Correlation between structural characteristics and immunological properties of the terpolymer L-glutamic acid60-L-alanine30-L-tyrosine10

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Induction of antitumor reactive cells or suppressor cells by different molecular species isolated from the same nonimmunogenic tumor

The inability of spontaneous and some laboratory-induced tumors to stimulate the immune system has continuously raised the question of the validity of using immunological maneuvers in order to control tumor growth. In this project we suggest that a tumor which is nonimmunogenic still has an immunogenic potential that can be revealed and used in order to stimulate antitumor immunity and consequently tumor destruction. YAC, a Moloney-virus-induced tumor of A mice, failed to stimulate immunological responses. This tumor homogenate was exposed to nonreduced sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). At the end of the electrophoresis, the gels were sliced and injected in sequential order into various groups of A mice. It was found that some of the gel slices (usually with M.W. of 100 K or less) induced cytotoxic responses, whereas other gel slices (usually with M.W. of about 150 K) induced suppressor cells. Similarly, certain gel slices induced cells that inhibited the in vivo tumor growth, whereas others enhanced the in vivo tumor growth. These last two types of cells did not present the same cellular population that mediated the cellular cytotoxicity or the suppressive effects respectively. It was concluded that poorly immunogenic tumor cells do possess immunogenic potential that can be revealed after dissociation between the immunogenic and suppressogenic entities.

Immunosuppressive factor(s) specific for L-glutamic acid50-L-tyosine50. IV. In vitro activity and immunochemical properties

The responsiveness of BALB/c spleen cells to the terpolymer L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT), the copolymer of L-glutamic acid50-L-tyrosine50 (GT) and the corresponding complexes with methylated bovine serum albumin (MBSA) has been studied in vitro in a modified Mishell-Dutton culture system. Cultures of BALB/c spleen cells respond to GAT, GAT-MBSA and GT-MBSA over a wide dose range. Contrary to in vivo findings BALB/c spleen cell cultures respond to GT in vitro although in a much narrower dose range. Lymphoid extracts from GT-primed BALB/c or B10.BR mice (GT-TSF) specifically suppress the GT-MBSA response in vitro. This culture system has allowed us to further investigate immunochemical properties of both BALB/c and B10.BR GT-TSF-GT-TSF from both strains display affinity for GT-Sepharose and bear determinants encoded by the I region of the H-2 complex. Moreover, we demonstrate that the suppressive activity from B10.BR mice is a molecule or a molecular complex which displays affinity for GT and bears determinants of the I-J subregion of the H-2k haplotype.