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T Boon

Publications and source records attributed to T Boon.

At least 163 records · Page 9Linked to original sources
PubMed1989

Presence on a human melanoma of multiple antigens recognized by autologous CTL.

We derived from blood lymphocytes of a melanoma patient a large number of cytolytic T-cell clones directed against a cell line of the autologous tumor. Three distinct groups of antigens were recognized by these CTL on the autologous melanoma cells: group A consisted of stable antigens present on all sublines, whereas antigens B and C appeared unstable and were expressed by distinct sublines. In vitro immunoselections with various anti-A CTL clones were applied to the melanoma cells and variants resistant to 3 different CTL clones were obtained. These variants remained sensitive to other anti-A CTL clones, indicating that group A comprises at least 4 different antigens (D, E, F and A'). From a total of 76 CTL clones obtained from lymphocytes collected from the patient at various times, we found that 45 were anti-B, 17 were anti-C, 2 were anti-D, 9 were anti-E, 2 were anti-F and I was anti-A'. It is therefore likely that the 6 antigens identified by these CTL clones represent all or nearly all the transplantation antigens recognized by autologous CTL on this human melanoma.

Antigens, Neoplasm↗
PubMed1989

Structure of the gene of tum- transplantation antigen P91A: the mutated exon encodes a peptide recognized with Ld by cytolytic T cells.

Mutagen treatment of mouse P815 tumor cells produces immunogenic mutants that express new transplantation antigens (tum- antigens) recognized by cytolytic T cells. We found that the gene conferring expression of tum- antigen P91A contains 12 exons, encoding a 60 kd protein lacking a typical N-terminal signal sequence. The sequence shows no significant similarity with sequences in current data bases. A mutation that causes expression of the antigen is located in exon 4; it is the only apparent difference between the normal and the antigenic alleles. A short synthetic peptide corresponding to a region of exon 4 located around this mutation makes P815 cells sensitive to lysis by anti-P91A cytolytic T cells. The mutation creates a strong aggretope enabling the peptide to bind the H-2 Ld molecule. Several secondary tumor cell variants that no longer express tum- antigen P91A were found to carry deletions in the gene.

Amino Acid Sequence↗
PubMed1989

T cell-recognized antigenic peptides derived from the cellular genome are not protein degradation products but can be generated directly by transcription and translation of short subgenic regions. A hypothesis.

It is now widely accepted that cytolytic T cells recognize their antigens in the form of small peptides bound to major histocompatibility complex molecules at the surface of the target cells. We present here the hypothesis that, when these antigenic peptides are derived from the cellular genome, they are not degradation products of cellular proteins but can be generated directly by the autonomous transcription and translation of short subgenic regions that we propose to name "peptons". We discuss some consequences of the notion that antigenic peptides can be produced in the absence of synthesis of messenger RNA and protein from the corresponding genes.

Animals↗
PubMed1989

Cytolytic T-cell clones against an autologous human melanoma: specificity study and definition of three antigens by immunoselection.

Cytolytic T-lymphocyte (CTL) clones against an autologous melanoma (SK-MEL-29) were generated by mixed lymphocyte tumor culture and subsequent cloning of responder lymphocytes at limiting dilutions. These CTL clones lysed autologous melanoma but not autologous Epstein-Barr virus-transformed B cells and none of the allogeneic tumor targets included in the specificity analysis. The lysis of autologous melanoma targets could be inhibited by monoclonal antibodies against monomorphic HLA class I determinants. For proliferation of CTLs, the stimulation with the relevant target antigen on autologous tumor cells was essential. Immunoselection experiments carried out with two CTL clones revealed the existence of melanoma subclones that were resistant to lysis by the CTL clones used for immunoselection but were still lysed by other autologous CTL clones. This analysis allowed us to identify three stable simultaneously expressed antigens on the melanoma cells defined by autologous CTLs.

Adult↗
PubMed1988

cDNA cloning of murine interleukin-HP1: homology with human interleukin 6.

Interleukin-HP1 (HP1) is a murine T cell-derived lymphokine, originally described as a growth factor for B cell hybridomas and plasmacytomas, that was recently shown to stimulate growth and differentiation of normal B and T lymphocytes. Here, we describe a cDNA for HP1 that was isolated from a library prepared using mRNA of a murine helper T cell clone activated with a clonotypic antibody. The cDNA, which hybridizes with a mRNA of approximately 1300 bp, encodes a polypeptide consisting of 211 amino acids with a typical signal sequence of 24 residues followed by 187 amino acids, which form the mature protein (Mr = 21,710). No N-glycosylation site but several potential O-glycosylation sites were identified in the predicted sequence. Comparison of the cDNA sequence of HP1 with that of human interleukin 6 disclosed a homology of 65% at the DNA level and of 42% at the protein level with a maximum of 57% for the segment spanning residues 42-102 of mature HP1. Considering the functional homology that was previously established between these two proteins, we therefore propose that HP1 be renamed murine interleukin 6.

Amino Acid Sequence↗
PubMed1988

Antigenic heterogeneity of a human melanoma tumor detected by autologous CTL clones.

Peripheral blood lymphocytes from a melanoma patient were stimulated with autologous melanoma cells in mixed lymphocyte tumor cultures (MLTC). After three restimulations, the lytic activity of the responder cells directed against the autologous melanoma cells was higher than that against K-562 and autologous Epstein-Barr virus-transformed B cell line (EBV-B) cells. From these MLTC-responder cells, we derived specific cytolytic T cell (CTL) clones that lysed the autologous melanoma cells and did not lyse K-562 or autologous EBV-B cells. Autologous melanoma clones were found that were resistant to some or all of these CTL clones. The autologous CTL clones recognized at least two different antigens (A, B) on the melanoma cells and three types of melanoma clones could be distinguished (A+B+, A+B-, A-B-). This antigenic heterogeneity of melanoma clones was confirmed by testing the CTL clones in cold target competition and also in antigen-dependent CTL proliferation assays performed with very small numbers of stimulator cells. The data further indicated an instability of the expression of a melanoma-associated antigen in the course of a long culture period. Among the melanoma clones that expressed antigen A, one was found to stimulate the proliferation of anti-A CTL clones much more effectively than the others. This represents a new type of heterogeneity among tumor cells which may be of significance for the elicitation of an autologous anti-tumoral immune response.

Adult↗
PubMed1988

Cytolytic response of human T cells against allogeneic small cell lung carcinoma treated with interferon gamma.

Human lymphocytes stimulated in vitro by allogeneic small cell lung carcinoma cell lines did not show any significant cytolytic activity against the stimulator tumor cells. However, a high level of lysis was observed when both stimulator and target small cell lung carcinoma cells were pretreated with interferon gamma, which increased considerably the expression of major histocompatibility class I molecules by these cells. The demonstration that small cell lung carcinoma cells can be lysed by cytolytic T lymphocytes, suggests that it will be feasible to study the autologous T cell response of patients against this tumor.

Carcinoma, Small Cell↗
PubMed1988

Immunogenic (tum-) variants of mouse tumor P815: cloning of the gene of tum- antigen P91A and identification of the tum- mutation.

Mutagen treatment of mouse P815 tumor cells produces tum- variants that are rejected by syngeneic mice because these variants express new surface antigens. These "tum- antigens" are recognized by cytolytic T lymphocytes but induce no detectable antibody response. Transfection of P815 cell line P1.HTR with DNA of tum- variant P91 yielded transfectants expressing tum- antigen P91A. They were detected by their ability to stimulate proliferation of cytolytic T lymphocytes [Wölfel, T., Van Pel, A., De Plaen, E., Lurquin, C., Maryanski, J. L. & Boon, T. (1987) Immunogenetics 26, 178-187]. A cosmid library of a cell line expressing antigen P91A was transfected into P1.HTR. Transfectants expressing the antigen were obtained. By packaging directly the DNA of a transfectant with lambda phage extracts, we obtained a small cosmid population containing as major component a cosmid that transferred the expression of P91A. The assay of various restriction fragments of this cosmid led to the isolation of an 800-base-pair fragment containing the P91A sequence required for transfection. Comparison with a homologous cDNA showed that this fragment contained only one of the several exons of the P91A gene. The normal and the tum- forms of the gene differ by one nucleotide located in this 137-base-pair exon. The essential role of this mutation, which produces an amino acid change, was confirmed by site-directed mutagenesis. No significant sequence similarity was found between the 800-base-pair fragment and any recorded gene.

Amino Acid Sequence↗
PubMed1988

Identification of genes encoding T cell defined tum- antigens.

Tum- mutants are immunogenic mutants obtained by mutagen treatment of mouse tumor cells. They express new "tum- antigens" recognized by cytolytic T cells (CTL) but not by specific antibodies. We have recently developed a method aimed at cloning the genes coding for such transplantation antigens. It is based on gene transfection and detection of transfectants by their ability to stimulate CTL. Tum- gene P91A has been isolated. It codes for a 60 kDa protein which does not carry a signal sequence at its N-terminus. The tum- allele differs from its normal counterpart by a point mutation. The sequence of this gene and that of two other tum- genes are totally unrelated with each other and with any sequence presently recorded in data banks. We will try to apply the same cloning method to isolate mouse and human tumor-specific transplantation antigens (TSTA).

Animals↗
PubMed1987

Production of stable cytolytic T-cell clones directed against autologous human melanoma.

We have attempted to optimize the production of stable human cytolytic T lymphocyte clones directed against autologous melanoma cell lines. MLTC were restimulated every week with irradiated melanoma cells in medium containing human serum and IL-2. After 21 to 35 days, in 5 out of 6 patients, these cultures expressed a preferential cytolytic activity against the autologous melanoma cells, as compared to autologous EBV-B cells or NK target K562. Limiting dilution of MLTC responder cells was performed at times varying from days 7 to 28, in medium containing IL-2 and allogeneic EBV-B cells as feeders. Approximately 1% of these responder cells gave rise to CTL clones that lysed the autologous melanoma cells, but did not lyse K562 or autologous B cells. It was possible to maintain in culture for several months a large number of CTL clones that retained this specificity with high activity, and multiplied more than 5-fold every week. Some of these CTL clones were dependent on the presence of the autologous melanoma cells for their growth. With one melanoma, the use of autologous CTL clones made it possible to identify 3 different antigens on the tumor cells.

Antigens, Neoplasm↗
PubMed1987

Immunogenic (tum-) variants obtained by mutagenesis of mouse mastocytoma P815. VIII. Detection of stable transfectants expressing a tum- antigen with a cytolytic T cell stimulation assay.

Mutagen treatment of mouse mastocytoma P815 produces highly immunogenic "tum-" variants. Most of these variants express potent transplantation antigens which are not present on the original P815 tumor cells. These tum- antigens, which appear to be specific for each variant, elicit a strong cytolytic T lymphocyte (CTL) response, but do not seem to induce a specific antibody response. As a first step in the isolation of the gene of a tum- antigen, we attempted DNA-mediated gene transfer. As a DNA recipient cell we used P1.HTR, a highly transfectable P815 cell line, whose selection has been previously described. For the detection of antigen-expressing cells in transfected populations we developed a procedure that relies on the ability of these cells to stimulate the proliferation of the relevant CTL. Using DNA from tum- variant P91 mixed with a plasmid carrying an antibiotic resistance gene, we obtained several independent transfectants expressing a tum- antigen, at a frequency of approximately 1 in 13,000 antibiotic-resistant transfectants. These transfectants express only one of the two tum- antigens that were identified on P91, suggesting that these tum- antigens correspond to different genes. We expect that the detection procedure described here will be suitable for the identification of transfectants for any gene that determines the expression of an antigen recognized by CTL.

Animals↗
PubMed1987

Variants with reduced virulence derived from Leishmania major after mutagen treatment.

After several in vitro treatments of a virulent population of Leishmania major with the mutagen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), five clones (vir-) were obtained that did not produce cutaneous lesions after subcutaneous injection of 10(6) promastigotes. All the control clones (vir+) obtained from the non-mutagenized parasite population produced progressive cutaneous lesions with as few as 10(3) parasites. Late lesions were observed occasionally after injection of 10(7) vir- parasites. These late lesions appeared to result from the selection of virulent revertants, since parasites isolated from these lesions produced progressive lesions in BALB/c mice almost as readily as the control parasites. Two vir- clones, one vir+ clone and one revertant clone were examined for survival in BALB/c macrophages in vitro. All clones were taken up by the macrophages and transformed into amastigotes. However, vir- clones failed to multiply inside the macrophages. A vir- clone was found to protect mice against a subsequent challenge with vir+ parasites.

Agglutination↗
PubMed1985

Use of irradiated mouse fibroblasts to improve the cloning and adaptation to culture of human melanoma cells.

By using irradiated BALB/c 3T3 mouse fibroblasts as feeder cells, we obtained a marked increase in the cloning efficiency of the 9 human melanoma cell lines that were tested. Four of these melanoma lines had a cloning efficiency that was lower than 0.0007 in the absence of feeder cells. In the presence of irradiated 3T3 cells, their cloning efficiency ranged from 0.017 to 0.26. For most melanoma cell lines the growth rate of cultures that were seeded at a low cell density was also increased by the use of 3T3 feeder cells. In high-density cultures, no effect was observed with most cell lines. The 3T3 effect was reversible. The pattern of surface antigens expressed by melanoma cells grown in the presence of 3T3 was similar to that observed without 3T3. The effect of feeder cells on the adaptation to culture of 5 primary melanomas was also tested. A definite improvement in cell yield was obtained with 4 of these melanomas.

Animals↗