How Do Monoclonal Antibodies Work?

Reviewed on 6/7/2022


Monoclonal antibodies are a class of drugs used to treat inflammatory autoimmune disorders (conditions in which the immune system attacks the healthy parts of the body and causes pain, swelling, and damage), skin disorders, certain types of arthritis (such as rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, and ankylosing spondylitis), and various cancers (chronic lymphocytic leukemia, Hodgkin’s lymphoma, and melanoma). The immune system is a complex network of cells, tissues, and organs. Together, they help the body to fight infections and diseases, and one of its primary functions is to detect and destroy the disease-causing agents, such as bacteria and viruses, and eliminate damaged or abnormal cells, such as cancer cells. The immune system recognizes an antigen (substances it sees as harmful or foreign) and produces antibodies (proteins that work to attack, weaken, and destroy antigens) that bind to the antigen and serves as a flag to attract disease-fighting molecules or as a trigger promoting cell destruction by other immune system processes.

Monoclonal antibodies are laboratory-produced molecules to serve as substitute antibodies that can restore, enhance, or mimic the immune system’s attack on cancer cells.

Monoclonal antibodies are prescription-only medicines and are available as a powder to be mixed with sterile water and administered intravenously (through a vein) in a prefilled syringe and as a solution (liquid) to inject subcutaneously (under the skin).

Monoclonal antibodies work in the following ways:

  • Flagging cancer cells: cancer cells that are coated in monoclonal antibodies may be more easily detected and targeted for destruction.
  • Triggering cell membrane destruction: monoclonal antibodies can trigger an immune system response that can destroy the outer wall (membrane) of a cancer cell.
  • Blocking cell growth: they block the connection between a cancer cell and proteins that promote cell growth—an activity that is necessary for tumor growth and survival.
  • Preventing blood vessel growth: a cancerous tissue needs blood supply to survive; they block the protein-cell interactions necessary for the development of new blood vessels.
  • Blocking immune system inhibitors: they bind to certain proteins which provide the cancer-fighting cells an opportunity to work with less inhibition.
  • Directly attacking cancer cells: they may attack the cell directly, leading to a series of events inside the cell that may cause it to self-destruct.
  • They block the inflammatory protein interleukin-6, which improves joint pain and swelling in arthritis and other symptoms caused by inflammation.
  • They slow down the body's defense system to prevent the body from rejecting the new organ after surgery (acute rejection).
  • In addition, they work by blocking the action of tumor necrosis factor, a protein in the body that causes inflammation and damage in arthritis and red scaly patches in psoriasis.


Monoclonal antibodies are used in conditions such as:

  • Rheumatoid arthritis (a condition in which the body attacks its own joints, causing pain, swelling, and loss of function)
  • Juvenile idiopathic arthritis (a condition that affects children in which the body attacks its own joints, causing pain, swelling, and loss of function and delays growth and development in children aged 2 years and older)
  • Psoriatic arthritis (a condition that causes joint pain and swelling and scales on the skin)
  • Ankylosing spondylitis (a condition in which the body attacks the joints of the spine and other areas causing pain and joint damage)
  • Plaque psoriasis (a skin disease in which red, scaly patches form on some areas of the body) 
  • Crohn’s disease (a condition in which the body attacks the lining of the digestive tract, causing pain, diarrhea, weight loss, and fever)
  • Ulcerative colitis (a condition that causes swelling and sores in the lining of the colon [large intestine] and rectum)
  • Hidradenitis suppurativa (a skin disease that causes pimple-like bumps in the armpits, groin, and anal area) 
  • Uveitis (swelling and inflammation of different areas of the eye)
  • Giant cell arteritis (an inflammation of the lining of the arteries)
  • Ebola virus infection
  • Behcet's disease (a rare disorder that causes blood vessel inflammation throughout the body)
  • Interstitial lung disease (a lung disease involving chronic inflammation of the lungs)
  • Idiopathic pulmonary fibrosis (a lung disease that results in scarring [fibrosis] of the lungs for an unknown reason)
  • Cytokine release syndrome (an acute systemic inflammatory syndrome characterized by fever and multiple organ dysfunction)
  • Cryopyrin-associated periodic syndrome (a group of illnesses related to defects in the protein “cryopyrin”)
  • Paroxysmal nocturnal hemoglobinuria (a rare blood disease that causes red blood cells to break apart)
  • Hemolytic uremic syndrome (a condition that can occur when the small blood vessels in your kidneys become damaged and inflamed)
  • Neuromyelitis optica spectrum disorder (a rare, autoimmune disease of the central nervous system that primarily attacks the optic nerves and spinal cord leading to blindness and paralysis)
  • Myasthenia gravis (a rare neuromuscular disorder that causes weakness in the skeletal muscles—the muscles used for movement)
  • Hemophilia A (an inherited bleeding disorder in which the blood does not clot properly)
  • Multiple sclerosis (a potentially disabling disease of the brain and spinal cord)
  • Follicular lymphoma (cancer that affects white blood cells called lymphocytes)
  • Diffuse large B-cell lymphoma (cancer that starts in white blood cells called lymphocytes)
  • Chronic lymphocytic leukemia (a type of cancer of the blood and bone marrow)
  • Clostridium difficile infection (a type of bacteria that can cause colitis, a serious inflammation of the colon)
  • Thrombotic thrombocytopenia purpura (a rare blood disorder characterized by clotting in small blood vessels [thrombosis], resulting in a low platelet count)
  • Familial Mediterranean fever (an inherited disorder manifested by episodic fevers, often with pain in the abdomen, joints, or chest)
  • Still’s disease (a rare type of inflammatory arthritis that features fevers, rash, and joint pain)
  • Tumor necrosis factor receptor-associated periodic syndrome (an inherited condition characterized by recurrent episodes of fever)
  • Hyperimmunoglobulin D syndrome/Mevalonate kinase deficiency (a rare genetic disorder characterized by recurrent febrile episodes typically associated with lymphadenopathy, abdominal pain, and elevated serum polyclonal immunoglobulin D levels)
  • Nonradiographic axial spondyloarthritis (a type of inflammatory arthritis that mainly affects the joints in the spine)
  • Graft versus host disease (a syndrome, characterized by inflammation in different organs after a transplant)
  • Prophylaxis in transplants of organs such as:
    • Kidney 
    • Heart
    • Liver
    • Lungs

Other potential uses for monoclonal antibodies being studied and are pending for Food and Drug Administration approval include:


Common side effects include:

  • Headache
  • Nausea
  • Vomiting
  • Joint pain
  • Tiredness
  • Runny/stuffed nose
  • Irritation, redness, or pain at the injection site 
  • Diarrhea
  • Sore throat
  • Loss of appetite
  • Constipation
  • Pyrexia
  • Abdominal pain
  • Weakness
  • Cough
  • Anxiety

Other rare side effects include:

  • Confusion
  • Vision changes
  • Severe stomach/abdominal pain.
  • Seizures
  • Swelling of the face, eyelids, tongue, or throat
  • Rash
  • Itching
  • Hives
  • Difficulty breathing
  • Tightness in the chest or throat
  • Muscle cramps
  • Unusual bruising or bleeding
  • Dizziness
  • Tachycardia
  • Hypotension
  • Upper respiratory tract infection 
  • Increased creatine phosphokinase
  • Hypoxia
  • Arthralgia
  • Elevated liver enzymes
  • Leukopenia
  • Hypoglycemia 
  • Thrombocytopenia

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.


Generic and brand names of monoclonal antibodies include:


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