Which of the following diseases is an example of Type II hypersensitivity?

Type II hypersensitivity reactions are characterized by the immune system producing antibodies against specific antigens on the surface of cells, which leads to cell destruction or dysfunction. This type of hypersensitivity is mediated by immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies and often involves complement activation, resulting in inflammation or lysis of the target cells.

A classic example of Type II hypersensitivity is a transfusion reaction. In this scenario, if a person receives blood containing antigens that their immune system recognizes as foreign (such as A or B antigens in the context of ABO blood typing), their pre-existing antibodies can bind to these antigens. This leads to the activation of the complement system, which results in the destruction of the transfused red blood cells and can cause serious complications like hemolytic anemia.

In contrast, Hashimoto's thyroiditis is an example of a Type IV hypersensitivity reaction, where T-cell mediated immune responses lead to thyroid gland damage. Steven-Johnson syndrome is an instance of a severe adverse reaction that is typically classified as Type IV hypersensitivity as well, linked to drug reactions and mediated by T cells. Hay fever, or allergic rhinitis, is primarily a Type I hypersensitivity reaction that