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D Collavo

Publications and source records attributed to D Collavo.

At least 37 records · Page 2Linked to original sources
PubMed1987

Temporary inhibition of Moloney-murine sarcoma virus (M-MSV) induced-tumours by adoptive transfer of ricin-treated T-lymphocytes.

The potential use of tumour-specific T-lymphocytes loaded with ricin in cell targeting experiments was investigated. Moloney-murine sarcoma virus (M-MSV)-specific T-lymphocytes, obtained in mass mixed leucocyte-tumour cell culture (MLTC) and a M-MSV-specific cytotoxic T-lymphocyte (CTL) clone, were incubated with 125I-labelled ricin in order to evaluate toxin uptake and release. The internalized ricin (4.5 X 10(-17) mol and 6.5 X 10(-17) mol per 10(2) MLTC and CTL clone cells, respectively) was released rapidly during the first 30 min following treatment, and at a constant but slower rate over the next few hours. The cytotoxic activity of ricin-treated cells evaluated against antigen-related target cells, in a short term incubation 51Cr release assay, was unaffected during the first 30 min after treatment but decreased with time over the next few hours. However, the growth of antigen related as well as of unrelated tumour cells was strongly inhibited by the addition of ricin-treated cells to the culture system, thus indicating that released ricin is toxic for untreated target cells. The in vivo localization pattern of ricin-treated radiolabelled MLTC cells was found to be comparable with that of untreated cells 1 h after i.v. injection into syngeneic sublethally irradiated mice. After 6 h, however, more radiolabel was recovered from the liver of mice receiving ricin-treated MLTC cells. Ricin-treated M-MSV-specific T-lymphocytes were injected i.v. into tumour bearing sublethally irradiated mice. A temporary tumour growth inhibition (up to 6 days) was achieved following transfer of low doses of ricin-treated MLTC or CTL clone cells (1 X 10(6) and 0.5 X 10(6), respectively). In contrast, in M-MSV injected control mice, receiving only free toxin (from 5 to 20 ng) or untreated tumour-specific effector cell tumours grew progressively. The therapeutic effect was apparently specific since the injection of ricin-treated alloreactive T-lymphocytes did not influence tumour growth. These results suggest that M-MSV-specific T-lymphocytes loaded with ricin can deliver toxin to the target tumour mass and have a transient therapeutic effect.

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PubMed1985

Reversibility of lymphokine-induced NK-like activity in virus-specific cytotoxic T-lymphocyte clones.

A limiting dilution microculture system, supplemented with a source of interleukin-2 (IL-2), was employed to evaluate the frequency of Moloney-murine leukaemia/sarcoma virus (M-MuLV/M-MSV)-specific cytotoxic T-lymphocyte precursors (CTL-p) which also exhibited NK-like activity. Spleen cells, obtained from M-MuLV/M-MSV regressor mice, were restimulated in bulk secondary mixed leucocyte-tumour cell cultures (MLTC), and subsequently plated in a culture medium supplemented with two different supernatants (SN) produced following PMA-stimulation of the same EL-4 thymoma cell line. SN 20, obtained from the cell line maintained in vitro, contained IL-2 and only negligible amounts (less than 3 U/ml) of interferon (IFN), while SN 19, obtained after passage of the ascitic form of EL-4 thymoma in syngeneic mice, contained both IL-2 and IFN in high titres. The frequency of CTL-p specific for MBL-2 lymphoma cells was high and comparable in cultures supplemented with both SN (1/2 X 84 cells and 1/2 X 40 cells, respectively), while the frequency of CTL-p directed against NK-susceptible YAC-1 target cells was low in SN 20 (1/90 cells) and high in SN 19 (1/5 X 40 cells). An analysis of individual microcultures established at low cell dose (1 cell/well) indicated that specific and NK-like activity could be ascribed to the same precursor cells. Furthermore, using different long-term CTL clones, we observed that, after passage in SN 20, double-reactive clones gradually lose the capacity to lyse NK-susceptible targets, while most of MBL-2 specific clones acquired NK-like activity following a few passages in SN 19. Therefore, the induction of NK-like activity is reversible and may be modulated by soluble factors present in supernatant in which CTL clones are maintained. Double-reactive clones were unable to lyse NK-resistant allogeneic tumour cells or normal syngeneic blast cells. A few clones cross-reacting with H-2d alloantigens also exhibited NK-like activity when maintained in SN 19. The different pattern of CTL clone activity was associated with a morphological change in the clones themselves: the acquisition of double activity was accompanied by an increase in cell size and the appearance of numerous cytoplasmic granules. All CTL clones were phenotypically Thy-1+ and Lyt-2+ on indirect immunofluorescence and complement-dependent cytotoxicity investigation.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1979

Lack of T-cell mediated cytotoxicity in M-MSV system depending on H-2 haplotypes.

The H-2 restriction phenomenon was evaluated with regard to the immune response to Moloney sarcoma virus (M-MSV)-induced tumours in the mouse. Using an in vitro 51Cr release assay the lytic activity of lymphocytes from M-MSV immune strains of mice, including several H-2 recombinant strains, was determined on leukaemic cell lines originally induced in mice of different strains by neonatal infection with Moloney leukaemia virus. In analogy with other experimental models, it was observed that a compatibility between effector and target cells at the K and/or D regions is generally necessary and sufficient to obtain the cytotoxic effect. However, for the H-2d and H-2b haplotypes, identity at the K or D region respectively was not sufficient for lysis to occur. Attempts to demonstrate that this lack of activity might be associated with the absence of H-2 linked Ir responder genes, were not successful.

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PubMed1978

Colony formation of cytolytic T cells in semisolid medium.

Addition of supernatant from concanavalin A-stimulated spleen cells to in vitro primed cytolytic T lymphocytes in semisolid medium stimulated the growth of colonies of cytolytic lymphocytes. Optimal results were obtained using a peritoneal adherent cell underlayer where a 10% plating efficiency (greater than or equal to 4 cells per colony) was achieved when between 5000 and 100 000 cells were plated per dish. Individual colonies were harvested and tested in a short term (5h) 51Cr release microassay, employing 200 target cells. The frequency of lytic colonies varied from 46--67%. The observed lytic activities were specific for the relevant allogeneic target cells.

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PubMed1978

Proliferative response of H-2 incompatible leukocytes to an Abelson virus-induced lymphoma cell line apparently not expressing Ia-antigens.

The proliferative response of normal lymph node cells from different mouse strains to an Abelson virus-induced leukemic cell line (MLVA) in mixed leukocyte culture (MLC) has been investigated. MLVA leukemic cells do stimulate a specific response and the stimulating determinants are controlled, most likely, by genes in the K-end of the H--2 complex. However, using two different anti-Ia sera and different assay systems, we were unable to detect the expression of Ia-antigens on MLVA. In addition, an alloantiserum raised against MLVA, and absorbed with P815, a nonstimulating mastocytoma cell line, showed no residual activity against MLVA cells.

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PubMed1978

Secondary in vitro generation of cytolytic T-lymphocytes (CTL's) in the murine sarcoma virus system. Virus-specific CTL induction across the H-2 barrier.

Following in vitro stimulation of murine sarcoma virus Moloney isolate (M-MuSV)-immune spleen cells with syngeneic antigenically related Moloney leukemia cells, highly efficient cytotoxic T-lymphocytes (CTL's) were generated. The cytotoxic effect was directed only against H-2-compatible target cells bearing M-MuSV tumor-associated antigens (TAA). However, in a cold target competition assay a weak but detectable capacity to block CTL activity was also obtained when allogeneic Moloney leukemia cells were added. Moreover, when M-MuSV-immune spleen cells from mice inoculated with virus 14 days previously were stimulated by allogeneic Moloney leukemia cells, a strong cytotoxic effect toward syngeneic and allogeneic tumor cells bearing M-MuSV TAA was elicited.

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PubMed1977

Genetics of murine sarcoma virus (MSV)--induced tumors in AKR mice: Evidence that late progressing and early regressing tumors are controlled by different gents.

The genetics of late appearing MSV tumors showing a progressive growth pattern in AKR mice was investigated. The late MSV tumor response in F1 hybrids depended on the genetic background of the non-AKR parent. Within the 4-month observation period following virus injection, (CBA X AKR) F1, (DBA/2 X AKR)F1, and (NIH X AKR)F1 developed progressing MSV tumors, which exhibited latency and growth behavior comparable to that seen in AKR mice, (BALB X AKR)F1, (B6 X AKR)F1, and (B10br x akr)f1 mice did not show any late MSV tumors. In contrast to early regressing M-MSV tumors, whose development is independent of Fv-1 genotype, late MSV tumor progression is largely a function of this gene, since all late tumors which appeared in (B10BR x AKR) x AKR were observed in Fv-1n homozygous mice, H-2k halotype is a further factor in the occurrence of late MSV tumors, at least in (B6 x AKR) x AKR mice. In crosses of AKR with Fv-1 compatible mice, tumor appearance was strongly associated with inheritance of AKR-Mulv, and MSV recovered from late tumors of first back-cross animals appeared to be a new pseudotype with the endogenous AKR-MuLV. It is suggested that the host genetic control in both early and late MSV tumors is exerted mainly on the helper component of the leukemia-sarcoma complex.

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PubMed1977

Inhibitory effect of YC8 leukaemia cell line on in vitro lymphocyte reactivity.

Mitomycin-treated transplantable Moloney virus-induced lymphatic leukaemia cells (YC8) not only failed to stimulate normal allogeneic lymphocytes in one-way mixed leucocyte culture (MLC) but also exerted a strong inhibitory effect on the proliferative response of normal lymphocytes, in MLC and after stimulation by mitogens. Potentially inhibitory factors which could be released in the culture fluids by the YC8 cells were not found, but a YC8-derived adherent cell subpopulation was identified as being responsible for the in vitro suppression.

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PubMed1977

In vitro secondary MLR. I. Kinetics of proliferation and specificity of in vitro primed responder cells.

We have examined the kinetics and specificity of secondary in vitro mixed lymphocyte reactions (MLR). With limited numbers of primed responder cells (PRC) in the presence of "excess antigen" it was possible to obtain proliferative responses that were proportional to the number of PRC initially placed in culture. The responding cells, after an initial lag period, seem to grow exponentially until day 3 of culture. The responses of PRC (with the strain combinations and culture conditions described in this report) seemed to be directed toward stimulator cell determinants whose expression was determined by genes in the I region of the MHC. In one case, the relevant incompatibilities could be further restricted to the I-A region. Although PRC responded best to stimulator cells sharing the I region with the priming stimulator cell, apparent cross-reactivity could be observed by restimulating PRC with stimulator cells that did not carry the MHC haplotype of the priming stimulator cell. The rate of proliferation (measured as 3H-thymidine incorporation) in these apparent cross-reactions was reproducible and comparable to the rate observed in response to the priming stimulator cell. It was possible, therefore, to estimate the proportion of PRC that reacted in the presence of third party stimulator cells compared to the response of these PRC to the priming stimulator cells. We have estimated that the response of A (B6) PRC against H-2d and H-2s haplotype stimulator cells is about half of the response of these PRC to H-2b, the priming stimulator cell.

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PubMed1976

Generation of cytotoxic cells in absence of blastogenesis by mouse leukemic cells in mixed cultures.

Primary virus-induced murine leukemias and transplantable leukemic cell lines, originally induced by virus, chemical or physical agents, failed to stimulate normal spleen cells differing at the H-2 complex or at Mls locus in the one-way mixed leukocyte culture. Lack of stimulation seems at least partially due to a nonspecific inhibitory effect since in a "three-party" culture system the leukemic cells interfered with the mixed leukocyte reaction (MLR) of normal allogeneic cells. Characterization of the leukemic cell populations used, according to their T or B cell origin, disclosed that in most cases T cell markers were present. Also, no Ia antigens were detected on leukemic cells. Furthermore, using a 51Cr release assay, leukemic cells could sensitize allogeneic normal lymphocytes to kill specifically normal as well as leukemic targets, even when no MLR was detected in parallel cultures.

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PubMed1976

Immune reactivity in the Moloney strain of murine sarcoma virus oncogenesis: requirement of thymus-derived lymphocytes for in vivo protection.

To study the function of different lymphocyte populations in the Moloney strain of murine sarcoma virus (M-MuSV) tumorigenesis, we gave M-MuSV injections to CBA mice selectively deprived of thymus (T) lymphocytes by thymectomy, X-rradiation, and syngeneic bone marrow injection. Although no tumors appeared in the control group, 80% of the derived mice had tumors that grew progressively and ultimately killed them. In deprived mice, grafted with a syngeneic thymus (reconstituted mice) before or after an M-MuSV injection, tumors regressed or did not develop. Histologically, the lymph nodes and spleens of reconstituted mice, compared to those of deprived animals, showed repopulation of the thymus-dependent areas and prominent follicles in the cortex. Moreover, tumor tissue of reconstituted mice was extensively infiltrated by lymphocytes. To evaluate the number of lymphoid cells needed to prevent or regress M-MuSV tumors, we injected varying amounts of lymphoid cells into deprived mice. Even low lymphocyte numbers (10(6) cells) were sufficient to exert, in some cases, protection against M-MuSV tumorigenesis. This effect was not abolished by subsequent splenectomy or antilymphocyte serum treatment. Finally, deprived mice, given repeated injections of antiserum (hyperimmune) against M-MuSV, had tumors which appeared only after a prolonged latency. From these results, it is concluded that T-cell population integrity is important in affording total host protection against the M-MuSV tumors.

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PubMed1975

Genetic control of oncogenesis by murine sarcoma virus Moloney pseudotype. I. Genetics of resistance in AKR mice.

Infection of Moloney mouse sarcoma virus (M-MSV) in adult mice of several inbred strains revealed that all strains except AKR are highly susceptible to M-MSV tumor development. F1 hybrids between AKR and CBA, DBA/2 or NIH mice are as resistant (93%) as the parental AKR strain, which indicates that resistance is transmitted as a dominant character. First backcross mice to the susceptible parent show a 3:1 ratio of resistant to susceptible mice. This is the expected ratio for two segregating loci which independently confer resistance. The incidence of resistant F2 mice is somewhat lower than expected. Further support for the two-gene hypothesis was obtained in second backcross mice. None of the major genes affecting MuLV infection (Fv-2 and H-2) seems to play any role in this system and no linkage was found with Thy. 1 and albino, dilute, agouti and brown markers.

Animals↗
PubMed1975

Genetic control of oncogenesis by murine sarcoma virus Moloney pseudotype. II. A dominant epistatic susceptibility gene.

We have shown in the preceding paper that AKR mice are highly resistant to M-MSV tumor development, and that resistance is transmitted as a dominant character. In the present studies the tumor-response pattern of F1 hybrids between resistant AKR and susceptible strains (C57Bl/6, BALB/c and B10BR) following injection with Moloney mouse sarcoma virus (M-MSV) resembles that of the non-AKR parent. Segregation is observed in first backcross (Bc1) and F2 mice, and the segregation ratios up to Bc3 mice fit a one-gene model. The data of triple cross hybrids suggests that this dominant susceptibility gene inhibits the phenotypic expression of M-MSV tumor resistance in some susceptible Fv1bb strains as well as in their hybrids with AKR. Neither Fv-1 nor H-2 exerts any significant influence on this complex system.

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