Antibodies are proteins produced by the immune system to recognize and neutralize pathogens, such as bacteria, viruses, and toxins.

IgM is the first antibody produced in response to an infection. It is a large antibody that is effective in neutralizing pathogens.

IgG antibodies are the most abundant type of antibody in the blood. They provide long-term immunity by binding to pathogens and preventing them from infecting cells.

IgA antibodies are found in mucosal secretions, such as saliva, tears, and breast milk. They protect mucosal surfaces from infection by binding to pathogens and preventing them from attaching to cells.

IgE antibodies are involved in allergic reactions. They bind to allergens and trigger the release of histamine and other inflammatory mediators, which cause allergy symptoms.

IgM antibodies are able to activate complement proteins, which are a group of proteins that work together to destroy pathogens.

IgD antibodies are found on the surface of B cells and help to activate B cells when they encounter an antigen.

IgG antibodies can cross the placenta from the mother to the fetus, providing the newborn with passive immunity against infections.

Vaccination works by introducing a weakened or inactivated form of a pathogen into the body. This allows the immune system to produce antibodies against the pathogen without causing disease. This provides active immunity, which means that the body is able to protect itself from future infection by the same pathogen.

Rh incompatibility can occur when a pregnant woman is Rh-negative and the fetus is Rh-positive. IgG antibodies can be given to the mother to prevent Rh incompatibility. These antibodies bind to Rh-positive fetal red blood cells and prevent them from crossing the placenta and causing an immune response in the mother.

Monoclonal antibodies are produced by a single clone of B cells, which means that they are all identical. This makes them more specific and effective than polyclonal antibodies, which are produced by multiple clones of B cells and are therefore more heterogeneous.

Antibody-drug conjugates (ADCs) are composed of a monoclonal antibody linked to a cytotoxic drug. The monoclonal antibody targets the cancer cells, while the cytotoxic drug kills the cancer cells.

In autoimmune diseases, the immune system produces antibodies that attack the body's own tissues. This can lead to inflammation and damage to various organs and tissues.

Passive immunotherapy involves the administration of antibodies to provide immediate protection against an infection or disease. Monoclonal antibodies are often used in passive immunotherapy because they are highly specific and effective.

In antibody-dependent cell-mediated cytotoxicity (ADCC), antibodies bind to target cells and activate natural killer cells to kill the target cells. This is an important mechanism for the immune system to eliminate infected cells and cancer cells.