摘要:

AbstractRecently, an experimental system has been described which allows for the isolation and antigenic stimulation of individual antigen‐specific helper T lymphocytes in collaboration with a nonlimiting number of primary B lymphocytes. In the studies presented in this report, this system has been employed to determine whether an individual T lymphocyte has the potential to interact with more than a single B lymphocyte, when the B cells are of different antigenic specificities. The results of these studies indicate that an individual influenza virus PR 8‐specific T lymphocyte has the ability to promote antibody responses of both trinitrophenyl (TNP)‐ and PR 8‐specific B lymphocytes in response to thein vitroantigen TNP‐PR 8. Similar results were obtained when T cells specific for the hapten TNP were used in collaboration with TNP‐ and PR 8‐specific B cells. These results demonstrate that an individual T lymphocyte has the potential to collaborate with more than one B lymphocyte, and that these B cells may differ in their antibody receptor for antigen. These results do not rule out a role for idiotype or allotype‐specific T cells in antibody responses but, rather, strongly argue that antigen‐specific T cells are able to independently initiate primary B cell responses of B cells with distinct antibody receptors. In addition, under these conditions, hapten‐specific helper T cells can be readily demonstrated and may facilitate the response of B cells specific for the same or dif

ISSN:0014-2980    

DOI:10.1002/eji.1830110202

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractCells that possess low levels of internal IgM (or μ chain), with none detectable on the surface, can be identified by immunofluorescence. These “pre‐B cells” in rabbits have been characterized and been compared with those of mice, in terms of their ontogeny, physical properties and surface phenotype — partly to reveal features that could be exploited in their purification. The timing of their appearance and their tissue distribution are, in principle, very similar, though they first appear 5‐7 days later in the rabbit than in the mouse. Thus, pre‐B cells could not be detected in rabbit fetal liver until days 17‐20 of gestation; however, their progenitors appeared to be present before that, since, in preliminary experiments, pre‐B cells (and subsequently B cells) were generatedde novoin closed organ cultures initiated at earlier times.In other respects, pre‐B cells are strikingly different in the two species. Rabbit pre‐B cells bear detectable surface Fc receptors, not found on these cells in the mouse, and they are almost uniformly large and low in density, whereas mouse pre‐B cells are much more heterogeneous and less readily purified. The evidence summarized here that the large pre‐B cells identified by immunofluorescence are equivalent to those detected by others in functional assays, amounts to a strong case for their precursor status. In the mouse, their immediate progeny seem to be small pre‐B cells which apparently already behave, in functional assays, like the newly developed B cells into which they can rapidly convert.This heterogeneity seen in pre‐B cells in mice is apparent instead in the B cells of rabbit lymphopoietic tissues. These vary considerably, not only in size and density, but also in their membrane Ig staining intensity, whereas the B cells in mouse bone marrow are almost exclusively small lymphocytes. In view of their relatively high frequencies in fetal tissues, it is proposed that the conspicuous large, low‐density rabbit B cells are intermediates in the development of pre‐B cells into small B lymphocytes, and it is therefore concluded that surface Ig and Fc receptors both appear at relatively earlier stages in the rabbit than in the mouse. This conclusion could be tested by culturing these immature B cells after purifying them by exploit

ISSN:0014-2980    

DOI:10.1002/eji.1830110203

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractRabbit pre‐B cells are almost uniformly large and low in density and bear a modest number of Fc receptors (McElroy, P. J., Willcox, N. and Catty, D.,Eur. J. Immunol.1981.11:76). A simple density gradient centrifugation procedure consistently and rapidly enriches them to 20‐35% frequencies. At the same time, it depletes them of most of the B cells, phagocytic and erythroid cells that are also common in bone marrow, and are of progressively higher densities. The low‐density fractions include 45‐55% of large blast‐like cells and have 35‐45% of cells with Fc receptors.By isolating the large Fc receptor‐bearing cells from low‐density fractions of baby rabbit bone marrow on a fluorescence‐activated cell sorter, pre‐B cells were obtained at approximately 60% frequency and virtually uncontaminated by B cells (or plasma cells). This level of purity is perhaps adequate for the critical experiments necessary to establish the precursor status of pre‐B cells definitively, and it might also prove valuable for studying the mechanisms of the genetic rearrangements that occur in ear

ISSN:0014-2980    

DOI:10.1002/eji.1830110204

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractThe genetic influences on the specific IgG antibody response to helical antigenic determinants of native soluble type III and V (AB2) human collagen have been studied in mice. H‐2‐linked Ir genes have been detected for each of these collagens, as have background effects. The alleles controlling high antibody responses can be distinguished from those previously described for bovine collagen type I and type I propeptide. Apparent two‐gene complementation in the response to type V (AB2) may indicate that this antigen will be a useful probe in further studies of the complex nature of antigen presentation for T cell recognition. The present studies may facilitate the production of specific, high‐affinity monoclonal antibodies for the human collagens which, in turn, will facilitate the study of connective tissue biology and pa

ISSN:0014-2980    

DOI:10.1002/eji.1830110205

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractExperiments were performed to study the influence of neonatal and adult splenectomy on B cell differentiation in mice. Lymph node cells of both groups were found to contain a significantly higher proportion of Ig‐bearing cells. Moreover, these cells expressed a higher density of membrane Ig and a higher IgM/IgD ratio. In addition, the response of these cells to different polyclonal B cell activators, especially dextran sulfate, was much higher than the response of the sham‐operated controls. Similar experiments were carried out in splenectomized and control animals that were lethally irradiated and reconstituted with different hemopoietic cell sources. The same pattern of results was obtained, except when reconstituting the irradiated animals with fetal liver cells.These experiments, which were performed at long time intervals post splenectomy, show that in the absence of the spleen, there is an accumulation of less mature B cells in the periphery implying an active role of the spleen in at least certain differentiation steps of the B cell line

ISSN:0014-2980    

DOI:10.1002/eji.1830110206

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractMitogen stimulation of cells from various lymphoid organs of C3H/He mice chronically infected with an isolate ofTrypanosoma congolensewas studied at different time intervals after infection, using concanavalin A (Con A) and lipopolysaccharide (LPS). At the same time, changes in the percentages of T, B and null lymphocytes in these organs were determined by immunofluorescence staining. The responses of T and B lymphocytes in the spleen were totally depressed, and the cellular composition was drastically altered by day 14 after infection. Unlike the spleen, the lymph nodes showed minor changes in their T and B lymphocyte responses and cell composition during the course of the infection, except the B cell response and composition which were altered late in the infection. The thymus and bone marrow did not show any appreciable changes in their mitogen responses and cell composition throughout the infection. The peripheral blood lymphocytes showed reduced B cell responses. Spleen cells from chronically infected mice suppressed lymphocyte stimulation induced in normal spleen and lymph node cell populations by Con A, LPS and allogeneic stimulator cells. Lymph node cells from the same group of mice did not exhibit any such suppressor activity.In the experimental system used here, the spleen is the primary site of immune depression, and other lymphoid organs such as the lymph nodes and thymus are very little affected.

ISSN:0014-2980    

DOI:10.1002/eji.1830110207

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractTo clarify reasons of the constant presence of IgM in human cord blood, some functions of this immunoglobulin class were analyzed. Cord IgM was collected from cord blood, and the cord IgM F(ab')2fragment was obtained by trypsin cleavage. Maternal T and adult T cells were stained with fluorescein isothiocyanate (FITC)‐conjugated cord IgM and FITC‐cord F(ab')2μ. Cord IgM, unlike cord IgG, bound to about one‐third of maternal and one‐fourth of adult T cells and killed them, but it killed only a small proportion of the B cells. However, adult F(ab')2μ did not kill these cells. Cord T cells were not killed by cord IgM. Thus, it is apparent that cord IgM contains cytotoxic antibodies against maternal and adult T cells. T lymphocy‐totoxic fetal antibody (TLFA) may be largely responsible for the absence of maternal T cells in cord blood. The percentage of [3H]thymidine incorporation into concanavalin A‐induced adult mononuclear cells treated with cord IgM containing TLFA was 56.0 ± 17.9% (p0.05) indicating the possibility that TLFA might kill a certain sub

ISSN:0014-2980    

DOI:10.1002/eji.1830110208

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractMouse peritoneal macrophages expressed increased cytolytic activity against tumor cells uponin vitroexposure to partially purified L cell interferon (IFN‐β). In contrast, treatment with human IFN or with mock IFN preparations did not enhance macrophage tumoricidal capacity. Macrophage activation by IFN was optimal with long exposure times and high IFN concentrations. Treatment with polymyxin B sulfate did not affect IFN‐induced macrophage cytotoxicity, thus excluding the possibility that bacterial lipopolysaccharide contaminants were responsible for macrophage activation. Conversely, treatment with a highly specific anti‐IFN antiserum completely abolished IFN effect on macrophages, but had no effect on lymphokine‐induced cytolysis. IFN and the lymphokine macrophage‐activating factor (MAF) were compared for their ability to provide the sequence of activation signals to macrophages from the normal responder C3H/HeN mice and from C3H/HeJ mice, which are defective for several macrophage responses. Like MAF, IFN was incapable of inducing tumoricidal activity in C3H/HeJ macrophages. However, whereas MAF provided the first “priming” signal to macrophages of both strains, IFN acted as first signal only for C3H/HeN macrophages, being inactive for cells of the defective C3H/HeJ strain. Fürthermore, IFN was not capable of providing the second “expression” signal to “primed” macrophages.These data suggest two different macrophage activation p

ISSN:0014-2980    

DOI:10.1002/eji.1830110209

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractLymph node cells derived from A.TH or A.TL mice primed with beef cytochromecshow striking patterns of reactivity when assayedin vitrofor antigen‐induced T cell proliferation. Whereas cells from A.TH mice respond specifically to beef cytochromecor peptides composed of amino acids 1‐65 and 81‐104, cells from A.TL mice respond neither to beef cytochromecnor to peptide 1‐65, but proliferate following exposure to either peptide 81‐104 or to a cytochromechybrid molecule in which the N‐terminal peptide of beef (1‐65) was substituted by a similar peptide obtained from rabbit cytochromec.Thus, T cells from mice phenotypically unresponsive to beef cytochrome may, in fact, contain populations of lymphocytes capable of responding to a unique peptide, the response to which is totally inhibited when the same fragment is presented in the sequence of the i

ISSN:0014-2980    

DOI:10.1002/eji.1830110210

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY

摘要:

AbstractLymphocytes from the mesenteric lymph nodes of Lewis rats were depleted of macrophages by absorption for 60 min at 37°C on 0.1‐mm glass beads in the presence of 30% fetal calf serum. Lymphocytes which passed the column (total recovery 30‐50%) contained less than 0.2% macrophages, as assessed by neutral red ingestion or nonspecific esterase staining. At cell densities which allowed optimal proliferation of concanavalin A (Con A)‐stimulated, untreated lymphocytes (2 × 106cells/ml), macrophage‐depleted lymphocytes were completely incapable of initiating DNA synthesis. The proliferative response to Con A was fully restored by adding back macrophages obtained from the peritoneal cavity. The help of macrophages was optimal at concentrations of 0.8 × 105cells/ml, which corresponds to about 4% of lymphocytes. Restitution of the mitotic response of macrophage‐depleted lymphocytes was also achieved by raising cell densities to 5 × 106/ml. At this cell density, addition of macrophages was without any effect. Early events in lymphocyte activation, such as the increase of the incorporation of14C‐oleate into membrane phospholipids after 4 h stimulation, was identical in the presence or absence of macrophages independent of the cell density ranging between 1 × 106and 10 × 106cells/ml. Similarly, the Con A‐stimulated early increase in the incorporation of [3H]uridine into RNA was indistinguishable in macrophage‐containing or ‐depleted lymphocytes. At low cell densities, only macrophage‐containing lymphocytes proceeded to increase RNA synthesis, until S‐phase, whereas in the absence of macrophages RNA synthesis approached background values after 40 h of Con A stimulation. Macrophage‐depleted lymphocytes, too, proceeded with an increase in RNA synthesis, when stimulated at high cell densities. The data suggest that macrophages are not required for the initiation of lymphocyte activation. Their role in supporting mitosis may be the contribution of a second signal close to the G1/S boundary extending the size of

ISSN:0014-2980    

DOI:10.1002/eji.1830110211

出版商:WILEY‐VCH Verlag GmbH    

年代:1981

数据来源: WILEY