Final answer:
Antigens can trigger an immune response and include substances such as pollen proteins, egg white proteins, blood cell surface molecules, serum proteins, and foreign tissue proteins. Antibodies produced by the immune system bind to these antigens, which can result in reactions such as allergies or organ rejection. The immune system's tolerance helps to prevent responses to non-threatening antigens.
Step-by-step explanation:
Examples of Antigens Triggering Immune Responses
An antigen is a substance that the immune system does not recognize as part of the body, known as "non-self," which triggers a defense response. Examples of antigens that can initiate an immune response include those found in pollen, specifically pollen proteins, which often cause allergic reactions. Proteins in egg whites, such as ovalbumin, can behave as antigens and induce allergies in some individuals. The surface molecules of blood cells, known as blood group antigens like A, B, or Rh factors, can elicit an immune response during incompatible blood transfusions. Certain serum proteins act as antigens when introduced into a different individual, potentially leading to a reaction. Lastly, foreign tissues, such as those in transplanted organs, contain antigens that can be recognized by the recipient's immune system, potentially resulting in organ rejection.
Antibodies, also known as immunoglobulins, produced by plasma cells, are crucial for immune responses as they attach to antigens and can cause foreign cells, such as bacteria or mismatched erythrocytes during a transfusion, to clump together or be targeted for destruction.
The immune system's capability to distinguish between harmful and harmless antigens, and thus avoid reactions against "self" antigens or non-threatening substances like food proteins, is a process called tolerance. This discrimination is vital as it prevents unnecessary and potentially harmful immune responses towards the body's own tissues or benign environmental substances.