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Biomedical subjects

G Degiovanni

Publications and source records attributed to G Degiovanni.

At least 19 recordsLinked to original sources
PubMed2005

A peptide derived from melanocytic protein gp100 and presented by HLA-B35 is recognized by autologous cytolytic T lymphocytes on melanoma cells.

A panel of autologous cytolytic T lymphocyte (CTL) clones have been isolated from blood lymphocytes of a melanoma patient after in vitro stimulation with autologous tumor cells. We previously reported the molecular definition of three distinct antigens recognized by some of these CTL clones. We describe here, the identification of a fourth antigenic peptide expressed by this melanoma line and recognized by a CTL clone restricted by HLA-B*3503. The antigenic peptide, which is nine-amino acid long, has the sequence LPHSSSHWL and is derived from melanocyte differentiation antigen gp100. As HLA-B35 is one of the most frequent HLA-B alleles, being present in 20% of the Caucasian individuals, this peptide may be a good target for peptide-based immunotherapy of melanoma.

Amino Acid Sequence↗
PubMed1999

A tyrosinase peptide presented by HLA-B35 is recognized on a human melanoma by autologous cytotoxic T lymphocytes.

We previously described different cytotoxic T lymphocyte (CTL) clones isolated from the blood lymphocytes of a melanoma patient after in vitro stimulation with autologous tumor cells. These CTL clones recognized at least 2 distinct antigens on the melanoma cells. Here, we show that one of them consists of a peptide derived from tyrosinase and presented by HLA-B35. The peptide is 9 amino acids long and has the sequence LPSSADVEF. It can be presented by the 2 major B35 allelic subtypes, B*3501 and B*3503. As HLA-B35 is one of the most frequent HLA-B specificities, being present in about 20% of Caucasian individuals, it may be a useful target for peptide-based immunotherapy of melanoma.

Alleles↗
PubMed1993

Relevance of tumor necrosis factor to graft-versus-host disease after small bowel transplantation.

The small bowel (SB), an organ replete with lymphocytes, may provoke graft-versus-host disease (GVHD) after transplantation (Tx). Since tumor necrosis factor (TNF) has been suspected of mediating the tissue lesions of GVHD, we sought to determine whether TNF could be detected in the serum of rats undergoing GVHD after SBTx or lymphocyte transfer. For this purpose, postoperative serum TNF activity was determined in Lewis x Brown Norway (LBNF1) hybrid rats suffering from GVHD after undergoing transplantation of an entire (group 1; n = 8) or a segmental (group 2; n = 4) Lew SB, or after i.p. injection with lethal doses (500 x 10(6)) of Lew lymphocytes (group 3; n = 3). Control LBNF1 received i.p. small doses (50 x 10(6)) of Lew lymphocytes (group 4; n = 4). Serum TNF activity was assessed using the WEHI bioassay. In rats with acute and lethal GVHD after entire SBTx (group 1) or injection with large doses of lymphocytes (group 3), TNF activity gradually increased and reached high levels by the time the rats were agonal. In segmental SBTx rats (group 2), GVHD was less severe than in entire SBTx rats. Similarly, the increase in TNF activity was less intense and only transient since it had returned to control levels by the time the rats had completely recovered from GVHD. In control rats primed with small doses of lymphocytes (group 4), GVHD did not occur and no increase in TNF activity was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1993

Membrane translocation and relationship with MHC class I of a human thymic neurophysin-like protein.

Thymic epithelial and nurse cells (TEC/TNC) synthesize an oxytocin (OT)-like peptide in association with a neurophysin (NP)-related protein in a way similar to in the hypothalamo-neurohypophysial (NHP) system. The central T-cell tolerance of the NHP neuroendocrine functions have been proposed to be mediated through these thymic NHP-related peptides due to their close homology with the NHP neurohormones OT and vasopressin (VP). In order to investigate their putative presentation by proteins of the major histocompatibility complex (MHC), human thymic membranes were purified and passed through an immunoaffinity column using mAb B9.12 directed to the monomorphic determinant of human MHC class I proteins. This methodology provided the following observations: (1) a NP-like protein is translocated in human thymic membranes and is retained by B9.12 on the column; (2) the MW of this NP-like material (50-55 kD) is quite different from the MW of hypothalamic NP proteins (10 kD), and (3) this thymic NP-like protein could be identified on Western blots with mAb B9.12. The precise extent of this relationship between the thymic NP-like protein and the Ig/MHC superfamily is actually investigated through the characterization of the genetic mechanisms responsible for the thymic expression of NHP-related peptides. Given the physiological importance of OT and of its binding to NP for transport along the axonal processes of the NHP tract, we postulate that, somewhat analogously, the thymic NP-/MHC class I-related protein could be involved in the presentation of the OT-like peptide to immature T-cells.

Amino Acid Sequence↗
PubMed1990

Antigens recognized on a melanoma cell line by autologous cytolytic T lymphocytes are also expressed on freshly collected tumor cells.

Peripheral blood lymphocytes of a melanoma patient were stimulated in vitro with a permanent cell line derived from the autologous tumor. Stable cytolytic T lymphocyte (CTL) clones were obtained that lysed the melanoma cell line and did not lyse autologous Epstein-Barr virus-transformed B lymphocytes or K-562 cells. These CTL clones were directed against two distinct antigens on the melanoma line. In view of the possibility that these antigens could be culture artefacts, we tested the stimulatory ability of tumor cells that had been freshly collected from metastatic relapses on the CTL clones. A considerable CTL proliferation was observed and it appeared to be specific. We conclude that the antigens recognized by the autologous CTL clones on the permanent melanoma cell line were expressed by the tumor cells in the patient.

Antigens, Neoplasm↗
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

[Preliminary study on nerve regeneration through an autologous venous tube].

Large posttraumatic defects in the peripheral nervous system bring up serious problems to the surgeon. There is no definitive answer yet. The authors present a model for nervous regeneration studies; venous autograft was used to bridge defects in a divided rat sciatic nerve; the venous tube guided the regenerating axons towards the distal stump over up to 1.9 cm length. Preliminary studies about nervous regeneration stimulation with autologous Schwann cells are discussed.

Animals↗
PubMed1987

Suppression of cytolytic T-lymphocyte responses through inactivation of non-T accessory cells.

The suppressive properties of nonspecific cytotoxic T lymphocyte (CTL) populations, derived from murine fetal calf serum (FCS)-precultured cells expanded in interleukin 2 (operationally defined as FCS-CM-expanded cells), were investigated on CTL responses generated by syngeneic alloreactive lymphoid cells. Our results suggest that the addition of FCS-CM-expanded cell populations can inhibit the CTL response by elimination of the bone marrow-derived macrophage (BM M phi) population used as non-T accessory cells. Indeed, in the culture conditions used, removal of IL-2 by the FCS-CM-expanded cells as well as a direct inactivating effect on the CTL precursors (CTL-P) could be excluded as a reason for inhibition. On the other hand, we were able to show that the BM M phi population was very sensitive to the cytolytic activity exhibited by the inhibiting cells in a 3 h 51Cr-release assay and that the suppressor effect observed could be partially circumvented by a second addition of BM M phi on the second day after the initiation of the culture.

Antigen-Presenting Cells↗
PubMed1985

Direct in vitro inactivation of murine alloreactive cytotoxic-T-lymphocyte precursors by syngeneic nonspecific cytotoxic-T-cell populations.

Nonspecific cytotoxic T-cell populations, derived from murine fetal calf serum (FCS)-precultured cells expanded in interleukin 2 (IL-2)-containing supernatant (operationally defined as FCS-CM-expanded cells), were investigated for their inactivating properties on syngeneic lymphoid cell populations containing alloreactive cytotoxic-T-lymphocyte precursors (CTL-P). CTL-P were detected and quantitated in a limiting dilution mixed leukocyte microculture (micro-MLC) system supplemented with IL-2. The data show a dramatic decrease in relevant CTL-P frequency in populations of fresh or Day 2 in vitro-alloactivated peripheral blood leukocytes (PBL) after coculturing them for 24 hr with syngeneic mitomycin C-treated populations of FCS-CM-expanded cells. On the contrary, no decrease in CTL-P frequency was observed when Day 7, instead of fresh or Day 2, in vitro-alloactivated PBL were used as responding cells. Throughout these experiments, it was clearly shown that a decrease or an absence of CTL response in the micro-MLC was neither due to a lack of IL-2 nor to a premature destruction of the stimulating cells by the inhibiting FCS-CM-expanded cells still present in the culture. FCS-CM-expanded cells can destroy (in a 3-hr 51Cr-release assay) Day 2 alloreactive PBL populations, and this raises the possibility that the direct inactivation of CTL-P by FCS-CM-expanded cells could result from their cytolytic activities.

Animals↗
PubMed1984

Suppression of CTL responses in vitro by large granular T cells.

The generation of large granular T cells (LGC) that display cytotoxicity similar to activated natural killer (NK) cells was described previously by the authors. To determine whether LGC can regulate the generation of allospecific CTL (C57BL/6, anti-DBA/2), we used primed responding T cells (Thy-1.2) and (Thy-1.1) to perform co-cultures. The cytolytic activities and the phenotype of the harvested T cells were examined after a co-culture period (3-6 days). We observed that the survival of fresh responding T cells was impaired in the co-cultures. Activated (4 days) responding T cells can survive in similar coculture conditions. This led to the conclusion that LGC can inactivate the CTL generation in fresh T-cell populations and that fresh and activated responding cells have different susceptibilities to LGC interactions.

Animals↗
PubMed1983

In vitro production of granular T cells and mast cells by use of different conditioned media. Ultrastructural and functional analysis.

Normal mouse spleen cells were cultured in different conditioned media (CM). Mixed lymphocyte culture supernatant (MLC SN) was shown to promote the proliferation of cytotoxic, Thy-1+, Lyt-1+, Lyt-2+, asialo-GM-1+, weakly adherent cells with numerous vacuoles and lysosome-like cytoplasmic granules. In contrast, the Con A SN induced the proliferation of non-cytotoxic, Thy-1-, Lyt-1-, Lyt-2-, asialo-GM-1-, non-adherent cells with numerous cytoplasmic granules. The ultrastructural morphology of these cells and the cytochemical characteristics of their granules enable us to identify them as mast cells. The different effects of both CM could be related to their T-cell growth factor (TCGF) content. When the amount of TCGF of these two CM was determined (by assaying growth-stimulating activity for T-cell colonies), it appeared that the MLC SN contained larger amounts of TCGF than the Con A SN used in these experiments.

Animals↗
PubMed1981

FCS-activated blast T cells inhibit the in vitro response of memory CTL precursors to alloantigens by removal of factor(s) from MLC supernatant.

The inhibitory effect of spleen cells, precultured in the presence of FCS, was assayed on the memory cytolytic T lymphocytes (CTL) response to alloantigens. For this, we have used in vitro conditions in which both particulate alloantigen and MLC SN are required to allow the generation of CTL. It was shown that the CTL response was totally inhibited in the presence of 5 to 7 days precultured spleen cells. This inhibitory effect was partly due to removal, by those precultured cells, of relevant factor(s) contained in the MLC SN. After velocity sedimentation at unit gravity, it was shown that the T cells able to inhibit the cytolytic response and to remove MLC SN factor(s) are found in the fractions containing the large proliferating cells. It was further demonstrated that in the presence of inhibiting cells, a significant CTL response may be obtained after addition of concentrated MLC SN. However, in this way, this inhibitory effect was not totally circumvented, which suggests that the memory CTL response is also impaired by other mechanisms.

Animals↗
PubMed1980

Generation of cytolytic T lymphocytes in vitro. XI. Accessory cell requirement in secondary responses to particulate alloantigen.

The non-T accessory cell requirement for cytolytic T lymphocyte (CTL) generation in vitro was studied in a system which makes use of particulate membrane preparations as a source of alloantigen, and spleen cells from alloimmune mice as a source of responding cells. It is shown that removal of nylon-adherent cells from the responding cell population strongly reduced CTL generation, whereas direct removal of Ig+, phagocytic or plastic-adherent cells had no effect. The CTL response of the nylon-nonadherent cell population could be reconstituted by the addition of normal spleen cells, which by themselves do not generate CTL in response to particulate alloantigen. The accessory cell function of normal spleen cells was not affected by depletion of T cells or of phagocytic cells, but was sensitive to gamma-irradiation (1000 rd). The system thus demonstrates the requirement for a nylon-adherent accessory cell population in the secondary CTL response to particulate alloantigens which does not exhibit the typical characteristics of T cells, B cells or macrophages.

Animals↗
PubMed1980

[Immunogenicity of nerve allografts in rats].

The state of sensitization of rats after nerve or skin allograft was studied in vitro by using spleen cells or peripheral blood leukocytes (PBL) as responding cells and particulate alloantigen for stimulation, in culture conditions requiring or not supernatant from mixed lymphocytes culture. It is shown that 2-4 weeks after nerve or skin grafting a small number of PBL generates similar cytotoxic lymphocytic responses. However the state of sensitization induced by the nerve allografts is shorter compared to the one exhibited after skin allografts. On the other hand, no significant differences were observed at the level of the humoral response between both groups of grafted rats.

Animals↗
PubMed1979

Generation of cytolytic T lymphocytes in vitro. XII. Detection of memory CTL precursors in peripheral blood of alloimmune mice.

The memory cytolytic T lymphocyte (CTL) response of mice was studied in vitro using peripheral blood leucocytes (PBL) of donors previously immunized with allogeneic cells as responding cells, and particulate alloantigen for stimulation. It is shown that alloimmune but not normal PBL respond to particulate antigen and that small numbers of PBL generate high CTL responses provided non-T accessory spleen cells are added to the cultures. The system provides means to analyse the kinetics of the appearance of memory CTL precursors after primary alloimmunization in individual mice.

Animals↗