ABSTRACT
Tamoxifen citrate, a non-steroidal anti-oestrogen has potential applications in treatment of breast cancer. Biodegradable microspheres of' PLGA 65:35 were prepared by o/w emulsification solvent evaporation method. In this study, different batches of varying concentration of drug, polymer, polyvinyl alcohol and solvent were prepared. All the batches prepared were characterized by particle size distribution, encapsulation efficiency and in vitro release behaviour. Drug, polymer and PVA concentrations were varied to obtain optimum release profile for sustaining the action of drug.
Subject(s)
Estrogen Antagonists , Lactic Acid , Microspheres , Polyglycolic Acid , Polymers , Tamoxifen , Biocompatible Materials , Biodegradation, Environmental , Delayed-Action Preparations , Drug Compounding/methods , Emulsifying Agents , Microscopy, Electron, Scanning/methods , Particle Size , Polylactic Acid-Polyglycolic Acid Copolymer , Polyvinyl Alcohol , Solubility , Solvents , Surface PropertiesABSTRACT
The effects of free and encapsulated allergens of Artemisia scoparia pollen on lymphocyte proliferation and immunoglobulin production in BALB/c mice were investigated. Splenic lymphocytes from mice immunized with liposome entrapped allergen (LEA) elicited a marked proliferative response upon in vitro stimulation with both free and encapsulated allergen in comparison to mice immunized with free allergen (FA). The serum immunoglobulin profile of mice administered LEA revealed a predominance of IgG1 antibodies concomitant with an enhancement of IgG2a, IgG2b, IgG3 and IgM responses and suppression of IgE responses. However immunization with FA resulted in significant production of IgE responses and low levels of IgG antibodies. The differential ability of free and encapsulated allergens to selectively induce immunoglobulin isotypes suggests that different presentation and T cell differentiation pathways may be followed by FA and LEA in the immune system. Proliferation studies involving macrophage depletion demonstrated that macrophages play an obligatory role in the processing of LEA. Analysis of cytokine production in sera of immunized mice (FA/LEA) revealed that LEA induced significant IFN-gamma responses and lower IL-4 responses than mice immunized with FA. The results of the present study indicate that liposomes synergise the proliferation by the antigen incorporated in it and polarizes the response towards Th1 type of cytokine production. The immunoadjuvant and immunomodulation property of liposomes make it an efficient vehicle for effective immunotherapy.
Subject(s)
Liposomes/immunology , Lymphocytes/immunology , Spleen/immunology , Allergens/administration & dosage , Allergens/immunology , Animals , Artemisia , Cell Division/immunology , Cells, Cultured , Cytokines/biosynthesis , Cytokines/blood , Dose-Response Relationship, Immunologic , Injections, Intraperitoneal , Injections, Intravenous , Injections, Subcutaneous , Macrophages/immunology , Mice , Mice, Inbred BALB C , Plants, Medicinal , Pollen/immunology , Spleen/cytology , T-Lymphocyte Subsets/immunologyABSTRACT
BACKGROUND: The conventional immunotherapy used for treating allergic individuals may at times lead to varying degrees of anaphylactic reaction. Liposomes have been proposed as a vehicle for safe and effective allergen-specific immunotherapy as multiple injections of liposome-entrapped allergen (LEA) have been shown to reduce specific IgE response and induce specific IgG response in BALB/c mice. OBJECTIVE AND METHODS: To elucidate the effect of LEA on polarization of T-cell responses, its effect on the relative production of TH1/TH2 type cytokines (namely IL-2, IL-4 and IFN-gamma by commercially available ELISA kits and immunoglobulin profile as measured by ELISA) were studied. Histamine release on challenge of immunized mice was measured to examine the efficacy of LEA in preventing anaphylactic reactions. RESULTS: Measurement of cytokine levels in serum and spleen cell culture supernatants of BALB/c mice injected repeatedly with either free allergen (FA) or LEA (three mice per group) indicate that LEA preferentially induces a TH1-type of response dominated by IFN-gamma and IL-2 production. Further, it was also shown that immunization of mice with FA or LEA and subsequent challenge with a large dose of the sensitizing allergen leads to fatal systemic reactions in 50-65% of the animals treated with FA, whereas no mortality was observed in mice injected with LEA. Analysis of IgG subclasses in sera of mice immunized with LEA revealed a sixfold higher production of IgG1 antibodies than mice immunized with FA. Serum IgG2a, IgG2b, IgG3 and IgM responses were also enhanced in the group of mice immunized with LEA in comparison with mice injected with FA. CONCLUSION: The results indicate that LEA confers protection against anaphylaxis to mice due to their ability to induce a high IFN-gamma:IL-4 ratio which may lead to decreased synthesis of IgE and reduced histamine release on challenge with FA.