Host Immune Effector Mechanisms Research Articles

A Phase I California Cancer Consortium Study of the Combination of Rituximab and Ipilimumab in Patients with Relapsed/Refractory CD20+ B-Cell Lymphoma; Efficacy, Safety and Immune Correlative Analysis

Background: As a single agent, rituximab produces an overall response rate (ORR) of 20-50% in patients with relapsed/refractory (r/r) indolent B-cell non-Hodgkin lymphomas (NHL). Acquired resistance occurs however, due, in part to defective host immune effector mechanisms. Efforts to augment immune function have included combining rituximab with immune modulators, e.g. IL-2, IL-12, interferon,and lenalidomide, which has resulted in improved response rates. CTLA-4 is a negative regulator of T-cell responses and Ipilimumab is a human IgG1κ monoclonal antibody (mAb) specific for the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4, CD152) expressed on activated T cells. Ipilimumab disrupts the interaction of CTLA-4 with its ligands, B7-1 (CD80) and B7-2 (CD86); thus augmenting the T cell activation. We therefore hypothesized that ipilimumab would augment the efficacy of rituximab.Methods: Patients ≥ 18 years old with r/r CD20+ NHL, measurable disease, KPS ≥ 70%, neutrophils ≥ 1000/mm3, platelets ≥ 50,000/mm3, and adequate kidney and liver function were eligible. In this phase I study with an expansion cohort, after establishing the recommended Phase II dose (RP2D), study patients would be randomized to differing treatment schedules of rituximab and ipilimumab to better assess the effects on rituximab-mediated cytotoxicity. As induction in the phase I component, ipilimumab was administered every 3 weeks for 4 doses and rituximab given every week for four weeks. Primary endpoints included: toxicity and determination of the maximum tolerated dose (MTD)/RP2D during the first 7 weeks of induction with ipilimumab (2 doses) when given in combination with rituximab (4 doses, 375mg/m2 per dose). Secondary end points included biomarkers of immune response, ORR, progression free survival (PFS) and overall survival (OS). In the phase I component a standard 3+3 design was used to determine the MTD/RP2D. After the RP2D was established, 20 more patients were randomized to one of two schedules: on Arm A, ipilimumab on Day 1 with rituximab, and on Arm B, rituximab day 1 and ipilimumab delayed until Day 15 to assess the ability of ipilimumab to augment the rituximab-mediated B cell depletion (a surrogate biomarker for ipilimumab-mediated augmentation of rituxan targeted ADCC). After induction in both the Phase I and the expansion cohorts, maintenance ipilimumab and rituximab were given every 12 weeks (+/- 1 week) on the same day for 1 year. Immune correlates included assessment of 16 serum cytokines using multiplex assays, and T cell subset and immunophenotypic analysis by flow cytometry.Results : As of August 1 2017, planned accrual was completed with 33 patients enrolled (2 small lymphocytic lymphoma, 13 follicular lymphoma, 7 diffuse large B cell lymphoma, 2 mantle cell lymphomaL, 9 indeterminate): 26 are assessable for toxicity at 7 weeks. The median age was 62 (32-77) and the median number of prior regimens was 3 (1-6). The RP2D of ipilimumab is 3 mg/kg, which was the highest dose tested when given with rituximab (375mg/m2). The most common grade 1-2 AEs (≥ 20%) were: anemia (21%), fatigue (33%), AST elevated (24%), low albumin (24%), elevated alkaline phosphatase (21%), edema limbs (21%), rash maculo-papular (21%). The most common grade 3-4 AEs (≥ 5%) were: lymphocytopenia (18%), anemia (12%), diarrhea (12%), leukopenia neutropenia, thrombocytopenia, hypokalemia, rash maculo-papular, and hyponatremia 9% each. There were no treatment-related deaths. Twenty-seven patients were evaluable for response; 12 had progressive disease, 7 stable disease, 6 partial response and 2 complete response for an overall response rate of 30%. Responses were observed in 6 of 11 evaluable FL patients (ORR 54%). At a median follow-up time of 4.8 months, the median PFS is 3.4 months and the median OS has not been reached (Figure 1). Serum cytokine analysis revealed elevated levels of IL-2, TNF-α, and GM-CSFpredicted response (p ≤ 0.05). B cell depletion, phenotypic and T cell subset analysis is ongoing.Conclusion: The RP2D of ipilimumab when given in combination with rituximab is 3 mg/kg and at this dose it is safe and moderately well tolerated. Efficacy is modest in this heavily pretreated patient population however more promising in FL patients with several patients having durable remissions. Immune correlative analysis has thus far potentially identified several cytokines that may predict response [Display omitted] DisclosuresTuscano:Takeda: Honoraria, Research Funding; Novartis Pharmaceuticals: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Ailawadhi:Takeda: Consultancy, Honoraria; Pharmacyclics: Research Funding; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Chen:Affimed: Research Funding; Seattle Genetics: Consultancy, Research Funding, Speakers Bureau; Merck: Consultancy, Speakers Bureau; Pfizer: Consultancy; Genentech: Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Jonas:AbbVie, Celgene, Daiichi Sankyo, Pharmacyclics, Genentech/Roche, Glycomimetics, Esanex, Kalobios: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Rigel: Consultancy. Wun:Pfizer: Other: Steering Committee: RESET study, Research Funding; Janssen: Other: Steering Committee for Cassini Study and Callisto Program, Research Funding.

A purified, fermented, extract of Triticum aestivum has lymphomacidal activity mediated via natural killer cell activation.

Non-Hodgkin lymphoma (NHL) affects over 400,000 people in the United States; its incidence increases with age. Treatment options are numerous and expanding, yet efficacy is often limited by toxicity, particularly in the elderly. Nearly 70% patients eventually die of the disease. Many patients explore less toxic alternative therapeutics proposed to boost anti-tumor immunity, despite a paucity of rigorous scientific data. Here we evaluate the lymphomacidal and immunomodulatory activities of a protein fraction isolated from fermented wheat germ. Fermented wheat germ extract was produced by fermenting wheat germ with Saccharomyces cerevisiae. A protein fraction was tested for lymphomacidal activity in vitro using NHL cell lines and in vivo using mouse xenografts. Mechanisms of action were explored in vitro by evaluating apoptosis and cell cycle and in vivo by immunophenotyping and measurement of NK cell activity. Potent lymphomacidal activity was observed in a panel of NHL cell lines and mice bearing NHL xenografts. This activity was not dependent on wheat germ agglutinin or benzoquinones. Fermented wheat germ proteins induced apoptosis in NHL cells, and augmented immune effector mechanisms, as measured by NK cell killing activity, degranulation and production of IFNγ. Fermented wheat germ extract can be easily produced and is efficacious in a human lymphoma xenograft model. The protein fraction is quantifiable and more potent, shows direct pro-apoptotic properties, and enhances immune-mediated tumor eradication. The results presented herein support the novel concept that proteins in fermented wheat germ have direct pro-apoptotic activity on lymphoma cells and augment host immune effector mechanisms.

Metabolic energy sensors as targets for designing host-directed therapies for tuberculosis.

A wealth of scientific and clinical evidence during the past few years has lent credence to the idea that key components of the host immune effector mechanisms can be targeted to boost current tuberculosis (TB) treatment and control patient relapse. These host-directed strategies not only accelerate the clearance of pathogens but also have the ability to limit overt inflammation and pathology, which are associated with the tissue damage. Studies have indicated that inflammatory responses are intrinsically linked to cellular metabolism and together drive the fate of many host responses, coupling host survival with the capacity to respond to infectious insult. Metabolic sensors such as mammalian target of rapamycin, AMP-activated protein kinase, and sirtuin 1 are central regulators of host metabolic alterations and play important roles in immune responses against infections. The present review discusses the functions of AMP-activated protein kinase and sirtuin 1, with a focus on their role in immune homeostasis and how manipulating the AMP-activated protein kinase-sirtuin 1 axis with drugs can modulate immunity to tuberculosis.

Suppressor Cell-Depleting Immunotherapy With Denileukin Diftitox is an Effective Host-Directed Therapy for Tuberculosis.

Host-directed therapies that augment host immune effector mechanisms may serve as important adjunctive therapies for tuberculosis treatment. We evaluated the activity of denileukin diftitox in an acute mouse model of tuberculosis (TB) infection and analyzed the cellular composition and bacterial burden in lungs and spleens. These in vivo studies show that denileukin diftitox potentiates standard TB treatment in the mouse model, an effect which may be due to depletion of T-regulatory and myeloid-derived suppressor cells during TB infection. Our results indicate that denileukin diftitox and other suppressor cell-depleting therapies may be useful adjunctive, host-directed therapies for TB.

Association of rituximab with graphene oxide confers direct cytotoxicity for CD20-positive lymphoma cells.

Non-Hodgkin lymphoma (NHL) is one of the most common hematologic malignancies among adults for which the chimeric monoclonal anti-CD20 antibody (Ab) rituximab (RTX) is used as first-line therapy. As RTX itself is not directly cytotoxic but relies on host immune effector mechanisms or chemotherapeutic agents to attack target cells, its therapeutic capacity may become limited when host effector mechanisms are compromised. Currently, refractory disease and relapse with NHL are still common, highlighting the need for novel anti-CD20 antibody strategies with superior therapeutic efficacy over current protocols. We hypothesized that making RTX directly cytotoxic might improve the therapeutic efficacy. Graphene oxide (GO) has recently emerged as a highly attractive nanomaterial for biomedical applications; and several studies have reported cytotoxic effect of GO on benign and malignant cells in vitro. Herein, we report that RTX can be stably associated with GO, and that GO-associated RTX (RTX/GO) demonstrates remarkably high avidity for CD20. Binding of GO-associated RTX to CD20-positive lymphoma cells induces CD20 capping and target cell death through an actin dependent mechanism. In vivo, GO-associated RTX, but not free RTX, quickly eliminates high-grade lymphomas in the absence of host effector mechanisms in a xenograft lymphoma mouse model. Our findings represent the first demonstration of using GO-associated antibody as effective cytotoxic therapy for human B cell malignancies in the absence of chemotherapy, and these findings could have important clinical implications.

Efficacy and Safety of Combined Rituximab and Ipilimumab to Treat Patients with Relapsed/Refractory CD20+ B-Cell Lymphoma

Background: As a single agent, rituximab produces an overall response rate (ORR) of 20-50% in patients with relapsed/refractory (r/r) B-cell non-Hodgkin lymphomas (NHL). Acquired resistance occurs, however, partially due to defective host immune effector mechanisms. Efforts to augment immune function have included combining rituximab with immune modulators such as IL-2, IL-12, interferonand lenalidomide. These efforts have resulted in improved efficacy of rituximab. Ipilimumab is a human IgG1κ monoclonal antibody (mAb) specific for the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4, CD152) expressed on activated T cells. CTLA-4 is a negative regulator of T-cell responses. Ipilimumab augments the immune response by disrupting the interaction of CTLA-4 with its ligands, B7-1 (CD80) and B7-2 (CD86). We therefore hypothesize that ipilimumab will augment the efficacy of rituximab. This phase I with an expansion cohort was designed to assess the safety of this combined therapy.Methods: Patients ≥ 18 years old with r/r CD20+ NHL, measurable disease, KPS ≥ 70%, neutrophils ≥ 1000, platelets ≥ 50,000 and adequate kidney and liver function were eligible. In this phase I with an expansion cohort, after establishing the recommended Phase II dose (RP2D), study patients would be randomized to differing treatment schedules of rituximab and ipilimumab. For induction in phase I, rituximab was given every week for four weeks and ipilimumab was administered every 3 weeks for 4 doses. Primary endpoints included toxicity and determination of the maximum tolerated dose (MTD)/RP2D during the first 7 weeks of induction of ipilimumab (2 doses) when given in combination with rituximab (4 doses, 375mg/m2 per dose). Secondary end points included immune response, ORR and progression free survival (PFS). In the phase I component, a standard 3+3 design was used to determine the MTD/RP2D. After the RP2D was established, 20 more patients would be randomized to one of two schedules: Arm A - ipilimumab on Day 1 together with the first dose of rituximab, or Arm B - ipilimumab on Day 15 together with the third rituximab dose. After induction in both the Phase I and the expansion cohorts, ipilimumab and rituximab were given every 12 weeks (+/- 1 week) on the same day for 1 year.Results: As of August 1 2015, 21 patients have been enrolled (1SLL, 9FL, 6DLCL, 1MCL, 4 indeterminate): 15 are evaluable for toxicity assessment at 7 weeks. The median age was 62 (32-71) and the median number of prior regimens was 2 (1-6). The RP2D of ipilimumab when given with rituximab (375 mg/m2) was 3 mg/kg, which was the highest dose tested. The most common grade 1-2 AEs (>20%) were:anemia (33%); diarrhea (20%); constipation (27%); nausea/vomiting (33%); fatigue (40%); anorexia (33%); low albumin (53%); hypocalcemia (33%); hyponatremia (27%). The most common grade 3-4 AEs (≥ 5%) were: anemia (20%); diarrhea (13%); leukopenia (13%); and hyponatremia (27%). There were no study related deaths. Twelve patients remain on treatment, 6 came off due to progression, 2 due to toxicity, and there was one death (unrelated).Conclusion: The RP2D of ipilimumab when given in combination with rituximab is 3 mg/kg. This dose is safe and moderately well tolerated. Enrollment continues in the expansion cohort to assess efficacy and the ability of ipilimumab to augment the rituximab-mediated immune response. DisclosuresOff Label Use: Ipilimumab to augment rituxan in treating lymphoma. Chen:Merck: Consultancy, Research Funding; genentech: Consultancy, Speakers Bureau; Millennium: Consultancy, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding, Speakers Bureau.

Purified, Fermented, Extract of Triticum Aestivum Has Significant Independent Lymphomacidal Activity and Augments the Activity of Rituximab

AbstractAbstract 2857 Background:Non-Hodgkin's lymphoma (NHL) affects over 400,000 people in the United States and its incidence increases with age. Treatment options include cytotoxic chemotherapy, which is often poorly tolerated by elderly patients, and monoclonal antibody (mAb) therapy. Nearly 70% of NHL patients eventually die of the disease. Development of effective alternate treatments with favorable toxicity profiles is necessary. Fermented wheat germ extract (FWGE) has shown anticancer potential in laboratory animals as well as in some small clinical studies; it is produced under GMP conditions in Europe and sold as Avemar™. The mechanism of action of FWGE is unclear, but is thought to involve metabolic pathways involved in tumor cell death. We examined the effects of FWGE on NHL and found significant lymphomacidal activity using in vitro and in vivo assays. We then further purified and characterized the active components of FWGE in order to develop a more potent form and to understand the mechanism of action, physiologic, and immunologic properties. Methods:FWGE was produced by fermenting purified wheat germ (Triticum aestivum) with Baker's yeast. The FWGE was further purified by removing insoluble material, precipitating proteins, freeze drying, fractionating with Sepharose and Sephadex columns, and then dialyzing to remove small molecules. The resultant fermented wheat germ proteins (FWGP) were assessed for in vitro cytotoxicity and pro-apoptotic activity using a panel of NHL cell lines. In vivo lymphomacidal activity was assessed in nude mice bearing Raji lymphoma xenografts. Mice were treated with increasing daily doses of FWGE by gastric lavage and compared to untreated controls as well as the commercially available fermented wheat germ product, Avemar. Results:In vitro killing assays with FWGE (regardless of the source) demonstrated lymphomacidal properties in three NHL cell lines (Jurkat, Raji, and Ramos). Pre-treatment of FWGE with heat or proteinase K reduced the lymphomacidal activity, suggesting that the active component was a protein. Nude mice bearing Raji lymphoma xenografts treated with FWGE confirmed the lymphomacidal properties of FGWE; there was no detectable toxicity as assessed by observation, mouse weight, or blood counts. The purified low molecular weight proteins (FWGP) also demonstrated lymphomacidal properties by cytotoxicity assays and murine NHL models, but at 1/1000th of the original dose. When FWGP was combined with rituximab, there was enhanced in vitro lymphomacidal activity, with over a 4000-fold reduction in the IC50. FWGP-induced NHL cell death was mediated by caspase-3-dependent apoptosis. FWGP augmented the host immune effector mechanisms, including ADCC and CDC, along with potent activation of NK-T cells (CD3/69/16), CD4+ T-cells and monocytes. Conclusions:FWGE can be easily produced and has cytotoxic effects in in vitro assays and in vivo. The purified FWGP are quantifiable, and are 10–1000 times more potent than FWGE. The mechanism of FWGP activity is based on direct pro-apoptotic effects as well as augmentation of host immune mediators. FWGP has activity against various subtypes of NHL. Studies are ongoing to further characterize the immune effects and anti-cancer properties of FWGP, as is planning for a human clinical trial +/− rituximab in patients with NHL. [Display omitted] Disclosure:No relevant conflicts of interest to declare.

The Secreted Protease Factor CPAF Is Responsible for Degrading Pro-apoptotic BH3-only Proteins in Chlamydia trachomatis-infected Cells

The Secreted Protease Factor CPAF Is Responsible for Degrading Pro-apoptotic BH3-only Proteins in Chlamydia trachomatis-infected Cells

Endothelial cells present antigens in vivo

BackgroundImmune recognition of vascular endothelial cells (EC) has been implicated in allograft rejection, protection against pathogens, and lymphocyte recruitment. However, EC pervade nearly all tissues and predominate in none, complicating any direct test of immune recognition. Here, we examined antigen presentation by EC in vivo by testing immune responses against E. coli β-galactosidase (β-gal) in two lines of transgenic mice that express β-gal exclusively in their EC. TIE2-lacZ mice express β-gal in all EC and VWF-lacZ mice express β-gal in heart and brain microvascular EC.ResultsTransgenic and congenic wild type FVB mice immunized with β-gal expression vector DNA or β-gal protein generated high titer, high affinity antisera containing comparable levels of antigen-specific IgG1 and IgG2a isotypes, suggesting equivalent activation of T helper cell subsets. The immunized transgenic mice remained healthy, their EC continued to express β-gal, and their blood vessels showed no histological abnormalities. In response to β-gal in vitro, CD4+ and CD8+ T cells from immunized transgenic and FVB mice proliferated, expressed CD25, and secreted IFN-γ. Infection with recombinant vaccinia virus encoding β-gal raised equivalent responses in transgenic and FVB mice. Hearts transplanted from transgenic mice into FVB mice continued to beat and the graft EC continued to express β-gal. These results suggested immunological ignorance of the transgene encoded EC protein. However, skin transplanted from TIE2-lacZ onto FVB mice lost β-gal+ EC and the hosts developed β-gal-specific antisera, demonstrating activation of host immune effector mechanisms. In contrast, skin grafted from TIE2-lacZ onto VWF-lacZ mice retained β-gal+ EC and no antisera developed, suggesting a tolerant host immune system.ConclusionResting, β-gal+ EC in transgenic mice tolerize specific lymphocytes that would otherwise respond against β-gal expressed by EC within transplanted skin. We conclude that EC effectively present intracellular "self" proteins to the immune system. However, antigen presentation by EC does not delete or anergize a large population of specific lymphocytes that respond to the same protein following conventional immunization with protein or expression vector DNA. These results clearly demonstrate striking context sensitivity in the immune recognition of EC, a subtlety that must be better understood in order to treat immune diseases and complications involving the vasculature.

Simian-human immunodeficiency virus SHIV89.6-induced protection against intravaginal challenge with pathogenic SIVmac239 is independent of the route of immunization and is associated with a combination of cytotoxic T-lymphocyte and alpha interferon responses.

Attenuated primate lentivirus vaccines provide the most consistent protection against challenge with pathogenic simian immunodeficiency virus (SIV). Thus, they provide an excellent model to examine the influence of the route of immunization on challenge outcome and to study vaccine-induced protective anti-SIV immune responses. In the present study, rhesus macaques were immunized with live nonpathogenic simian-human immunodeficiency virus (SHIV) 89.6 either intravenously or mucosally (intranasally or intravaginally) and then challenged intravaginally with pathogenic SIVmac239. The route of immunization did not affect mucosal challenge outcome after a prolonged period of systemic infection with the nonpathogenic vaccine virus. Further, protection from the SIV challenge was associated with the induction of multiple host immune effector mechanisms. A comparison of immune responses in vaccinated-protected and vaccinated-unprotected animals revealed that vaccinated-protected animals had higher frequencies of SIV Gag-specific cytotoxic T lymphocytes and gamma interferon (IFN-gamma)-secreting cells during the acute phase postchallenge. Vaccinated-protected animals also had a more pronounced increase in peripheral blood mononuclear cell IFN-alpha mRNA levels than did the vaccinated-unprotected animals in the first few weeks after challenge. Thus, innate as well as cellular anti-SIV immune responses appeared to contribute to the SHIV89.6-induced protection against intravaginal challenge with pathogenic SIVmac239.

Longitudinal analysis of feline leukemia virus-specific cytotoxic T lymphocytes: correlation with recovery from infection.

Feline leukemia virus (FeLV) is a common naturally occurring gammaretrovirus of domestic cats that is associated with degenerative diseases of the hematopoietic system, immunodeficiency, and neoplasia. Although the majority of cats exposed to FeLV develop a transient infection and recover, a proportion of cats become persistently viremic and many subsequently develop fatal diseases. To define the dominant host immune effector mechanisms responsible for the outcome of infection, we studied the longitudinal changes in FeLV-specific cytotoxic T lymphocytes (CTLs) in a group of naïve cats following oronasal exposure to FeLV. Using (51)Cr release assays to measure ex vivo virus-specific cytotoxicity, the emerging virus-specific CTL response was correlated with modulations in viral burden as assessed by detection of infectious virus, FeLV p27 capsid antigen, and proviral DNA in the blood. High levels of circulating FeLV-specific effector CTLs appeared before virus neutralizing antibodies in cats that recovered from exposure to FeLV. In contrast, persistent viremia was associated with a silencing of virus-specific humoral and cell-mediated host immune effector mechanisms. A single transfer of between 2 x 10(7) and 1 x 10(8) autologous, antigen-activated lymphoblasts was associated with a downmodulation in viral burden in vivo. The results suggest an important role for FeLV-specific CTLs in retroviral immunity and demonstrate the potential to modulate disease outcome by the adoptive transfer of antigen-specific T cells in vivo.

Radioimmunotherapy of B-cell non-Hodgkin's lymphoma.

In the past decade, several new antibody-based therapies - using either radiolabelled or unlabelled monoclonal antibodies - have become available for the treatment of patients with refractory or recurrent non-Hodgkin's lymphoma (NHL). Unlabelled monoclonal antibodies (mAbs) kill lymphoma cells by activating host immune effector mechanisms, or by inducing apoptosis. These mAbs can also be used to guide radionuclides to the lymphoma. This radioimmunotherapy (RIT) has been studied with various nuclides (131I, 90Y, 67Cu and 186Re) and with various mAbs. In this review the radionuclides, methods of dosing and recent RIT studies in patients with B-cell NHL are reviewed. Most of these studies demonstrate that RIT is an effective new treatment modality for NHL.

Alginate-based microcapsules for immunoprotected islet transplantation.

Islet transplantation is a promising therapeutic approach for the treatment of insulin-dependent diabetes mellitus. Nevertheless, its broader clinical use is hampered by the shortage of human organ donors as well as the need for a permanent immunosuppressive drug therapy in order to avoid rejection. Microencapsulation shall help to overcome this problem by creating an immunoprotected transplantation site. Biocompatibility of the encapsulation material and the possible immuno-interaction of the grafted tissue and the host immune system need to be examined very carefully. In transplantation experiments, we could show that the long-term function of the graft is dependent on the species of the islet donor, indicating that there has to be a recognition of the encapsulated islet despite the encapsulation membrane. This could be confirmed by in vitro data in the mixed lymphocyte islet culture (MLIC). Moreover, morphological studies of the tissue reaction toward encapsulated syngeneic vs. allogeneic vs. xenogeneic encapsulated islets reveal that the greater the difference between donor and recipient species the greater the amount of fibrous tissue formation. Thus, for the outcome of transplantation experiments, not only the material-related biocompatibility but as well the reaction towards the whole device (consisting of the capsule plus the encapsulated tissue) are crucial. Therefore, immunoprotection does not only comprise the protection of the grafted tissue from the host immune effector mechanisms but as well the inhibition of the recognition of the graft by the host immune system.

Helminth Immunity and Vaccines in Sheep

Vaccination of domestic animal species against various parasitic helminths using attenuated parasites or nonliving parasitic material is possible. Improved prospects for vaccines composed of somatic and metabolic parasite components hinge on the isolation and characterization of helminth protective antigens and their synthesis by modern bioengineering techniques. Vaccination strategies beg an understanding of the host's immune effector mechanisms for their most efficient prolonged stimulation. Parameters of importance are antigen dose, frequency of and interval between doses, use of liposomes or other antigen delivery vehicles, and the use and choice of adjuvants.

Electrophoretic patterns of protein synthesis and turnover in apical plasma membrane and outer bilayer of Schistosoma mansoni

Polypeptide fractions labelled with [ 14C]leucine and associated with fractioned inner plasma membrane and outer bilayer (envelope) from the apical double bilayer complex of the surface epithelium of the human blood fluke, Schistosoma mansoni, were analyzed by two-dimensional electrophoresis and fluorography. In contrast to the distribution of alkaline phosphatase, the polypeptide profiles of the two bilayer fractions were similar due to cross contamination between one membrane containing larger amounts of protein (inner) and the second bilayer having more heavily labelled proteins (outer bilayer). Convincing evidence for only two of 35 polypeptides could be provided for localization to the outer bilayer. These results suggest that the marker enzyme used for the inner bilayer, alkaline phosphatase, may not be homogeneously distributed in this membrane. In pulse-chase studies a correction factor for cross-contamination was derived. The rate to turnover of the polypeptide fractions was twice as fast for the outer compared to the inner membrane, this difference being consistent with the view that multilamellar bodies are the precursors of the apical double bilayer complex. Comparing the rates of surface renewal in adult and juvenile schistosomes leads to the suggestion that membrane turnover can be correlated with susceptibility to host immune effector mechanisms.