Immunoglobulin structure and function: the interaction between antibody and antigen

An approach towards development of monoclonal IgY antibodies against SARS CoV-2 spike protein (S) using phage display method: A review

The present state of diagnostic and therapeutic developmental race for vaccines against the SARS CoV-2 (nCOVID-19) focuses on prevention and control of this global pandemic which also represents a critical challenge to the global health community. Although development of novel vaccines can prevent the SARS CoV-2 infections, it is still impeded by several other factors and therefore novel approaches towards treatment and management of this disease is the urgent need. Passive immunotherapy plays a vital role as a possible alternative to meet this challenge and among various antibody sources, chicken egg yolk antibodies (IgY) can be used as an alternative to mammalian antibodies which have been previously studied against SARS CoV outbreak in China. In this review, we discuss the strategies for the use of chicken egg yolk (IgY) antibodies in the development of rapid diagnosis and immunotherapy against SARS CoV-2. Also, IgY antibodies have previously been used against various respiratory bacterial and viral infections in humans and animals. Compared to mammalian antibodies (IgG), chicken egg yolk antibodies (IgY) have greater binding affinity to specific antigens, ease of extraction and lower production costs, hence possessing remarkable pathogen-neutralizing activity of pathogens in respiratory and lungs. We provide an overall importance for the use of monoclonal chicken egg yolk antibodies (IgY) using phage display method describing their potential passive immunotherapeutic application for the treatment and prevention of SARS CoV-2 infection which is simple, fast and safe way of approach for treating patients effectively.

Anabolic androgenic steroids effects on the immune system: a review

Androgenic anabolic steroids (AAS) are synthetic derivatives of the male hormone testosterone. AAS are used by athletes and recreational users of all ages to enhance their athletic performance and/or physical appearance. While several adverse effects of AAS abuse have been described, their effect on the immune system has not been clearly elucidated. The literature generally indicates that supraphysiologic doses of AAS with an intact steroid nucleus are immunosuppressive, that is they reduce immune cell number and function. While those with alterations to the steroid nucleus are immunostimulatory as they induce the proliferation of T cells and other immune cells. Specifically, several common AAS have been shown to adversely influence lymphocyte differentiation and proliferation, antibody production, Natural Killer Cytotoxic activity and the production of certain cytokines, thereby altering the immune reaction. These effects may be profound and long lasting depending on the dosing regime, types or combinations of AAS used and the extent and duration of AAS abuse. Nevertheless, the effects of long term use of supraphysiologic doses of AAS on the immune system remain uncertain.

Monoclonal antibodies as targeted therapy in hematologic malignancies in older adults

BACKGROUND

Biological agents are proving to be increasingly useful and exciting additions to the antineoplastic armamentarium, but many clinicians are unfamiliar with the properties of these types of agents.

OBJECTIVES

This review focuses on monoclonal antibodies (MAbs) that are used in the treatment of hematologic malignancies. Our goal was to provide the reader with information on trials that led to US Food and Drug Administration (FDA) approval of commonly used MAbs in hematologic malignancies, including their mechanisms of action and pharmacokinetics, with specific emphasis on use in elderly patients; we also present data on toxicities and precautions to be aware of when administering these drugs.

METHODS

Materials for this review were gathered based on a computerized literature search (English-language articles only) using the PubMed database covering the period January 1998 to December 2005. Search terms used included the following: elderly, monoclonal antibodies, and neoplasms.

RESULTS

Alemtuzumab is a recombinant DNA-derived, humanized MAb directed against the CD52 B-cell antigen. It is indicated for the treatment of B-cell chronic lymphocytic leukemia (CLL) in patients who have been treated with alkylating agents and who have failed to respond to fludarabine therapy. Gemtuzumab ozogamicin is an MAb conjugated with a cytotoxic antitumor antibiotic, calicheamicin. It has been approved for use in patients with CD33-positive acute myeloid leukemia (AML) in first relapse who are aged > or =60 years and who are not considered candidates for other cytotoxic chemotherapy. Rituximab, one of the first MAbs approved by the FDA for use in human cancers, is an antibody directed against the CD20 antigen found on the surface of normal and malignant B lymphocytes. It is extensively used in the treatment of B-cell malignancies, such as CLL, and non-Hodgkin's lymphomas (NHLs), such as follicular lymphoma and diffuse large B-cell lymphoma.

CONCLUSIONS

It is noteworthy that while there have been a number of studies using these agents in the younger population, there continues to be a paucity of clinical trials targeting the elderly patient in particular; this continues to be an area of research interest. More clinical studies of these agents--conducted specifically in elderly patients with CLL, NHL, AML, and other hematologic malignancies--are needed.

Effect of three elution buffers on the recovery and structure of monoclonal antibodies

Antibodies are routinely purified by acid/salt elution from antigen affinity columns. The antibodies recovered with this procedure are active, but the recovery of protein is often low. We investigated the effect of acid and other denaturing or chaotropic solvents on the conformation of monoclonal antibodies (mAbs) made against the extracellular region of Her2 receptor (sHer2) derived from Chinese hamster ovary cells. The mAb remain almost completely folded in the 0.1 M glycine, pH 2.9, commonly used for elution, with the beta-sheet secondary structure intact, and only very small changes detected in the environment of the tryptophans. In 7 M urea, 50 mM NaAc pH 4.0, the antibody was partially unfolded, with the Trp environment further perturbed and some of the beta-sheet structure converted to disordered structure. In 6 M guanidine HCl, 50 mM NaAc, pH 4.0, the antibody is completely unfolded, with no secondary or tertiary structure present. The antibodies exposed to glycine or urea were refolded by dialysis into phosphate-buffered saline (PBS), while the guanidine HCl-denatured antibodies were refolded by dialysis into 7 M urea, pH 4.0, followed by dialysis into PBS. The refolded antibodies were capable of forming antigen-antibody complexes which could be isolated by gel filtration chromatography. Two different mAbs were subjected to immunoaffinity chromatography on sHer2-Sepharose. mAb86 was eluted by 0.1 M Gly, pH 2.9, while mAb52 was eluted with the 7 M urea, 50 mM NaAc, pH 4.0. The isolated antibodies were refolded by dialysis into PBS, analyzed for their ability to recognize native sHer2 by immunoprecipitation, and denatured sHer2 by Western blot analysis. Both preparations recognized the native protein, but precipitated slightly different forms of sHer2, indicating that they might recognize different epitopes. The mAb52 is a more sensitive reagent for Western blot analysis. Thus, this procedure can be used to recover antibodies which would not be recovered with glycine as the only eluate. It is also possible that the antibodies can be fractionated by the different eluants into populations which can be used for different applications.

Conformational study of a peptide epitope shows large preferences for beta-turn conformations

The conformational preferences of the 7-residue peptide Glu-Val-Val-Pro-His-Lys-Lys was investigated using a global search algorithm, namely the Electrostatically Driven Monte Carlo (EDMC) method, and the ECEPP/2 potential energy function. This particular sequence corresponds to the N-terminal portion of a 19-residue peptide antigen whose three dimensional structure, when complexed to a cognate antibody, was reported recently. As a result of this study a series of low-energy conformations were identified showing a common folding pattern with residues Val-3, Pro-4, His-5 and Lys-6 forming a beta turn. A comparison of the computed conformations with the one determined by X-ray crystallography in the antibody-antigen complex reveals marked similarities. In most of the cases rms deviations smaller than 1.1 A were found for the backbone atoms of the four residues forming the turn. These results suggest that the recognition process is accomplished in this case through the interaction of the antibody with relatively stable conformers of the antigenic peptide.