bluuebunny/crossref_metadata_2025 huggingface dataset:
Antigen presentation by human monocytes: Effects of modifying major histocompatibility complex class II antigen expression and interleukin 1 production by using recombinant interferons and corticosteroids
Authors: Rhodes John , Ivanyi Juraj , Cozens Peter
Published: February 2007

Lymphocyte proliferation in response to monocytes pulsed with an antigenic extract of Candida albicans was measured in vitro and the effects of modifying major histocompatibility complex (MHC) class II antigen expression at the surface of the antigen‐presenting cells was investigated. The study shows that no simple correlation exists between changes in MHC class II antigen expression and changes in the effectiveness of antigen presentation. Recombinant interferon‐αl (rIFN‐αl), rIFN‐γ and hydrocortisone were found to increase the expression of monocyte class II MHC antigens. In contrast, rIFN‐α2 did not increase class II antigen expression although it did increase MHC class I expression. Treatment of monocytes with rIFN‐αl, rIFN‐α2 or corticosteroids during antigen pulsing resulted in a reduction in the subsequent proliferative lymphocyte response. In all cases this inhibitory effect was restricted to antigen‐specific proliferative responses since the polyclonal lymphocyte response to pokeweed mitogen‐pulsed monocytes remained unaffected. Only rIFN‐γ treatment of antigen‐pulsed monocytes resulted in enhancement of the subsequent specific lymphocyte proliferative response. The suppressive effects of hydrocortisone could not be attributed to its well documented inhibitory effects on arachidonic acid metabolism. The effect of C. albicans antigen, IFN and corticosteroids on interleukin 1 (IL1) production by monocytes was also investigated. C. albicans antigen alone induced IL 1 production. So too did IFN‐αl and IFN‐γ IFN‐α2 did not induce IL 1 production. Addition of interferons together with C. albicans, however, resulted in the same level of IL1 productions as with C. albicans antigen alone. Neither antigen nor IFN had any effect on IL1 action in the thymocyte assay.

Corticosteroids did not affect IL 1 production by monocytes but were potent antagonists of IL 1 in the thymocyte proliferation assay. Mitogen‐induced thymocyte proliferation was also inhibited by corticosteroids. Pretreatment of monocytes with hydrocortisone followed by washing did not markedly affect their subsequent ability to produce IL 1 neither was it possible to reverse the inhibitory effects of hydrocortisone on antigen presentation by addition of exogenous IL1. Thus, signals which alter class II MHC antigen expression influence the antigen‐presenting capacity of monocytes by a mechanism independent of IL 1. No simple correlation exists between class II expression and antigen‐presenting capacity.
Suppression of interferon gamma production in mice treated with carrageenan
Authors: Suzuki Fujio , Maeda Hiroshi , Pollard Richard B.
Published: February 2007

Effects of carrageenan (CAR) treatment on the response of interferon (IFN) production in vivo and in vitro after stimulation with an IFN‐γ inducer, staphylococcal enterotoxin A (SEA), was investigated. The IFN‐γ production in mice stimulated with SEA was impaired after i.v. administration of a 20 mg/kg dose of CAR. Spleen cells (SC) from CAR‐treated mice had decreased ability to produce IFN in vitro after stimulation with the same inducer. SC obtained from mice during the suppressive state inhibited IFN‐γ production when they were co‐cultured with mononuclear cells prepared from spleens of untreated control mice. This suppressor cell activity could be removed from SC by an adherence technique to plastic surface. The SC with suppressor activity were not inactivated by treatments with monoclonal anti‐Thy‐1.2 antibody, anti‐asialo GM1 antisera and anti‐mouse immunoglobulin antisera followed by complement. The suppressive activity was detected in cell‐free culture fluids of macrophage fractions containing suppressor cell activity. These results suggest that the decrease in IFN‐γ production in mice pretreated with CAR may associate with the presence of suppressor cells characterized to the monocytelmacrophage lineage.
Induction or prevention of immunopathological disease by cloned cytotoxic T cell lines specific for lymphocytic choriomeningitis virus
Authors: Baenziger Jürg , Hengartner Hans , Zinkernagel Rolf M. , Cole Gerald A.
Published: February 2007

Cloned lymphocytic choriomeningitis virus (LCMV)‐specific cytotoxic T lymphocyte (CTL) lines were prepared from spleens of 129/J (H‐2b) mice immunized 7‐9 months earlier with LCMV (UBC strain), or of C57BL/10J (H‐2b) mice immunized 4 to 5 weeks earlier with LCMV (Armstrong strain). One uncloned and 3 cloned cytotoxic T cell lines were assessed for their respective abilities to produce, or protect against, fatal disease upon transfer to appropriate recipients or to induce specific footpadswelling reaction. The effects of all lines were essentially identical. In recipient mice acutely infected with LCMV and immunosuppressed either by irradiation (750‐990 rds) or treatment with cyclophosphamide, cloned T cells administered intracerebrally (i.c.) caused a convulsive disease and death within 1‐4 days. No disease was produced when the same CTL were transferred to uninfected recipients or when they had been frozen and thawed prior to transfer to infected recipients. When admixed with 500 plaque‐forming units of LCMV and transferred i.c. to immunocompetent H‐2b mice, the T cell clones prevented overt disease. Allogeneic (H‐2k) recipients of this same admixture all developed typical LCM disease as did H‐2b recipients of the admixture after T cells had been frozen and thawed. Inoculation of cloned CTL into preinfected footpads induced a specific footpad‐swelling reaction, which reached maximum levels after about 36 h. Irradiated and infected recipients of cloned LCMV‐specific T cells showed the footpad‐swelling reaction only when they had been reconstituted with bone marrow cells. In contrast, cloned T cells induced LCM disease in i.c. infected and irradiated mice independent of bone marrow reconstitution. These findings indicate that both fatal LCMV‐induced neurologic disease and protection against it are mediated directly by virus‐specific CTL.
Rearrangements of T cell receptor loci can be found only rarely in B lymphoid cells
Authors: Traunecker André , Kiefer Michael , Dembić Zlatko , Steinmetz Michael , Karjalainen Klaus
Published: February 2007

We have studied the rearrangement status of the T cell receptor genes in 64 B lymphoid cell lines, and we found that, unlike the immunoglobulin heavy chain genes in T lymphocytes, T cell Receptor β and related γ chain genes are almost always in germ‐line configuration in B lymphoid cells. The only exception was a myeloma MOPC511 (IgA,x) which contained all T cell receptor genes, β1, β2, γ1, γ2, γ3, and α, in rearranged configuration in both homologous chromosomes. This exception supports the concept that all immunoglobulin and T cell receptor genes exploit the same recombinase to build their complete variable regions. Obviously, in MOPC511 cells the regulation, which confers the tissue specificity i.e. T vs. B lymphocytes, has failed.
Epithelial cell heterogeneity in the guinea pig thymus: Immunohistochemical characterization of four thymic epithelial subsets defined by monoclonal anti‐keratin antibodies
Authors: Nicolas Jean F. , Reano Alain , Kaiserlian Dominique , Thivolet Jean
Published: February 2007

Keratins are a family of related polypeptides constitutive of the cytoskeleton of epithelial cells and are never found in nonepithelial tissues. Thymic epithelial cells (TEC), known to induce T cell differentiation, are the keratin‐containing cells within the thymus. Using four monoclonal anti‐keratin antibodies (KL1, KL4, AE2, AE3) directed against keratins of different molecular weight, we have investigated the guinea pig thymic epithelium. The immunohistochemical analysis of thymic cryostatic sections revealed that the keratin expression of TEC varied according to their location in the thymic lobula; the thymic cortex was specifically stained by AE3 whereas the thymic medulla and the subcapsular cortex were recognized by KL4. In addition, KL1 and AE2 exclusively labeled Hassall's corpuscles. The biochemical analysis of keratins extracted from the thymus showed that each TEC subset was characterized by an unique pattern of keratin polypeptides. This study extends the concept of thymic epithelium heterogeneity and suggests that anti‐keratin antibodies which allow the typing of TEC subsets may be valuable tools for studying the differentiation of thymic epithelium and its in vitro function on T lymphocytes.
Selective reversal of H‐2‐linked genetic unresponsiveness to lysozymes: II. Alteration in the T helper/T suppressor balance, owing to gene(s) linked to Ir‐2, leads to responsiveness in BALB.B
Authors: Sadegh‐Nasseri Scheherazade , Dessi Vitalia , Sercarz Eli E.
Published: February 2007

Immune responsiveness to lysozyme in H‐2b mice is under the control of H‐2‐linked Ir genes, with T suppressor (Ts) cells playing a dominant role in strains such as C57BL/6 (B6), C57BL/10 and A.BY. However, non‐H‐2‐genes were found to be capable of specific reversal of the effect of the H‐2‐linked genes in responsiveness to chicken lysozyme (HEL), but not to human lysozyme (HUL).

Therefore, studies were performed to identify any lesion in the suppressor circuit in BALB.B. It was known that HUL‐induced suppressor cells could cross‐suppress the anti‐HEL response in B10.Q mice, which are responsive to HEL but nonresponsive to HUL. Similarly, BALB.B Ts cells were able to suppress the anti‐HEL response, using as T helper (Th) source a T cell line (BB‐l), derived from HEL‐primed BALB.B periaortic and inguinal lymph node cells. A protocol designed to examine the in vivo suppression by the use of HUL‐induced suppressor cells also demonstrated a significant suppression to the anti‐HEL response.

Since the suppressive circuitry seemed intact in the BALB.B, the possibility was examined that a step in T‐B cell collaboration was more efficient in this strain than in the B6 nonresponder. With a B6‐derived HEL‐specific T cell line, BO1H, the B cell and antigen‐presenting (B/APC) populations from B6 required addition of concanavalin A supernatant for anti‐HEL antibody formation, whereas BALB.B B/APC were capable of responding to HEL in culture without the addition of concanavalin A supernatant. In agreement with this finding, when B/APC cell populations from BALB.B and B6 were compared for their extent of anti‐HEL responsiveness, as measured with BB‐1 Th cells, BALB.B B/APC populations responded significantly higher than B6 populations when the responses were activated by picogram/nanogram amounts of HEL. The response level of (BALB.B × B6)F1 B/APC measured in the same assay resembled that of B6. However, when HEL was used at the microgram level, both B6 and BALB.B strains responded equivalently.

The above data are consistent with the expression of the reversing non‐H‐2 Ir gene(s) resulting from the balance of antigen presentation to Th and Ts cells in the H‐2b mouse. In the B6, processing and handling of antigen may be inefficient in activating response‐enhancing Th, and more effective in triggering Ts cells, while the reverse may be true for the BALB.B.
In vivo induction of H‐2K/D antigens by recombinant interferon‐γ
Authors: Momburg Frank , Koch Norbert , Möller Peter , Moldenhauer Gerhard , Hämmerling Günter J.
Published: February 2007

B10.BR mice received i.v. increasing doses of recombinant interferon‐γ (rIFN‐γ) on three consecutive days. Using an immunoperoxidase technique the distribution of H‐2K/D antigens was studied in frozen tissue sections of thirteen organs (kidney, liver, pancreas, esophagus, stomach, small intestine, colon, lungs, heart, brain, thymus, lymph node and spleen). Class I antigens were shown to be induced or enhanced in almost every organ after exposure to IFN‐γ. This effect was particularly conspicuous for renal tubular cells, hepatocytes, bronchiolar epithelial cells, gastric mucous cells, thymic cortical lymphocytes and capillary endothelial cells in heart and kidney. Neurons, glial cells, gastric chief and parietal cells, and pancreas cells were not inducible. The findings show that i.v. application of IFN‐γ leads to strong induction or enhancement of major histocompatibility complex class I antigens in a wide variety of tissues.
Anti‐interleukin 2 receptor monoclonal antibodies. Respective role of epitope mapping and monoclonal antibody‐receptor interactions in their antagonist effects on interleukin 2‐dependent T cell growth
Authors: Olive Daniel , Raymond Jérǒme , Dubreuil Patrice , Charmot Dominique , Jacques Yannick , Mawas Claude
Published: February 2007

Functional studies, using mainly interleukin 2 (IL 2)‐dependent growth of human T cell lines or clones but also mixed lymphocyte cultures and mitogen T cell activation, allowed a collection of locally produced anti‐IL2 receptor monoclonal antibodies (mAb) to be classified. They fell into two groups: one with strong to moderate inhibition of IL2, the other without any detectable functional activity in in vitro assays. Direct and sequential immunoprecipitation as well as peptide mapping confirm that all the mAb recognize the same surface molecule. The parameters responsible for such functional dichotomy were characterized: the main parameter was found to be linked to the epitopic cluster recognized on the molecule by the mAb. All functional mAb pertained to a given epitopic cluster and all the nonfunctional ones to an alternative cluster. Studies on mAb receptor and IL2 receptor interactions confirmed these findings and strongly suggest that functional mAb interact with a region on the IL2 receptor identical or very close to the site of ligand‐receptor interaction. These data could facilitate the choice of mAb to be used in therapeutical approaches in vivo when ethical objections could be overcome by appropriate committees.
Analysis of the role of interferon‐gamma, interleukin 2 and a third factor distinct from interferon‐gamma and interleukin 2 on human B cell proliferation. Evidence that they act at different times after B cell activation
Authors: Romagnani Sergio , Giudizi Grazia M. , Almerigogna Fabio , Biagiotti Roberta , Alessi Anna , Mingari Cristina , Liang Chi‐Ming , Moretta Lorenzo , Ricci Mario
Published: February 2007

Recombinant interferon‐gamma (rIFN‐γ) was able to induce proliferation of human tonsillar B cells activated with suboptimal concentrations of anti‐μ antibody. The B cell growth factor (BCGF) activity of rIFN‐γ was not due to substances contaminating the IFN‐γ preparation, nor was it mediated by factors released by T cells or large granular lymphocytes following activation by rIFN‐γ. The response of B cells to rIFN‐γ peaked on day 3 of culture and rapidly declined thereafter, whereas the response of parallel anti‐μ‐activated B cell cultures to recombinant interleukin 2 (rIL2) appeared on day 3, but continued at least until day 5. In addition, B cells responsive to rIFN‐γ could be at least in part separated from those responsive to rIL2, the former being primarily contained in B cell fractions enriched for high‐density small B lymphocytes. Finally, the addition to anti‐μ‐stimulated B cell cultures of very low concentrations of rIFN‐γ potentiated the B cell proliferation promoted by rIL2.

The simultaneous addition of monoclonal antibodies against IFN‐γ and T cell activation antigen to anti‐μ‐stimulated B cell cultures strongly reduced the B cell proliferative response promoted by three different crude BCGF preparations obtained by polyclonal T cell activation in mixed lymphocyte culture. However, the supernatant from a T cell clone (DP5/11) apparently free of IL2, which manifested a BCGF activity similar to that of rIFN‐γ, still maintained its ability to promote proliferation of anti‐μ‐activated B cells after complete removal of IFN‐γ.

Taken together, our data indicate that although some T cell clones are able to produce a BCGF distinct from both IFN‐γ and IL2, these lymphokines account for most of the BCGF activity of supernatants obtained from polyclonal T cell populations. They also suggest that IFN‐γ and the BCGF distinct from IFN‐γ and IL 2 act primarily in the earlier phases of B cell activation and potentiate the proliferative response of activated B cells to IL2.
Virgin B cell recruitment and the lifespan of memory clones during antibody responses to 2,4‐dinitrophenyl‐hemocyanin
Authors: Gray David , Maclennan Ian C. M. , Lane Peter J. L.
Published: February 2007

The extent to which B cells newly formed in the bone marrow contribute to primary and secondary B cell responses was investigated. This was assessed by constructing chimeras between congenic strains of rats differing in their kappa light chain allotype. Recipient animals received 800 cGy whole body irradiation with hind limb shieldin to protect a proportion of their hemopoietic capacity. These rats then received 3 × 108 kappa allotype‐marked thoracic duct lymphocytes from donors previously immunized twice with either dinitrophenylated spider crab (Maia squinada) hemocyanin (DNP‐MSH) or MSH alone. The chimeras were immunized with DNP‐MSH and the production of anti‐DNP antibody of both donor and host origin was measured. In the period immediately after immunization both newly formed host virgin B cells and donor memory B cells gave rise to substantial proportions of the anti‐DNP antibody. After this initial period, antibody production became sustained by activation of memory B cells only. The chimeras were reimmunized with DNP‐MSH at 32 days after their first immunization. There was again evidence of a brief period of both virgin and memory B cell activation followed by memory B cell activation only. Donor B cell clones remained dominant in the established response throughout the 5 months each chimera was studied. The data are interpreted as indicating two phases of B cell activation. It is suggested that the first phase where both virgin and memory B cells are activated may be associated with antigen presentation on dendritic or interdigitating cells outside follicles. It is argued that the second phase where only memory B cells are activated is more likely to be associated with antigen on follicular dendritic cells.
Effect of liposomes on lymphocytes: Induction of proliferation of B lymphocytes and potentiation of the cytotoxic response of T lymphocytes to alloantigens
Authors: Grover Amita , Sundharadas G.
Published: February 2007

Liposomes of certain lipid composition prepared by the detergent removal method (Brunner, J. et al., Biochim. Biophys. Acta 1976. 455: 322) induced the proliferation of spleen cells from different mouse strains. Spleen cell populations enriched in B lymphocytes and those obtained from nude mice were induced to proliferate, whereas spleen cell fractions enriched in T lymphocytes and thymocytes were not. The mitogenic effect of liposomes resembled that of lipopolysaccharide (LPS) and it depended upon their lipid composition. Liposomes prepared from dimyristoyl lecithin (DML), 2:1 dimyristoyl lecithin:cholesterol (DML:C), 2:1 dioleoyl lecithin: cholesterol (DOL:C), and 2:1 egg yolk lecithin:cholesterol (EYL:C) were mitogenic, whereas liposomes prepared from egg yolk lecithin (EYL) alone were not mitogenic for spleen cells. The mitogenic effects of these liposome preparations were in the decreasing order DML > DOL: C ⩾ EYL: C > DML: C > EYL. The results suggest a correlation between the membrane fluidity of liposomes and their mitogenic effect.

Although no proliferative response was induced on T lymphocytes, two of these liposomes, DML and EYL: C, had the ability to potentiate the cytotoxic response of T lymphocytes to alloantigens in mixed leukocyte culture. In responder‐stimulator combinations which differed for the H‐2K, H‐2D or the entire H‐2 region, these liposomes potentiated the cytotoxic response significantly. The results suggest that liposomes have an ability to modulate T lymphocyte response.
Autonomous activation of B and T cells in antigen‐free mice
Authors: Pereira Pablo , Forni Luciana , Larsson Eva‐Lotta , Cooper Max , Heusser Christoph , Coutinho Antonio
Published: February 2007

The spleen of adult antigen‐free mice contains a sizable proportion (5‐15%) of activated cells in all lymphocyte sets, as marked by the membrane expression of immunoglobulins, L3T4 and Lyt‐2 antigens. The frequency of activated cells is very high in early post‐natal life, and reaches adult levels by 6 weeks of age when it is comparable to that observed in healthy unmanipulated mice raised in conventional conditions. The effector B cell compartment is quantitatively similar in antigen‐free mice and specific pathogen‐free mice, but the former is deficient in isotype diversification, since IgG‐ and IgA‐secreting cells are drastically reduced. The effector T cell compartment is slightly reduced in number, but is equally competent in providing help or suppression of syngeneic B cells. The results indicate the existence of a compartment of the immune system displaying autonomous self‐determined activity which is predominant early in life. This compartment, physically localized to the spleen, appears to be distinct from an antigen‐dependent compartment which is essential for the development of peripheral lymphoid organs draining sites of “natural” environmental immunization.
Age‐ and strain‐dependent polymorphism in IgE antibody against the phosphorylcholine hapten
Authors: Gerber Verena , Ponnappan Usha , Heusser Christoph H. , Blaser Kurt , Cinader Bernhard
Published: February 2007

The magnitude of the IgE antibody response against the phosphorylcholine (PC) hapten and the rate of age‐related change of IgE formation is polymorphic in the three long‐lived and six relatively short‐lived strains of mice studied. Long‐lived mice showed an early increase, followed by a decline in the levels of anti‐PC IgE antibody. The rate of increase and decrease was strain dependent. Among short‐lived strains, MRW/Mp‐lpr and MRL/Mp‐+ mice showed an early decline in IgE antibody. The extent and rate of decline with age was more rapid in MRL/Mp‐lpr animals than in MRL/Mp‐+ mice. In contrast, there was an early increase of IgE antibody in female SJL, NZB/BIN, BXSB/Mp and male BXSB/Mp. Thus, opposite age‐related changes in IgE antibody production can occur in animals with a tendency to develop autoimmune disease. In hybrids of (SJL × BALB/c)F1 and (BALB/c × MRL/Mp‐lpr)F1, the levels of IgE antibodies were higher than those observed in either parental strain, and declined steeply with advancing age. We suggest that this could be attributed to recessive inheritance.
Peptides related to the antigenic determinant block T cell recognition of the native protein as processed by antigen‐presenting cells
Authors: Lakey Ellen K. , Margoliash Emanuel , Flouret George , Pierce Susan K.
Published: February 2007

A mouse T cell hybrid specific for pigeon cytochrome c in the context of I‐Ekresponds by secreting interleukin 2 when co‐cultured with the native antigen and the B cell lymphoma, LK‐35.2, or naive splenic B cells as antigen‐presenting cells (APC). Cytochromes c and their corresponding C‐terminal fragments which are not capable of stimulating the TPc9.1 cells, including the autologous mouse cytochrome c, block the T cells' response to pigeon cytochrome c. In contrast, nonstimulatory N‐terminal peptides of cytochrome c, which share no homology with the antigenic peptide, do not block. Blocking is observed when the nonstimulatory cytochromes c or peptides are present in culture with the live APC and nonsaturating concentrations of pigeon cytochrome c. it can be overcome with supraoptimal concentrations of pigeon cytochrome c. With tobacco hornworm moth cytochrome c as antigen, a protein for which the T cell has a higher functional affinity, the response of TPc9.1 cannot be blocked by the nonstimulatory cytochromes c or by peptides, even when limiting concentrations of the tobacco hornworm moth cytochrome c are used. When paraformal‐dehyde‐fixed APC are employed, no native cytochrome c can stimulate the T cells, including the tobacco hornworm moth protein which with the live APC is effective at 50 to 100‐fold lower concentrations than pigeon cytochrome c. However, with fixed APC the T cells are stimulated by the C‐terminal fragments containing residues 81‐ 104 of the pigeon protein or residues 81‐103 of the tobacco hornworm moth protein as readily and with the same relative efficiencies as the native protein, presented by live APC. The nonstimulatory peptides, but not the native cytochromes c, block T cell activation by pigeon cytochrome c pulsed‐fixed APC, indicating that the nonstimulatory peptides compete with the stimulatory pigeon cytochrome c peptides produced by the APC. This competition appears to be due to nonstimulatory peptides which associate at the APC surface and not to those acting from solution because the APC which have been incubated with pigeon cytochrome c and nonstimulatory peptides and washed free of excess antigen and peptides are not stimulatory to the T cell hybrid. It was concluded that the activation of a pigeon cytochrome c‐specific T cell, which recognizes a peptide fragment of the native protein on the surface of an APC, can be blocked by an excess of nonstimulatory homologous peptides when these are also associated on the surface of the APC. The ability to block T cell activation does not appear to be competition for processing of the native molecule but may represent a competition for specific peptide binding sites on the APC or on the T cell receptor.
Resistance to cellular immune response in AKR leukemias
Authors: Schäfer Andreas , Schmidt Wilhelm
Published: February 2007

Spontaneous AKR leukemias express murine leukemia virus (MuLV) gag and env gene‐encoded structural proteins on their cell surface. Cytotoxic T lymphocytes (CTL) induced in AKR mice by syngeneic leukemia 369 which expressed high amounts of H‐2 antigens recognized viral gag polyproteins in association with H‐2K antigens as target antigens. H‐2K‐negative leukemias were resistant to lysis by AKR/ Gross MuLV‐specific CTL and did not induce a cellular immune response. However, they became susceptible after stimulation with interferon. H‐2K‐positive leukemias induced CTL which were cytotoxic for 369 cells. However, the majority of H‐2K‐ positive leukemias was not lysed by CTL induced by autologous immunization. These leukemias were also resistant to lysis by anti‐369 CTL, but could restimulate AKR/ Gross‐specific CTL in vitro, and were susceptible to lysis by H‐2Kk‐ restricted CTL against AKR minor histocompatibility antigens. Thus, there could be specific defects of the H‐2Kk antigens of these tumors. However, there were also qualitative and quantitative differences in antigenic determinants of the gag target antigens in these leukemias.
Interferon: a cytotoxic T lymphocyte differentiation signal
Authors: Chen Likuang , Tourvieille Bcatrice , Burns Gordon F. , Bach Fritz H. , Mathieu‐Mahul Danièle , Sasportes Marilyne , Bensussan Armand
Published: February 2007

Human T cell clones which were able to proliferate in response to specific stimuli but could not kill even in the presence of lectins were found to acquire the specific lytic function when interferon alpha or gamma was added on day 1 of the 7‐day restimulation culture. These results demonstrate that interferon may act as a cytotoxic T lymphocyte differentiation signal. This signal can be blocked by the monoclonal antibody LeoA1 which recognizes a 70‐kDa cell surface structure, involved in cytotoxic T lymphocyte differentiation.
Differentiation factors for human specific B cell response
Authors: Vazquez Aimé , Gerard Jean‐Philippe , Delfraissy Jean‐François , Dugas Bernard , Auffredou Marie‐Thérèse , Crevon Marie‐Claude , Fradelizi Didier , Galanaud Pierre
Published: February 2007

Nonspecific T cell factors produced by lectin‐activated human peripheral blood lymphocytes (PBL) were used to restore the T‐dependent B cell response to trinitro‐phenyl‐polyacrylamide (TNP‐PAA). Preincubation experiments with the particulate antigen TNP‐PAA and/or a soluble TNP‐protein conjugate show that a first specific signal provided by the antigen and nonspecific lymphokines sequentially acts on B cells. By gel filtration the T cell‐replacing factor (TRF) activity is present in the 30–15‐kDa fraction of T cell supernatants and is associated to interleukin 2 (IL 2). However, absorption of IL 2 does not abolish the TRF activity. Moreover, chromatofocusing of this 30–15‐kDa material allows the obtaining of an IL2‐free fraction containing a differentiation factor (with an isoelectric point of 5.7 ± 0.2). The ability of this fraction to restore the anti‐TNP response is manifest in the presence of a 50‐kDa B cell growth factor. This latter, prepared by a combination of absorption on concanavalin A‐Sepharose and gel filtration, was IL2 free and unable to support the anti‐TNP response. We thus directly demonstrate that in the absence of IL2 three separate signals (the antigen, T cell‐derived growth and differentiation factors) are involved in human‐specific B cell response.
Unrestricted recognition of class I neodeterminants generated by exon shuffling
Authors: Horstmann Ulrike , Arnold Bernd , Hämmerling Günter J.
Published: February 2007

We and others have previously reported that homologous exchange of ä1 or α2domains between different alleles led to loss of most determinants recognized by cytotoxic T lymphocytes (CTL) raised against the parental H‐2 class I antigens. Here we demonstrate that exchange of α1 or α2 domains between the Kk and Kd allele results in the formation of neodeterminants against which allospecific CTL can be generated in responder mice of various related and unrelated H‐2 haplotypes. In fact, only CTL against the neodeterminants on the hybrid molecules were found and none against the parental Kk and Kd determinants. In addition our data show that recognition of the neodeterminants is H‐2 unrestricted. These findings suggest that in the hybrid molecules the basic structure of a major histocompatibility complex molecule has been preserved although most parental allodeterminants on the α1 and α2 domains have been modified.
Autoreactive or self restricted?
Authors: Julius Michael H. , Heusser Christoph H.
Published: February 2007

Putative major histocompatibility complex (MHC) class II‐specific T cell clones were isolated from nominal antigen‐primed T cell populations propagated in vitro under antigen selection. However, unlike the proliferative responses of nominal antigen‐specific, MHC class II‐restricted T cell clones derived from the same population, the former's MHC‐specific proliferative responses required that the culture medium be supplemented with serum. The role of xenogeneic antigens in the generation of this category of “autoreactive” T cells is discussed.
The bulk of endogenously produced IgG2a is eliminated from the serum of adult C57BL/6 mice with a half‐life of 6–8 days
Authors: Vieira Paulo , Rajewsky Klaus
Published: February 2007

The concentration of IgG2a in the serum of C57BL/6 mice suppressed for the production of IgG2a was measured over a period of 3 months after suppression. The elimination of a minimum of 96% of the endogenous IgG2a molecules from the serum follows an exponential decay with a half‐life of 6–8 days. A monoclonal IgG2a antibody injected into suppressed or normal mice is eliminated from the serum in the same fashion. We conclude that there are few, if any, “long‐lived” IgG2a molecules present in the serum of C57BL/6 mice under physiological conditions.
An investigation of T cell receptor gene rearrangement and expression in organ cultures of normal embryonic thymus and Thy‐1+ cells of nude mice
Authors: Owen Michael J. , Jenkinson Eric J. , Williams Gwyn T. , Kingston Rosetta , Owen John J. T.
Published: February 2007

We have shown that beginning with 14‐day mouse embryo thymus, rearrangements of T cell receptor β‐chain genes and transcripts of α and β chains culminating in the generation of T cell receptor‐bearings cells can be obtained in organ cultures. We have failed to detect rearrangement β chain genes, and β chain transcripts or membrane receptors in concanavalin A‐activated nude spleen cells, although we cannot exclude the possibility that a minor subpopulation of nude Thy‐1+ cells may express T cell receptors. Our results suggest that the thymus is both necessary and sufficient for generation of T cell receptor‐bearing cell and that organ culture provides a system for further investigation of the mechanisms involved.
Antibodies reactive with the B1 molecule inhibit cell cycle progression but not activation of human B lymphocytes
Authors: Tedder Thomas F. , Forsgren Arne , Boyd Andrew W. , Nadler Lee M. , Schlossman Stuart F.
Published: February 2007

The B1 cell surface molecule (CD20) is a 35‐kDa phosphoprotein expressed by B lineage cells during most stages of differentiation. Some monoclonal antibodies reactive with B1 induce activation while others, anti‐B1a, inhibit B lymphocyte function. To further determine the requirement of B1 molecule function in proliferation and differentiation the effects of anti‐B1a antibody binding on early cellular activation events were examined. Immunoglobulin secretion of lymphocyte cultures stimulated with pokeweed mitogen was maximally inhibited if the antibody (1‐10μg/ml) was added during the first 24 h of culture. However, even high antibody concentrations were unable to inhibit increases in free intracellular Ca2+ concentrations immediately following cross‐linkage of cell surface immunoglobulin, or inhibit cell enlargement and the expression of transferrin and interleukin 2 receptors. Antibody binding to B1 inhibited RNA synthesis (37‐80%) and progression through cell cycle following activation. In contrast, proliferation induced by phorbol myristate acetate was not inhibited by antibody binding to the B1 molecule. The findings that the earliest activation events and phorbol myristate acetate‐induced proliferation were not inhibited by antibody binding to B1 suggest that inhibition is due to the blocking of a step of the activation process required for cell cycle progression and differentiation, rather than blocking initial signal transduction across the membrane or providing a negative or suppressive signal.
Characterization of the role for calcium influx in mitogen‐induced triggering of human T cells. Identification of calcium‐dependent and calcium‐independent signals
Authors: Gelfand Erwin W. , Cheung Roy K. , Grinstein Sergio , Mills Gordon B.
Published: February 2007

Entry of Ca2+ into the cell is recognized as an important activation signal for mitogeninduced lymphocyte proliferation. Changes in free cytosolic Ca2+ ([Ca2+]i) can now be measured directly using the fluorescent reagent quin‐2. To analyze the role of [Ca2+]i in human T cell activation, we have determined the effect of the calcium channel blocker, nifedipine, on phytohemagglutinin (PHA)‐induced lymphocyte proliferation. At a concentration of 50 μM, nifedipine is nontoxic, and prevents PHA‐induced proliferation. In parallel the drug prevents the lectin‐induced increase in concentration of [Ca2+]i and interleukin 2 (IL2) secretion; IL2 receptor expression is unaffected. In the presence of exogenous IL2, cell proliferation proceeds normally. Treatment of the cells with the tumor promoter 12‐O‐tetradecanoylphorbol 13‐acetate prevents the inhibitory effect of nifedipine on cell proliferation. Since TPA is itself nonmitogenic and does not affect levels of cytosolic Ca2+, these data and the data on IL2 receptor expression indicate that PHA can generate an activation signal(s) which is [Ca2+]i independent.
The roles of interleukin 2 and interferon‐γ in human B cell activation, growth and differentiation
Authors: Jelinek Diane F. , Splawski Judy B. , Lipsky Peter E.
Published: February 2007

The roles of interleukin 2 (IL 2) and interferon‐γ (IFN‐γ) in human peripheral blood B cell activation, growth and differentiation were examined. Highly purified B cells stimulated with Cowan I Staphylococcus aureus (SA) proliferated minimally and generated no immunoglobulin‐secreting cells (ISC) without the addition of T cell supernatants (T sup) produced by mitogen‐activated T cells. Recombinant IL 2 (rIL 2) alone was able to promote maximum proliferation and generation of ISC in cultures of highly purified SA‐stimulated B cells when present from the initiation of the incubation. IFN‐γ, by contrast, could not support either response alone. When a twostep culture system was employed to determine the effect(s) of T cell influences during both initial activation and in propagating the response following activation, it was found that B cells activated by SA alone subsequently responded maximally to T sup but only minimally to IL 2 and not at all to IFN‐γ. However, the presence of T sup, rIL 2, or rIFN‐γ during initial activation with SA was found to facilitate greatly the subsequent capacity of the activated B cells to proliferate and differentiate in response to either T sup or IL 2. These data suggest two distinct pathways of human B cell responsiveness. Activities in T sup other than IL 2 or IFN‐γ can support the growth and differentiation of B cells initially activated with SA alone, whereas rIL 2 is capable of promoting these responses maximally only when B cells have been initially activated by SA in the presence of T cell lymphokines, such as IL 2 or IFN‐γ. The results emphasize the role of specific T cell factors in determining the outcome of humoral immune responses.
Lysis of bystander target cells after triggering of human cytotoxic T lymphocytes
Authors: Fleischer Bernhard
Published: February 2007

Human cloned cytotoxic T lymphocytes (CTL) specific for class I HLA antigens were used to investigate whether triggering of CTL leads to killing of innocent bystander target cells. After triggering of CTL by their specific target cells, lysis of bystander targets was detected in a 7‐h cytotoxicity assay. Considerable differences were found in the susceptibility of various target cells to this type of lysis. Targets susceptible to this bystander lysis were also susceptible to lysis by CTL triggered by F(ab')2 fragments of an anti‐T3 monoclonal antibody, whereas other targets were resistant to both types of cytotoxicity. Triggering of CTL by oxidized target cells or via a T3‐independent activation pathway led to bystander lysis detectable already after 4 h. Bystander lysis was considerably enhanced under conditions that facilitated a nonspecific cell contact between CTL and bystander target. We conclude that a function besides antigen recognition of the T cell receptor on CTL is to direct killing to the target cell. This directing, however, is incomplete and destruction of innocent bystanders can be detected under appropriate conditions.
Transhybridomas from fusion gene transgenic lymphocytes can be used to produce foreign protein of biological interest
Authors: Babinet Charles , Morello Dominique , Rougeot Catherine , Rouyre Sylvie
Published: February 2007

A method is described for achieving the efficient production of proteins of biological interest by the establishment of hybridomas from lymphocytes of transgenic animals carrying a fusion gene having promoter‐regulatory sequences functional in lymphocytes fused to the coding sequences of the protein to be produced. While possible improvements in the method are discussed, it is anticipated that the method will ultimately be applicable to the production of any protein of interest.
Priming immune response to cholera toxin induced by synthetic peptides
Authors: Jacob Chaim O. , Grossfeld Shoshana , Sela Michael , Arnon Ruth
Published: February 2007

A systematic study has been conducted of the priming effect in the immunization against cholera toxin (CT). We demonstrate that a priming phenomenon can be achieved by synthetic peptides of the CT B subunit, leading (after a subsequent booster with a subimmunizing dose of the intact toxin) to an efficient anti‐CT neutralizing antibody response. This effect is obtained even upon a single administration of a peptide conjugate and even by peptides that as such are not able to induce CT cross‐reactive antibodies whatsoever. This effect is specific and dose dependent. A macromolecular carrier as well as an adjuvant are essential for the induction of antitoxin response. In this respect, a totally synthetic priming agent, CTP3‐poly (DL‐alanyl)–poly(L‐lysine), was adequate for an effective priming response. The specificity of the antibodies formed after the booster was mainly towards the whole CT molecule and only a small fraction of them were specific towards the peptide used for priming. The ability of synthetic peptides to prime the immune system towards a secondary stimulus with whole organism or native protein might be of general practical value, especially in endemic areas where the population is probably constantly exposed to a low level of a particular infectious agent. This exposure, which has no influence on the unprimed immune system, could serve as a booster in the case of individuals primed with an appropriate peptide, leading to a secondary immune response.
Functional characterization of monoclonal auto‐antiidiotype antibodies isolated from the early B cell repertoire of BALB/c mice
Authors: Vakil Meenal , Kearney John F.
Published: February 2007

A large number of hybridomas were constructed by fusion of B cells from perinatal liver and spleen. Many of these showed multispecificity, high interconnectivity and anti‐idiotype (Id) activity. Several of these were subjected to a detailed analysis to evaluate their influence on the developing immune system.

A hybridoma BD2 (μ,χ), derived from 2‐day‐old liver, was shown to have anti‐T15 and anti‐J558 activity by inhibition enzyme‐linked immunosorbent assay and by in vivo administration. BD2 reduced primary T15 and J558 Id in adult BALB/c by 50%. In contrast, timed administration of this antibody during neonatal periods resulted in enhancement of responses to phosphorylcholine (PC) and a(l ‐>3)‐linked dextran (Dex) when these mice were challenged as adults. Another hybridoma DB3 (μ,χ), derived from a lipopolysaccharide‐stimulated fetal liver, reacts with GB4–10 (anti‐ T15) and not with PC. It also reacts with BD2. It is thus anti‐anti‐Id with respect to T15 and J558. Early administration of this antibody also led to an enhancement of anti‐PC and anti‐Dex responses, apparently via expansion of a set of intermediate anti‐Id BD2‐like B cells. In adult mice it suppressed responses to both antigens. A third hybridoma FC4 (μ,χ), derived from 3‐day‐old spleen, reacts with GB4–10 as well as EB3–7 (anti‐J558). Introduction of this antibody into neonatal mice enhanced anti‐ Dex responses while in adults it caused suppression of T15 Id. The results presented here suggest a possible role for neonatal anti‐Id B cells in the primary activation of antigen‐reactive B cells by Id selection.
T cell involvement in the decrease of antigen‐responsive B cells in aged mice
Authors: Zharhary Dorith
Published: February 2007

The role of T cells in the reduced frequency of splenic B cells specific for several antigens in aged mice was studied by assessing B cell responsiveness in (a) aged nude mice and (b) irradiated young mice repopulated with splenic B cells or with Ig− bone marrow cells from young mice and T cells from aged vs. young mice. Using the fragment culture technique to assess B cells specific for 2,4‐dinitrophenyl (DNP) and for (4‐hydroxy‐3,5‐dinitrophenyl) acetyl, we found that the frequency of responsive splenic B cells in aged B ALB/c nude mice was very similar to that of young nude mice. In addition, we found that in chimeric mice constructed with either bone marrow or splenic B cells from young mice and T cells from aged mice the frequency of DNP‐ specific splenic B cells was significantly lower than that in control chimeras constructed with T cells from young mice. These results indicate that T cells from aged mice can down regulate B cell responsiveness and that a mature, naive B cell may be its possible target. The results of both experimental approaches are consistent with a role for T cells in the regulation of responsive B cells in aging.
Isolation and characterization of maerophage‐derived C1q and its similarities to serum C1q
Authors: Rabs Ulrich , Martin Harry , Hitschold Thomas , Golan Mario D. , Heinz Hans‐Peter , Loos Michael
Published: February 2007

Recently, we have shown that the collagen‐like, Fc‐recognizing subcomponent C1q of the first complement component is synthesized by human, guinea pig and mouse peritoneal macrophages. To test whether macrophages may contribute to the serum pool of C1q, C1q was purified from guinea pig serum and from guinea pig peritoneal macrophage supernatants and compared for similarities. Both molecules had a similar sedimentation rate (macrophage C1q: 11.3S, serum C1q: 11.2S) and showed on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis under reducing conditions three identical bands with molecular weights of Mr 29 000, Mr 27 000 and Mr 23 000 for the A, B and C chains, respectively. Both C1q molecules migrated by immunoelec‐ trophoresis in the gamma region and, in Ouchterlony analysis, showed complete antigenic identity with rabbit anti‐serum C1q. These experiments demonstrate the antigenic and protein chemical similarities between serum C1q and C1q secreted by macrophages supporting the idea that macrophages have to be considered as one potential source of serum C1q. Furthermore, macrophage‐derived C1q may be of importance in the local microenvironment at an inflammatory site involving macrophages.
Immune serum from mice contact‐sensitized with picryl chloride contains an antigen‐specific T cell factor that transfers immediate cutaneous reactivity
Authors: Van Loveren Henk , Ratziaff Robert E. , Kato Kazuyuki , Meade Robin , Ferguson Thomas A. , Michael Iverson G. , Janeway Charles A. , Askenase Philip W.
Published: February 2007

This report describes an activity in serum from mice that were contact‐sensitized with picryl chloride (PCl) 1 to 4 days earlier. Immune serum, when given i.v., transfers the ability to elicit an immediate hypersensitivity‐like ear swelling reaction in naive recipients following local challenge with PCl. This serum activity is due to an antigen‐ binding T cell factor that shares some properties with IgE antibody. The activity is antigen specific, and due to an antigen‐binding moiety that is heat labile (56°C, 4 h). However, unlike IgE antibody the serum activity is resistant to reduction and alkylation, and is retained by columns of Sepharose beads coupled with polyclonal or monoclonal antibodies that react with antigen‐specific T cell factors from other systems. These columns did not retain IgE antibody activity in our experiments. Importantly, the serum activity was not retained by columns linked with antibodies directed to mouse immunoglobulins, which do retain IgE activity.

We conclude from these data that the activity in PCl immune serum is not caused by IgE antibody, and is due to the presence of the previously described antigen‐specific T cell factor (PCl‐factor), that can activate serotonin‐containing cells, such as mast cells, to release the vasoactive amine serotonin. PCl‐factor transfers the ability to elicit an immediate hypersensitivity‐like reaction that is an early component of delayed‐type hypersensitivity. The presence of this T cell factor in the serum of actively sensitized mice provides a means to sensitize tissues throughout the body for this required, initial, serotonin‐dependent component of delayed‐type hypersensitivity reactions.