Neutralizing Antibodies Research Paper

 Briefly describe the four categories of antibody effector functions.
One of the several means of protection of the body against pathogens is the activation of B cells and their generation of antibodies. These antibodies can be involved in four main functions: neutralization, opsonization, complement fixation and mediation of cytotoxicity. Neutralizing antibodies are the ones that block pathogens from gaining access to the cell by binding to receptors that the pathogen uses for this purpose. In other words, certain viruses like HIV and influenza express specific proteins that are meant to bind cell surface receptors in order to induce endocytosis and cause infection. The role of neutralizing antibodies is to bind those proteins and block the viruses from binding to and thus infecting the cell. Following this same binding pattern, neutralizing antibodies can also prevent toxins from getting inside the cell. Antibody pathogen complexes are then deteriorated through phagocytosis.
When it comes opsonization, antibodies surround the antigen and then interact with phagocytic cells of the innate immune system including, macrophages and neutrophils,
through the Fc receptors. This binding of macrophages (or neutrophils) to the antibody allows then the destruction of the pathogens through phagocytosis.
In complement fixation, specific antibodies (some IgGs and IgMs) bind the surface of the pathogens and then induce a complement cascade that ends with generating the membrane attack complex (MAC). Those last component of the complement cascade are then involved in the killing and destruction of the pathogen that was initially bound to the antibody through phagocytosis or lysis.
Antibodies can also bind Natural Killer cells through their Fc receptor and thus provide these cells with antigen specificity. Therefore, whole the Fc part of the antibody is bound to receptors on NK cells, the Fab parts are linked to an infected or tumor cell, and that is how antibodies mediated cytotoxicity through the recruitment of NK cells and their ability to induce apoptosis.
 What is the limitation of monoclonal antibodies in the treatment of cancer?
One of the limitation of mAbs based therapies is the biological efficacy, selectivity and affinity of these antibodies.
Although they are good at targeting only tumor cells and not healthy cells, different cancer cell types might have different antigens and so the same antibody would not necessarily be effective and selective to all of those types. Additionally, tumor cells are known for their high mutation characteristic; thus, there would be a need to develop new antibodies depending on the change of antigen due to mutation, which is hard to track at the molecular level. Additionally, immunotherapies are currently used as a last resort, after surgery and chemotherapy. This means that the immune system is already damaged by these first methods, which gives immunotherapy less of a chance to be biologically
effective.