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

The humoral immune response is the part of the adaptive immune system that involves the production of antibodies by B cells.

An antibody molecule consists of two heavy chains and two light chains, which are held together by disulfide bonds.

The CDR (complementarity-determining region) is the part of the antibody molecule that is responsible for binding to specific antigens.

The Fc region of an antibody molecule binds to Fc receptors on immune cells, which triggers various immune responses, such as phagocytosis and antibody-dependent cell-mediated cytotoxicity.

IgG is the most abundant class of antibodies in the blood, accounting for approximately 75% of all antibodies.

IgA is the primary class of antibodies found in mucosal secretions, where it helps to protect against infections at mucosal surfaces.

IgE is the class of antibodies involved in allergic reactions. It binds to allergens and triggers the release of histamine and other inflammatory mediators from mast cells and basophils.

IgM antibodies are the first antibodies produced in response to an infection. They are large, multimeric antibodies that can activate complement proteins and bind to Fc receptors on immune cells.

Memory B cells are a type of B cell that is generated during an immune response. They remain in the body after the infection has been cleared and can quickly produce antibodies upon re-exposure to the same antigen.

Active immunity is acquired when the body produces its own antibodies in response to an infection or vaccination. Passive immunity is acquired when antibodies are transferred from one individual to another, either through the placenta or through blood transfusions.

Antibodies help to distinguish between self and non-self antigens. They bind to non-self antigens and trigger an immune response, while ignoring self antigens.

Antibodies can be used in cancer immunotherapy to target and destroy cancer cells. They can be engineered to bind to specific antigens on cancer cells and deliver toxic payloads or activate the immune system against the cancer cells.

Monoclonal antibodies are antibodies produced by a single B cell clone. They are identical in structure and specificity, and they can be produced in large quantities using hybridoma technology.

Antibody-based therapies can have potential side effects, including infusion reactions, hypersensitivity reactions, and autoimmune reactions. These side effects can range from mild to severe and can vary depending on the specific antibody and the individual patient.