation to a similar plateau in recipient nude mice. This indicates that peripheral T lymphocytes are tightly regulated by homeostatic mechanisms that control pool sizes and CD4/CD8 ratios, in a manner independent of the cell input into the peripheral compartment. This kinetic behavior of mature T cells permits the maintenance at the periphery of any T cell specificity previously selected in the thymus. The expansion capacity of peripheral T cells may also allow extensive modulation of peripheral T cell specificities, which would confer a major role to post‐thymic selection of mature peripheral T cell repertoires.
Interleukin 4 strongly augments or inhibits DNA synthesis and differentiation of B‐type chronic lymphocytic leukemia cells depending on the costimulatory activation and progression signals
Authors: Carlsson Mats , Sundström Christer , Bengtsson Mats , Tütterman Thomas H. , Rosén Anders , Nilsson Kenneth
Published: March 2007

This study describes the opposing effects that interleukin (IL) 4 exerts on the B cell stimulatory factor (BSF‐MP6) and IL 2‐dependent proliferation and differentiation of cells of one selected B‐type chronic lymphocytic leukemia cell clone (I83), which depend on the nature of the activation inducer. In I83 cells activated by a 1‐h pulse of 12‐O‐tetradecanoylphorbol 13‐acetate, the BSF‐MP6‐dependent DNA synthesis was strongly enhanced by 50–100 U/ml of recombinant IL 4. Recombinant IL 2 stimulation was necessary only when a suboptimal dose of BSF‐MP6 was used. The differentiation was also markedly enhanced by IL 4 as measured by quantitation of IgM secretion both at the population (enzyme‐linked immunosorbent assay analyses of the supernatant) and single‐cell level (enzyme‐linked immunospot technique), by morphological examination of the maturation stage and flow cytometric analysis of differentiation‐associated surface antigens (CD11c, FMC7, PCA‐1 and CD38). No Ig isotype switch was found. In contrast, DNA synthesis and differentiation of I83 cells, activated by Staphylococcus aureus Cowan strain I (SAC) and co‐stimulated with BSF‐MP6 plus IL 2, were strongly inhibited by IL 4, both when it was added simultaneously with SAC or after 2 days of SAC exposure. Analysis of the cell‐cycle progression of SAC and BSF‐MP6 plus IL 2 and IL 4‐stimulated cells by acridine orange staining and fluorescence‐activated cell sorter (FACS) analysis demonstrated an arrest of a minor cell population in G0 and a block of the transition of G1 cells to S phase. Neither the enhancing nor the inhibitory effect of IL 4 on the proliferation and differentiation of I83 cells was an indirect effect via IL 4‐induced activation of contaminating T cells, monocytes or natural killer cells, as shown by experiments where these cell types were depleted by FACS sorting. Furthermore the expression of CD23 and CD25 was not inhibited by IL 4. The results thus demonstrate contrasting biological effects of IL 4 on clonal leukemic B cells depending on the nature of the activation and progression stimuli. This adds to the emerging picture of a very complex cytokine and cell‐to‐cell contact‐mediated regulation of the activation and subsequent growth and/or differentiation of human B cells.
Collagen receptor on T lymphocytes and the control of lymphocyte motility
Authors: Arencibia Ignacio , Sundqvist Karl‐Gösta
Published: March 2007

Human lymphocytes, freshly isolated from blood, were allowed to settle on surfaces coated by collagen type 1, fibronectin, laminin, IgG or albumin at different concentrations. In separate cultures the lymphocytes were also exposed to these proteins in soluble form. The lymphocytes, predominantly T cells, attached to two‐dimensional collagen substrata both in the presence and absence of serum but did not adhere or adhered poorly to substrata coated with fibronectin, laminin, IgG and albumin. In contrast, T blasts induced in a mixed lymphocyte culture adhered to fibronectin‐coated substratum. During contact with substratum‐bound collagen for a 24‐h period, 47 ± 15% of the freshly purified lymphocytes from separate individuals developed motile behavior whereas 16 ± 4% of the cells became motile on fibronectin. Gelatin (denatured collagen) also mediated attachment of lymphocytes to surfaces but only at comparatively high concentrations (40 mg/ml). Collagen and gelatin in solution also caused agglutination and motility of the vast majority of freshly isolated T lymphocytes whereas fibronectin and other proteins, when presented in soluble form, did not. Cell agglutination was maximal at moderate (10 or 20 mg/ml) and cell motility at low gelatin concentrations (1 to 10 mg/ml). High gelatin concentrations (20 and 40 mg/ml) did not induce motile behavior. Cytochalasin B augmented the proportion of adherent cells on gelatin‐coated substrata. In the presence of cytochalasin B gelatin mediated substrate‐adhesion at concentrations below those which normally induced adhesion indicating that motile behavior counteracted persistent lymphocyte adhesion to the substratum. Noteworthy, gelatin/collagen is unique among ligands (e.g. plasma fibronectin and other serum proteins) in its capacity to induce motility in the vast majority of resting lymphocytes freshly isolated from blood within a relatively short period. Taken together these results indicate that circulating lymphocytes have a collagen/gelatin‐binding plasma membrane component. Cross‐linking of this component is a likely explanation for the selective inducing effect of gelatin and collagen on lymphocyte motility. The present results showed that the lymphocyte plasma membrane contains collagen‐binding components with a relative molecular mass of 130 and 55 kDa. The 55‐kDa component also reacted with an anti‐fibronectin antibody. Thus, interactions with the extracellular matrix may control lymphocyte locomotor capacity.
Expression of CD5, a lymphocyte surface antigen on the endothelium of blood vessels
Authors: Gogolin‐Ewens Kathryn , Meeusen Els , Lee Chee‐Seong , Brandon Malcolm
Published: March 2007

CD5 is a lymphocyte surface antigen considered to be a pan‐T cell marker although it is also expressed on a small population of B cells. In this report we present evidence that four different monoclonal antibodies specific for the CD5 antigen also recognize a molecule present on the endothelium of blood vessels in certain regions (placentomes) of the pregnant sheep uterus. The identity of the CD5 antigen on the endothelium with that expressed on T lymphocytes was confirmed by molecular mass analysis of the CD5 antigen in membrane extracts of lymphocytes, thymocytes and placentomes which showed that all three antigens have an apparent molecular mass of 67 kDa. Possible implications of this finding in relation to the function of the CD5 molecule and lymphocyte migration are discussed.
Alpha‐globulins suppress human leukocyte tumor necrosis factor secretion
Authors: Scuderi Philip , Dorr Robert T. , Liddil James D. , Finley Paul R. , Meltzer Paul , Raitano Arthur B. , Rybski James
Published: March 2007

The secretion of tumor necrosis factor (TNF) by human peripheral blood mononuclear cells was suppressed by either whole human plasma α‐globulins or purified α1 acid‐glycoprotein, α1‐antitrypsin and α2‐macroglobulin in a concentration‐dependent manner. α1‐Antitrypsin was found to be the most suppressive of the purified proteins tested and completely blocked TNF release at concentrations above 1.25 mg/ml. Both α1‐acid glycoprotein and α1‐antitrypsin blocked TNF secretion by leukocytes which were simultaneously stimulated with either recombinant human interferon‐γ (IFN‐γ) or lipopolysaccharide (LPS). IFN‐γ and LPS‐activated cells were also susceptible to suppression mediated by these two α‐globulins and the inhibition produced by 5 mg/ml α1‐antitrypsin was greater than that caused by either 1 m̈M prostaglandin E2 or 10 ng/ml transforming growth factor‐pi. The level of TNF mRNA in TNF‐secreting and α‐globulin‐suppressed cells was examined and found to be equal in both groups. The suppressive effect of whole α‐globulins was confined to the inhibition of TNF secretion and these plasma proteins had no effect on the cytolytic activity of the recombinant cytokine as measured on murine L‐929 target cells. Thus the α‐globulins, which are a major fraction of the circulating plasma proteins, may function in TNF homeostasis by controlling TNF secretion without inhibiting the biological activity of the released cytokine.
The influence of cyclosporin A on the alternative pathways of human T cell activation in vitro
Authors: Bloemena Elisabeth , Van Oers Rien H. J. , Weinreich Stephanie , Stilma‐Meinesz Anneke P. , Schellekens Peter T. H. A. , Van Lier René A. W.
Published: March 2007

To gain further insight into the mechanism of action of the immunosuppressant cyclosporin A (CyA), we investigated the influence of CyA on proliferative responses of human T lymphocytes, induced via different membrane molecules. As was previously shown, activation of T cells via the T cell receptor (Ti)/CD3 complex with an anti‐CD3 monoclonal antibody was inhibited by CyA. Likewise, triggering of T lymphocytes via the alternative, CD2(T11)‐mediated pathway of activation was strongly inhibited. In contrast, responses induced by phorbol myristate 13‐acetate (PMA; 100 ng/ml) or the combination of an anti‐CD28 monoclonal antibody and a suboptimal concentration of PMA (1 ng/ml) were found to be insensitive to CyA. CyA‐induced inhibition of both anti‐CD3 and anti‐CD2‐mediated proliferation could not be reversed by addition of either PMA (1 ng/ml) or anti‐CD28.

An increase in the intracellular free Ca2+ concentration ([Ca2+]i) is an early event observed after stimulation of T cells via CD3 or CD2, whereas stimulation with PMA and anti‐CD28 does not lead to a rise in [Ca2+]i This suggests that the inhibitory action of CyA is related to Ca2+‐dependent signaling pathways. Since we observed that CyA does not interfere with anti‐CD3‐ or anti‐CD2‐induced increases of [Ca2+]i, our data suggest that CyA‐mediated inhibition is related to a later event in these intracellular signaling pathways.
Restricted idiotypic profile of anti‐phosphorylcholine antibodies induced by carrier‐specific helper T cell clones
Authors: Strickland Faith M. , Cerny Jan , Currier Patricia , Infante Anthony J.
Published: March 2007

The primary antibody response of C57BL/6 mice to phosphorylcholine (PC) is dominated by immunoglobulins of the T15 idiotype family. Using monoclonal antibodies that define individual idiotopes (Id) of T15, it has been shown that the antibody plaque‐forming cells (PFC) arise from heterogeneous population of B cells that may express some but not all T15 Id. In the present study, we tested the ability of antigen (keyhole limpet hemocyanin, KLH)‐specific CD4+ T cell clones (Th) to provide help for various T15 B cell subsets in response to PC‐KLH in vitro. Four independently derived, KLH‐specific Th clones were found to provide quantitative help (80–120 PFC/culture of 106 B cells) which was comparable to KLH‐primed, unselected T cells. However, the response in the presence of the cloned T cells was idiotopically restricted: T15 idiotopes B24–44 and B36–75 were expressed on 60% to 90% PFC, whereas Id AB1–2 and B36–82 were not present (0%–20% PFC). All of these Id were highly expressed in cultures with KLH‐primed, unselected splenic T cells. Evidently, the cloned Th cells provided help to only a subset of idiotypically distinct B cells. Bulk spleen T cells from unprimed donors by themselves did not provide any help for the primary response to PC‐KLH. However, when these cells were added to the cultures containing B cells and KLH‐specific Th clones, the repertoire of the response was fully restored, including the AB1–2/B36–82 Id (50%–80% PFC). These results suggest the existence of an auxiliary helper mechanism that may be required for activation of some B cells in addition to the antigen‐specific Th cells.
Interleukin 6 stimulates synthesis of complement proteins factor B and C3 in human skin fibroblasts
Authors: Katz Yitzak , Revel Michel , Strunk Robert C.
Published: March 2007

Human interleukin (IL) 6 is a multifunctional cytokine which is synthesized by fibroblasts in response to many stimuli, including bacterial lipopolysaccharide (LPS). During acute‐phase response, liver cells secrete a specific group of proteins among which components of the complement system and IL 6 appear to be an important mediator of this response. Human skin fibroblasts also synthesize at least seven proteins of the complement system. Each of these seems to be characteristically regulated by soluble mediators of the inflammatory process. Here we report that in fibroblasts, IL 6 induces increases in the rate of synthesis of factor B and C3, activator proteins of the alternative pathway of complement activation. The increases in factor B and C3 were concentration dependent reaching about 40‐ and 15‐fold, respectively. The protein increases were observed within 4 h after IL 6 addition to the cells and were accompanied by increase in factor B and C3 mRNA. The data suggest that the induction of factor B and C3 by LPS may be mediated, at least in part, by IL 6 induced by LPS. This new function of IL 6 could provide a local protection against invading agents through activation of the antibody‐independent alternative pathway of complement activation.
Both virgin and memory T cells cluster with dendritic cells during autologous and allogeneic mixed leukocyte reaction
Authors: Vakkila Jukka
Published: March 2007

The T cell population is comprised of two distinct reciprocal subsets identifiable by UCHL1 and 2H4 antibodies. 2H4+ cells are virgin T cells and UCHL1+ cells are memory T cells. Previously it has been shown that dendritic cells (DC) form clusters with T cells. In this study we have examined the proportions of UCHL1+ and 2H4+ T cell subtypes in DC‐T cell clusters. DC and T cells were purified from human peripheral blood and cultured in autologous or allogeneic combinations. Clusters, which were visible after culture for 24–48 h, were separated and the phenotype of the cells in the clusters was analyzed. It was found that the ratio of UCHL1+ and 2H4+ cells was the same among both clustered and nonclustered cells. Autologous clusters contained the same proportions of UCHL1+ and 2H4+ cells as allogeneic clusters. Experiments with separated UCHL1+ and UCHL1− T cells demonstrated that in autologous mixed leukocyte reaction mainly UCHL1− cells proliferated. Separated clusters were cultured for a total period of 7 days, which demonstrated that the majority of the T cells derived either from autologous or allogeneic clusters were UCHL1+ activated blasts. The remaining 2H4+ T cells resembled inactivated T cells. Thus it is concluded that the initial binding of T cells to autologous or allogeneic DC is mediated by a mechanism which is unaffected by the differentiation of virgin T cells into memory T cells. The low proliferative response of memory T cells to autologous DC suggested that clustering with DC does not necessarily lead to proliferative activity. Autoreactive T cells do not differ from alloreactive cells in acquiring the antigenic phenotype of memory T cells after activation.
Isolation and characterization of a cDNA encoding a putative cytokine which is induced by stimulation via the CD2 structure on human T lymphocytes
Authors: Chang Hsiu‐Ching , Reinherz Ellis L.
Published: March 2007

To define activation‐specific sequences in human T lymphocytes, a cDNA library was constructed by subtractive hybridization using resting and stimulated peripheral blood lymphocyte pairs. Stimulation of peripheral blood lymphocytes was achieved by triggering with mitogenic anti‐CD2 (T11) monoclonal antibodies. Differential library screening with cDNA probes derived from stimulated vs. resting peripheral blood lymphocytes led to identification of a novel sequence, termed HC21. The predicted primary and secondary structure of HC21 deduced from the translated nucleotide sequence suggest that the gene encodes a secreted protein of 92 amino acids including a 23‐residue leader sequence. Northern blot analysis demonstrates that HC21 mRNA is induced in peripheral blood T lymphocytes and interleukin 2‐dependent T cell clones within 10 min following stimulation via CD2, while steady‐state RNA expression is maximal by 2 h. Although the kinetics of HC21 expression are similar after stimulation via the antigen/major histocompatibility complex receptor (CD3‐Ti), CD3‐Ti triggering leads to less accumulation of HC21 RNA than CD2 triggering. In contrast, recombinant interleukin 2 does not induce detectable HC21 RNA expression in T cell clones. Transient expression of the HC21 cDNA in COS cells results in a readily detectable protein band in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis analysis of radiolabeled cell supernatants consistent with HC21 encoding a secreted product. Protein sequence analysis reveals a striking homology (up to 76% identity at amino acid level) with other members of a recently described lymphokine family whose functions are yet to be defined.
Reticulum cell sarcomas of SJL mice have rearranged immunoglobulin heavy and light chain genes
Authors: Stavnezer Janet , Lasky Jennifer L. , Ponzio Nicholas M. , Scheid Margrit P. , Jeanette Thorbecke G.
Published: March 2007

The immunoglobulin (Ig) heavy (H) and light (L) chain gene rearrangements of the high incidence SJL lymphomas (reticulum cell sarcoma, RCS) have been analyzed. Both primary and transplanted RCS show rearrangements of H and χ L chains, demonstrating that these tumors are of B cell origin. These data are consistent with previous results indicating that these tumors are a mouse model for follicular lymphoma. A long‐term transplanted line and the in vitro line derived from it, cRCS‐X, have a single rearranged JH−Cγ2a fragment and one rearranged Cα gene fragment which does not hybridize with a probe for the JH gene segments. These cell lines also have two rearranged Jχ−Cχ fragments. Primary tumors and early passages are more heterogeneous with respect to Ig gene rearrangements, possibly because more than one B cell clone is present.

Although no synthesis of IgG2a, or of any Ig, could be detected by the in vitro cRCS‐X cells, these cells contain abundant poly(A)+ RNA that hybridize with γ2a and χ probes as well as lesser amounts of α and ε RNA. None of these H chain RNA hybridized with probes for the JH gene segments. The ε and α RNA are the same size as transcripts of germ‐line CH genes which have been identified in other systems. However, the γ2a RNA are smaller than previously described germ‐line Cγ2a RNA and appear to be transcribed from aberrantly rearranged JH−Cγ2a genes.
Inhibition of T cell response with peptides is influenced by both peptide‐binding specificity of major histocompatibility complex molecules and susceptibility of T cells to blocking
Authors: Lehmann Paul V. , Cardinaux Francis , Appella Ettore , Muller Simone , Falcioni Fiorenza , Adorini Luciano , Nagy Zoltan A.
Published: March 2007

Synthetic peptides corresponding to sequences 46–62 and 51–62 of mouse lysozyme and 46–61 of hen egg‐white lysozyme (HEL) were used as competitors in a variety of T cell responses. The competitors, according to their binding specificity for major histocompatibility complex (MHC) were expected to inhibit T cell responses restricted to I‐Ak, but not those restricted to I‐Ad, I‐Ek molecules. In competition experiments with T cell hybridomas, the poor binder I‐Ed molecule required 10‐ to 15‐fold higher competitor concentrations than the good binder I‐Ak molecule to achieve 50% inhibition of antigen presentation. Similarly, the nonresponder state of H‐2d mice to HEL peptide 46–61 could be overcome by increasing the immunizing dose, and proliferative T cell responses to different antigens in association with a variety of class II MHC molecules could be blocked by the mouse lysozyme and HEL peptides. Thus, the capability of some and failure of other MHC molecules to bind certain peptides appeared quantitative, rather than of an all or none nature, in these experimental systems. The susceptibility of uncloned T cell lines to peptide competitors was found to decrease with time. Lines maintained by repeated restimulation with antigen and APC, but without exogeneous interleukin 2, acquired resistance within weeks. In contrast, T cell clones retained their susceptibility to peptide competitors over a long period of time. The latter data raise the possibility that a competition between ubiquitous (self) peptides and foreign antigen may result in the selection of T cells that have high avidity for the activating antigen‐MHC complex, and are thus relatively resistant to competition at the level of antigen presentation.