Understanding Artificial Immunity and Immune System Disorders

Artificial Immunity

Artificial immunity involves administering substances to help the body overcome pathogenic infections.

a) Active Immunity or Vaccination

This involves the administration of a preparation (vaccine) containing specific antigens that trigger a primary immune response, providing protection against disease. Pathogens are often inactivated or weakened, or toxins are neutralized. To avoid dangerous reactions, modern vaccines are made with pure surface proteins or antigens. Vaccination is a highly effective preventive measure, though its effects vary in duration. It is not effective once the body is already infected.

b) Passive Immunity or Serum Therapy

This involves the injection of purified antibodies. It is used when an infection is suspected and harmful effects could occur rapidly, such as in cases of tetanus or venomous bites. It has a short-term curative effect, but because the antibodies are of foreign origin, the organism may react against them.

Abnormalities of the Immune System

During development, the immune system learns to distinguish "self" from "non-self." Tolerance is the recognition of the body's own tissues, which requires immunological education, primarily in the thymus during fetal life.

• Immunodeficiency: A lack of tolerance or an inability to defend the body.
• Autoimmunity: A failure of tolerance where the organism reacts against itself.

Autoimmunity

This occurs when tolerance of B or T lymphocytes toward the body's own cells disappears. Examples include myasthenia gravis and rheumatoid arthritis.

Immunodeficiency

This occurs when the immune response is ineffective:

• Primary or Congenital: Caused by genetic factors affecting the immune system (e.g., "bubble kids").
• Acquired: Appears at any time in life due to factors like viral infections (AIDS) or medical treatments such as radiotherapy.

Allergies

Allergies are an overreaction against harmless substances or weak antigens, known as allergens (e.g., pollen, dust mites). They can cause rhinitis, asthma, or urticaria. The most severe form is systemic or widespread, known as anaphylactic shock. This leads to widespread dilation of blood capillaries, a sudden drop in blood pressure, and constriction of the airways.

Transplants

Transplants involve replacing damaged organs. Rejection is the immune response developed by the recipient's body upon recognizing foreign tissue from the donor. Rejection always occurs and involves T cells, unless the donor and recipient are genetically identical. To avoid rejection, histocompatibility testing is performed, and the immune response is suppressed using medication.