Final answer:
The effector mechanisms of antibody-mediated diseases often involve the activation of downstream signaling pathways when antibodies stimulate a receptor without the hormone. This can lead to various physiological responses and is a critical component of the immune system's defense.
Step-by-step explanation:
Effector Mechanisms of Antibody-Mediated Diseases
Antibodies, or immunoglobulins, play a critical role in the immune system's ability to combat infections. The effector mechanisms of antibody-mediated diseases typically involve antibodies that stimulate a receptor without the presence of the hormone normally required for activation. In this context, the correct answer for how the antibody stimulates the receptor would be B) Activation of downstream signaling pathways. When antibodies bind to a receptor, they mimic the action of the natural hormone and subsequently trigger the activation of pathways within the cell that can lead to various physiological responses. This can happen with endocrine-related antibodies, where the target is usually a hormone receptor.
Additionally, antibodies can inhibit infections by preventing antigens from binding to their targets, tagging pathogens for destruction by macrophages and neutrophils, or activating the complement cascade. Neutralizing antibodies, such as those stimulated by vaccines, bind to key sites on pathogens, enhancing their infectivity and preventing progression of an established infection.