Antigen presentation by human antigen-presenting cells to antigen-specific xenogeneic murine T cells

Successful antigen presentation by xenogeneic human antigen-presenting cells (APC) to stimulate the proliferation of antigen-specific, keyhole limpet hemocyanin (KLH)-specific, ovalbumin (OVA)-specific, and purified protein derivative of Mycobacterium tuberculosis (PPD)-specific murine T cells was observed. Evidence indicating a direct cell interaction between antigen-specific murine T cells and xenogeneic human APC was given by experiments using antigen-specific murine T cell clones. The OVA-specific B10.S(9R) T cell line (9-0-A1) and PPD-specific B10.A(4R) T cell line (4-P-1) were stimulated by both xenogeneic human APC and murine APC from syngeneic or I-A compatible strains, while the PPD-specific human T cell line (Y-P-5) was stimulated by autologous human APC but not by murine APC. Anti-HLA-DR monoclonal antibodies (MoAb) blocked the xenogeneic human APC-antigen-specific murine T cell clone interaction. Thus, human xenogeneic APC can stimulate antigen-specific murine T cells through HLA-DR molecules in the same manner as syngeneic murine APC do through Ia molecules coded for by the I region of the H-2 complex, while murine APC failed to present antigen to stimulate human antigen-specific T cells.     

Antigen presentation by Hodgkin's disease cells

The L428 tumor cell line is a long-term tissue culture of Reed-Sternberg cells which was derived from the pleural effusion of a patient with Hodgkin's disease. The L428 cells express all known cell surface antigens, cytochemical staining, and cytologic features of freshly explanted Reed-Sternberg cells. In addition to the previously described HLA-DR cell surface antigens, the L428 cells are now demonstrated to express both DS and SB alloantigens. Thus, the L428 cells express all of the known subclasses of the human immune response genes that are located in the major histocompatibility complex. Furthermore, the L428 cells are capable of presenting soluble antigen to T cells in a genetically restricted fashion. T cell lines were established from normal donors previously immunized with tetanus toxoid. The T cells utilized were incapable of tetanus toxoid-induced proliferation unless antigen-presenting cells were added to the cultures. However, T cells from the two normal donors, which like the L428 cells expressed HLA-DR 5, demonstrated significant proliferative responses when cultured with tetanus toxoid and L428 cells. No proliferative response was observed when the L428 cells were used as antigen-presenting cells for a DR (4,-), DR (2,-) or DR (1,7) T cell line. The tetanus toxoid dose-response curve was similar regardless of whether autologous mononuclear leukocytes or L428 cells were used as antigen-presenting cells. The T cell proliferation induced by soluble antigen was also blocked by anti-HLA-DR antibody. Thus, functionally, Hodgkin's disease may be classified as a tumor of antigen-presenting cells.     

IL-1 secretion and membrane IL-1 expression by neonatal spleen cells during soluble antigen presentation

Antigen presentation and IL-1 production by neonatal spleen cells were studied in a murine model. The T-helper-cell line (D10-G4.1) (D10), which is specific for soluble antigen presented on syngeneic antigen-presenting cells and dependent on IL-1 for its proliferation, was used as an indicator cell for the ability of syngeneic neonatal or adult spleen cells to present antigen and produce IL-1. The antigen-presenting capacity of neonatal spleen cells is low as attested by D10 proliferation. During antigen presentation there is an augmentation of IL-1 production by the antigen-presenting spleen cell population. However, neonatal spleen cells do not respond to the same levels as do adult spleen cells. These reduced levels of secreted IL-1 cannot be attributed to a low potential for producing IL-1 as attested by the high levels of IL-1 made by these cells after induction by a crude IL-1 inducer factor (IL-1-IF) and by the stimulus of the IL-1-IF produced by D10 cells during antigen presentation by paraformaldehyde-fixed adult cells. The spontaneous expression of membrane IL-1 by neonatal cells is low. Membrane IL-1 levels on neonatal cells can be brought to adult levels by induction with IL-1-IF. Neonatal spleen cells have an impaired capacity to process and/or present soluble antigen. This impairment leads to a decreased stimulus of the T helper cell to produce inducer factors and thus a reduced level of IL-1 production by the neonatal cells during antigen presentation.     

Tumor antigen presentation by murine epidermal cells

The ability of epidermal Langerhans cells to present Ag for CD4-dependent immunity is well documented, and it has been hypothesized that Langerhans cells participate in the generation of immunity against incipient epidermal neoplasms by presentation of tumor-associated Ag in situ. This study examined the ability of murine epidermal cells (EC) to present tumor-associated Ag for the induction of in vivo antitumor immunity. Murine epidermal cells were deleted of Thy-1-bearing cells, cultured in 50 U/ml granulocyte-macrophage-CSF for 14 to 18 h, and pulsed with tumor fragments (TF) derived from S1509a-fibrosarcoma cells. These TF-pulsed EC were injected s.c. into syngeneic recipients at weekly intervals for a total of three immunizations and challenged with viable S1509a tumor cells 1 wk after the last immunization. Control animals received TF-pulsed allogeneic EC or EC treated identically but not pulsed with TF. EC that were pulsed with tumor cell fragments were able to induce protective immunity to tumor growth in vivo and to immunize for a significant delayed-type hypersensitivity response to injected tumor cells. The induction of antitumor immunity with TF-pulsed EC was genetically restricted, and culture of EC in granulocyte-macrophage-CSF was required for development of significant immunity. Furthermore, deletion of I-A+ cells by antibody and complement-mediated lysis eliminated the generation of immunity. Thus, I-A+ epidermal cells are capable of presenting S1509a tumor Ag for the generation of protective antitumor immunity in vivo.     

Suppressor factor produced by neonatal mouse spleen cells

Spleen cells from 5- to 6-day- old BDF₁ mice produce a soluble suppressor factor (SF) when cultured for 2–4 days in the presence of 10% fetal calf serum. This suppressor factor inhibits the mixed lymphocyte reactivity of adult mouse spleen cells as well as the in vitro generation of cytotoxic cells. The SF which is not H₂-restricted or antigen specific is most effective when added in the early phase of the culture period. The SF is resistant to heat and uv treatment and appears to consist of a large and small component. It is resistant to treatment with pronase or trypsin. The SF appears to be produced by neonatal spleen cells which are not adherent to plastic or Sephadex G-10 and are insensitive to treatment with anti-Thy 1.2 and complement. Incubation of SF with peritoneal exudate cells reduces suppressor activity.     

Antigen presentation

This paper reviews some of the cellular events involved in the immune recognition of foreign proteins. The recognition of an antigen by T lymphocytes is essential for its effective elimination by the host. T lymphocytes of the CD4 or CD8 subset recognize antigen but only after the antigen is handled by antigen-handling cells (antigen-presenting cells). Antigen molecules are recognized after an internal processing event by antigen-presenting cells that results in the generation of immunogenic peptides. Such peptides associate with histocompatibility molecules to form bimolecular complexes on the cell surface. The T cell receptors for antigen recognize the bimolecular complex and initiate the events that result in an inflammatory response. Antigen-presenting cells also produce molecules - termed costimulators - that stimulate the growth and differentiation of T lymphocytes.     

Antigen presentation by the BCL1 murine B cell line: in vitro stimulation by LPS

We examined the antigen-presenting capacity of BCL1 tumor cells, which are capable of differentiating in vitro with respect to immunoglobulin synthesis/secretion under the influence of LPS. In vivo passaged BCL1 cells depleted of host cell contamination either by positive selection employing panning with anti-lambda reagents, or by elimination of latex-ingesting adherent cells, are capable of MHC-restricted antigen presentation to a GAT-immune T cell line. The BCL1 cells act as antigen-presenting cells when freshly explanted, but gradual loss of this function occurs, and cells cultured for 3.5 days cannot present antigen unless LPS is included during the culture period. BCL1 cells are equivalently Ia+ after the culture period with or without LPS stimulation. Other B cell lines capable of antigen presentation appear to express this trait constitutively, and the in vivo passaged BCL1 line is therefore unique among B cell lines in having antigen-presenting cell function that can be modulated. The data suggest that freshly explanted or LPS-cultured BCL1 cells are heterogeneous with respect to antigen-presenting capacity, and the basis for this heterogeneity is being sought. BCL1 offers an opportunity to study requirements for antigen presentation by B cells.     

Antigen processing and presentation by macrophages

The classical macrophage is one of the most important cells involved in presenting antigen to helper T cells, because of its ability to regulate its expression of Ia molecules and to encounter and process particulate and soluble antigens. We have summarized in this report studies examining the handling by macrophages of two different antigens, the bacteria Listeria monocytogenes and the protein hen egg white lysozyme (HEL). The purpose was to identify potential sources of immunogenic peptides. Presentation of Listeria required an intracellular processing stage sensitive to lysosomotropic drugs. The Listeria required internalization and processing, after which immunogenic molecules were recognized by T cells on the macrophage surface. Metabolic studies showed that Listeria-derived peptides were released by macrophages that had phagocytosized the bacteria. The release of these peptides was a temperature-dependent process, unaffected by inhibiting lysosomal catabolism by treatment with chloroquine. Listeria-derived peptides were also detected on the surface of the macrophage. These peptides behaved like integral membrane proteins, some of which persisted for at least 24 hr at the macrophage surface. When tested for immunogenicity, the released peptides were very weakly immunogenic. The membrane-associated peptides alone could not stimulate Listeria-specific T cells, but could be reprocessed by additional macrophages and subsequently stimulate the T cells. A defined antigen system using HEL-specific T-cell hybridomas was used to examine the processing of HEL. Presentation of HEL required a chloroquine-sensitive intracellular processing stage. In examining two T-cell hybridomas, a differential requirement for antigen processing was determined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Antigen presentation capacity and cytokine production by murine splenic dendritic cell subsets upon Salmonella encounter

Salmonella typhimurium is an intracellular bacterium that replicates in the spleen and mesenteric lymph nodes (MLN) of orally infected mice. However, little is known about the Ag presentation and cytokine production capacity of dendritic cells (DC), particularly CD8alpha(+), CD8alpha(-)CD4(-), and CD8alpha(-)CD4(+) DC, from these organs in response to SALMONELLA: Infection of purified splenic DC with S. typhimiurium expressing green fluorescent protein (GFP) and OVA revealed that all three splenic DC subsets internalize bacteria, and splenic as well as MLN DC process Salmonella for peptide presentation. Furthermore, presentation of Salmonella Ags on MHC-I and MHC-II was evident in both CD8alpha(+) and CD8alpha(-) splenic DC subsets. Direct ex vivo analysis of splenic DC from mice infected with GFP-expressing Salmonella showed that all three subsets harbored bacteria, and splenic DC purified from mice given Salmonella-expressing OVA presented OVA-derived peptides on MHC-I and MHC-II. Cytokine production analyzed by intracellular staining of splenic DC infected with GFP-expressing Salmonella revealed that TNF-alpha was produced by a large percentage of CD8alpha(-) DC, while only a minor proportion of CD8alpha(+) DC produced this cytokine following bacterial exposure. In contrast, the greatest number of IL-12p40-producing DC were among CD8alpha(+) DC. Experiments inhibiting bacterial uptake by cytochalasin D as well as use of a Transwell system revealed that bacterial contact, but not internalization, was required for cytokine production. Thus, DC in sites of Salmonella replication and T cell activation, spleen and MLN, respond to bacterial encounter by Ag presentation and produce cytokines in a subset-specific fashion.     

Antigen presentation by liver sinusoidal lining cells after antigen exposure in vivo

The ability of liver sinusoidal lining cells (LSLC), a mixture of Kupffer cells and endothelial cells, to function as antigen-presenting cells (APC) was examined. Guinea pig LSLC were found to present antigen in vitro, albeit somewhat less effectively than a reference population of peritoneal exudate macrophages. The difference in APC function could not be explained by a deficiency of interleukin 1 (IL 1), as LSLC secreted IL 1 and expressed membrane-bound thymocyte stimulatory activity. The ability of LSLC to take up antigen from the portal blood in vivo and present it to primed T lymphocytes in vitro was also investigated. Trinitrophenyl-ovalbumin was injected intraportally into either strain 13 or strain 2 guinea pigs. The LSLC were subsequently isolated by collagenase digestion and density separation and assessed for the ability to induce proliferation of antigen-primed accessory cell-depleted syngeneic peritoneal exudate T lymphocytes in vitro. The in vivo antigen-pulsed LSLC were found to present antigen in vitro to primed T cells in an antigen-specific and genetically restricted manner. T cell DNA synthesis induced by antigen-bearing LSLC could be augmented by coculture with additional accessory cells, but not IL 1-containing macrophage supernatants. Enhancement of responsiveness was not genetically restricted. The demonstration that LSLC can take up, process, and retain antigen in vivo and present it to primed T cells in vitro suggests that LSLC are capable of contributing to the immune response to antigens appearing in portal blood.     

Arsonate-specific murine T cell clones. V. Antigen presentation by L cells transfected with normal and mutant class II genes

Class II-restricted murine T cell clones specific for the immunogenic determinant L-tyrosine-p-azobenzenearsonate failed to proliferate to Ag presented by L cell lines transfected with and expressing the appropriate class II genes, but are activated to kill the APC in an Ag-dependent, MHC-restricted manner. Inhibition of APC proliferation was used as an assay to determine the relative contributions of polymorphic sites on the class II alpha- and beta-chains to MHC-restricted activation of I-A beta k-restricted cloned T cells. Transfectants expressing A beta k in conjunction with the alpha chain of k, u, or d were equally effective APCs, whereas transfectants expressing A beta u were completely ineffective, implicating the beta-chain as more critical for the presentation of L-tyrosine-p-azobenzenearsonate. Site-directed mutagenesis of polymorphic positions in the beta chain revealed a remarkable stringency for the k haplotype, in contrast to the relaxed alpha-chain requirement. These results, in conjunction with others, indicate that the relative contribution of polymorphic sites on class II alpha- and beta-chains to T cell Ag recognition can differ markedly, and, furthermore, may vary as a function of the Ag.     

Modulation of IL-4 production in murine spleen cells by prostaglandins

Recently, it has been reported that IL-4 production by murine Th2 cell lines is insensitive to inhibition by E-type prostaglandins. In the present study, IL-4 production in vitro by freshly isolated concanavalin A (Con A)-stimulated murine spleen cells was readily suppressed by PGE₂ with an I₅₀ of 2 nM. Comparable suppression by PGE₂ was seen after priming by anti-CD3? antibody instead of Con A or with other changes in the culture conditions. PGE₂ was an effective inhibitor after elimination of Ly2.2⁺ T cells, consistent with a direct effect on Th2 cells. In the absence of added prostaglandins, IL-4 production was enhanced 1.5- to 7.0-fold by 0.2–2.0 μM indomethacin, indicating that endogenous arachidonate metabolites such as PGE₂ and PGI₂ regulate IL-4 production in our usual culture system. The inhibition of Th2 cell secretion by PGE₂in vitro may have physiologic and pharmacologic implications for the regulation of Th2 cell function and IgE production in vivo.     

Down-regulating effect on cellular immunity of the NSF17 factor produced by murine neonatal spleen cells fused with BW 5147 thymoma cells.

The non-specific factor NSF17 produced by mouse newborn splenocytes fused with BW 5147 thymoma cells was tested in vivo for its immunosuppressive activity. NSF17 administered i.p. in a single dose into adult mice significantly decreased the PHA-induced proliferative response of lymphocytes, regional graft-versus-host reaction, and delayed-type hypersensitivity.     

Antigen presentation abrogated in cells expressing truncated Ia molecules

Oligonucleotide site-directed mutagenesis was used to introduce a premature stop codon in wildtype A beta k and A alpha k cDNA clones to create truncated A beta k and A alpha k molecules lacking the cytoplasmic domain. Transfected B lymphoma cells expressing an I-Ak molecule with a truncated beta-chain or with truncated alpha- and beta-chains showed profound defects in two Ia-related functions: Ia-restricted Ag presentation and intracytoplasmic signaling. The ability of these transfected cell lines to activate autoreactive T hybrids was markedly impaired whereas loss of Ag presentation to nominal Ag-specific T hybrids was more subtle. Ia-mediated transmembrane signaling as measured by PKC translocation from cytosol to nucleus after stimulation with anti-Ak antibody was greatly affected by truncation of the A beta and A alpha cytoplasmic domains. These results indicate an important role for the highly conserved cytoplasmic domain in Ia-mediated responses.     

Antigen presentation for priming T cells in central system

Generation of myelin antigen-specific T cells is a major event in neuroimmune responses that causes demyelination. The antigen-priming of T cells and its location is important in chronic and acute inflammation. In autoimmune multiple sclerosis, the effector T cells are considered to generate in periphery. However, the reasons for chronic relapsing-remitting events are obscure. Considering mechanisms, a feasible aim of research is to investigate the role of antigen-primed T cells in lupus cerebritis. Last thirty years of investigations emphasize the relevance of microglia and infiltrated dendritic cells/macrophages as antigen presenting cells in the central nervous system. The recent approach towards circulating B-lymphocytes is an important area in the context. Here, we analyze the existing findings on antigen presentation in the central nervous system. The aim is to visualize signaling events of myelin antigen presentation to T cells and lead to the strategy of future goals on immunotherapy research.     

Antigen presentation by macrophage-enriched cells from the mouse Peyer's patch

Macrophage-enriched cells derived from Peyer's patches were prepared with or without preincubation of whole patches in collagenase-containing medium. The cells thus obtained were pulsed with ovalbumin (OVA), added to OVA-primed whole lymph node (LN) cells or LN T cells and proliferative responses stimulated in the latter cells were assessed after 5 days by thymidine incorporation. Macrophage-enriched cells obtained from Peyer's patches (PP) preincubated with collagenase presented antigen as well or better than macrophage-enriched cells obtained from spleens. In contrast, macrophage-enriched cells obtained from PP which were not preincubated with collagenase were frequently unable to function as antigen-presenting cells. In further studies, macrophage-enriched cells obtained from mice which had been fed OVA were found to be capable of stimulating antigen-primed LN T cells in an antigen-specific manner without further exposure to antigen in vitro. These results indicate PP macrophage-enriched cells are fully capable of supporting the induction of immune responses in vitro and that macrophages from PP of orally primed mice may present antigen without further antigen exposure. Thus macrophages in PP may participate in the induction of immune responses to gastrointestinal antigens in vivo.     

Immune reactivity of frozen-thawed murine spleen cells.

Spleen cells from mice immunized with SRBC were subjected to controlled rate freezing to ?100 °C. Complete recovery of PFC was obtained with DMSO used as the cryopreservative. Simple dilution of spleen cells in DMSO, or a single cycle of freezing and thawing in DMSO prior to short-term culture, resulted in early loss of recoverable cells. A single cycle of freezing and thawing inhibited the in vitro immune response to SRBC while having little effect on the response to TNP-T4. The in vitro blastogenic responses to LPS and PHA-P were severely reduced in cultures of frozen and thawed cells.     

Prolongation of H--Y incompatible skin grafts in mice by neonatal spleen cells

Prolongation of H--Y incompatible skin graft survival can be achieved by the injection of adult female recipients with neonatal spleen cells. The suppressive effect depends mainly on the sex of neonatal syngeneic and allogeneic donors.