Final answer:
Excess antibody can lead to type III hypersensitivity reactions, while excess antigen can lead to type II hypersensitivity reactions.
Step-by-step explanation:
Excess antibody or excess antigen can lead to different types of immune reactions.
In the case of excess antibody, it can result in a type III hypersensitivity reaction. This occurs when immune complexes form and deposit in tissues, leading to damage in blood vessels, heart tissue, joints, skin, and/or kidneys. The excess antibody-antigen interaction triggers complement activation, an inflammatory response, and the recruitment and activation of neutrophils, all of which contribute to tissue damage.
In the case of excess antigen, it can result in a type II hypersensitivity reaction. This type of reaction involves IgG and IgM antibodies binding to cell-surface antigens or matrix-associated antigens, leading to the activation of complement and an inflammatory response that can result in cell lysis or antibody-dependent cell-mediated cytotoxicity (ADCC).