Biomedical subjects

G P Linette

Publications and source records attributed to G P Linette.

25 records · Page 2Linked to original sources

PubMed1986

Production of a fibroblast-stimulating factor by Schistosoma mansoni antigen-reactive T cell clones.

Fibrosis in schistosomiasis is the terminal event of a complex pathophysiologic cascade involving interactions between fibroblasts and both host and parasite products. In the present study, the effect of lymphokines produced by cloned Schistosoma mansoni antigen-reactive T cells on the proliferation of murine fibroblasts was investigated. These T cells previously have been shown to proliferate, produce lymphokines, mediate delayed-type hypersensitivity responses, and generate in vitro granulomas in response to soluble egg antigen (SEA). T cells, co-cultured with irradiated antigen-presenting cells and pulsed with SEA, produced levels of fibroblast-stimulating factor (FSF) comparable to equivalent numbers of dispersed hepatic granuloma cells isolated from infected mice. Supernatants of cloned T cells pulsed with Con A (in the absence of macrophages) contained no detectable interleukin 1 activity, but did stimulate fibroblast activation and growth. T cell FSF activity was trypsin-sensitive, was stable at 56 degrees C but not to boiling, and was retained by Con A Sepharose. Activity was associated with HPLC fractions corresponding to an m.w. of 10,000 to 40,000. Neither recombinant interferon-gamma nor affinity-purified interleukin 2 was capable of stimulating fibroblast proliferation. In functional studies, the degree of fibroblast proliferation was related to the length of exposure to the factor. In addition, quiescent fibroblasts were maximally stimulated by T cell FSF only if a second co-factor such as insulin or epidermal growth factor was present. The synergism between T cell FSF and known progression factors suggests that FSF-T may provide a competence signal to fibroblasts. The present results suggest that a direct molecular link may exist between T cells and fibroblasts in schistosomiasis.

Animals↗

PubMed1986

Induction of anti-HIV neutralizing antibodies by synthetic peptides.

Two synthetic peptides containing amino acid sequences analogous to the envelope glycoprotein of human T-lymphotropic virus (HTLV) type III (HTLV-III) and lymphadenopathy associated virus (LAV) were produced and used to immunize rabbits. The subsequent rabbit antisera neutralized HTLV-III infectivity in vitro. The two synthetic peptides corresponded to regions associated with the gp120 or gp41 subunits respectively, of human immunodeficiency virus (HIV). This data indicates that at least two neutralizing epitopes are present on the envelope glycoprotein of HIV and these epitopes are associated with two distinct virus envelope glycoproteins. Antisera generated against these peptides neutralized infectivity of two different isolates of HTLV-III. The data is discussed in terms of possible strategy for developing an effective vaccine against the etiologic agents of acquired immune deficiency syndrome (AIDS).

Amino Acid Sequence↗

PubMed1986

In vitro granuloma formation using defined antigenic nidi.

The in vitro granuloma model provides an excellent tool to study granulomatous hypersensitivity. In our studies of granuloma formation in schistosomiasis, we have demonstrated the utility of the model with respect to analysis of human PBL responses, cloned T cells, purified antigens of the parasite, and regulatory mechanisms. We have also presented data which demonstrate the applicability of this model to other antigenic systems. While the suggestion that this model may be suitable for the study of sarcoidosis may be premature, we would propose that the system may be adapted to screen potentially causative antigens. Furthermore, with the identification of the critical antigen(s), the in vitro granuloma model will facilitate studies at the clinical level.

Animals↗

PubMed1986

Allogeneic substitution for nominal antigen-specific T-cell clone reactivity in schistosomiasis.

The present studies have established the nature of a T-cell clone which demonstrates dual reactivity directed against Schistosoma mansoni antigen presented by syngeneic antigen presenting cells and against allogeneic cells. Clone G4, when stimulated by either antigen (SEA) or allogeneic cells (PL/J), exhibits similar functional and phenotypic characteristics. A subclone of G4, G4A.1, which has been maintained in continuous mixed lymphocyte culture for 12 months (in the absence of SEA), retains comparable reactivity with respect to proliferation and ability to produce lymphokines, transfer delayed-type hypersensitivity, and produce in vitro granulomas in response to SEA. Normal antigenic stimulation is highly contingent upon I-Ab compatibility while antibody blocking experiments map allo-reactivity to I-Eu. The failure of B10.PL spleen cells to stimulate G4, however, suggests that alloreactivity may be directed against the recently described Mls X locus. Both allogeneic and nominal antigen induced T-cell activation are blocked by antibody directed against L3T4A, confirming Class II MHC restriction for both types of stimulation. These studies suggest that stimulation of T cells by either alloantigen or nominal antigen elicits qualitatively similar functional profiles, and further suggest the feasibility of producing large numbers of nominal antigen reactive cloned T cells in the absence of nominal antigen under mixed lymphocyte culture conditions.

Animals↗

PubMed1985

In vitro delayed hypersensitivity granuloma formation: development of an antigen-coated bead model.

Previously, we have described an in vitro model of granulomatous hypersensitivity around Schistosoma mansoni eggs in both the murine model of schistosomiasis and in human schistosomiasis. These studies describe a new model of in vitro granuloma formation that complexes soluble egg antigen from S. mansoni eggs, a partially purified protein derivative of Mycobacterium tuberculosis (PPD), or bovine serum albumin to carrier beads. Ultrastructural and morphologic evaluations demonstrate that there are initial macrophage interactions, followed by the recruitment of antigen-specific T cells that interact with and recruit macrophages, lymphocytes, granulocytes, and fibroblasts. Finally, there is a stage of granulomatous organization involving fibroblast proliferation and collagen deposition. The in vitro reactivity, defined by a quantitative granuloma index, correlates with in vivo granulomas around S. mansoni eggs in the livers of infected cell donor animals. In vitro granuloma formation against PPD-coated beads correlated with delayed cutaneous hypersensitivity against PPD, which was judged by footpad swelling. The reactions demonstrate antigenic specificity and were intrinsically modulated in a manner that is analogous to that previously shown with the in vitro egg granuloma model. This model of in vitro granuloma formation promises to be a useful tool for elucidating mechanisms of cellular immunity and regulation.

Animals↗

PubMed1985

Characterization of Schistosoma mansoni antigen-reactive T cell clones that form granulomas in vitro.

Granuloma formation and modulation in schistosomiasis are a consequence of discrete subpopulations of T lymphocytes and the mediators they produce. In the present study, T cell clones reactive to soluble egg antigen (SEA) were developed to analyze the roles of T cells in Schistosoma mansoni egg-induced granuloma formation. In an in vitro granuloma assay, 1 X 10(5) T cells specifically augmented the response of 2 X 10(6) normal spleen cells to SEA-coupled but not purified protein derivative-coupled polyacrylamide beads. In vitro granulomatous responses by individual clones were correlated with their capacity to mediate local delayed-type hypersensitivity reactions in footpad swelling assays. Phenotypic analysis of the seven clones characterized in the present study demonstrated that they were L3T4+, Ly-2.2-. An analysis of supernatants of T cells pulsed with concanavalin A or SEA + antigen-presenting cells was also undertaken in an attempt to correlate in vitro granuloma formation with lymphokine production. Stimulated T cells (but not unstimulated T cells) produced interleukin 2, macrophage activating factor, migration inhibitory factor, and eosinophil stimulation promoter in response to both mitogenic and antigenic stimuli. The results suggest that individual clones of T cells are capable of producing a variety of mediators that influence their ability to activate and to recruit cells into granuloma formation. The model may be useful in the analysis of specific antigens and regulatory interactions and their contribution to granuloma formation.

Animals↗

PubMedDate not supplied

Adjuvant high-dose interferon alfa-2b in patients with high-risk melanoma.

We performed an analysis of toxicity and survival in stage III melanoma patients receiving adjuvant interferon alfa-2b (IFN). This was a retrospective single-arm analysis of 40 patients with stage III melanoma who received (IFN) administered at maximum tolerated doses of 20 mU/m2/day intravenously (i.v.) for 1 month and 10 mU/m2 three times per week subcutaneously (s.c.) for 48 weeks. Toxicity in our series is comparable to that experienced in the Eastern Cooperative Oncology Group (ECOG) 1684 trial, except for higher rates of dose-limiting myelosuppression and hepatotoxicity. All 40 patients experienced constitutional symptoms, but only 14/40 (35%) experienced grade 3 to 4 symptoms. Of the 40 patients, 36 (90%) experienced neurologic symptoms, but only seven (17.5%) experienced grade 3 to 4 neurotoxicity. Two patients stopped treatment because of severe psychiatric symptoms; one patient attempted suicide, and a psychosis developed in another. Thirty-nine (97.5%) patients experienced myelosuppression; 31 (77.5%) developing grade 3 to 4 myelosuppression. Hepatotoxicity was evident in 39 (97.5%) patients, and 26 (65%) experienced grade 3 to 4 hepatotoxicity. Three patients (7.5%) experienced mild renal toxicity. At a median follow-up of 27 months from initiation of therapy, there have been 19 relapses (47.5% disease-free survival [DFS]) and 10 deaths (75% OS) resulting from progression of disease. The DFS compares with the treatment arm in ECOG 1684 at 27 months, but overall survival is higher in our series of patients at the same time point. In a single program setting, IFN can be administered with similar side effects and outcome profiles seen in multi-institutional studies. Modifications in the induction regimen resulted in notably higher hematologic and hepatic toxicities but did not preclude administering further therapy and did not result in increased attrition rate among patients: only nine patients (22.5%) had their treatment stopped as a result of IFN-related toxicity. In comparison, 26% of patients had to have their treatment discontinued because of toxicity in ECOG 1684.

Adult↗