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C J Melief

Publications and source records attributed to C J Melief.

At least 19 recordsLinked to original sources
PubMed1992

Genomic organization and chromosomal localization of the human CD27 gene.

CD27 is a lymphocyte-specific member of a recently identified receptor family with at least 10 members that includes the receptors for nerve growth factor and TNF, CD40, and Fas. Several members of this family play a role in cell differentiation, proliferation, and survival. Within the amino terminal ligand binding domain of these receptors, repeat motifs have been identified. These repeats contain many cysteine residues in a conserved pattern, characteristic of this family. We have isolated and characterized the human CD27 gene to gain insight into the evolution of this type of receptor domain. The gene was localized on chromosome 12, band 12p13. Sequence analysis showed no correlation between the intron/exon organization and the subdivision of the protein into distinct domains. Structural information for the cysteine-rich domain is contained within three exons. In addition, the splice sites in the CD27 gene are located in a different position from those in the related nerve growth factor receptor gene. However, a comparison of the splice sites within the regions encoding the respective ligand-binding domains of the CD27 and nerve growth factor receptor genes identifies the archetypal cysteine-rich building blocks, from which the members of this family may have arisen during the course of evolution. From this observation, we propose a new organization of the repeat motifs.

Amino Acid Sequence↗
PubMed1992

A rapid isolation procedure for dendritic cells from mouse spleen by centrifugal elutriation.

The standard isolation procedure for antigen presenting dendritic cells (DC) takes 2 days and includes selective adherence to tissue culture plates which may lead to the activation of these cells. This report describes the isolation of DC by centrifugal elutriation (CE). Murine spleen cells were separated on the basis of size and density into 7 CE fractions. This method took 90 min. Cells from each CE fraction were characterized by fluorescence activated cell sorter (FACS) analysis and their antigen presenting cell (APC) activity was determined by a secondary Sendai virus specific T cell proliferation assay. CE fraction 5 contained most of the DC with a concentration of 6-10%, representing an approximately 15-fold enrichment compared to unseparated spleen cells (< 1% DC). This CE fraction also exhibited the highest APC activity, which was almost completely abolished after depletion of DC by treatment with monoclonal antibody 33D1 (DC-marker) and complement. Further enrichment of CE fraction 5 by discontinuous density gradient centrifugation resulted in a cell population containing 35-55% 33D1-positive cells with similar characteristics as DC isolated by the standard procedure, such as the capacity to induce a primary viral peptide specific CTL response. Two-color FACS analysis showed an increase in MHC expression on 33D1-positive cells of CE fraction 5 after 18 h culture involving cell adhesion to a similar level as the MHC expression on DC isolated by the standard procedure. During this same period their morphology changed from a round to a dendritic appearance. In conclusion, our results indicate that CE is well suited for isolating DC more rapidly and without activation of these cells by adherence, a process which readily occurs in the standard isolation procedure.

Animals↗
PubMed1992

Role of LFA-1 and VLA-4 in the adhesion of cloned normal and LFA-1 (CD11/CD18)-deficient T cells to cultured endothelial cells. Indication for a new adhesion pathway.

Patients with the leukocyte adhesion deficiency (LAD) syndrome have a genetic defect in the common beta 2-chain (CD18) of the leukocyte integrins. This defect can result in the absence of cell surface expression of all three members of the leukocyte integrins. We investigated the capacity of T cell clones obtained from the blood of an LAD patient and of normal T cell clones to adhere to human umbilical vein endothelial cells (EC). Adhesion of the number of LAD T cells to unstimulated EC was approximately half of that of leukocyte function-associated antigen (LFA)-1+ T cells. Stimulation of EC with human rTNF-alpha resulted in an average 2- and 2.5-fold increase in adhesion of LFA-1+ and LFA-1- cells, respectively. This effect was maximal after 24 h and lasted for 48 to 72 h. The involvement of surface structures known to participate in cell adhesion (integrins, CD44) was tested by blocking studies with mAb directed against these structures. Adhesion of LFA-1+ T cells to unstimulated EC was inhibited (average inhibition of 58%) with mAb to CD11a or CD18. Considerably less inhibition of adhesion occurred with mAb to CD11a or CD18 (average inhibition, 20%) when LFA-1+ T cells were incubated with rTNF-alpha-stimulated EC. The adhesion of LFA-1- T cells to EC stimulated with rTNF-alpha, but not to unstimulated EC, was inhibited (average inhibition, 56%) by incubation with a mAb directed to very late antigen (VLA)-4 (CDw49d). In contrast to LAD T cell clones and the LFA-1+ T cell line Jurkat, mAb to VLA-4 did not inhibit adhesion of normal LFA-1+ T cell clones to EC, whether or not the EC had been stimulated with rTNF-alpha. We conclude that the adhesion molecule pair LFA-1/intercellular adhesion molecule (ICAM)-1 plays a major role in the adhesion of LFA-1+ T cell clones derived from normal individuals to unstimulated EC. Adhesion of LFA-1-T cells to TNF-alpha-stimulated EC is mediated by VLA-4/vascular cell adhesion molecule (VCAM)-1 interactions. Since we were unable to reduce significantly the adhesion of cultured normal LFA-1+ T cells to 24 h with TNF-alpha-stimulated endothelium with antibodies that block LFA-1/ICAM-1 or VLA-4/VCAM-1 interactions, and lectin adhesion molecule-1 and endothelial leukocyte adhesion molecule-1 appeared not to be implicated, other as yet undefined cell surface structures are likely to participate in T cell/EC interactions.

Cell Adhesion↗
PubMed1992

Protection from lethal graft-vs.-host disease by donor stem cell repopulation.

Graft-vs.-host reaction (GVHR) induced in non-irradiated F1 mice with DBA/2J parental spleen and lymph node (LN) cells usually does not lead to acute GVH disease (GVHD). This contrasts with the GVHR induced in other parent-F1 combinations involving both major histocompatibility complex (MHC) class I and class II differences between donor and host. Most signs of acute GVHD in non-irradiated F1 mice relate to immunodeficiency following destruction of the lymphohemopoietic system of the host, which leads to wasting and death due to infections. This sequence of events is prevented when donor lymphoid cells, originating from grafted stem cells, repopulate the destroyed lymphohemopoietic system of the host. To examine whether a "silent" repopulation of the F1 host by donor stem cells might underly the absence of clinical signs of acute GVHD when GVHR is induced with DBA/2J lymphoid cells, GVHR was induced with LN cells, which do not contain stem cells. Indeed, GVHR induced in (C57BL/10 x DBA/2J)F1 (BDF1) mice with 80 x 10(6) DBA/2J LN cells led to acute GVHD. Signs of acute GVHD such as wasting and death did not occur when donor stem cells, from an inoculum of DBA/2J spleen and LN cells, were allowed to repopulate the lymphohemopoietic system of the host. The effect of donor stem cells on clinical signs of acute GVHD was more apparent when (B10.D2 x DBA/2J)F1, instead of DBA/2J, lymphoid cells were used to induce GVHR. The detection of alloreactive anti-host cytotoxic T lymphocyte (CTL) activity during acute GVHD induced with DBA/2J donor lymphoid cells supports the hypothesis that such CTL contribute to the destruction of the host immune system in acute GVHD.

Animals↗
PubMed1992

Both LFA-1-positive and -deficient T cell clones require the CD2/LFA-3 interaction for specific cytolytic activation.

We investigated the capacity of T lymphocytes from a leukocyte adhesion-deficient (LAD) patient to respond to alloantigen. Leukocytes of this patient completely lacked LFA-1 surface expression due to the absence of mRNA coding for the LFA-1 beta chain. Despite the absence of LFA-1, T lymphocytes obtained from this patient, cultured with allogeneic stimulator cells (lymphoblastoid B cells JY), were capable of lysing JY cells. Furthermore, two T cell clones (one CD4+ and one CD8+), generated from this lymphocyte culture, specifically lysed the allogeneic lymphoblastoid JY cells. The cytolytic capacity of LFA-1-negative T lymphocytes and T cell clones was comparable to that of control LFA-1-positive T cells with allospecificity against JY. Detailed analysis of the CD4 positive and LFA-1-negative T cell clone demonstrated that it specifically recognized HLA-DQ. Antibody inhibition studies showed that the CTL/target cell interaction was mediated through the CD2/LFA-3 adhesion pathway. LFA-1 expressed by the target cells did not participate in the CTL/target cell conjugate formation and contributed only minimally to the cytotoxic activity. Moreover, when allogeneic LFA-1-deficient B cells, bearing the appropriate HLA-DQ alloantigen, were used as target cells, significant levels of specific cytotoxicity were measured, further excluding a role for LFA-1 in this interaction. The adhesion molecules, VLA-4, CD44 and L-selectin (LECAM1) were not involved. These results demonstrate that LFA-1-negative T lymphocytes can exert allospecific cytotoxicity and that CTL/target cell contact is mediated through the CD2/LFA-3 route. This observation may explain in part why in LAD patients viral infections, cleared largely by T cells, are less frequently observed than bacterial infections, in which phagocytic cells play a major role.

Antibodies, Monoclonal↗
PubMed1992

Cytotoxic T lymphocytes against the antigen-processing-defective RMA-S tumor cell line.

RMA-S is an antigen processing-defective cell line, obtained from a Rauscher virus-induced tumor. The cells express only a low level of cell surface major histocompatibility complex (MHC) class I molecules, which are supposed to be devoid of internally derived antigenic peptides. We investigated Rauscher virus expression and Rauscher peptide presentation to virus-specific cytotoxic T lymphocytes (CTL) by this cell line. Viral proteins are expressed properly, both intracellularly and at the cell surface of RMA-S. Rauscher peptides are presented to virus-specific CTL in the groove of both the class I H-2Kb and Db molecules, but at a low level. Culture of RMA-S cells at room temperature increases their susceptibility to CTL. The RMA-S defect thus affects, but not totally abrogates, Rauscher peptide presentation by MHC class I molecules via the endogenous pathway. This indicates that the RMA-S antigen processing deficit is not absolute.

Animals↗
PubMed1992

Processing and presentation of intact hen egg-white lysozyme by dendritic cells.

Dendritic cells in lymphoid tissues are of key importance as highly specialized antigen-presenting cells for the induction of T lymphocyte responses. Conflicting results have been published regarding antigen processing of intact proteins by dendritic cells. We now report that highly purified dendritic cells isolated from H-2k mouse spleens very efficiently generated immunogenic fragments of intact hen egg-white lysozyme (HEL) protein to present to an I-Ak-restricted T hybridoma cell line, specific for HEL peptide 46-61. Dendritic cells required 100 times less HEL protein than lipopolysaccharide-induced B cell blasts for effective presentation. Uptake of 125I-labeled HEL protein by dendritic cells and inhibition of presentation of HEL protein by chloroquine treatment was observed. This indicates an endocytotic process and the involvement of acidified compartments. Since the supernatant of dendritic cells, that were incubated with intact HEL protein, contained immunogenic fragments, further evidence for processing of HEL protein by dendritic cells was obtained. When HEL protein was covalently coupled to beads, dendritic cells were not able to ingest these beads, but could still process HEL protein for presentation. This suggests cell surface processing of HEL protein, although internalization of HEL protein released from the beads cannot be excluded. Taken together, these data show that H-2k dendritic cells are capable of processing and presenting intact HEL protein.

Animals↗
PubMed1992

Mechanisms of induction of primary virus-specific cytotoxic T lymphocyte responses.

We have investigated the ability of various antigen-presenting cell (APC) types to induce primary anti-viral cytotoxic T lymphocyte (CTL) responses by single in vitro stimulation. Of these APC types, only dendritic cells (DC) and RMA-S lymphoma cells could induce primary CTL responses, but by divergent mechanisms. DC were capable of generating primary virus-specific CTL, either by presenting viral peptide or processed infectious virus. In contrast, RMA-S cells could not present endogenous antigen, e.g. after virus infection, but this cell line very efficiently presented exogenous viral peptides to induce primary virus-specific CTL in vitro. Spleen cells, lipopolysaccharide-induced B cell blasts or the non-mutated RMA cells did not have the ability to trigger unprimed T cells by single in vitro stimulation. We have investigated several characteristics important for primary CTL response induction by DC and RMA-S cells (summarized in Fig. 6). Primary CTL response induction by DC or RMA-S cells was blocked by anti-LFA-1 or anti-CD8 monoclonal antibodies (mAb). DC rapidly aggregated with unprimed T cells, which was independent of LFA-1 and CD8 molecules. RMA-S cells did not form conjugates with unprimed T cells. Despite their abundant major histocompatibility complex (MHC) class I cell-surface expression, DC did not bind much exogenously added viral peptide. In contrast, the MHC class I molecules on RMA-S cells bound a large quantity of exogenously administered peptide. Powerful adhesion by DC and high expression of relevant MHC/peptide complexes on RMA-S cells are important features in the initial contact with unprimed T lymphocytes. In a later stage of contact, both DC and RMA-S cells activate LFA-1 (and CD8) molecules at the T cell surface to strengthen and maintain the contact between T cell and APC.

Amino Acid Sequence↗
PubMed1992

A phase I study of prolonged continuous infusion of low dose recombinant interleukin-2 in melanoma and renal cell cancer. Part I: Clinical aspects.

The optimal schedule for recombinant interleukin-2 (rIL-2) administration is unclear. Because the clinical and immunological effects of prolonged continuous exposure to rIL-2 are unknown, we have conducted a phase I study to assess the toxicity and feasibility of continuous low dose infusion of rIL-2 (EuroCetus) using central venous access with a portable infusion device on an out-patient basis. Twenty-two patients entered the study, 13 with melanoma and nine with renal cell cancer, age range 26-66 years (median 51), performance status less than or equal to 1. They were treated with one of the following doses per m2 per 24 h: 0.18 x 10(6) IU, 0.6 x 10(6) IU, 1.8 x 10(6) IU, 3 x 10(6) IU, 6 x 10(6) IU and 9 x 10(6) IU. Toxicity was evaluable in 20 patients receiving greater than or equal to 3 weeks treatment duration or in whom treatment was discontinued prematurely because of toxicity. Constitutional symptoms consisting of fatigue, malaise and fever up to 40 degrees C without significant organ dysfunction occurred with doses greater than or equal to 1.8 x 10(6) IU m-2. The maximum tolerated dose was 6 x 10(6) IU m-2 24 h-1. In all patients toxicity reached a peak at 3 weeks and resolved thereafter despite continued rIL-2 treatment. Peripheral blood eosinophilia (up to 66% of white blood cell count) followed the same pattern. An infection of the central venous access occurred in 55% of the patients but this was mostly asymptomatic. Thirteen patients were treated greater than or equal to 6 weeks and were evaluable for tumour response. A partial remission occurred in a patient with melanoma with a dose of 1.8 x 10(6) IU rIL-2 m-2 24 h-1.

Adult↗
PubMed1992

Adhesion of T and B lymphocytes to extracellular matrix and endothelial cells can be regulated through the beta subunit of VLA.

Investigating the regulation of very late antigen (VLA)-mediated functions, we found that TS2/16, a mAb directed against the beta chain of the VLA group of integrins, can induce binding of resting peripheral blood lymphocytes, cloned T lymphocytes, and Epstein Barr virus-transformed B cells to extracellular matrix components, fibronectin, laminin, and collagen, but not to fibrinogen. The antibody stimulates VLA-4-, VLA-5-, and VLA-6-mediated binding. Furthermore, it induces VLA-4-mediated binding to vascular cell adhesion molecule-1 expressed by rTNF-alpha-stimulated endothelial cells, but it does not stimulate homotypic aggregation of cells as described for a number of anti-VLA-4 alpha antibodies (Bednarczyk, J.L., and B. W. McIntyre. 1990. J. Immunol. 144: 777-784; Campanero, M. R., R. Pulido, M. A. Ursa, M. Rodríguez-Moya, M. O. de Landázuri, and F. Sánchez-Madrid. 1990. J. Cell Biol. 110:2157-2165). Therefore, the stimulating activity of this anti-beta 1 antibody clearly contrasts with that of the anti-VLA-4 alpha antibodies, which induce homotypic cell aggregation, but not binding of cells to extracellular matrix components or endothelial cells, indicating that TS2/16 may generate different signals. The observation that also F(ab')2 or Fab fragments of this anti-beta 1 antibody stimulate binding to extracellular matrix components and endothelial cells excludes the possibility that binding requires receptor crosslinking, or is Fc receptor mediated. Induction of this adhesion is cation and energy dependent and requires an intact cytoskeleton. Although changes in the conformation of VLA integrins induced by this antibody may regulate their functional activity, the dependence on metabolic energy indicates that intracellular processes may also play a role.

Antibodies, Monoclonal↗
PubMed1992

Lessons from T cell responses to virus induced tumours for cancer eradication in general.

Immunotherapy of virus induced tumours by adoptive transfer of virus specific cytotoxic T cells (CTL) is now feasible in experimental murine systems. These CTL recognize viral peptide sequences of defined length presented in the groove of MHC class I molecules. Effective eradication of large tumour masses requires coadministration of IL-2. In essence, T cell immunity against virus induced tumours does not differ from anti-viral T cell immunity in general. Tumour escape strategies are numerous but, in various instances, can be counteracted by defined measures. Initiation of CTL responses against poorly immunogenic non-virus induced tumours (the majority of human cancer) requires novel strategies to overcome T cell inertia. Rather than waiting to see whether tumour specific CTL (against unknown antigens) can be cultured from TIL, we propose an alternative strategy in which CTL are raised against target molecules of choice, including differentiation antigens of restricted tissue distribution (autoantigens) or mutated/overexpressed oncogene products. The various steps proposed include: (a) identification of target molecules of choice; (b) identification in these target molecules of MHC allele specific peptide motifs involved in peptide binding to MHC molecules; (c) evaluation of actual binding of such peptides to specific MHC class I molecules; (d) in vitro CTL response induction by such peptides, presented either by highly efficient antigen presenting cells (such as processing defective cells, which carry empty MHC class I molecules) loaded with a single peptide or by dendritic cells, both cell types being capable of primary CTL response induction in vitro and (e) adoptive transfer of tumour specific CTL generated in vivo or, more conveniently, vaccination with immunodominant peptides. The latter possibility seems to be feasible because peptide vaccination with a single immunodominant viral peptide can install CTL memory and confer protection against lethal virus infection.

Animals↗
PubMed1992

Polyclonal expansion of T-cell receptor-gamma delta+ T lymphocytes associated with neutropenia and thrombocytopenia.

A patient with large granular lymphocyte (LGL) expansion (T-gamma lymphocytosis), neutropenia and thrombocytopenia was studied longitudinally. Analysis of peripheral blood mononuclear cells (PBMC) demonstrated an unusual large proportion of CD3+ T-lymphocytes expressing a gamma delta T-cell receptor (TcR-gamma delta). Immunofluorescence (IF) stainings with subset-specific monoclonal antibodies showed a fluctuating expansion of TcR-gamma delta+ T-cells expressing V gamma 9 and V delta 2 variable (V) gene segments. Biochemical characterization of PBMC showed the presence of a disulphide-linked TcR-gamma delta. TcR gene rearrangement studies on sorted TcR-gamma delta+ T-cells showed rearrangements of V gamma 9-J gamma 1.2 and V delta 2-J delta 1 V and joining (J) gene segments, thereby confirming the IF staining results. These data alone did not allow us to determine whether the TcR-gamma delta+ LGL expansion represented a polyclonal or monoclonal proliferation, because the combinatorial repertoire of TcR-gamma delta receptors is limited due to the availability of only a few V and J segments within the TcR-gamma and TcR-delta genes and because of the preferential usage of V gamma 9-J gamma 1.2 and V delta 2-J delta 1 rearrangements by TcR-gamma delta+ T-cells in blood of healthy individuals. We therefore used polymerase chain reaction (PCR)-mediated amplification of the TcR-gamma delta rearrangements, using specific V gamma 9, J gamma 1.2, V delta 2, and J delta 1 oligonucleotides to determine the junctional diversity of the TcR-gamma delta+ T-cell population. Sequence analysis of the PCR products obtained revealed a mixture of different junctional region sequences compatible with a polyclonal expansion. This is in contrast to the few reported TcR-gamma delta+ LGL and the majority of TcR-alpha beta+ LGL expansions, which appeared to consist of monoclonal proliferations.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Pretransplantation blood transfusion revisited.

BACKGROUND: Blood transfusion before organ transplantation has a beneficial effect on allograft survival; the mechanism of this effect has remained a mystery. In murine models, the presence of common histocompatibility antigens in the blood donor and the recipient favors the induction of allograft tolerance. METHODS: To investigate the effect of HLA compatibility between blood donor and recipient on the induction of allograft tolerance, we determined the relative frequency of cytotoxic T-lymphocyte precursors specific for donor cells before and at several times after blood transfusion in 23 patients awaiting a first renal transplant. We correlated the results with the presence of shared HLA antigens. RESULTS: T-cell nonresponsiveness against donor cells developed after blood transfusion in 10 of the 23 patients. Tolerance developed only if the blood donor and the recipient had one HLA haplotype or at least one HLA-B and one HLA-DR antigen in common (as was observed in 9 of these 10 patients). Tolerance developed relatively late after blood transfusion (one to two months) and was long-lasting. No decline in the T-cell response against donor alloantigens was observed in any of the 13 patients who received transfusions without having HLA-antigen compatibility with the donor. CONCLUSIONS: Blood transfusion in which there is a common HLA haplotype or shared HLA-B and HLA-DR antigens induces tolerance to donor antigens. This finding may lead to the development of new strategies with which to induce tolerance for transplantation after blood transfusion. Perhaps transplant donors will be selected not only by HLA-antigen matching, but also on the basis of acceptable HLA-antigen mismatches associated with T-cell non-responsiveness induced by selected blood transfusion.

Blood Transfusion↗
PubMed1991

Peptide selection by MHC class I molecules.

Synthetic peptides have been used to sensitize target cells and thereby screen for epitopes recognized by T cells. Most epitopes of cytotoxic T lymphocytes can be mimicked by synthetic peptides of 12-15 amino acids. Although in specific cases, truncations of peptides improves sensitization of target cells, no optimum length for binding to major histocompatibility complex (MHC) class I molecules has been defined. We have now analysed synthetic peptide captured by empty MHC class I molecules of the mutant cell line RMA-S. We found that class I molecules preferentially bound short peptides (nine amino acids) and selectively bound these peptides even when they were a minor component in a mixture of longer peptides. These results may help to explain the difference in size restriction of T-cell epitopes between experiments with synthetic peptides and those with naturally processed peptides.

Amino Acid Sequence↗
PubMed1991

Protection against lethal Sendai virus infection by in vivo priming of virus-specific cytotoxic T lymphocytes with a free synthetic peptide.

The only peptide of Sendai virus that is recognized by cytotoxic T lymphocytes (CTL) in B6 mice was found with (i) the use of recombinant vaccinia virus constructs containing separate genes of Sendai virus and (ii) a set of overlapping peptides completely spanning the identified nucleoprotein (NP) gene product. This immunodominant NP peptide is recognized by Sendai virus-specific CTL that are known to have therapeutic effects in vivo. By subcutaneous immunization, this peptide induced Sendai virus and NP peptide-specific CTL memory responses in vivo. Most importantly, mice that had been immunized with this peptide were protected against a lethal virus dose, indicating that viral peptides can be used as antiviral T-cell vaccines. The induction of T-cell memory by free peptide immunization potentially has wide applicability in biology and medicine, including protection against infectious disease.

Animals↗
PubMed1991

Peptide loading of empty major histocompatibility complex molecules on RMA-S cells allows the induction of primary cytotoxic T lymphocyte responses.

The antigen processing-defective mutant cell line RMA-S expresses at the cell surface major histocompatibility complex (MHC) class I molecules devoid of peptide that can be efficiently loaded with exogenous immunogenic peptides. We now report that viral peptide-loaded RMA-S cells, unlike parental RMA cells, can induce primary cytotoxic T lymphocyte (CTL) responses in vitro, in a T helper cell-independent fashion. This was shown for an H-2Kb-binding peptide of Sendai virus nucleoprotein and an H-2Db-binding peptide of adenovirus type 5 E1A protein with responding spleen cells of C57BL/6 mice, the strain of origin of RMA and RMA-S cells. Primary Sendai peptide-induced CTL lyse both peptide-loaded and virus-infected cells. Pre-culture of RMA-S cells at low temperature (22 degrees - 26 degrees C), which increases the amount of empty MHC class I molecules at the cell surface, decreases the peptide concentrations required for the induction of primary CTL responses. Primary peptide-specific CTL responses induced by peptide-loaded RMA-S cells are CD4+ cell- and MHC class II+ cell-independent. CTL response induction is blocked by the presence of anti-CD8 monoclonal antibody during culture. Direct peptide binding studies confirm the efficient loading of empty MHC molecules on RMA-S cells with peptide and show 2.5-fold more peptide bound per RMA-S cell compared to RMA cells. An additional factor explaining the difference in primary response induction between RMA and RMA-S cells is related to the CD8 dependence of these responses. MHC class I molecules occupied with irrelevant peptides (a majority present on RMA, largely absent on RMA-S) may interfere in the interaction of the CD8 molecule with relevant MHC/peptide complexes. The results delineate a novel strategy of peptide based in vitro immunization to elicit CD8+ cytotoxic T cell responses.

Adenoviridae↗
PubMed1991

Fine peptide specificity of cytotoxic T lymphocytes directed against adenovirus-induced tumours and peptide-MHC binding.

A peptide encoded by the adenovirus type 5 early region I (Ad5 EI) is the target structure for H-2Db-restricted cytotoxic T lymphocytes (CTL) that are capable of tumour eradication in vivo. With the use of a set of peptides in which each individual amino acid (aa) was deleted out of the sequence, we analyzed to what extent these deletion mutant peptides were still recognized by an Ad5-specific CTL clone and which deletion mutant peptides still bound to major histocompatibility-complex (MHC) class-I molecules. Binding was analyzed with RMA-S cells that express largely empty and unstable MHC-class-I molecules which are stabilized by peptide binding. We show here that flanking an 8 mer aa sequence, originally described by us as the minimal epitope recognized by CTL, 2 additional aa are important for MHC binding. This leads to the conclusion that this 10-mer peptide is optimal for MHC binding and T-cell recognition. Areas of the peptide primarily involved in binding to MHC or in T-cell recognition are delineated.

Adenoviruses, Human↗