Biomedical subjects

R T Kubo

Publications and source records attributed to R T Kubo.

At least 19 recordsLinked to original sources

PubMed1992

Invariant chain peptides in most HLA-DR molecules of an antigen-processing mutant.

Class II major histocompatibility complexes bind peptides in an endosome-like compartment. When the class II null cell line 721.174 was transfected with class II DR3 genes, DR molecules were produced in normal amounts. However, the DR molecules were abnormally conformed and unstable because deletion of an antigen-processing gene had impaired intracellular formation of most class II-peptide complexes. Yet, 70 percent of the DR molecules still bore peptides, 80 percent of which were 21- to 24-amino acid fragments of the class II-associated invariant chain. These peptides were rare on DR3 from control cells. Thus, a defect in the main antigen-processing pathway revealed a process in which DR molecules bind long peptides derived from proteins present in the same compartment.

Amino Acid Sequence↗

PubMed1992

Translocation of spectrin and protein kinase C to a cytoplasmic aggregate upon lymphocyte activation.

We have previously reported that mammalian tissue lymphocytes exhibit significant heterogeneity with respect to the subcellular distribution of spectrin and that this phenomenon may result from a dynamic behavior of spectrin in response to activation signals. Here, we further characterize the involvement of spectrin in lymphocyte activation by examining its relationship with protein kinase C (PKC). PKC isoenzymes are a family of cytosolic kinases that translocate from the soluble to particulate fraction upon cell stimulation. It is reported here that activation of lymph node T cells through the antigen-specific receptor, or direct activation of PKC by phorbol esters, results in a striking increase in cells expressing a cytoplasmic aggregate of spectrin. Additionally, a concurrent increase in cells expressing aggregates of the beta II isozyme of PKC is observed. Immunofluorescence staining revealed that spectrin and PKC beta II are colocalized in untreated lymphocytes and that these two proteins are coincidently translocated to the same focal aggregate within the cytoplasm following stimulation. This redistribution of spectrin and PKC beta is blocked by pretreatment with calphostin C, a specific inhibitor of PKC. Solubility studies showed that there is an increase of both proteins in the detergent-insoluble fraction of lymphocytes upon activation, and immunoprecipitation studies indicated that the soluble form of these molecules may be associated directly or indirectly as part of a complex of proteins. These data indicate that the positioning of the spectrin-based cytoskeleton is sensitive to activation signals and may play a role in the function or positioning of PKC beta II.

Animals↗

PubMed1992

Physical association of CD4 with the T cell receptor.

The coreceptor hypothesis postulates that physical association of CD4 with the TCR is required for effective signaling for T cell activation. A variety of studies has suggested that the coreceptor function of CD4 allows responses to 10- to 100-fold lower levels of peptide:self MHC class II ligand. We test the hypothesis of CD4 physical association with the TCR in two different ways. First, we use a panel of soluble antibodies directed at different TCR epitopes to activate a cloned T cell line, and show that activation by antibodies directed at a particular TCR epitope can be inhibited by anti-CD4 antibodies binding to a certain CD4 epitope. These effects establish that the interaction of CD4 and the TCR occurs in a specific orientation. Second, we use the same system to provide evidence that the physical association of CD4 with the TCR is required for effective tyrosine phosphorylation of the TCR zeta-chain subunit, presumably reflecting delivery of p56lck (lck) to the TCR. Only anti-TCR antibodies that induce physical association of CD4 with the TCR as monitored by cocapping can induce efficient tyrosine-phosphorylation of the TCR zeta-chain, unless second antibodies are used to force CD4 and the TCR to associate. Furthermore, the phosphorylation of the TCR zeta-chain exactly parallesl physical association in time and drug sensitivity. We conclude from these studies that stimuli that drive physical association of CD4 and the TCR strongly favor T cell activation, supporting the coreceptor hypothesis of CD4 function.

Animals↗

PubMed1992

Glycosylphosphatidyl inositol-linked membrane protein expression by intestinal intraepithelial lymphocytes.

Murine intestinal intraepithelial lymphocytes (ilEL) represent a heterogeneous population of cells which contains both TCR alpha beta+ and TCR gamma delta+ cells. In contrast to the TCR alpha beta+ cell population in peripheral lymphoid organs, the TCR alpha beta+ ilEL contain high numbers of Thy-1- cells. This negativity of ilEL for Thy-1, a glycosylphosphatidyl inositol (GPI)-linked membrane protein, is not the result of conformational changes of the Thy-1 molecule. The absence of Thy-1 on TCR gamma delta+ and a subset of TCR alpha beta+ ilEL is furthermore not caused by a general defect in the processing of GPI-linked proteins, since Thy-1- ilEL mainly express another GPI-linked protein, Qa-2. However, TCR alpha beta+ and TCR gamma delta+ ilEL are also virtually negative for two other members of this family of activation-associated GPI-linked proteins, Ly-6A and Ly-6C. This unusual pattern of GPI-linked protein expression on TCR+ ilEL may be related to differences in cellular activation and signal transduction pathways between TCR+ ilEL and regular peripheral T cells.

Animals↗

PubMed1992

Characterization of defective I-A surface expression in a mixed isotype expressing murine B cell lymphoma: continued expression of E alpha d A beta d despite competition from restored A alpha d A beta d pairs.

The BALB/c-derived mouse B cell lymphoma line, 2PK3, expresses mixed isotype E alpha dA beta d and classical I-E class II molecules on its surface, but normal surface I-A expression is not detectable. Northern blot analysis showed comparable amounts of A alpha mRNA in 2PK3 as compared to another Iad expressing B cell lymphoma, A20, which predominantly expresses I-A and I-E. Sequence analysis of 2PK3 A alpha cDNA revealed a single nucleotide difference in the signal sequence that would result in a proline for leucine substitution at position - 12. In vitro translation of 2PK3 A alpha mRNA gave results suggesting that the signal peptide mutation prevented translocation of the A alpha protein across the rough endoplasmic reticulum which would provide an explanation for the lack of I-A expression in 2PK3. I-A expression was restored by transfecting a functional A alpha d gene into 2PK3. Although I-A was expressed at high levels in some transfectants, in all cases significant levels of mixed isotype were still detected. Functional studies performed using antigen-specific I-A(d)-restricted and E alpha d-A beta d-specific T cell hybridomas confirmed the levels of expression of I-A(d) and E alpha dA beta d respectively on the transfectants and showed that these molecules were functional. An interesting observation from this study is the continued expression of significant levels of E alpha dA beta d in spite of competition from restored expression of I-A(d).

Amino Acid Sequence↗

PubMed1991

Surface expression of a T cell receptor beta (TCR-beta) chain in the absence of TCR-alpha, -delta, and -gamma proteins.

The antigen receptor expressed by mature T cells has been described as a disulfide-linked alpha/beta or gamma/delta heterodimer noncovalently associated with CD3, a complex of transmembrane proteins that communicates signals from the T cell receptor (TCR) to the cell interior. Studies suggest that all component chains must assemble intracellularly before surface expression can be achieved. We described, however, a CD4+/CD8+ transformed murine thymocyte, KKF, that expresses surface TCR-beta chains in the absence of gamma, delta, and alpha proteins; these beta chains are only weakly associated with CD3-epsilon and CD3-zeta. Furthermore, KKF responds differently to stimulation through TCR-beta and CD3-epsilon, a functional dissociation that has been ascribed to a CD4+/CD8+ subpopulation of normal thymocytes. KKF's unique TCR structure may offer an explanation for the functional anomalies observed.

Animals↗

PubMed1991

In vivo administration of monoclonal antibodies to the CD3 T cell receptor complex induces cell death (apoptosis) in immature thymocytes.

Some thymocytes, upon activation via the TCR complex in vitro, undergo apoptotic cell death. In this report, we examine the cell death induced in the thymus after administration of anti-CD3 or anti-TCR antibodies. We found that shortly after antibody injection, cortical thymocytes undergo apoptosis as characterized by morphologic changes and DNA fragmentation. Anti-CD3 administration led to depletion of nearly all CD4+CD8+ thymocytes, and approximately 50% of CD4+CD8- thymocytes. This depletion predominantly affected cells bearing low levels of CD3, although some depletion also occurred among cells expressing intermediate and high levels. Administration of an anti-TCR antibody also induced apoptosis, but affected significantly fewer thymocytes than anti-CD3. This effect was probably not due to different binding affinities for the two antibodies, because both antibodies show similar dose response effects in an in vitro model of activation-induced apoptosis. This work demonstrates that findings on activation-induced apoptosis in vitro can be extended to the in vivo situation, and further, that the activation of cortical thymocytes, in situ, results in apoptosis and removal of the activated cells. The possible relationships between this activation-induced cell death in immature thymocytes and the process of negative selection of autoreactive T cells is discussed.

Animals↗

PubMed1991

Analysis of the interaction site for the self superantigen Mls-1a on T cell receptor V beta.

Superantigen bound to major histocompatibility complex (MHC) products have been shown to stimulate T cells in a V beta-specific manner. Mouse T cells bearing V beta 8.1 usually respond to the self superantigen, Mls-1a, whereas T cells bearing V beta 8.2a do not. Previously, using site-directed mutational analysis, we identified the residues of natural variants of T cell receptor (TCR) V beta 8.2 that conferred Mls-1a reactivity. These residues are predicted to lie on a beta-pleated sheet of the TCR V beta element, well away from the expected binding site for antigen and MHC proteins. This study was undertaken to determine the effect of glycosylation on this beta-pleated sheet on Mls-1a reactivity and to map the extent of the interaction site on V beta 8.2 for Mls-1a. to Mls-1a, as well as to peptides derived from the conventional protein antigen, chicken ovalbumin. Here we demonstrate that first, N-linked carbohydrate on the lateral surface of V beta blocks the interaction of the TCR V beta with the self superantigen, Mls-1a, but has no effect on the TCR interaction with peptide antigen and MHC, second, that the interaction site for Mls-1a extends over the surface of the solvent-exposed beta-pleated sheet on the side of the TCR, and third, that mutations which affect both superantigen and peptide antigen reactivity lie at the beginning of the first complementarity determining region of V beta, consistent with models of the trimolecular complex of TCR-peptide-MHC.

Animals↗

PubMed1991

A T helper cell hybridoma produces an antigen-specific regulatory activity. Relationship to the T cell receptor by serology and antigenic fine specificity.

We have previously shown that a T cell hybridoma, A1.1, constitutively produces an Ag-specific regulatory factor with specificity for poly-18, a synthetic polypeptide. This cell also responds to poly-18 plus I-Ad by producing lymphokines. The antigenic specificity of the factor and the T cell appeared to be the same. This suggested the possibility that some part of the TCR, responsible for antigenic specificity of the cell, also imparts specificity to the A1.1-derived factor. This was supported by the observation that the factor was bound and eluted from a monospecific anti-TCR antiserum. Further, we demonstrated that antisense oligodeoxynucleotides corresponding to the TCR V alpha of A1.1 (but not TCR V beta) block production of the Ag-specific factor. Herein, we report recent findings that strengthen the proposed relationship between the TCR and the A1.1-derived factor. The factor was bound and eluted from a monoclonal anti-TCR C alpha antibody, but not from anti-TCR beta, anti-V beta 6, nor anti-CD3 epsilon. The anti-TCR C alpha antibody bound a Mr 46-kDa protein from A1.1 supernatants, which is the same apparent size at which activity could be eluted from an SDS-PAGE gel separation of concentrated factor. Antigenic fine-specificity analysis revealed that two amino acids in poly-18 are critical for the recognition of the antigen by the Ag-specific factor. These two amino acids appear to be those recognized by the TCR. The factor that was bound and eluted from the monoclonal anti-TCR C alpha showed this fine-specificity as well. This, combined with our earlier studies, supports the view that the A1.1-derived factor is encoded, at least in part, by TCR-alpha.

Amino Acid Sequence↗

PubMed1991

T-cell development and transmembrane signaling: changing biological responses through an unchanging receptor.

The antigen receptor repertoire is conditioned by discriminating forces in the thymus. Cells that see antigen only in the context of self major histocompatibility gene products are positively selected and those that recognize self antigens are deleted. The molecular mechanisms by which this complex conditioning is achieved via a single antigen receptor is one of the most fascinating problems in immunology. Here Terri Helman Finkel and colleagues review the literature and present a unifying mechanistic model of this process.

Animals↗

PubMed1990

Cloned suppressor T cells derived from mice tolerized with conjugates of antigen and monomethoxypolyethylene glycol. Relationship between monoclonal T suppressor factor and the T cell receptor.

Cloned Ts cells specific for the Ag, human monoclonal (myeloma) IgG, were derived from spleen cells of mice that had been immunosuppressed by treatment with a tolerogenic conjugate of HIgG and monomethoxypolyethylene glycol. The cloned Ts cells (clone 23.32) suppressed in vitro antibody responses in an Ag-specific and MHC-restricted manner. By FMF with appropriate antibody reagents, these cells were shown to be Thy-1+, CD4-, CD5-, and CD8+ and to express CD3 and the alpha beta-TCR. These results are consistent with the view that Ts cells use Ag recognition structures similar to those reported for Th cells and CTL. A soluble factor (TsF) extracted from the cloned Ts cells also suppressed in vitro antibody responses in an Ag-specific and H-2Kd-restricted manner, i.e., restricted to MHC class I molecules. The suppressive activity of this TsF could be abrogated by addition of mAb H28-710 that reacts with a determinant on the alpha-chain of TCR. Moreover, the TsF bound to and could be recovered from an immunosorbent consisting of the anti-alpha-TCR mAb H28-710 coupled to Sepharose 4B. In contrast, the TsF was not bound by immunosorbents consisting of mAb to the beta-chain of TCR (H57-597) or to V beta 8 (F23.1). It was, therefore, concluded that the TsF of clone 23.32 is serologically related to the alpha-chain of the TCR; however, it is not identical to TCR, because it lacks the determinants expressed on the TCR beta-chain that are recognized by the two anti-beta mAbs used in this study.

Animals↗

PubMed1990

Expression of functional alpha beta T cell receptor gene rearrangements in suppressor T cell hybridomas correlates with antigen binding, but not with suppressor cell function.

We have examined the expression of TCR genes in 4-hydroxy-3-nitrophenyl-acetyl (NP)-specific Ts cell hybridomas. Each of three independently isolated hybridomas expressed in-frame TCR alpha-chain rearrangements derived from the original suppressor Ts cell. Different V alpha and J alpha gene segments were rearranged and expressed in each Ts cell line. The only TCR beta-chain expressed in these cells was derived from the BW5147 fusion partner. Expression of the BW5147 beta-chain was found to correlate with cell surface Ag binding, inasmuch as subclones derived from one of the original Ts lines expressed greatly reduced levels of beta-chain mRNA and no longer bound to NP-coupled RBC. Subclones that continued to express beta-chain mRNA did bind to NP-coupled RBC. This suggests that the Ag receptor on Ts hybridomas is a TCR-alpha beta dimer composed of a unique alpha-chain and the BW5147 beta-chain. Ag binding could be modulated by preincubation of Ts hybridoma cells with anti-TCR-alpha beta antibody, thereby supporting this conclusion. Suppressor factor activity was measured in the conditioned media of Ts subclones that differed by 250-fold in levels of beta-chain mRNA expression. No difference in suppressor factor activity was found; conditioned media from these subclones suppressed both plaque-forming cell responses and delayed-type hypersensitivity responses at approximately equivalent dilutions. Suppressor factor activity in the conditioned media of both a beta-chain negative subclone and a beta-chain positive subclone could be absorbed with an antibody that recognizes the TCR alpha-chain, but not with an antibody that recognizes the TCR beta-chain. We conclude that suppressor factor activity in the conditioned media of these Ts hybridomas is not derived from surface TCR-alpha beta receptors, although it does share TCR alpha-chain determinants.

Amino Acid Sequence↗

PubMed1990

DNP-specific/class I MHC-restricted suppressor molecules bear determinants of the T cell receptor alpha- and beta-chains. The V beta 8+ chain dictates restriction to either K or D.

To examine in greater detail the relationship between DNP-specific/class I MHC-restricted suppressor molecules (SSF) that inhibit contact sensitivity to 2,4-dinitrofluorobenzene and the receptors on the T cells that produce them, we have generated two T cell hybridomas that can be induced to produce and secrete these molecules. In order to become activated to produce SSF, the Ts 15.15 and 15.31 cells required recognition of complexes of DNP/Dd on presenting cells. The suppressor molecules produced by each of the Ts hybrids had the same specificity, recognizing DNP/Dd on cells in the immune lymph node cell target population. The activation of the Ts hybrids was blocked when the cells were treated with the anti-V beta 8 antibody F23.1 before coculture with the DNP-presenting cells. Reduction of the 15.15 and 15.31 SSF followed by affinity chromatography on DNP-bovine-gamma-globulin-Sepharose beads indicated that these molecules are dimers and that one of the chains (Ag-binding(AgB] binds to cellfree DNP and one (non-Ag-binding (NAgB) chain) does not. The AgB chain was found to express an epitope bound by a mAb specific for a TCR alpha-chain-constant region determinant. Alternatively, the NAgB chain expressed an epitope bound by the anti-V beta 8 mAb F23.1. Active hybrid suppressor molecules were generated by combining the NAgB chain from a DNP-specific/H-2Kd-restricted SSF (produced by Ts hybridoma 3-10) with the AgB chain from Ts 15.31 and by combining the NAgB chain from Ts cell 15.15 with the 3-10 AgB chain. In each case, the class I MHC element (i.e., Kd or Dd) restricting the activity of these hybrid SSF correlated with the source of the V beta 8+, NAgB chain. Thus, these secreted immunoregulatory molecules have the Ag/MHC specificity of the T cells producing them and are structurally and serologically related to the TCR-alpha/beta. The results further suggest that for some hapten-specific/class I MHC-restricted TCR, the alpha-chain may have avidity for the hapten and the beta-chain may dictate the MHC restriction element (K or D) recognized by the receptor.

Animals↗

PubMed1990

Antigen-specific and antibody-mediated growth inhibition of suppressor T cell hybridomas. Roles of H-2 and the CD3-T cell receptor-alpha/beta complex.

Eight different Ts cell hybridomas (including inducer (Ts1) and effector (Ts3) suppressor cells) specific for the 4-hydroxy-3-nitrophenyl acetyl (NP) hapten were tested for their ability to respond to Ag or anti-CD3 antibody in a growth-inhibition assay. Results suggest that the expression of the TCR-CD3 complex on Ts hybridomas is required for the Ag or anti-CD3-mediated growth inhibition. One of the CD3+, Ts hybridomas (CKB-Ts3-9.H3) was tested in detail; this CD4- effector suppressor cell hybridoma showed specific inhibition of growth in the presence of NP or NIP-coupled protein conjugates but not in the presence of other irrelevant hapten-protein conjugates. In addition, growth of this hybridoma was specifically inhibited by anti-CD3 and anti-TCR-alpha/beta antibodies but not by control hamster antibodies. In order to study the role of MHC molecules in Ag-mediated growth inhibition, Ts cell hybridomas were incubated with Ag (NP-keyhole limpet hemocyanin) in the presence of spleen cells from various H-2 congenic strains. The results suggest that the Ts hybridomas that express donor Ts-derived TCR beta-chain recognize Ag in an MHC-restricted manner, whereas the two Ts3 hybridomas that utilize BW5147-derived TCR-beta recognize Ag in H-2 unrestricted way. Co-incubation of anti-CD3 and anti-TCR-alpha/beta antibodies with specific Ag enhanced the Ag-mediated growth inhibition, whereas anti-LFA-1 antibody completely blocked the Ag-mediated effect. The combined data suggest that, like Th hybridomas, expression of CD3-associated-TCR complex is essential for the Ag responsiveness of Ts cell hybridomas.

Animals↗

PubMed1990

Relationships between antigen-specific helper and inducer suppressor T cell hybridomas.

Ts1, or inducer suppressor T cells, share many phenotypic and functional characteristics with helper/inducer subset of T cells. In order to evaluate the relationship between these cell types, we made a series of new Ts1 hybridomas by the fusion of Ts1 cells with the functionally TCR alpha/beta-negative BW thymoma (BW 1100). Three Ts1 hybridomas (CKB-Ts1-38, CKB-Ts1-53, and CKB-Ts1-81) were established that express TCR and produce Ag-specific suppressor factors constitutively, thus making it possible to study the nature and specificity of Ag receptors, MHC restriction, and lymphokine production by the Ts1 hybridomas. Results presented in this report demonstrate that all the Ts1 hybridomas described here express CD3-associated TCR-alpha beta. These three Ts1 hybridomas recognize Ag (NP-KLH) specifically in a growth inhibition assay and this recognition is restricted by IE molecules. Two of the hybridomas also produce IL-2 or IL-2 and IL-4 upon Ag-specific activation. Thus, by these three criteria the Ts1 hybridomas appear indistinguishable from Th cells. These three Ts1 hybridomas, however, release suppressor factors (TsF1) in the supernatant that suppress both in vivo DTH and in vitro PFC responses in an Ag-specific manner. Like the TsF1 factors characterized previously, the suppression mediated by these factors are Igh restricted and lack H-2 restriction. These factors mediate suppression when given in the induction phase but not during the effector phase of the immune response. The TsF1 factors are absorbed by Ag (NP-BSA), and anti-TCR affinity columns and the suppressor activity can be recovered by elution. The data are consistent with the interpretation that Ts1 inducer-suppressor T cells are related to Th cells; the feature that distinguishes these cells is the ability to produce Ag-binding factors that specifically suppress immune responses.

Animals↗

PubMed1989

Relationship between T cell receptors and antigen-binding factors. I. Specificity of functional T cell receptors on mouse T cell hybridomas that produce antigen-binding T cell factors.

Upon antigenic stimulation with OVA-pulsed syngeneic macrophages, the mouse T cell hybridoma 231F1 produced glycosylation inhibiting factor (GIF) having affinity for OVA and IgE-suppressive factors, whereas another T cell hybridoma, 12H5, cells produced OVA-binding glycosylation enhancing factor (GEF) and IgE-potentiating factor. The OVA-binding GIF from the 231F1 cells is an Ag-specific Ts cell factor, whereas OVA-binding GEF from the 12H5 cells is an Ag-specific augmenting factor. Both hybridomas express CD3 complex and functional TCR-alpha beta. Cross-linking of TCR-alpha beta or CD3 molecules on the hybridomas by anti-TCR-alpha beta mAb or anti-CD3 mAb and protein A resulted in the formation of the same factors as those obtained by the stimulation of the cells with OVA-pulsed syngeneic macrophages. It was also found that both the 231F1 cells and 12H5 cells formed IgE-binding factors upon incubation with H-2d and H-2b APC, respectively, with a synthetic peptide corresponding to residues 307-317 in the OVA molecules (P307-317). Six other synthetic peptides, including those containing the major immunogenic epitope, i.e., P323-339, failed to stimulate the hybridomas in the presence of APC. Indeed, all of the 10 T cell hybridoma clones, which could produce either OVA-binding GIF or OVA-binding GEF, responded to P307-317 and APC for the formation of IgE-binding factors. In contrast, GIF/GEF derived from six other hybridoma clones, whose TCR recognized P323-339 in the context of a MHC product, failed to bind to OVA-coupled Sepharose. The results indicate the correlation between the fine specificity of TCR and the affinity of GIF/GEF to the nominal Ag. The amino acid sequence of P307-317 suggested that TCR on the cell sources of Ag-binding factors are specific for an external structure of the Ag molecules.

Animals↗

PubMed1989

Relationship between T cell receptors and antigen-binding factors. II. Common antigenic determinants and epitope recognition shared by T cell receptors and antigen-binding factors.

The T cell hybridomas 231F1 and 12H5 constitutively secrete glycosylation-inhibiting factor (GIF) and glycosylation-enhancing factor (GEF), respectively, which lack affinity for OVA-coupled Sepharose. When the 231F1 and 12H5 cells were stimulated by OVA-pulsed syngeneic macrophages, however, GIF and GEF produced by the cells had affinity for OVA. Both the OVA-binding GIF from the 231F1 cells and OVA-binding GEF from the 12H5 cells bound to a mAb against TCR-alpha beta and a mAb against TCR-alpha, suggesting a serologic relationship between TCR and OVA-binding factors. However, the OVA-binding GIF and GEF bound to mAb 14-12 and 14-30, respectively. Because these mAb do not bind TcR alpha beta-chains, it appears that the Ag-binding factors are different from TCR itself. The OVA-binding factors from both 12H5 cells and 231F1 cells do not bind to urea-denatured OVA. The binding of the factors to OVA Sepharose was inhibited by a peptide corresponding to residues 307-317 (P307-317) in the native OVA, but not by the peptide corresponding to residues 323-339 (P323-339). Furthermore, the OVA-binding factors bound to P306-319-coupled Sepharose but not to P323-339-coupled Sepharose, and were recovered by elution of the former Sepharose at acid pH. The binding of OVA to anti-OVA antibodies was not inhibited by either peptide. Inasmuch as the 231F1 cells and 12H5 cells can be stimulated by P307-317 in the context of a MHC product, it appears that the Ag-binding factors and TCR-alpha beta on the cell sources of the factors may recognize the same epitope in the OVA molecules. The results also showed that Ag-binding factors and antibodies recognize distinct epitopes in the Ag molecules.

Animals↗

PubMed1989

Limited receptor repertoire in a mycobacteria-reactive subset of gamma delta T lymphocytes.

The physiological role of lymphocytes bearing the gamma delta T-cell receptor (TCR) is still unclear. A function for a subset of these cells, however, is inferred from the finding that certain gamma delta chain-bearing lymphocytes are stimulated in a receptor-dependent fashion by mycobacterial antigens. We found that hybridomas derived from such cells in newborn murine thymus not only responded to mycobacterial purified protein derivative (PPD), but also exhibited an apparent autoreactivity. In neither response was haplotype-specific major histocompatibility (MHC) restriction demonstrable. To investigate the nature of antigen recognition by these gamma delta+ cells, we sequenced the gamma- and delta-chains from 28 PPD-reactive hybridomas, and found that a specific gamma-chain, together with one of a limited set of delta-chains, was needed to generate the PPD specificity. The reactive gamma delta pairs exhibited considerable junctional diversity, which may act to produce differences in the fine specificities of the responding cells.

Amino Acid Sequence↗