The antigen- antibody interaction is bimolecular irreversible association between antigen and antibody. The association between antigen and antibody includes various non-covalent interactions between epitope (antigenic determinant) and variable region (VH/VL) domain of antibody in a similar manner to that in which proteins bind to their cellular receptors, or enzymes bind to their substrates.
Macrophages are specialized cells involved in detection, phagocytosis and destruction of bacteria. Macrophages, widely distributed in organs and connective tissue plays central roles in innate and adaptive immunity. In addition to ingesting microbes, macrophages also ingest dead host cells, including cells that die in tissues because of trauma or interrupted blood supply and neutrophils that accumulate at sites of infection.
Direct immunofluorescence test is used to detect unknown antigen in a cell or tissue by employing a known labeled antibody that interacts directly with unknown antigen. If antigen is present, it reacts with labeled antibody and the antibody coated antigen is observed under UV light of fluorescence microscope
T lymphocytes can be divided into : effector, memory, and regulatory cells. Each type performs a distinct function during an immune response to foreign antigens. Effectors cells include helper T cells and Cytotoxic T cells.
These are differentiated by the expression of unique cell surface markers, such as CD4 for helper T cells and CD8 for cytotoxic T cells.
Neutralization tests are performed in vitro at cellular level including cells in the form of organs and at sub-cellular level. They assess efficacy of antibody fragments, or antibodies, to inhibit critical stages of activities which are generally deleterious to humans. These tests mostly employed to viruses and toxins.
Toxin neutralization tests are based on the principle that biological action of toxin is neutralized on reacting with specific neutralizing antibodies called antitoxins.
Virus neutralization Tests are serological tests to detect presence and magnitude of functional systemic antibodies (Monoclonal and polyclonal) that prevent infectivity of a virus. E.g. viral hemagglutination inhibition test. Neutralization of a virus is defined as loss of infectivity through reaction of virus with specific antibody i.e. neutralization of viruses by their specific antibodies are called virus neutralization tests.
Virus Neutralization Tests can be reversible neutralization or stable neutralization.
Neutralization tests are performed in vitro at cellular level including cells in the form of organs and at sub-cellular level. When a neutralizing antibody defends a cell from an antigen or infectious body by neutralizing any biological effect, it is termed “neutralization”.
In diagnostic immunology and virology laboratories, evaluation of neutralizing antibodies, which destroy the infectivity of viruses, can be measured by neutralization method.