T-cell hybridoma specific for a cytochrome c peptide: specific antigen binding and interleukin 2 production

Antigen processing of glycoconjugate vaccines; the polysaccharide portion of the pneumococcal CRM(197) conjugate vaccine co-localizes with MHC II on the antigen processing cell surface

Pneumococcal (Pn) polysaccharides (PS) are T-independent (TI) antigens and do not induce immunological memory or antibodies in infants. Conjugation of PnPS to the carrier protein CRM(197) induces PS-specific antibody in infants, and memory similar to T-dependent (Td) antigens. Conjugates have improved immunogenicity via antigen processing and presentation of carrier protein with MHC II and recruitment of T cell help, but the fate of the PS attached to the carrier is unknown. To determine the location of the PS component of PnPS-CRM(197) in the APC, we separately labeled PS and protein and tracked their location. The PS of types 14-CRM(197) and 19F-CRM(197) was specifically labeled by Alexa Fluor 594 hydrazide (red). The CRM(197) was separately labeled red in a reaction that did not label PS. Labeled antigens were incubated with APC which were fixed, permeabilized and incubated with anti-MHC II antibody labeled green by Alexa Fluor 488, followed by confocal microscopy. Labeled CRM(197) was presented on APC surface and co-localized with MHC II (yellow). Labeled unconjugated 14 or 19F PS did not go to the APC surface, but PS labeled 14-CRM(197) and 19F-CRM(197) was internalized and co-localized with MHC II. Monoclonal antibody to type 14 PS bound to intracellular type 14 PS and PS-CRM(197). Brefeldin A and chloroquine blocked both CRM(197) and PS labeled 14-CRM(197) and 19F-CRM(197) from co-localizing with MHC II. These data suggest that the PS component of the CRM(197) glycoconjugate enters the endosome, travels with CRM(197) peptides to the APC surface and co-localizes with MHC II.

Major histocompatibility complex independent T cell receptor-antigen interaction: functional analysis using fluorescein derivatives

We have isolated T cell receptor (TCR) cDNAs from fluorescein (FL)-specific human T cell clones (alpha FL beta FL), and transferred them to TCR beta- Jurkat cells in order to study direct FL-binding to the TCR. Using either FL-conjugated polymers (FL-polymer) or FL-substituted Sepharose beads, we are able to demonstrate the direct binding of antigen to the T cell surface, and the functional activation of the T cell transfectants. We present evidence against the involvement of major histocompatibility complex (MHC) molecules or antigen presentation in the interaction of FL with the alpha FL beta FL transfectants. Additionally, we have examined the effect of ring substitutions on the FL molecule as well as specific alterations of substituents attached to the 5' position, and we have found that all of them interfere with the functional recognition of the alpha FL beta FL TCR. These experiments demonstrate that TCRs like antibodies have intrinsic affinities for antigen, even without the involvement of MHC molecules.

Analysis of T cell reactivities to phosphorylcholine-conjugated hen egg lysozyme in C57BL/6 mice: hapten-conjugate specificity reflects an altered expression of a major carrier epitope

We have selected several different T cell hybridoma clones reactive to hen egg lysozyme (HEL) conjugated to phosphorylcholine (PC) after fusion of PC-HEL-primed C57BL/6 lymphocytes with BW5147 parent cells. These hybridoma clones preferentially recognize PC-HEL over unconjugated HEL, but not other carrier molecules conjugated with the same hapten. All the PC-HEL-reactive clones are similarly responsive to not only p-azobenzenearsonate (ABA)-conjugated HEL (ABA-HEL) but also to a variety of other diazotized hapten-HEL conjugates. However, these clones are not stimulated by fluoresceinated or dinitrophenylated HEL beyond the level of HEL carrier alone. Therefore, the type of hapten linkage (diazonium) to the carrier molecule appears to affect T cell recognition. The hybridoma clones apparently recognize the carrier molecule alone, although the level of stimulation is relatively low compared to that induced by either PC-HEL or ABA-HEL. Interestingly, HEL unfolded by S-carboxymethylation is capable of stimulating the hybridomas to a level comparable to that obtained with PC-HEL. T cell recognition of the unfolded HEL is independent of antigen processing, which is different from that of PC-HEL. The peptide sequence corresponding to the amino acids 81-93 of HEL appears to contain the epitope region for the hybridoma clones based on testing stimulation activity with synthetic peptides. Previously, the peptides including this region (81-96) have been reported as the determinant recognized by T cells derived from C57BL/6 mice after immunization with an HEL peptide (HEL 13-105) but not with native HEL. These results suggest that a hapten conjugation via diazonium linkage modifies antigen presentation and consequently the presentation of the major T cell epitopes similar to that of the HEL fragment.

Major histocompatibility complex class I-restricted activation of cloned T cells by a soluble protein in the absence of accessory cells

A T-cell clone, 10BK.1, was established from the draining lymph nodes of (B10 x B10.BR)F1 mice immunized with ovalbumin (OVA) according to standard protocols. Upon coculture with the antigen, 10BK.1 cells reacted by production of lymphokines and by proliferation despite the absence of additional antigen-presenting cells. These T cells do not express major histocompatibility complex (MHC) class II molecules on the cell surface as assessed on the basis of several criteria: by cytofluorometric analysis I-A and I-E determinants were not detectable; 10BK.1 cells could not act as antigen-presenting cells for long-term-cultured MHC class II-restricted T-cell clones; and monoclonal antibodies directed at both MHC class II isotypic complexes (I-A, I-E) did not suppress their OVA-induced activation. In contrast, proliferation of 10BK.1 T cells in response to OVA was abrogated by antibodies directed at H-2Kb antigens. Inhibition experiments employing antibodies directed at Lyt-2 and L3T4 antigens in addition to cytofluorometric analysis revealed that T-cell clone 10BK.1 exhibits the Thy-1+,Lyt-2+,Ly-1-,L3T4- phenotype. 10BK.1 cells pulsed with OVA and fixed with glutaraldehyde induced proliferation of untreated 10BK.1 cells. These data support the theory that 10BK.1 T cells present the exogenous globular protein OVA to one another in an MHC class I-restricted manner, resulting in cell activation and proliferation independent of added accessory cells.

Activation of specific T cell lines by the antigens avidin and myelin basic protein in the absence of antigen-presenting cells

We have investigated the specific activation by soluble antigen of rat or mouse long-term T helper cell lines using antigen-presenting cell (APC)-free culture conditions. Some T cell lines specific for avidin or myelin basic protein responded to native antigen in the absence of added APC. Responses in the absence of APC were substantial and specific although, as would be expected, lower than in the presence of APC. Proliferation could not be inhibited by culture with anti-Ia antibodies and the ability of lines to respond to antigen in the absence of APC did not correlate with the endogeneous surface Ia expression of the lines. Furthermore, irradiated T cells were unable to act as presenting cells for lines cells of the same or a different specificity. This suggests that the T cells did not present antigen to each other, and demonstrates, along with other data shown, that activation cannot be attributed to undetected APC remaining in the cultures. Anti-avidin T cell lines differed markedly in their ability to respond to avidin in the absence of added APC.S2, an anti-avidin line of H-2s genotype consistently responded well to avidin seen in the absence of added APC; K2, an H-2k anti-avidin line, responded moderately and B3, and H-2b anti-avidin line, although the most prolific responder in the presence of APC, never responded to antigen in their absence. Z1a, a Lewis rat-derived T cell line specific for myelin basic protein, proliferated well in response to the antigen in the absence of added APC. The present findings demonstrate that some T cells can recognize and respond to native antigens without the mediation of specialized APC.

Differential requirements for the processing and presentation of soluble and particulate bacterial antigens by macrophages

The requirements for antigen processing and presentation by macrophages using various forms of antigens derived from Listeria monocytogenes have been studied. Antigen presentation was monitored by T cell-macrophage binding and interleukin production using T cells from Listeria monocytogenes-infected mice and specific T cell hybridomas. Antigen processing requirements were defined by three criteria: (a) inhibition by lysosomotropic agents, NH4Cl and chloroquine; (b) kinetic relationships between antigen uptake and antigen presentation; and (c) antigen presentation by macrophages pre-fixed with glutaraldehyde. In comparing heat-killed Listeria monocytogenes (HKLM) with soluble listerial proteins (SLP), the presentation of SLP was less sensitive to lysosomotropic agents, showed faster antigen processing kinetics than with HKLM and could occur using pre-fixed macrophages. Transitions between particulate and soluble forms had dramatic influences on processing requirements. Antigens associated with HKLM could be converted to soluble forms which did not require processing by preculture with macrophages and also by physical (e.g. sonication) and chemical (sodium dodecyl sulfate) treatments in the presence of protease inhibitors. Conversely, antigen processing was required when SLP were converted to a particulate form by covalent binding to latex beads. Analysis of SLP by molecular sieve chromatography and preparative SDS-polyacrylamide gel electrophoresis revealed that high molecular weight proteins (greater than 60 kDa) could be presented by prefixed macrophages without prior processing. We conclude that the transition from a particulate to soluble antigenic form can be a significant antigen processing event.

Antigen-specific, MHC nonrestricted T helper cell-induced B cell activation

We used a cloned, TNP-specific, MHC-restricted, human Th cell line, E-11, and an assay of cognate Th-B cell interaction, BLAST-2 antigen expression on the B cell surface, to investigate the functional nature of the Th cell antigen receptor. We observed that E-11 induces BLAST-2 expression by resting B cells in a hapten-dependent, hapten-specific, but MHC nonrestricted manner. The implication of these results for the Th cell receptor are discussed.

A single germline VH gene segment of normal A/J mice encodes autoantibodies characteristic of systemic lupus erythematosus

These experiments tested the hypothesis that unmutated germline genes from normal mice can encode autoantibodies. We found that the unmutated VHIdCR gene segment, which encodes a large proportion of antiarsonate antibodies in A/J mice, also encodes antibodies with the ability to bind to DNA and cytoskeletal proteins. After Ars immunization, at a time when the VHIdCR gene segment mutates and antibody affinity for the hapten increases, reactivity with the autoantigens was lost. Six antibodies obtained after immunization with Ars bound both the Ars and DNA. Results of competitive inhibition assays suggested that the same variable region site in the antibodies bound to both Ars and DNA. The properties of the individual germline-encoded antibodies, which include reactivity to both DNA and cytoskeletal proteins, suggest that autoantibodies characteristic of SLE might be a subset of antibodies encoded by unmutated germline V genes.

Peptides related to the antigenic determinant block T cell recognition of the native protein as processed by antigen-presenting cells

A mouse T cell hybrid specific for pigeon cytochrome c in the context of I-Ek responds 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. 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 paraformaldehyde-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.(ABSTRACT TRUNCATED AT 400 WORDS)

T-cell recognition of antigen and the Ia molecule as a ternary complex

T-lymphocyte co-recognition of antigen and major histocompatibility complex (MHC)-encoded molecules (such as murine Ia molecules) is thought to be mediated by a single cell-surface receptor, although the molecular mechanism by which this occurs is controversial (reviewed in ref. 1). One possibility is that the antigen molecule and the Ia molecule interact physically, either before or after encountering the T-cell antigen-specific receptor. Alternatively, both molecules could bind to the receptor independently of one another, accounting for the dual specificity of the receptor without postulating a physical interaction between a limited number of Ia molecules present in any given animal and the myriad antigens to which T cells can respond. Here, we used a recently described approach for analysing the relative avidity of the T-cell receptor for different ligands to address these two possibilities. We describe a T-cell clone whose response to a single antigen, presented in the context of two different Ia molecules, strongly suggests that the antigen and the Ia molecule interact physically.

Antigen valence determines the binding of nominal antigen to cytolytic T cell clones

We have shown that cytotoxic T cell clones specific for the nominal antigen FL will bind high molecular weight (600,000 to 2,000,000) polyacrylamide and Ficoll polymers conjugated with 200-600 FL groups per molecule. Low molecular weight polymers (40,000) with the same epitope density did not give stable binding. A high molecular weight polymer with a lower epitope density also failed to bind. Taken together, these results suggest that a substantial degree of multivalence is a necessary factor in the stable binding of nominal antigen to T cell clones.

Immunochemical similarities between monoclonal antibacterial Waldenstrom's macroglobulins and monoclonal anti-DNA lupus autoantibodies

Six monoclonal IgM from patients with Waldenstrom's macroglobulinemia that react with Klebsiella polysaccharides were tested for their ability to bind to nucleic acid antigens. One of the macroglobulins bound to the polynucleotide poly(G), and one bound to poly(G), poly(I), and single-stranded DNA. The reaction with the polynucleotides was specifically inhibited by the Klebsiella polysaccharide K30. A monoclonal lupus anti-DNA antibody (16/6) was found to react weakly with the Klebsiella polysaccharides K30 and K21. Five of the Waldenstrom macroglobulins shared an idiotypic determinant with the 16/6 anti-DNA antibody. The reaction between the macroglobulins and the antiidiotype serum was specifically inhibited by Klebsiella polysaccharides, an indication that the idiotypic marker was in the antigen-binding site of the macroglobulins. These results indicate the existence of widely dispersed conserved variable region genes that encode idiotypically related immunoglobulins with the capacity to bind to both bacterial polysaccharides and nucleic acids. Such genes can be expressed by patients with either Waldenstrom's macroglobulinemia or systemic lupus erythematosus.

Direct evaluation of antigen binding to human T lymphocyte clones: involvement of major histocompatibility complex products in antigen binding

Cloned human helper T lymphocytes reactive with a defined peptide (p20; residues 306-329) of the HA-1 molecule of influenza virus hemagglutinin were analyzed for their capacity to specifically bind peptide antigen. Three different methods of analyzing antigen binding to T cell receptors were compared. One method involved the binding of radiolabeled T cells to antigen-pulsed populations of sheep erythrocyte rosette-negative (E-) cells (B cells and monocytes). The binding was antigen specific, in that only E- cells pulsed with the appropriate antigen bound the treated T cells, and was inhibitable by free peptide. Furthermore, antigen binding was major histocompatibility complex-restricted in that only E- cells histocompatible at the HLA-D region locus bound the T cells, and monoclonal antibody of the relevant specificity was able to inhibit the binding. Secondly, it was demonstrated that tritiated T cells could bind to insolubilized antigen (p20) in the absence of E- cells. The binding was inhibited by anti-class II antibody suggesting that the interaction of antigen with the T cells involves recognition of T cell major histocompatibility complex class II determinants. Finally, radiolabeled peptides were also used to detect binding to the appropriate clones in the absence of presenting cells. This binding was specific, inhibitable by the appropriate unlabeled peptide and temperature dependent. These studies demonstrate that the process of antigen binding to receptors is analyzable and should in turn facilitate the analysis of the mechanism of T cell activation.

Immunoregulation of lysozyme-specific suppression. II. Hen egg-white lysozyme-specific monoclonal suppressor T cell factor suppresses the afferent phase of delayed-type hypersensitivity and induces second-order suppressor T cells

Culture supernatant from a monoclonal T cell lymphoma line (LH8-105) obtained by radiation leukemia virus-induced transformation of hen egg-white lysozyme (HEL)-specific suppressor T lymphocytes is able, when injected into mice, to specifically suppress the delayed-type hypersensitivity (DTH) reaction induced by HEL. The suppressor T cell factor (TsF) exhibits fine antigenic specificity since it suppresses the DTH response induced by HEL without affecting the DTH response induced by ring-necked pheasant egg-white lysozyme (REL), a lysozyme closely related to HEL. Conversely, LH8-105 TsF is able to suppress the DTH response induced by human lysozyme, distantly related to HEL but sharing a common epitope critical for induction of suppressive activity. The fine antigenic specificity of LH8-105 TsF for a restricted epitope on the HEL molecule is confirmed by binding to HEL but not to REL immunosorbents. This TsF also bears I-J determinants, as demonstrated by binding to monoclonal anti-I-J immunosorbents, and it suppresses the afferent but not the efferent phase of the DTH response to HEL. The afferent suppression is controlled by genes apparently mapping in the I-J subregion of the H-2 complex since I-J-incompatible mice are not suppressed by LH8-105 TsF injection. This inducer-type TsF induces second-order effector suppressor T cells only in HEL-primed mice indicating the primary role of antigen, in association with H-2 (I-J) products, in the afferent portion of this suppressive circuit.